GB2530254A

GB2530254A - X-Ray system

Info

Publication number: GB2530254A
Application number: GB1416189.7A
Authority: GB
Inventors: Gary Lock
Original assignee: XSTRAHL Ltd
Current assignee: XSTRAHL Ltd
Priority date: 2014-09-12
Filing date: 2014-09-12
Publication date: 2016-03-23
Also published as: WO2016038366A1; GB201416189D0

Abstract

An X-ray generator 100 with an end-window X-ray tube 110 has: an X-ray target 120 adjacent to the end-window within the tube; a tube housing 112 to receive a removable X-ray filter 140; a fitting for a transparent conical removable applicator 160; one or more collimator(s) (primary 130 and secondary 150) between the X-ray tube and the surface to be treated, the collimator(s) having an aperture and an absorbing portion; a moveable support arm for supporting the X-ray tube; a means to cool the X-ray tube and a power supply. The generator may have an LED lighting ring (170, figure 2) for illuminating a treatment field. Preferably the X-ray beam has a beam angle of at least 35 degrees. The X-ray filter may have a filtering region of non-uniform thickness. Validation logic may prevent incorrect or unsafe use of the generator. The generator may incorporate multiple cameras for providing 3D imaging of the skin surface.

Description

Intellectual Property Office Application No. GB1416189.7 RTI\4 Date:24 April 20t5 The following terms are registered trade marks and should be read as such wherever they occur in this document: Varian (page 36) Comet (page 36) Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo

X-RAY SYSTEM

FIELD OF THE INVENTION

The present invention relates to X-ray systems. More particularly, but not exclusively, the present invention relates to an X-ray apparatus for delivering X-ray radiotherapy for superficial therapy and for the treatment of skin conditions.

BACKGROUND OF THE INVENTION

X-rays can be used for analytical applications, such as imaging the skin and/or bones. X-rays are also used for non-medical applications where the dosage and reliability are less critical, but such systems cannot be used for medical applications without alteration.

Humans can develop certain skin conditions, which it is desirable to treat. The face, neck and hands are particularly vulnerable in such cases, since they are normally exposed to the sun more frequently and for longer than other parts of the body.

X-ray radiation can be used as an alternative to, or in conjunction with, surgery for treating conditions at or near the surface of the skin, for example, malignant or benign skin cancers or superficial skin lesions (e.g. scars). Some conditions (e.g. malignant skin cancers) may pose a risk to patient health, as they could spread to cause cancers throughout the body. Some conditions can cause discomfort, and others are merely disfiguring. X-ray treatment is relatively painless and can pose fewer risks to patients than surgery. X-ray treatment can be less disfiguring than surgery as it does not cause scarring, which can be particularly advantageous on visible areas of the body, such as the face and neck.

Conventional medical X-ray systems typically use side-window X-ray tubes and require a high power input and are bulky. There have also been some proposals to use smaller end-window X-ray tubes for producing a small beam diameter for treating particularly e.g. rectal conditions, using a small insertion area and beam application.

However, since medical X-ray apparatus has traditionally been expensive and bulky, requiring a large shielded room and large power sources, the use of such therapies is limited.

SUMMARY OF THE INVENTION

Aspects of the invention are set out in the independent claims and preferred features are set out in the dependent claims.

An aspect of the present invention seeks to provide an improved radiotherapy X-ray apparatus for delivering a sufficient X-ray dose across a suitable field size particularly suitable for skin application or a surface on or within the patient's body.

However, the use of X-ray systems described herein are not limited to skin, and may for example be used for providing X-ray treatment for the eye, optic nerve, tongue, breast (e.g. following lumpectomy or mastectomy), lips or mouth (intra-oral). The apparatus may be more compact, lightweight and/or run at a lower input power than previous apparatus.

In addition to surgical and medical treatment, we have found that low energy X-rays can be used in cosmetic procedures to alleviate superficial pigmentation variation caused by non-malignant melanomas. Moreover, by providing a potentially "wide" field and short treatment distance, large skin areas can be treated with lower power, with less irradiation of tissue and lesser shielding requirements.

According to a first aspect there is described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 350; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of the one or more collimator(s) allows through an X-ray beam with a beam angle of at least 35° in at least one plane; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; and at least one removable filter having a filtering region with a non-uniform thickness for adjusting the X-ray beam intensity profile based on the X-ray beam profile from the X-ray tube; wherein the filter is arranged for use with at least one applicator.

We have found that surprisingly a combination of wide beam angle with an end-window tube and provision for a replaceable filter and applicator can allow reliable medical or cosmetic grade treatment of skin lesions in particular with lower power sources and less shielding, making said therapies more widely useful. Using a wider beam angle means a relatively large skin surface can be treated even at a short focus to skin distance (FSD). Moreover, particularly with skin treatment, using a lower power and a shorter FSD means that the effect of X-rays in underlying tissue is dramatically reduced. At short FSDs the problem of non-uniform beam intensity across wide beam angles is exacerbated and we have found that by providing non-uniform filters it is possible to compensate for the non-uniform intensity of the beam and produce an X-ray beam with an intensity suitable for clinical applications. By providing a removable filter and applicator along with validation logic for validating allowable combinations of filters and applicators with X-ray beam power levels, it is possible to offer flexible treatments, using wide beam angles and low power over a large treatment surface, and which are safe and reliable.

An X-ray beam with a full angle of at least 35° has a half angle width, measured from the normal to the end-window of the X-ray tube (i.e. the axis of the X-ray tube), of 17.5°. Beam angles of at least 50° (or ±25° from the normal to the X-ray window), preferably of at least 60° (or ±30°) or even of at least 700 (or ±35°) are preferred. By providing an X-ray target close to the end-window of the X-ray tube, it may be possible to obtain X-rays from a very wide beam angle (e.g. up to 80° or ±40°). Wide beam angles can allow a beam with a wide diameter, to treat a larger area at a shorter distance.

The width of the beam angle should be understood to refer to the full angle of the section of the beam that has a substantial intensity i.e. a clinically useful intensity, rather than the widest beam angle produced due to stray or grossly attenuated X-rays. This intensity is normally measured as a normalised intensity (i.e. intensity measured on a flat surface). Preferably a beam of substantial intensity has an intensity at the widest angle of at least 50% of the intensity at the centre of the beam (00 from the normal), more preferably the intensity at the widest angle is at least 70% of the intensity at the centre of the beam.

The beam may require collimating e.g. in order to provide a beam of a known angle, with a clean" edge. Thus at least one collimator is normally fixed in the housing between the end-window of the X-ray tube and the fitting for receiving an applicator.

A cooling means may be provided, for example air or water cooling pipes surrounding the X-ray tube. However other fluids could also be used, such as gases or oils within piping or jackets, or fans.

A power supply for the X-ray tube may be located remotely from the X-ray tube head, with e.g. a power cable running to connect to the X-ray tube head.

Working at a shorter FSD provides many advantages, such as allowing a lower power input for a given X-ray beam dose output. As an example, previous radiography systems typically have a shortest FSD working distance of at least 15 to 20cm. By taking into account the inverse square law, which states that intensity is inversely proportional to the square of the distance from the source, operating at 5cm would give a 9 times higher dose of X-rays for the same X-ray source than operating at 15cm. In the system described herein, the X-ray tube preferably has a power output of greater than SW, preferably a power rating of less than about 250W, preferably less than 150W, or more preferably less than 75W. Preferably the power output of the tube is between 25W and 75W.

When X-rays with a lower power are used, the shielding and collimation for the device can also be reduced, which further decreases the size and weight of the X-ray apparatus. Lower power devices may require less extensive safety precautions, for example a reduction in the amount of shielding required for a room in which a device is used. It may also be safe for an operator to remain in the room when low power X-ray devices are in use, rather than having to exit the room as with more powerful X-ray devices. Furthermore, less excess heat is produced when generating X-rays at lower power, so the cooling system for the X-ray generation tube can also be smaller and lighter. Smaller, lighter devices are more easily and quickly manoeuvrable for efficient patient care. It is relatively easy to transport small, lightweight devices, so it may be possible to provide treatment at patient's houses or local clinics, rather than at large, central, specially built medical centres. There are also cost advantages, in that the lower power tubes and smaller support components used, which are made of less material, often have cheaper manufacturing and/or ongoing running costs.

It is important to ensure that the X-ray beam is directed towards the X-ray treatment area, or surface, correctly, which may be accomplished be means of an applicator. One end of the applicator is attached to the end of the X-ray tube housing, and in use the opposing end should be in contact with the surface of the X-ray treatment area, allowing the X-ray beam to pass through the applicator to the X-ray treatment area.

By providing a removable applicator, a variety of interchangeable applicators can be used, which allow different X-ray beam fields to be provided for different X-ray treatment areas, depending on the size of the treatment area and the required X-ray depth penetration. The applicator may be used in combination with different second collimators and/or filters to change the composition of the X-ray beam and the X-ray field at the treatment area. For example, different applicators may be provided that channel the beam towards a larger or smaller X-ray treatment area. Different applicators may be used for X-ray treatment areas that require different working distances (FSD) between the X-ray source and X-ray treatment surface. When the applicator defines a small distance between the X-ray target and treatment surface (i.e. a working distance or FSD), a better beam quality and intensity across a larger area can be provided for the same input X-ray power compared to at larger working distances. This therefore helps reduce the size and weight of the X-ray apparatus. Preferably, the working distance or FSD defined by the applicator will be less than 10cm, less than 8cm, or more preferably less than 6cm. It has been found that a working distance of 5cm provides a suitable field size and quality for clinical requirements. However, working distances smaller than 4cm or 3cm are also possible, depending on the desired application. The working distance would normally have to be defined to be greater than 2cm, and certainly greater than 1cm due to the components (e.g. filter & collimator(s)) that are required for correct use of the device and are attached to the X-ray tube. However, at working distances of less than 3cm we have found that problems may be encountered; for example, the length of applicator visible below the X-ray tube is very short, so it is hard to accurately position the applicator. Additionally the dose variance for a 1-2mm change in FSD below 3cm is fairly large, which means more care and precision is need in the treatment. A working distance of 3-10cm is preferred.

In the preferred design both the filters and applicators are interchangeable, with the system incorporating both filter and applicator recognition, so the system can automatically detect which filter and applicator is fitted to the X-ray system. The system can then check if the correct filter and applicator is fitted for the requested treatment (i.e. the selected X-ray energy). If there is a mis-match the system can prevent a treatment from being given until this is corrected (i.e. X-ray beam generation will be disabled). This is a safety interlock to ensure the correct and selected treatment is being given to the patient (i.e. at the required field size, the required beam quality, and the required dose).

By providing a controller for allowing an X-ray energy, or power level, which has been selected (e.g. by operator selection), it is possible to provide e.g. different treatment beams. The X-ray beam energy is normally measured in kV.

The control apparatus may be located remotely from the X-ray housing, e.g. in a control box fixed to a wall of the X-ray treatment room. By positioning the control apparatus remotely from the generator, it may be possible to offer a smaller and more easily manoeuvrable X-ray generator for efficient and accurate positioning on the patient.

The control apparatus may be provided in a unit mounted on a base (e.g. a base of the generator support structure), however we have found that it is preferable to position at least a portion of the control apparatus in a separate unit. For example, this can make it easier to provide control means accessible from outside a shielded room, containing the X-ray generator.

The logic may include hardwired logic and/or software.

It has been found that an end-window X-ray apparatus with these features is particularly suitable for skin application as it allows the cross-sectional area of the beam to be relatively large, while still providing a sufficiently large dose of X-ray radiation for applying to a patient's skin from a low X-ray power input. However, the X-ray beam generated could also be used for deeper conditions, such as conditions below the surface of the skin or within body cavities, e.g. the rectum or vagina. The system may also, for example, be used for providing X-ray treatment for the eye, optic nerve, tongue, breast (e.g. following lumpectomy or mastectomy), lips or mouth (intra-oral).

Preferably, the at least one removable filter arranged for use with at least one applicator is configured for filtering said X-ray beam dependent on the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface defined by said applicator.

By providing a filter for filtering the beam based on the size and FSD of the treatment surface defined by the applicator, the beam can be tailored to provide the most suitable treatment required.

Preferably, the at least one applicator comprises an applicator treatment face for defining the X-ray treatment surface; and the at least one removable filter arranged for use with at least one applicator is configured for filtering said X-ray beam dependent on said applicator treatment face.

By providing a filter with a filtering region which is based on the applicator treatment face, the beam can be manipulated accordingly. For example, applicators which define different treatment surfaces may require different degrees of filtration across the beam angles (e.g. a different beam profile applicator was used i.e. a flat field applicator, or a spherical faced Convex or Concave applicator). For example, the profile (i.e. shape or thickness) of the filter material can be altered dependent on the shape of the applicator face.

Preferably, said applicator treatment face is flat, concave or convex.

By providing an applicator with a flat, concave or convex treatment face, differently shaped areas or surfaces on the patient can be treated more effectively, e.g. eyelids, neck, nose, because a better applicator to treatment surface contact can be made.

Preferably, the provision for receiving an exchangeable X-ray filter comprises integrating the at least one filter into the at least one removable applicator.

Since the filter alters the field of the X-ray beam, by integrating the filter into the applicator component, the operator needs to change fewer components to alter the characteristics of the X-ray field. Applicators which define different treatment surfaces may require different degrees of filtration across the beam angles (e.g. if a different shaped treatment face was used i.e. a flat field applicator, or a spherical faced Convex or Concave applicator). Thus integrating the filter into the applicator makes the operation of the X-ray apparatus more efficient, as fewer steps are required, and also reduces the likelihood of user error caused by fitting the wrong combination of applicator and filter.

Preferably, the provision for receiving a removable X-ray filter comprises an aperture in the housing for engaging the filter; and the at least one X-ray filter comprises a securing portion for attaching directly to the aperture in the housing for engaging the filter.

By including a securing portion, such as a ring-shaped piece of holder (i.e. "shoe") for supporting the filter material and slotting into the aperture for receiving the filter, the filter material can easily be inserted into the tube housing, and exchanging filters to alter the beam qualities is a quick and simple procedure. For example, a ring, or shoe", which can be slotted onto the end of the X-ray apparatus can provide a secure, but easily detachable means for fitting the applicator to the X-ray apparatus. The ring may comprise, for example, a lip and may be formed of stainless steel, which is hard, easily machinable and fairly inexpensive. A filter carrier, or securing portion, provides a means for easily handling the filter material, as well as providing a mechanical means for accurately aligning the filter in the X-Ray beam, and also providing filter encoding (for identifying the filter).

Depending on how the system is used (e.g. if it was used with a single beam energies and beam quality) there could be convenience in fitting the filter in the applicator, however if a range of beam qualities needed to be used then this approach could quickly become more complex (i.e. if there are 3 beam qualities used then there would need to be 3 times as many applicators, with an applicator needed for every beam quality and filter variant). Thus, there are advantages to providing the applicator and filter as separate, changeable components. Different combinations could create different X-ray treatment fields, useful in different situations (e.g. different filters could be used with the same applicator to provide different dose depths). It may be cheaper to provide the filter and applicator separately to allow for the combinations, rather than duplicating the same filter/applicator designs in separate, fixed components to allow for the different combinations.

Preferably, the securing portion of the filter comprises a filter identifier encoding portion for storing the filter identifier; and the aperture in the housing for engaging the filter comprises a filter identifier slot for receiving said filter identifier encoding portion and for obtaining said filter identifier.

By providing an encoding portion (e.g. a chip or pin) for the filter it is possible for the system to recognise automatically that a filter has been fitted and to identify automatically the type of filter that has been attached. This may be useful for preventing accidental emission of X-rays when no filter is fitted, or for automatically determining the correct X-ray power supply for the X-ray tube. The encoder pin or chip could be attached to the securing portion of the filter, so that when the filter is fitted to the housing, a processor can read the filter identification. An indicator of this identification can be sent, for example, to a processor on the X-ray system, e.g. a processor in a control box attached to the wall of the X-ray treatment room.

Preferably, the filter identifier encoding portion comprises: optical encoding means; a magnetic stripe; a barcode; one or more mechanical formations; and/or mechanical means to operate an electrical switch.

Optical encoding such as a bar code, which uses, for example, LED5 or lasers for reading the identification data, can be provided. However, there can be problems with contamination. Identification data could be stored magnetically. RFID or contact-based data transfer may be used. However, we have found that a compact, inexpensive, reliable and robust encoding is provided by simply providing mechanical formations such as protrusions (e.g. pins) or recesses which are "read" by corresponding sensors.

Alternatively, mechanical means (e.g. protrusions or pins) on the filter encoding portion can operate one or more electrical switches positioned in the housing in the aperture in the housing for receiving a filter.

Preferably, the thickness of the filtering region decreases towards the outer edges, such that the filter is configured to adjust the X-ray beam intensity profile to achieve a substantially uniform X-ray dose intensity across the surface of the X-ray treatment surface.

The filter can be shaped to provide a uniform X-ray field across the X-ray field exiting the filter and/or across the X-ray treatment area and thus ensure each point on the treatment surface receives the same X-ray dose. By altering the thickness, or profile, of the filter material it is possible to create a uniform (or improved -i.e. close to uniform) dose of field across the surface of a treatment area e.g. a flat, a convex or a concave treatment surface. This is particularly useful when treating areas of a patient where the skin is not flat, such as the nose or chin. In such situations it would also be preferable to provide an applicator with a convex or concave face. When a filter is for producing a uniform intensity across a concave treatment surface, the filter material may not be thinner at the edges (i.e. in the path of higher angle X-ray beams), but may be thicker at the edges, and in a concave treatment surface, the beam may travel a shorter distance to reach the surface at wider angles.

Preferably, the thickness of the filtering region varies across its surface to compensate for difference in X-ray intensity across the X-ray beam due to the difference in distance travelled between the X-ray target and the X-ray treatment surface by the beam at different beam angles.

For example, it is possible to compensate for the difference in X-ray intensity across the X-ray field due to distance travelled between beam and the surface of the X-ray treatment area by using the inverse square law. As the angle between X-ray radiation and the direction perpendicular to the end-window of the X-ray tube increases, the X-ray beam must travel further to reach a flat surface compared to X-rays at a smaller angle. This effect is particularly pronounced when a wide-angle X-ray beam, such as that produced by the X-ray tube of the present system is used. If a uniform thickness, flat filter is provided to filter the X-ray beam, the beam path through the filter material would be greater at larger angles and so experience a higher level of filtration.

In addition, the X-ray beam would already be reduced in intensity at larger angles due to the inverse square law, and thus require less filtration.

Preferably, the thickness of the filtering region is based on the X-ray energy.

By providing a filter with a thickness that is based on the X-ray energy, or power, the beam quality can be altered. Filters can be changed if a different beam quality is required for a treatment (i.e. a higher level or lower level of filtration to change the nominal half value layer, HVL, or penetration of the beam). The thickness of the filter material can be changed to allow the X-ray apparatus to be powered at different energies (i.e. applying different voltages to the X-ray tube -e.g. 30kV to 320kV). More powerful (higher energy or voltage) X-rays have a higher penetration depth, and therefore the thickness of the filter material should be adjusted accordingly (e.g. by providing a filter which is thicker at its widest point for higher energy X-rays). For example, when the X-ray dose is to be deposited at the skin surface, it is preferable to minimise the X-ray dose that penetrates below the surface of the skin, which can be achieved by using low energy X-rays (i.e. running the tube at a lower voltage) with a thin filter. However, when the X-ray dose should be deposited below the skin surface, a deeper penetration of the dose is required, which can be achieved by increasing X-ray energy (higher tube voltage) and thicker filter. The penetration depth of the dose increases as the FSD is decreased and as the diameter of the treatment area increases.

Thus, the field size, treatment distance and/or X-ray beam energy can be taken into account when choosing a filter in order to provide the correct dose depth for the treatment surface. Using filter material of a different thickness will achieve different X-ray beam quality and depth dose profiles. Interchangeable filters can be provided to allow the quality and depth dose profiles of the X-ray apparatus to be changed.

Preferably, the filtering region is formed of aluminium, copper, or tin.

By providing a filter formed of aluminium, copper or tin, the X-ray beam can be attenuated in accordance with the desired X-ray beam profile. Aluminium is a particularly good material to use since it is very lightweight and exhibits good X-ray absorption. For example, only 1-2mm of aluminium is required for filtering X-rays from a -50kV X-ray tube.

Preferably, the system further comprises at least two non-uniform removable filters, each filter having a filtering region with a different thickness profile, such that each filter provides a corresponding adjustment to the beam intensity profile.

By providing a plurality of filters, which can each filter the X-ray beam in a different way, the X-ray generator can be used at different energies, different beam shapes and/or qualities can be provided. Some unique surface profiles could be the same shape, but have different thicknesses, e.g. a thicker filter allows a "harder" X-ray beam for deeper skin penetration, as more high energy X-rays pass through.

Preferably, the removable filter adjusts the X-ray beam field such that for an X-ray beam having an angle of at least 36°, the variation of the X-ray dose across a substantially flat treatment surface is less than 5% within at least 80% of the X-ray beam

field.

By providing an X-ray filter which has little variation in the X-ray dose across a wide beam angle, i.e. a fairly uniform intensity across the treatment field, the beam can be used safely for clinical and/or medical treatment. E.g. the treatment provided can be more consistent and/or repeatable than in a less uniform X-ray dose. Preferably, the variation in does is less than 5% within at least 85% of the X-ray beam field, more preferably within at least 90% of the field. Preferably this would apply for X-ray beams having an angle of at least 4Q°, and/or even for beams with a beam angle of at least 50° or6O°.

Preferably, the X-ray beam controller is configured for controlling the beam to at least two X-ray beam qualities, each X-ray beam quality corresponding to the half value layer, HVL, of the beam in the centre of the X-ray beam field at the treatment surface; each of the at least two X-ray beam qualities may be selected by a user; and the at least two X-ray beam qualities have an HVL of between 0.5mm Aluminium and 3mm Aluminium.

By providing a selection of at least two beams with these qualities, the beam can be suitable for treating certain skin conditions, e.g. cancers, lesions and/or melanomas.

By providing multiple beam qualities, different treatments can be provided with the same system. Preferably, the X-ray system can provide multiple different qualities, e.g. at least 3, 4 or 5 different values.

Preferably, the X-ray beam controller is operable to select at least one X-ray beam energy greater than 70kV.

By providing such a beam of this energy, it is possible to provide power suitable for skin applications. E.g. lower energy beams may not deliver enough energy and/or power to treat skin conditions, and may be suitable only for contact therapy and/or intraoperative treatment. Preferably, the system is operable to produce beams with an energy of between 5kV and 100kV, preferably an energy greater than 50kV, more preferably greater than 65kV, or more preferably greater than 75kV.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; two or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the two or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the distance between the X-ray target and the aperture of each of the two or more collimator(s) is less than 35mm; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; and at least one removable filter.

By providing at least two collimators for collimating and absorbing so close to the X-ray tube, the size and weight of the apparatus can be reduced, compared to systems in which the collimator is further from the X-ray target. Blocking X-rays so close to the source also reduces secondary backscatter, which improves the quality of the X-ray beam. The distance is measured from the edge of the X-ray target closest to the end-window of the X-ray tube to the edge of the aperture closest to the end-window and in the centre of the X-ray beam. Preferably, the collimators may be positioned within 30mm of the X-ray target, or even within 25mm of the X-ray target.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; wherein the at least one removable applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface and wherein the side walls are formed substantially of a material that is transparent, such that a user can view the treatment surface through the applicator side walls; and at least one removable filter.

It is helpful for the X-ray apparatus operator to be able to view the X-ray treatment area in conjunction with the X-ray applicator, both for ensuring the apparatus is initially set up correctly, and for ensuring the apparatus remains correctly positioned during the X-ray application procedure. By providing an applicator that allows some electromagnetic light (e.g. visible light) to pass through (i.e. transparent or at least translucent), it is possible to provide visual feedback to the operator, e.g. the operator can directly see the treatment area through the applicator walls, or can obtain images of the applicator in relation to the treatment surface when in operating position, for example using ultraviolet or infrared light.

Preferably, said transparent material is a plastic, preferably Perspex or Acrylic.

Perspex, i.e. poly(methyl methacrylate), is a good material for forming the applicator because it is lightweight, strong, cheap and easy to mould into the desired shape. Perspex also has a good level of X-ray attenuation, while being capable of offer high (e.g. 92%) optical or visible light transmission.

Preferably, the system comprises two or more collimator(s) provided in the housing between the end-window X-ray tube and the treatment surface, the two or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; and the distance between the X-ray target and the aperture of each of the two or more collimator(s) is less than 35mm.

Preferably, the system is operable to provide an X-ray beam for a treatment surface having a maximum diameter of at least 35mm; and wherein said treatment surface is at a distance of 3cm to 5.5cm from the X-ray target.

By providing a wide treatment surface at a close FSD, a suitable X-ray beam for treatment can be provided over a significant area, with many advantages, some of which have been described above e.g. lower power, better quality beam, more compact and/or generator. Preferably the FSD is 4.5cm to 5.5cm. Preferably the treatment surface may have a maximum diameter of at least 40mm, or more preferably at least 45mm, or even at least 50mm.

Preferably, the generator is arranged to operate with at least one removable applicator which defines an X-ray treatment surface with a maximum diameter of at least 4-6cm at a distance of 3-7cm from the X-ray target.

Preferably the treatment surface has a diameter of between 4cm and 6cm, at a distance of between 4cm and 6cm FSD. More preferably, the system is operable to work with an applicator defining a treatment surface of diameter 4.5-5.5cm at 4.5-5.5cm FSD.

Preferably, a collimator is integrated with the mounting portion of the at least one removable applicator, such that the applicator comprises a mounting portion with an aperture for allowing X-rays to pass through and an absorbing portion for absorbing X-ray radiation outside the aperture.

Different X-ray fields are required for different treatment areas, which may depend on the shape of the treatment area and/or the required depth penetration. In order to achieve this, the X-ray beam may require further collimation based on the desired X-ray treatment area. In such cases it is desirable to provide a removable collimator (which may be a second collimator, on top of a primary collimator fixed in the X-ray tube housing), so that different collimation can be provided depending on the specific X-ray treatment area. The degree of collimation provided by the aperture of the second collimator is determined by the size and shape of the aperture; i.e. a smaller aperture would reduce the largest angle of X-ray allowed to pass through and block X-rays propagating at larger angles. Thus a smaller aperture would produce a narrower beam, e.g. for applying X-rays to a smaller treatment surface, and/or a surface at a longer FSD. The size of the applicator is linked to the field size and quality required at the treatment area. By integrating a (secondary) collimator into the applicator component, the operator would only need to change one component to alter the size of the X-ray field. This makes the operation of the X-ray apparatus more efficient, as fewer steps are required, and also reduces the likelihood of user error caused by fitting the wrong combination of applicator and removable collimator. However, there are also advantages to providing the applicator and (second) collimator as separate changeable components, as different combinations could create different X-ray treatment fields, useful in different situations. In such a case, it may be cheaper to provide these separately to allow for the combinations, rather than duplicating the same collimator/applicator designs in separate, fixed components to allow for the different combinations.

Preferably, when the removable applicator is received in the housing, the distance between the X-ray target and the aperture of the collimator integrated with the mounting portion of the removable applicator is less than 35mm.

Providing a collimator so close to the X-ray target allows a short FSD, for which advantages are discussed above. The collimator can also be smaller, since the X-ray beam is less wide closer to the source. This provides a smaller, lighter arrangement.

Preferably, distance between target and aperture is less than 30mm, more preferably less than 25mm.

Preferably, the absorbing portion of the applicator is formed of tungsten.

In order to block X-rays effectively, the material used to absorb the X-rays must be very dense and/or very thick. By manufacturing the collimator from dense materials such as lead or tungsten, only a small thickness is needed to provide X-ray shielding.

Tungsten is denser than lead, and so when using tungsten, a collimator can be even thinner (e.g. 1mm for X-rays of energy <100kV) compared to when using lead. Tungsten is also much harder than lead, which means it has a high mechanical integrity and it is possible to form detailed structures with a very thin (i.e. 1mm or less) wall thickness, which are strong and accurately reproducible. This means sufficient shielding and collimation can be provided in a very small space and the size of the apparatus can be minimised.

Preferably, the system comprises one or more light sources for coupling to the at least one applicator for illuminating at least a portion of the X-ray treatment surface.

By providing illumination for the X-ray treatment area, the X-ray operator can view all or part of the treatment field, which allows for more accurate initial positioning of the X-ray applicator, and can provide a check that the X-ray applicator remains correctly positioned during treatment. Correct positioning of the X-ray apparatus is important for minimising inaccuracies in the treatment to ensure an accurate and uniform dose across the treatment area and e.g. for eliminating "stand off' (a reduction in dose provided to the treatment area due to improper positioning of the applicator).

Preferably, the system further comprises at least one camera for coupling to the X-ray housing for imaging the X-ray treatment surface.

By providing a camera coupled to the X-ray tube (i.e. integrated into the X-ray apparatus) for imaging the X-ray treatment area photos, and/or video imaging of the treatment area can be easily provided during treatment, without the need for additional equipment. Separate imaging equipment would need to be moved separately from the radiotherapy apparatus, which could significantly increase operator setup time as it may require adjustment every time the position of the applicator is adjusted. By integrating a camera into the equipment, photos and/or videos can be provided live, during treatment.

This allows an operator to continue to view the treatment area and/or applicator even during treatment, especially while the operator may have left the room for safety reasons, which can be useful for ensuring that the X-ray equipment and applicator remain correctly positioned during the procedure. A camera can also be used to provide patient treatment records easily and quickly, which are useful for traceability and for assessing the effectiveness of treatment e.g. over multiple X-ray treatment sessions. As mentioned above, when illuminating the treatment area or surface with light outside the visible spectrum (e.g. UV or IR) a camera is essential, but better identification of skin lesions can be provided, as surface deflection may be minimised and image contrast enhanced. When polarised light is used, a polarisation filter may also be fitted in front of the camera.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of the one or more collimator(s) allows through an X-ray beam with a beam angle of at least 35° in at least one plane; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; at least one removable filter; an electronic distance measuring device coupled to the X-ray tube housing for measuring the distance between the X-ray target and the X-ray treatment surface; and at least one of: means for providing an indication to an operator in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than 5mm during treatment; and means for disabling the X-ray beam in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than 5mm during treatment.

A distance measuring device can provide a further level of safety for X-ray treatment. A distance measuring device can help to ensure the applicator is correctly positioned prior to treatment. The distance measuring device can be positioned within the X-ray applicator (i.e. within the treatment field), or outside the applicator. Placing the device inside the field may provide a more accurate distance measurement, as the path between the distance measuring means and treatment is less likely to be obstructed.

However, when the treatment measuring device is placed outside the X-ray field, it is easier to protect it from damage by the X-ray beam. If the measuring device detects that after being correctly set up, the X-ray apparatus has moved in relation to the X-ray treatment area by more than a predetined distance (e.g. 2mm, 3mm, 4mm or 6mm), the system can interrupt the treatment and/or provide an indication to the system operator.

This can make the system safer as it is possible to automatically ensure that an X-ray beam is only provided when the system remains correctly set up.

Preferably, the control apparatus comprises: a memory for storing a set of approved X-ray treatment plans; wherein each treatment plan comprises a combination of parameters for the treatment plan, the parameters including one or more of: an X-ray beam energy; an applicator identifier; a filter identifier; and a treatment time or treatment dose.

By providing specified or approved treatment plans, it is possible to ensure safe use of the system. The X-ray beam energy and/or power can alter the beam quality and treatment provided. The treatment time (or beam duration) and treatment dose are also important to consider.

Preferably, the system further comprises: a user interface, comprising user input means for allowing a user to select a desired X-ray treatment plan from the set of approved X-ray treatment plans; and control logic for receiving an indication of the selected desired X-ray treatment plan; wherein the control logic determines at least one combination of an applicator and a filter based on the selected X-ray treatment plan compatible with the selected X-ray treatment plan; wherein the user interface further comprises display means for displaying to a user an indication of said at least one combination of an applicator and a filter.

By allowing a user to select a desired treatment plan and then provide the user with an indication of the correct applicator and/or filter combination to use, the system can be easier, simpler and safer to use, with less scope for operator error.

Preferably, the user interface further comprises: a display for displaying to a user a menu comprising at least a portion of the set of approved X-ray treatment plans.

By providing options for treatment plans in a menu, the user or operator can quickly and easily select the desired plan.

Preferably, the user input means allows the user to input an indication of at least one treatment option, the treatment options comprising: the size of the X-ray treatment surface; the profile of the X-ray treatment surface defined by an applicator, wherein said profile is chosen from a list comprising at least one of: a flat treatment surface, a concave treatment surface and a convex treatment surface; and the desired beam quality; and wherein the control logic is configured to determine at least one suitable approved X-ray treatment plan based on said indication of the at least one treatment option.

By allowing a user to input certain treatment parameters, treatment plans can be more easily and more suitably chosen for individual patients.

Preferably, the system comprises a removable collimator associated with the at least one removable applicator for collimating said X-ray beam dependent on the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface defined by the applicator; said removable collimator comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the housing has provision for receiving the removable collimator.

Different X-ray fields are required for different treatment areas, which may depend on the shape of the treatment area and/or the required depth penetration. In order to achieve this, the X-ray beam may require further collimation based on the desired X-ray treatment area. In such cases it is desirable to provide a removable collimator (which may be a second collimator, on top of a primary collimator fixed in the X-ray tube housing), so that different collimation can be provided depending on the specific X-ray treatment area.

Preferably, the removable collimator is integrated with the mounting portion of the at least one removable applicator, such that the applicator comprises: a mounting portion with an aperture for allowing X-rays to pass through and an absorbing portion for absorbing X-ray radiation outside the aperture; and conical side walls arranged to extend from the X-ray tube housing such that the diameter of the applicator increases with distance from the X-ray target.

By providing a collimator integrated into the applicator, a convenient means of correctly collimating the beam for each applicator size and shape is provided.

Preferably, when the removable applicator is received in the housing, the distance between the X-ray target and the aperture of the removable collimator is less than 40mm.

By providing a removable collimator so close to the X-ray target, a short FSD can be provided. It is advantageous to place the (secondary) removable collimator close to the X-ray target because less material is needed for blocking larger angles compared to when the (secondary) removable collimator is placed further from the X-ray target.

Preferably, the second collimator is less than 35mm, less than 30mm from the X-ray target, or even less than 25mm from the X-ray target. The removable (secondary) collimator would normally be located further from the X-ray target than a primary collimator.

Preferably, the aperture of at least one collimator is conical, such that the diameter of the aperture increases with distance from the X-ray target.

By providing a conical, or tapered, aperture with the width, or cross-sectional area, of the aperture increasing with distance from the target, the outside edge of the aperture can be aligned along the line of the widest angle X-ray beam allowed through the collimator. This helps to provide a better collimation than if the aperture was of a constant diameter to provide a beam with a cleaner edge. The body of the primary collimator may also be thicker in the region immediately surrounding the aperture (e.g. 2- 3mm thick compared to 1mm for the rest of the collimator body), as it has been found that this provides a better performing collimator with a sharper edge to the beam at wide angles. X-Rays which are diverging from the centre of the target (i.e. a "point source"), along with secondary and back-scatter X-rays, is blocked by end and tapered sides of the collimator, therefore giving a cleaner edge for the permitted X-ray beam.

Preferably, at least one of the collimators is formed predominantly of tungsten or lead.

Preferably, the portion of one of the one or more collimator(s) for absorbing X-rays comprises a recess complementary with the end-face of the X-ray tube and dimensioned to locate and receive the end of the X-ray tube, and wherein said collimator is further positioned for collimation of the X-ray beam and absorption of X-rays.

By providing the primary collimator with a recess for fitting to the end of the X-ray tube, the aperture of the collimator and the end-window of the X-ray tube can be easily aligned when the system is constructed. This also reduces the size of the X-ray arrangement, which has many advantages, such as a more easily manoeuvrable X-ray tube head, or X-ray housing.

Preferably, the portion of at least one of the one or more collimator(s) for absorbing X-rays extends around the X-ray target in a direction substantially perpendicular to the end-window of the tube for absorbing X-rays that propagate from the target towards the side of the X-ray tube.

X-rays can damage living cells so for safety it is sensible to limit unnecessary exposure to X-rays of, for example, preventing parts of the patient's body that don't require X-ray treatment, or of operational/medical staff. Therefore it is important to prevent X-ray emission from the X-ray apparatus outside the usable X-ray beam. By providing a housing or collimator that surrounds the X-ray target around the sides of the X-ray tube, as well as at the end, unwanted X-rays propagating towards the side of the X-ray tube are absorbed close to the source. By having an X-ray absorbing (e.g. tungsten) "cap" around the X-ray tube target on three sides, this cap is essentially providing almost all the X-Ray shielding for the system in a very small and compact part, blocking and suppressing the unnecessary or unwanted X-rays as close as possible to source. X-rays outside the maximum used X-ray beam are suppressed. By performing this as close to the source (i.e. X-ray target) as possible, and in the same structure as the first collimator, the size of the shielding required is kept to a minimum as the X-rays have a shorter distance in which to disperse. Sufficient shielding for X-rays propagating from the top side of the X-ray target can be provided by the X-ray tube body, as the X-rays have a longer distance to travel through the tube before reaching the exterior of the X-ray tube housing, which serves to provide suitable attenuation.

Preferably, one of the one or more collimator(s) comprises a shield comprising: a recess dimensioned for receiving and locating the X-ray emitting end of the elongate end-window X-ray tube, the recess having a portion arranged to extend around the sides of the X-ray tube to surround the X-ray target radially and absorb a portion of the X-ray radiation that does not pass through the end-window end of the X-ray tube; and an aperture arranged to align with the end-window for allowing an X-ray beam emitted from the end-window of the X-ray tube through the shield; wherein the aperture is shaped and dimensioned for collimating the X-ray beam to provide a beam angle of between 35° and 900 and narrower than the beam emerging from the X-ray tube window.

By providing a shield which is dimensioned to receive and locate an end-window X-ray tube, unwanted X-rays can be suppressed as close to the source as possible. This is particularly useful for a large beam angle (e.g. a full beam angle of 50-90°, which gives the angle between the normal and the widest beam of 25-45°), which diverges quickly with distance from the source. This means secondary backscatter can be kept at a minimum, which indirectly improves the quality of the X-ray beam, and the support metalwork can be made smaller. By extending the shield around the sides of the X-ray tube and target, the additional metalwork required to provide shielding can be kept to a minimum.

Preferably, the distance between the X-ray target and the aperture of one or more collimator(s) is less than 35mm.

This allows for a shorter FSD, which has several advantages described herein.

Preferably, the distance between the X-ray target and the aperture of one or more collimator(s) is greater than 6mm.

Due to the size of the end-window and the distance of the X-ray source from the end of the tube, it would be difficult to position the collimator any closer to the X-ray target. Preferably, the aperture of the primary collimator would be more than 8mm from the X-ray target, or preferably less than 30mm or more preferably less than 20mm, or 15mm, or 12mm from the X-ray target. In one embodiment the aperture is 10mm from the X-ray target. To help provide a uniform intensity, it is useful to collimate the X-ray beam, in particular by blocking X-rays extending at large angles to the normal to the end of the X-ray tube, where there is a sharp reduction in the normalised intensity. The largest angle between the X-ray and the normal to the end of the X-ray tube, which is allowed through by the first collimator may be in the range 25-30° (50-60° total beam angle), 26-29° (52-58° total beam angle), or more preferably 28-29° (56-68° total beam angle).

Preferably, the at least one removable applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface and wherein the side walls are formed substantially of material that is transparent to at least a portion of the frequencies of electromagnetic light.

It is helpful for the X-ray apparatus operator to be able to view the X-ray treatment area in conjunction with the X-ray applicator, both for ensuring the apparatus is initially set up correctly, and for ensuring the apparatus remains correctly positioned during the X-ray application procedure. By providing an applicator that allows some electromagnetic light to pass through, it is possible to provide visual feedback to the operator, e.g. the operator can directly see the treatment area through the applicator walls, or can obtain images of the applicator in relation to the treatment area during when in operating position, for example using ultraviolet or infrared light.

Preferably, said material is transparent to visible light.

By providing an applicator that has at least a portion of the walls transparent (or at least translucent) to visible light, the operator can view the X-ray treatment area directly when the applicator is in place, without the need for specialist image detection equipment.

Preferably, said applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface and wherein the side walls are formed substantially of Perspex or Acrylic.

Preferably, said applicator comprises an X-ray treatment face for contacting the X-ray treatment surface and wherein said X-ray treatment face is formed substantially of Polystyrene.

By providing a polystyrene treatment face, preferably transparent polystyrene, the treatment face has significantly lower X-ray absorption, as well as well as significantly better stability when exposed to X-rays for a prolonged period compared to Perspex (i.e. prolonged exposure to X-rays does not change the structure of the polystyrene, nor will it discolour. Thus it is a good material for allowing the X-ray beam through to reach the treatment surface, and for providing good contact on the (skin) surface.

Preferably, the securing portion of the applicator comprises an applicator identifier encoding portion for storing the applicator identifier; and the fitting for receiving a removable applicator comprises an applicator identifier slot for receiving said applicator identifier encoding portion and for obtaining said identifier code.

It is advantageous to have a secure attachment means for coupling the applicator to the X-ray tube. A ring, or "shoe", which can be slotted onto the end of the X-ray apparatus can provide secure, but easily detachable, fixing of the applicator to the X-ray apparatus. The ring may comprise, for example, a lip and may be formed of stainless steel, which is hard, easily machinable and fairly inexpensive. For example, the applicator may comprise means for the applicator to be held on the end of the X-ray tube metalwork and aligned in the X-ray beam. In addition the applicator may be mechanically aligned and mechanically retained when fitted, as well as having encoding to detect what applicator is fitted. For convenience this may be by means of a small stainless Horseshoe" design with a ball-plunge. The two flat sides of the horseshoe retain and aligning the applicator in 2-planes, with the ball-plunger engaging when the applicator is exactly centralised in the beam (i.e. alignment in the 3rs plane). The ball plunger exerts a nominal force that means the applicator, when fitted and aligned, is retained in position for treatment. This design may also be used for fixing the filter. By providing an encoder pin, it is also possible to identify the type of applicator that has been attached. This may be useful for preventing accidental emission of X-rays when no applicator is fitted, or for automatically determining the correct X-ray power supply to the X-ray tube.

For example, it is possible to arrange the system such that, if the ball-plungers are not engaged (i.e. the filter and/or applicators incorrectly aligned), then recognition switches are not engaged, and will be detected by the system as "No Filter Fitted" or "No Applicator Fitted". This is an important and critical safety feature in the system, as X-ray production would then be disabled.

Various means are available to fit and retain the filter and/or applicator in the system (e.g. a circular rotating bayonet fitting, a side sliding system, as well as a door catch system). A side sliding system, as described above, has been chosen for the small size, the lightweight, and mechanical simplicity. In the design the applicator shoe and/or the filter carrier material may be stainless steel. This is chosen as it is hard wearing and will take the rigours of daily use over at least a 10-year period.

Preferably, the applicator identifier encoding portion comprises: optical encoding means; a magnetic stripe; a barcode; one or more mechanical formations; or mechanical means to operate an electrical switch.

Alternatively, mechanical means (e.g. protrusions or pins) on the applicator encoding portion can operate one or more electrical switches positioned in the housing in the aperture in the housing for receiving a filter.

Preferably, the applicator comprises conical side walls arranged to extend from the housing at an angle of less than 31° to the normal to the X-ray generation tube end-window.

The side walls of the X-ray applicator can be formed to extend from the end of the X-ray tube at angles suitable for the X-ray area to be treated. The angle is measured from the normal to the end of the X-ray tube (i.e. the direction perpendicular to the end of the X-ray tube). This will depend on the size of the X-ray treatment area and the desired working distance (FSD). For example, to provide a field with a diameter of 5cm at a working distance of 5cm, would require an angle of 30°. To provide a field with a diameter of 3cm at a working distance of 5cm would require an angle of 17° to the nearest degree. The side walls of the X-ray applicator can also be arranged to provide further collimation for the beam, since any X-rays extending into the side walls of the applicator would have to travel a significant distance through the applicator side walls, which would result in X-ray absorption. Thus the side walls can also define the edge of the X-ray treatment beam.

Preferably, the system further comprises: one or more light sources for coupling to the at least one applicator for illuminating at least a portion of the X-ray treatment surface.

Preferably, the one or more light sources are integrated in the housing and provided with a light pipe for coupling to the at least one applicator.

By incorporating the light sources (i.e. electromagnetic radiation sources) into the tube housing, e.g. in a ring at the end of the X-ray generation tube, the X-ray treatment area can be illuminated without the need for separate equipment, which may obstruct the operator's access to the X-ray treatment area. Separate illumination equipment would also need to be moved separately from the radiotherapy apparatus, which could significantly increase operator setup time as it may require adjustment every time the position of the applicator is adjusted. Providing a light pipe for coupling to the applicator and/or positioning the light sources within the profile of the treatment applicator further minimises shadows and increases visibility of the treatment area.

Preferably, the one or more light sources are integrated into the at least one applicator.

By incorporating the light sources into the applicator, shadows can be reduced and the visibility of the treatment area increased.

Preferably, the one or more light sources are configured to illuminate an area inside and outside the X-ray treatment surface.

By illuminating both inside and outside the treatment area, the operator can more easily view and position the applicator in relation to the treatment area. For example, an LED lighting ring which may illuminate both inside and outside (around) the treatment field combined with a transparent applicator means that is possible for an operator to clearly see the treatment area, and quickly and efficiently align the applicator, and treatment beam for a treatment.

Preferably, the at least one applicator comprises side walls arranged to extend from the X-ray tube housing for contacting the X-ray treatment surface; wherein the side walls are formed substantially of material that is transparent to at least a portion of the frequencies of light emitted from said one or more light sources; and wherein the applicator is arranged such that when coupled to the light sources, the applicator transmits light from the light sources through the applicator side walls to the X-ray treatment surface.

By providing light sources coupled to an applicator that acts as a light pipe, i.e. a light tube or waveguide, for guiding or transporting light from the electromagnetic light sources towards the edge, or perimeter, of the X-ray treatment area, the light can form a ring or "halo" on the skin surface immediately outside of the X-ray treatment area. This allows the operator to ensure the X-ray applicator is correctly positioned. Preferably, the light sources will be integrated inside the profile of the applicator. The provision of an (LED) lighting ring in conjunction with a transparent Perspex applicator (i.e. acrylic or other transparent plastic) has several advantages. The light from the LED lighting ring can be coupled into the cone of the Perspex applicator, with the wall of the applicator acting like a light pipe'. The result of this is that when the applicator front face is in good contact with a patient's skin surface a defined Halo" or lighting ring is seen on the skin surface. If the applicator is moved away from the skin surface, the light very quickly disperses and diffuses, changing the appearance of the lighting on the skin surface. This provides a very effective means for the operator to see if they have made good skin contact. If the applicator front edge is moved away from the skin surface in any part around the treatment field (i.e. stand-off), then this is visibly confirmed. This allows sub-mm to millimetre "stand-off' to be visibly confirmed with the operator, allowing more accurate treatment set-up, and as result more accurate treatment dose.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; and a moveable support structure for the X-ray tube; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; and one or more light sources for coupling to the at least one applicator for illuminating at least a portion of the X-ray treatment surface; wherein the at least one applicator comprises side walls arranged to extend from the X-ray tube housing for contacting the X-ray treatment surface; wherein the side walls are formed substantially of material that is transparent to at least a portion of the frequencies light emitted from said one or more light sources; and wherein the applicator is arranged such that when coupled to the light sources, the applicator transmits light from the light sources through the applicator walls to the X-ray treatment surface.

Preferably, the transmitted light is visible when the emitting surface of the applicator walls is in contact with the edge of the X-ray treatment surface; and the light disperses within a small distance when the emitting surface of the applicator walls is a small distance from the target X-ray surface.

By providing light that disperses when the end of the applicator walls are not in contact with the surface of the skin at the X-ray treatment area, the operator can easily observe when the applicator makes a good and even contact with the skin, as a clear, unbroken ring of light will be shown. When the contact is poor, the light disperses, leaving a broken or indistinct ring. The light may disperse within a distance of less than 1mm from the skin surface, or even less than 0.5mm.

Preferably, said light sources emit one or more of: visible light; ultraviolet light; infrared light; and polarised light.

Illuminating the X-ray treatment area with different types of light provides different advantages. For example, visible light allows the operator to view the X-ray treatment area quickly and clearly without any other special equipment. This may allow the operator to provide more accurate X-ray treatment and also to treat more patients each day. Using ultraviolet (UV) light can show more detail in skin conditions than visible light, sometimes UV imaging can even show skin conditions e.g. age spots, that are not noticeable with visible light. Infrared (IR) light can also show skin conditions in more detail and be particularly useful in diagnosing malignant melanomas. Thus by incorporating UV and IR light into the X-ray apparatus, it is possible for an operator to accurately monitor and position the X-ray applicator in relation to skin conditions which are not detectable using visible light. Using linearly polarised light can also provide details of skin conditions which cannot be seen using visible light, in particular superficial tissue layers below the skin surface are detectable because light reflected from one or two scattering events retains some polarisation, whereas multiply scattered light behave as unpolarised light. Previous methods of reducing skin surface reflection normally required a liquid medium to be placed between the detection instrument and the skin, but this is not required when polarised light is used. When UV, IR or polarised light is used, additional equipment, such as UV or IR cameras, or polarisation filters are required in order to view and analyse the treatment area.

Preferably, the light sources are light-emitting diodes, LED5.

Light-emitting diodes (LED5) provide good quality light. LEDs are available for producing visible, UV or 1k light, and also have the advantage of emitting light of a precisely known spectrum, rather than of a large variation in wavelengths. There are other light sources that could be readily used instead of LED5 (such as a tungsten bulb), however the advantage of using small surface-mounted LED5 are they are very small size, and easy to integrate, for easy positioning and coupling to the applicator (for illumination in and around the treatment site as well as coupling into the applicator cone to form a light pipe). E.g. LED5 as thin as 0.2mm may be available. Preferably LED5 with a thickness of less than 0.5mm, less than 0.4mm or 0.1 to 0.3mm would be used. With this arrangement the LED5 can be positioned and aligned immediately above a light coupling ring on the applicators, allowing the light of the LEDs to be directly coupled to the applicator cone and/or side walls. This means that we can integrate the LED lighting solution into the X-Ray tube-head metalwork and it only requires a height of 1 to 2mm to accommodate.

Preferably, the one or more light sources are arranged in a ring surrounding the X-ray beam zone at the X-ray emitting end of the X-ray tube housing.

By integrating the light sources within the X-ray device in a ring, an even distribution of light with minimal shadows on the treatment area can be provided, ensuring the operator has a clear view of the treatment area and applicator device.

Preferably, the system further comprises: at least one camera for coupling to the X-ray housing for imaging the X-ray treatment surface.

This allows an operator to continue to view the treatment area and/or applicator even during treatment, especially while the operator may have left the room for safety reasons, which can be useful for ensuring that the X-ray equipment and applicator remain correctly positioned during the procedure. A camera can also be used to provide patient treatment records easily and quickly, which are useful for traceability and for assessing the effectiveness of treatment e.g. over multiple X-ray treatment sessions. As mentioned above, when illuminating the treatment area with light outside the visible spectrum (e.g. UV or IR) a camera is essential, but better identification of skin lesions can be provided, as surface deflection may be minimised and image contrast enhanced.

When polarised light is used, a polarisation filter may also be fitted in front of the camera.

Preferably, at least one camera is configured to be removably fitted to the housing within an X-ray beam zone.

Providing at least one camera within the path of the X-ray beam allows photos and imaging of the target X-ray area with clear visibility of the applicator positioned around skin lesion and/or treatment site. When positioned within the zone of the X-ray field, the camera would provide a clear image of the X-ray treatment area without obstruction from other components of the X-ray apparatus. However, it can be difficult to provide a camera within the X-ray field which is not damaged by the X-ray treatment beam, so a camera within the X-ray applicator would normally have to be removed during X-ray treatment (i.e. during X-ray beam emission). A camera for placing inside the treatment field which can be put in position temporarily before treatment could, for example, be provided by integrating the camera into a component designed to fit within the means for receiving an X-ray filter. The camera could then be moved by the system operator. Alternatively, electronic and/or mechanical means could be used to move the camera in/out of the X-ray beam.

Preferably, the X-ray generator is configured such that X-ray generation tube is disabled while the camera is positioned within the X-ray beam zone.

By disabling the X-ray beam (e.g. by providing means for identifying when a camera is inserted and control logic to prevent power being supplied to the X-ray tube, or by moving a shutter across the beam path), damage to the camera from the X-ray beam can be prevented.

Preferably, at least one camera is fitted to the X-ray housing outside an X-ray beam zone.

By providing a camera fixed to the X-ray apparatus and positioned outside the X-ray applicator (and therefore outside the X-ray field), the camera can remain in place during operation of the X-ray apparatus as the camera will not be damaged by firing of the X-ray beam. Therefore, and/or video of the applicator positioned over the treatment area can be taken. This can be viewed by the operator during treatment to confirm that the applicator remains correctly positioned, e.g. it a patient moves during treatment and the treatment needs to be paused, the patient settled and the X-ray head reset before completing treatment dose. This is particularly useful when the X-ray dose is sufficient to make it safer for the operator to leave the treatment room when the X-ray beam is firing.

Preferably, the X-ray applicator is formed substantially of material that is transparent to at least a portion of the frequencies of light which the camera fitted outside the X-ray beam zone is operable to detect.

When a camera is positioned outside the X-ray applicator, it is parbcularly advantageous for the applicator to allow through the frequencies of light which the camera can detect, as the camera can then also provide an image of the X-ray treatment area before and during operation of the X-ray device.

Preferably, the system further comprises a computer program, computer program product or non-transitory computer-readable storage medium storing one or more instructions which, when executed by one or more processors, cause the one or more processors to detect motion from the output of the at least one camera; and a processor for executing said instructions for detecting motion from images of the target X-ray area.

By providing movement detection, the X-ray system can provide an indication to the operator that the apparatus has moved in relation to the treatment area and/or pause X-ray production should the apparatus move more than a certain amount, which ensures X-rays are safely administered.

Preferably, the system comprises at least two cameras for imaging the target X-ray area and arranged such that images from the at least two cameras can be combined to produce 3-dimensional imaging of the treatment surface.

By providing two cameras which can be used to create 3-D images of the target X-ray area, measurement of skin lesion surface profile and depth is possible. This can be useful information when determining the required X-ray dose to be applied, and allows quick and simple recording of details of the target X-ray area at the time of X-ray application.

Preferably, the 3-dimensional imaging of the treatment surface provides an indication of one or more of: the height of a skin abnormality above the skin surface; and the depth of a skin abnormality below the skin surface.

By providing a height and/or depth indication of a skin lesion, the operator and/or other medical personnel can more easily diagnose the skin condition correctly and/or decide on a more useful treatment plan.

Preferably, the system further comprises an electronic distance measuring device coupled to the X-ray tube housing for measuring the distance between the X-ray target and the X-ray treatment surface.

However, when the treatment measuring device is placed outside the X-ray field, it is easier to protect it from damage by the X-ray beam. If the measuring device detects that after being correctly set up, the X-ray apparatus has moved in relation to the X-ray treatment area by more than a predefined distance (e.g. 2mm, 3mm, 4mm or 6mm), the system can interrupt the treatment and/or provide an indication to the system operator.

Preferably, the distance measuring device obtains a measure of distance using one or more of: an infrared, IR, sensor; one or more lasers; and ultrasound.

The distance measuring device can use one of a number of means for measuring the distance. Ultrasonic sensors are good for use in medical applications, as there are no known long-term side effects (e.g. it is used for safely imaging foetus development during pregnancy). Infrared sensors can often be cheaper and have faster response times than ultrasound sensors. Laser measuring devices provide a smaller wavelength than ultrasound and are thus more accurate for measuring distance.

Preferably, the system further comprises: means for providing an indication to an operator in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.

An indication may be provided e.g. aurally or visually, by sounding an alarm, switching on a warning light or displaying an error message on a display.

Preferably, the system further comprises means for disabling the X-ray beam in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.

Disabling may be accomplished electronically, e.g. by cutting power supply to the generator, or mechanically, e.g. by using a shutter to block the X-ray beam.

Preferably, the predetermined threshold value is smaller than or equal to 6mm; preferably wherein the predetermined threshold value is smaller than or equal to 4mm; preferably wherein the predetermined threshold value is smaller than or equal to 3mm; or preferably wherein the predetermined threshold value is smaller than or equal to 2mm.

The threshold value could be user or treatment specific, and/or could be incorporated into the initial setup of the system. It may be chosen by a user or operator.

When providing radiotherapy to a patient, it is important to be able to easily change the position of the X-ray generating apparatus so that the X-ray field falls on the treatment area correctly and precisely. This can require a large range of movement for positioning the X-ray tube head (e.g. over a space of 60cm x 60cm x 60cm) as well as the capability of rotation through a large range of angles for alignment of the tube head (e.g. ±900, more usually in the range ±600 and preferably at least ±300 in 2 or 3 axes).

Additionally, once the apparatus is correctly positioned, it is important for the apparatus to remain in position during treatment (i.e. while the X-ray beam is applied to the treatment area). Some of the above-described features allow for a very compact and lightweight X-ray tube head (i.e. -2kg), which is therefore very manoeuvrable. It is thus advantageous to provide an X-ray support structure that allows such a device to be easily repositioned. However, such support structures for easily moving and repositioning a tube head are also applicable for side-window X-ray tubes as well as end-window X-ray tubes. Some support structures described herein may be capable of supporting and providing a means for moving an X-ray tube head of as much as 10- 15kg, or even 20kg.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient, comprising: a housing for receiving an X-ray tube, the housing having a fluid pipe or an air pipe for fluid or air cooling the X-ray tube and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; one or more collimator(s) integrated into the housing, the one or more collimator(s) for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering said X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, one or more collimator(s), X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the moveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a joint and a distal end; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein at least one of the first and second elongate sections comprises a parallelogram linkage; wherein the X-ray tube housing is attached to the second elongate section via at least one joint which permits movement of the X-ray housing relative to the second elongate section; and a biasing arrangement and maintaining arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.

By providing a support structure, or arm, with at least two elongate sections, which can be moved independently, the support arm can provide multiple degrees of freedom in the movement of the X-ray tube head for precise positioning. For example, the first elongate section may allow movement about one axis, whereas the second elongate section can allow movement about a second axis. Forming at least one of the elongate sections from a parallelogram linkage (i.e. two substantially rigid struts which are maintained in parallel alignment by hingeably connecting the struts at or near each end by connectors of the same length), provides a strong support section, which can be easily moved, but maintain its position without clamping. It is also easier to provide counter-balance weights and springs to help provide easy movement and stability. By providing such a support structure for the X-ray apparatus, the X-ray housing can be easily moved by just one person. It can be accurately and reliably positioned against a desired treatment location and remain in position until moved. The force required from one person to move the support structure may be in the range iN to 150N, greater than 5N, greater than ION, and/or less than 80N, less than 60N or less than 40N. The force required may also be in the range 20-30N.

A fluid or air pipe could be provided as air or water cooling pipes surrounding the X-ray tube. However, the fluid or air pipe may also be replaced by another cooling means, such as gases or oils in pipes, or fans. An air blower or water cooler could, for example, be located in a base unit.

Preferably, the biasing arrangement comprises one or more of: one or more gas springs; one or more tension springs; one or more compression springs; one or more coil springs; one or more torsion springs; and one or more weights.

Springs are effective for exerting balancing forces on the support structure, which aids in making the structure easy to move for repositioning and stable for maintaining the desired position. Although many types of spring can be used (e.g. a coil spring, which may be cheaper), a gas spring produces a very steady and predictable force and can require less maintenance than other springs. Multiple gas springs can be used in the support arm; this is useful when the arm allows motion in several directions (i.e. multiple degrees of freedom), as different strength counter-balancing may be required in each direction. The spring(s) can be configured to counteract the gravitational force caused by the weight of the arm and the X-ray tube head, so that the arm can be moved (e.g. by the operator) and the spring(s) will maintain the arm position until the arm is moved again. Weights are also useful for counter-balancing the forces on the elongate sections.

Preferably, the maintaining arrangement comprises one or more of: friction of one or more joints; electronic braking; and manual braking.

By providing a friction, or torque, joint for maintaining the position of the support structure, a stable but easily manoeuvrable support can be provided. For example, a friction joint may be provided to fix the first and second sections of the arm together and the friction set to allow the joint to be manually moved, but remain stable when left in position. Other joints, such as the one connecting the first section to the base support unit, could also be friction joints for the stabilising of other movements. The combination of friction joint(s) and gas spring(s) in the support arm can provide a very stable but manoeuvrable arm. By providing a mechanical braking mechanism (e.g. a locking handle), it is possible to provide a simple and easy means of locking a joint. For example, a mechanical braking mechanism would not require an electrical power supply, making installation and setup easier and reducing running costs. By providing an electronic braking mechanism, the operator can lock and unlock the joint with very little effort, for example by simply pressing a single button. It is normally easier to actuate an electronic braking means than one that is purely mechanical because mechanical braking may require the application of a force. It is also easier to place the actuation means for an electronic braking means in a convenient place for the operator to reach while positioning the tube head, whereas a mechanical braking means may have to be positioned at, or close to, the joint.

Preferably, both of the first and second elongate sections comprise a parallelogram linkage.

By providing two support sections with a parallelogram linkage, a higher degree of flexibility and stability can be achieved in the support arm.

There is also described herein a radiotherapy X-ray tube support arm for supporting an X-ray tube head of mass 1kg to 15kg, the support arm comprising: a first elongate section for connecting to a base support unit; and a second elongate section, movably coupled to the first elongate section, the second elongate section for attaching to the X-ray tube head; wherein the first and second elongate sections each comprise at least one parallelogram linkage.

It is possible to provide a support arm or structure as described herein for any X-ray tube type and/or configuration, in particular an end-window or side window tube (e.g. a Varian NDI-226, or Comet MXR-1 01).

Preferably, each parallelogram linkage comprises: a first elongate substantially rigid member having a first end and a second end; a second elongate substantially rigid member having a first end and a second end; a first substantially rigid linkage member fixed to the first end of each elongate member by a pivot joint, such that the second ends of the elongate members are maintained at a constant separation distance; wherein the second ends of each elongate member are pivotably fixed such that the second ends of the elongate members are maintained at a constant separation distance, equal to the separation distance of the first ends of the elongate members; such that the two elongate members are configured to rotate in an arc while remaining parallel.

Preferably, a second substantially rigid linkage member fixed to the second end of each elongate member by a pivot joint the second ends of each elongate member for maintaining the second ends of the elongate members at said constant separation distance.

By providing two members, or struts which are kept parallel either by fixing each of the struts a given length apart at one end and providing a hinged linkage of the same length between the two at the other ends, or by providing two hinged linkages of the same length between the struts, the parallelogram linkages are strong, stable and manoeuvrable.

Preferably, the maintaining arrangement comprises at least one friction component for applying friction to one or more of: the hinged joint coupling the first and second elongate sections; the joint attaching the X-ray tube housing to the second elongate section; and the joint fixing the first elongate section to the base support arrangement; wherein the level of friction applied by the friction component is adjustable.

By providing a joint in which the degree of friction can be changed or controlled, the balancing and movement of the arm can be finely adjusted. For example, when a friction joint may be provided to fix the first and second sections of the arm together and the degree of friction in the joint can be adjusted to give the desired degree of manoeuvrability and stability in the movement of the two sections pivot about their joint. Other joints, such as the one connecting the first section to the base support unit, could also be adjustable friction joints for adjusting the manoeuvrability and stability of other movements.

Preferably, the degree of applied friction is adjustable by means of a spring washer.

A spring washer provides an easily adjustable means for adjusting the degree of friction in a joint.

Preferably, the degree of applied friction is adjustable by means of a Belleville washer.

A Belleville washer (or coned-disc spring, conical spring washer or disc spring) has a frusto-conical shape which makes it act like a spring, and is very effective for providing an adjustable force. For example, Belleville washers have a high fatigue life, so don't require frequent replacement, a low creep tendency, so don't require frequent adjustment, and have a high load capacity with small spring deflection, which makes them very space-efficient.

Preferably, the degree of applied friction is adjustable by means of a Wave washer.

A wave washer has a "wave" in the axial direction, which makes it behave like a spring when compressed. Wave washers generally produce a smaller force than Belleville washers of the same size. However, this could be an advantage in an adjustable friction joint where only a small adjustment in the friction is desired. Thus it may be advantageous to provide a friction joint comprising both wave and Belleville washers.

Preferably, the degree of applied friction is adjustable by means of a compressible plastic component.

Using a piece of compressible plastic for providing an adjustable friction force can be advantageous as plastic components are cheap and easy to manufacture to exact specifications. For example, a nylon or Delrin (i.e. polyoxymethylene) block or washer could be used.

Preferably, the joint attaching the X-ray tube housing to the second elongate section comprises: a dual axis joint configured to allow rotation about at least a first axis and a second axis.

It is easier to position the X-ray tube head correctly and precisely on the required patient treatment area when the tube head can be moved translationally in several directions (this movement is provided by the support arm, as described above) and also rotationally in several directions so that it can point in any direction, i.e. to change the orientation. Part of this rotational movement can be provided by rotating the support structure, but by allowing the X-ray tube head to rotate in relation to the end of the support arm about at least two axes, the positioning is more flexible and finely adjustable. A ball joint can be used to allow rotation in more than one plane. However, the frictional forces provided by a ball joint are the same along all axes, but the forces that need to be counteracted by the joint are different in each axis. Thus it is often necessary to provide separate counterbalancing means when using a ball joint. By providing a dual axis joint, the friction on the rotational movement is provided about two axes which can each be controlled separately.

There is also described herein radiotherapy X-ray system for delivering X-ray radiation to a patient, comprising: a housing for receiving an X-ray tube, the housing having a fluid pipe or an air pipe for fluid or air cooling the X-ray tube and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; one or more collimator(s) integrated into the housing, the one or more collimator(s) for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering said X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, one or more collimator(s), X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the moveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a joint and a distal end; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein the X-ray tube housing is attached to the second elongate section via a dual axis joint configured to allow rotation about at least a first axis and a second axis which permits two degrees of freedom in the movement of the X-ray housing relative to the second elongate section; and a biasing arrangement and maintaining arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.

Preferably, the dual axis joint comprises a friction joint.

By providing a dual-axis friction or torque joint, the tube housing can be easily repositioned with respect to the end of the second section, but also independently maintain its position when left.

Preferably, the first axis is in the plane containing the first and second elongate sections; the second axis is perpendicular to the plane containing the first and second elongate sections; and the dual axis friction joint is configured such that the friction about the second axis is greater than the friction about the first axis.

By providing different degrees of friction, or torque, about the two axes, the force applied for maintaining the tube head in position around each axis can be optimised separately. For example, "nodding", or up-down, direction requires a fairly high level of friction for counterbalancing the weight of the tube head compared to the side-to-side, or "rotational", direction. As mentioned above in relation to the frictional joint for balancing the arm, the friction in each axis may be provided by one or more Belleville washers, Wave washers and/or compressible plastic components.

Preferably, the dual axis joint is configured such that: the torque required for rotation about the first axis is greater than 1Nm1, preferably greater than 1.25Nm1 and/or less than 2.5Nm1, preferably less than 2Nm1, more preferably less than 1.75Nm 1; and/or the torque required for rotation about the second axis is greater than 2Nm1, preferably greater than 2.5 Nm1, more preferably greater than 2.75Nm and/or less than 10Nm1, preferably less than 5 Nm1 and/or more preferably less than 3.25Nm1.

By providing such torque values, the tube head can be easily moved by an operator, while maintaining its position when an operator is not applying a force.

Preferably, the joint for fixing the proximal end of the first elongate section to the base support arrangement comprises a rotation joint.

By providing a rotation joint for attaching the support structure to the base support or base unit, a further degree of freedom is provided, in that the first section of the support can rotate about the base unit while the second support section can move independently of the first section e.g. to pivot about the end of the first section.

Preferably the axis of rotation is about a vertical axis.

Preferably, the maintaining arrangement comprises a braking mechanism for locking said rotation joint.

By providing a braking mechanism for locking the rotational joint, the support arm can be locked so that it cannot rotate once it is in the correct position to provide a stable support for the tube head. When joints have a braking mechanism, it is also possible to make them easier to move (i.e. by providing less friction in the joint), which would make it easier, and possibly also quicker, for the operator to reposition the support structure by rotating it about this joint. The braking mechanism means this joint can be actively controlled by the operator.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient, comprising: a housing for receiving an X-ray tube, the housing having a fluid pipe or an air pipe for fluid or air cooling the X-ray tube and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; one or more collimator(s) integrated into the housing, the one or more collimator(s) for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering said X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, one or more collimator(s), X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the moveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a rotation joint and a distal end; a braking mechanism for inhibiting movement of said rotation joint; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein the X-ray tube housing is attached to the second elongate section via at least one joint which permits movement of the X-ray housing relative to the second elongate section; and a biasing arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.

Preferably, said braking mechanism comprises a mechanical braking mechanism.

By providing a mechanical braking mechanism (e.g. a locking handle), it is possible to provide a simple and easy means of locking the rotational joint of the support structure. For example, a mechanical braking mechanism would not require an electrical power supply, making installation and setup easier and reducing running costs.

Preferably, said braking mechanism comprises an electronic braking mechanism.

By providing an electronic braking mechanism, the operator can lock and unlock the rotational joint of the support arm with very little effort, for example by simply pressing a single button. It is normally easier to actuate an electronic braking means than one that is purely mechanical because mechanical braking may require the application of a force. It is also easier to place the actuation means for an electronic braking means in a convenient place for the operator to reach while positioning the tube head, whereas a mechanical braking means may have to be positioned at, or close to, the joint. The rotational joint for base connection may often be some distance from the position of the X-ray tube head, making this impractical.

Preferably, the braking mechanism is operable from the X-ray tube housing.

Positioning a user braking control mechanism in or on the X-ray tube head makes it very easy for the operator to access the controls and activate or deactivate the brakes while repositioning the tube head. This can improve efficiency while using the device as the operator can position the tube head more quickly.

Preferably, the moveable support structure further comprises: one or more cosmetic covers for covering one or more of the elongate sections; wherein the fluid pipe or air pipe and a power supply cable are routed through at least a part of said one or more cosmetic covers.

There is also described herein a support structure for a radiotherapy X-ray generation tube head, comprising: at least two elongate sections for securing the X-ray generation tube head to a base support unit; and a plurality of joints for allowing the X-ray generation tube to move with multiple degrees of freedom; wherein the plurality of joints includes: at least one passive joint; and at least one actively controlled joint.

By providing a support structure for an X-ray tube head that has a several joints, some of which have actively controlled stabilising components (i.e. the operator must perform an action to enable them to hold a position), and some of which have passively controlled stabilising components (i.e. the joints automatically hold whichever position they are placed in without any operator action), the tube head position can easily be adjusted. The support structure requires many joints to enable movement of the tube head in different directions so that it can be positioned flexibly. Actively controlled joints can be easier to move and allow a greater range of movement because they do not require the stabilising components to be constantly actuated. However, when there are multiple joints each may require several adjustments, particularly in response to the other joints being adjusted (i.e. when adjusting a first joint causes the location of a second joint to move, the second joint may requires a further adjustment). In such cases, it is can be repetitive and time-consuming for an operator to lock and unlock each joint after each movement, and difficult tor operator to support the entire arm and tube mechanism while keeping all the joints unlocked (i.e. free to move). The passively controlled friction joints are also cheaper than the actively controlled electronically locking joints, so using a combination of the two provides a cost-effective solution.

Therefore it is advantageous to provide a combination of active joints for a large range of movement and passive joints for ease of adjustment.

Preferably, the movement of the at least one passive joint is dependent on friction in the joint.

Frictional or torque provides an easily adjustable and stable means of controlling movement in a joint.

There is also described herein an X-ray generator, preferably for use in any radiotherapy system described herein, comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of one or more collimator(s) allows through an X-ray beam with a beam angle of at least 35° in at least one plane; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; wherein the generator is arranged to operate with at least one removable applicator which defines an X-ray treatment surface with a 4-6cm diameter at a distance of 4-6cm from the X-ray target.

There is also described herein an X-ray generator control apparatus, preferably for use with any system or generator described herein, the control apparatus comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected power level corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; wherein at least a portion of the control apparatus housing is provided in a housing, said housing configured to be positioned remotely from the generator.

There is also described herein an X-ray applicator, preferably for use with any radiotherapy system or X-ray generator described herein, the applicator defining an X-ray treatment surface on a patient; the applicator having a mounting portion for engaging with a fitting in an X-ray tube housing for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between an X-ray target and the X-ray treatment surface; wherein the applicator is arranged to transmit light from one or more light sources provided on the X-ray tube housing to the X-ray treatment surface.

An applicator which can define a short distance between the X-ray source and treatment area (i.e. working distance" or FSD) is advantageous because a wider beam angle, and smaller, lighter devices with a lower power input can be used to provide an X-ray field that is sufficient for clinical applications. It is also useful to provide several, interchangeable applicators for providing different treatment beams from the same X-ray tube. Providing an applicator that acts as a light pipe for channelling or transmitting light towards the X-ray treatment surface can help illuminate the treatment surface and may provide a clear visual indication that the applicator is in contact with the patient's skin and/or mark the area that will be irradiated by the X-ray beam.

Preferably, the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; preferably less than 10cm, less than 8cm, less than 6cm or even less than 5cm and/or preferably more than 1cm, or preferably more than 2cm. An advantageous working distance has been found to be between 4.5cm and 5.5cm.

Preferably, the mounting portion comprises a portion for absorbing X-ray radiation and an aperture for providing secondary collimation for an X-ray beam.

The collimation of the X-ray beam should be altered when the working distance is changed. Since the applicator can define the working distance, it is also useful to integrate a collimator into the applicator, so that the beam can be collimated correctly.

Preferably, the applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface for contacting the X-ray treatment surface to define the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; and wherein the side walls are formed substantially of material that is transparent.

Providing an applicator with a substantially transparent (or at least translucent) portion, the operator may have a good view of the X-ray treatment area and may be able to position the X-ray applicator more efficiently.

Preferably, the applicator comprises a light pipe for extending through the mounting portion and coupling the transparent side walls of the applicator to one or more light sources provided in the X-ray tube housing; and wherein the applicator side walls acts as a light pipe for channelling light from the light sources towards an X-ray treatment surface and emitting light from the end of the side walls for contacting the X-ray treatment surface, such that the edge of the treatment surface is illuminated when the applicator makes contact with said treatment surface.

Providing an applicator that acts as a light pipe for channelling light towards the X-ray treatment surface can help illuminate the treatment surface and may provide a clear visual indication that the applicator is in contact with the patient's skin and/or mark the area that will be irradiated by the X-ray beam.

There is also described herein a plurality of interchangeable X-ray filters for a radiotherapy X-ray system, preferably for use with any radiotherapy system or X-ray generator described herein, wherein the thickness of each filter varies across the filtering region to alter the shape of the X-ray beam dose intensity in a different way to compensate for variation in X-ray beam intensity caused by the non-uniform output of an X-ray tube.

By providing multiple filters which can change the shape of the X-ray beam dose to compensate for the variation with angle in the normalised intensity produced by an X-ray tube, which may make it possible to use a relatively large beam angle to produce a dose of uniform intensity. Normally the filter would be thicker in the centre, so that the X-ray beam at larger angles (where the normalised intensity is less) will experience less attenuation from the filter. Using a large beam angle can reduce the input power required to generate an X-ray beam of a given intensity across a given area.

Furthermore, it is also possible to change the shape of the X-ray beam to give a uniform dose across treatment areas that are not flat (e.g. concave or convex).

Preferably, at least one of the plurality of filters has a thickness that varies across the filtering region to compensate for variation in X-ray beam intensity due to the difference in distance travelled between an X-ray target and an X-ray treatment surface by the beam at different beam angles.

Since beams propagating at larger angles travel further before reaching a flat surface, the intensity is decreased because the beam is more dispersed. Due to the inverse square law, this effect becomes significant at large angles and particularly as distance increases; thus it can be helpful to change the thickness of the filter material across the filter dependent on the angle and the desired FSD. E.g. for a flat treatment surface the filter material would be thicker in the centre of the beam. The distance the beam travels through the filter material at different angles may also be taken into account, again by reducing the thickness of the filter material in the centre of the filter.

There is also described herein a shield for an elongate end-window X-ray tube having a tube diameter of between 20mm and 75mm, the tube comprising an X-ray target for generating an X-ray beam positioned adjacent the end window, the shield comprising: a recess dimensioned for receiving and locating the X-ray emitting end of the elongate end-window X-ray tube, the recess having a portion arranged to extend around the sides of the X-ray tube to surround the X-ray target radially and absorb a portion of the X-ray radiation that does not pass through the end-window end of the X-ray tube; and an aperture arranged to align with the end-window for allowing an X-ray beam emitted from the end-window of the X-ray tube through the shield; wherein the aperture is shaped and dimensioned for collimating the X-ray beam to provide a beam angle of between 35° and 90° and narrower than the beam emerging from the X-ray tube window.

Preferably, the shield is formed substantially of tungsten.

By forming the shield of tungsten, the thickness of the shield can be reduced as tungsten provides very good X-ray absorption and has a high mechanical integrity, so it is possible to form strong and thin (e.g. <1mm) detailed structures accurately.

Preferably, the recess is dimensioned for positioning the aperture between 8mm and 30mm from the X-ray target.

By collimating the X-ray beam close to the X-ray target, the size of the shield can be reduced as even a wide angle beam has a narrow diameter close to the source.

Preferably, the recess is dimensioned for positioning the aperture less than 10mm from the X-ray target.

There is also described herein a radiotherapy X-ray tube head, preferably for use with any radiotherapy system or X-ray generator described herein, the tube head comprising a housing for an end-window X-ray tube, the housing having provision for attaching an applicator for defining an X-ray treatment surface and an X-ray treatment beam zone, the tube head further comprising: provision for attaching a camera within the X-ray beam zone for imaging the X-ray treatment surface; and means for disabling the X-ray tube while the camera is positioned within the X-ray beam zone.

By placing a camera within the X-ray beam zone, a very accurate image of an X-ray treatment surface with the applicator positioned over it can be provided.

There is also described herein a radiotherapy X-ray tube head, preferably for use with any radiotherapy system or X-ray generator described herein, the tube head comprising a housing for an end-window X-ray tube, the housing having: provision for attaching an applicator for defining an X-ray treatment surface and X-ray treatment beam zone; and a camera for imaging the X-ray treatment surface fitted to the X-ray housing outside the X-ray beam zone.

By placing a camera outside the X-ray beam zone, live images of the applicator placed on the treatment surface can be obtained, which can help ensure the X-ray tube apparatus remains properly and safely set up during operation. For example, motion detection software can be used to identify when the X-ray applicator moves by more than a threshold distance after set-up.

Preferably, the housing further having provision for attaching at least two cameras for imaging the X-ray treatment surface and arranged such that images from the two cameras can be combined to produce 3-dimensional imaging.

By providing two cameras for producing 3-0 images of the X-ray treatment surface, an easy and efficient means for obtaining 3-D images of patient treatment sites is provided. These can be used for diagnosis and/or keeping a treatment record.

There is also described herein a radiotherapy X-ray tube head comprising a housing for an end-window X-ray tube, preferably for use with any radiotherapy system or X-ray generator described herein, the housing having provision for attaching an applicator for defining an X-ray treatment surface and an electronic distance measuring device coupled to the X-ray housing for measuring the distance between the X-ray target and the X-ray treatment surface.

By providing an electronic distance measuring means for an X-ray tube head, the setup of the X-ray applicator in relation to the treatment area can be monitored. This is useful for safety.

Preferably, the tube head further comprises: means for providing an indication to an operator in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.

Preferably, the tube head further comprises: means for disabling the X-ray beam in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.

There is also described herein a method of configuring an X-ray filter for use with an X-ray apparatus including an end-window X-ray tube for generating an X-ray beam, means for supporting a filter in a plane across the path of the X-ray beam, and an applicator defining a patient treatment surface, the method comprising the steps of: determining the divergence of the X-ray beam at a plurality of points in the plane across the path of the X-ray beam; calculating the variation in beam intensity across the treatment surface based on the variation with beam angle of X-rays emitted by the X-ray apparatus and the variation of path length from the X-ray apparatus to points on the treatment surface; and calculating a filter profile based on the attenuation of the filter material, the divergence of the X-ray beam in the plane and the calculated variation in beam intensity to give a desired intensity profile across the treatment surface.

By providing a method of configuring an X-ray filter in which the profile of the filter is calculated based on the variation in beam intensity across the treatment surface with angle, it is possible to provide a filter which gives a desired beam intensity for X-ray treatment.

Preferably, the desired intensity profile is of substantially uniform intensity across the treatment surface.

By configuring an X-ray filter to give a uniform intensity across the treatment surface, an improved X-ray treatment can be provided.

Preferably, the treatment surface is concave, convex or flat.

By providing an X-ray filter which gives a desired treatment profile across a concave, convex or flat treatment surface, X-ray treatment can be tailored to different treatment areas on a patient's body, e.g. lips, neck, eyelids.

There is also described herein a method for cosmetically treating a non-malignant skin condition, comprising: providing an X-ray generation tube comprising an X-ray target and an end-window at one end of the tube for emitting said X-ray beam, the X-ray tube providing a beam having a beam angle of at least 35°; positioning the X-ray generation tube such that the distance between the X-ray target and an X-ray treatment surface on a patient is less than 10cm, preferably less than 7cm, preferably between 4.5cm and 5.5cm; and generating an X-ray beam using the X-ray generation tube; wherein said X-ray treatment surface contains at least a portion skin affected by said non-malignant skin condition.

By cosmetically treating non-malignant skin conditions in this way, the treatment can be more effective, the treatment time shorter and the cost less than with previous methods.

Preferably, the X-ray beam generated has an energy of between 5kV and 100kV, preferably an energy greater than 50kV, more preferably greater than 65kV, or more preferably greater than 75kV.

Preferably, the X-ray tube is operable to deliver a dose at the treatment surface of greater than iGy/min with a half-value layer of 0.9mm Aluminium or greater.

By providing a dose of this kind, it is possible to treat skin disorders effectively.

Preferably, the X-ray tube provides a beam having a normalised intensity on a flat surface of at least 70% across a beam angle of at least 50°.

The width of the beam angle should be understood to refer to the full angle of the section of the beam that has a substantial intensity i.e. a clinically useful intensity, rather than the widest beam angle produced due to stray or grossly attenuated X-rays. This intensity is normally measured as a normalised intensity (i.e. intensity measured on a flat surface). Preferably a beam of substantial intensity has an intensity at the widest angle of at least 50% of the intensity at the centre of the beam (0° from the normal), more preferably the intensity at the widest angle is at least 70% of the intensity at the centre of the beam.

Preferably, the X-ray beam controller is operable to select at least one X-ray beam energy between 5kV and 100kV.

Preferably, the distance between the X-ray target and the end-window of the X-ray tube is less than 25mm, preferably less than 15mm, more preferably less than 10mm, more preferably less than 8mm and/or greater than 4mm.

By providing such a small distance between the X-ray target and the end-window of the X-ray tube, it is possible to provide a wide beam angle and/or a short FSD. By providing a target close to the end of the tube, it may also be possible to reduce the size of other components of the X-ray apparatus, such as the collimators and filters, because close to the end of the X-ray tube, the X-ray beam is still narrow. This may create a lighter-weight and more compact design. Furthermore, when these components are smaller, it is possible to use the X-ray beam at a very short working distance or focus skin distance (FSD), i.e. the distance between the focus (or X-ray target) of an X-ray tube to the surface of incidence on a patient, which is normally measured along the axis of the X-ray beam. Preferably the distance between the X-ray target and the end-window of the X-ray tube is less than 10mm, or less than 7mm, or more preferably between 5.5mm and 6.5mm.

Some of the systems described herein comprise several components, which may be provided individually, particularly when they are removable and/or interchangeable parts of the system.

There is also described herein radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for conducting a cooling fluid supply and a power supply to the X-ray tube; provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; a primary collimator provided in the housing between the end-window and the fitting for receiving a removable applicator, the primary collimator for collimating said X-ray beam, and the primary collimator comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of the primary collimator allows through an X-ray beam with a beam angle of at least 35°; and a moveable support structure for the housing; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam power controller for controlling the beam to at least one selected X-ray beam power level; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray beam power level correspond to an allowable combination and selectively enabling the X-ray generator only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; and wherein the applicator is arranged to co-operate with the applicator detection logic to communicate the applicator identifier thereto; and at least one removable filter having a filtering region with a non-uniform thickness for adjusting the X-ray beam intensity profile based on the X-ray beam profile from the X-ray tube; wherein the filter is arranged for use with at least one applicator; and wherein the filter is arranged to co-operate with the filter detection logic to communicate the filter identifier thereto.

There is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the distance between the X-ray target and the end-window of the X-ray tube is less than 10mm and wherein the X-ray tube provides a beam having a normalised intensity on a flat surface of at least 70% across a beam angle of at least 500; a housing for receiving the X-ray tube, the housing having: provision for conducting a cooling fluid supply and a power supply to the X-ray tube; provision for receiving an X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; and a primary collimator provided in the housing between the end-window and the fitting for receiving a removable applicator, the primary collimator for collimating said X-ray beam, and the primary collimator comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of the primary collimator allows through an X-ray beam with a beam angle of at least 500; and a moveable support structure for the housing; and at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; and wherein the system is arranged to operate with at least one applicator which defines an X-ray treatment surface with a 5cm diameter at a distance of 5cm from the X-ray target.

According to another aspect, there is also described herein a radiotherapy X-ray system for delivering X-ray radiation to a patient, comprising: a housing for receiving an X-ray tube, the housing having connections for a cooling fluid supply and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; a primary collimator integrated into the housing, the primary collimator for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering the X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, primary collimator, X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the nioveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a joint and a distal end; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; a cooling fluid supply cable and a power supply cable, each flexibly attached to the moveable support structure; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein at least one of the first and second elongate sections comprises a parallelogram linkage; wherein the X-ray tube housing is attached to the second elongate section via at least one joint which permits movement of the X-ray housing relative to the second elongate section; and a biasing arrangement and maintaining arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.

Any of the optional or preferred features described above in relation to the X-ray apparatus, may also be provided as an independent aspect and/or applied to the individual components, which may be individually removable, such as the collimator, X-ray filter or applicator.

Definitions Half-Value Layer (HVL) is the thickness of a material at which the intensity of radiation entering it is reduced by one half.

Focal Spot Distance is (FSD) is the distance between the focus (or X-ray target) of an X-ray tube to the surface of incidence on a patient, which is normally measured along the axis of the X-ray beam.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, by way of example only and with reference to the accompanying drawings, in which: Figure 1 illustrates an example embodiment of an X-ray apparatus for radiotherapy; Figure 2 illustrates shows a portion of a second embodiment of an X-ray apparatus for radiotherapy; Figure 3 illustrates an example embodiment of an X-ray tube head; Figure 4 illustrates an enlarged view of an area of Figure 3; Figure 5 is a graph illustrating the output intensity of an X-ray tube; Figure 6A illustrates an example embodiment of a uniform, flat filter; Figure 60 illustrates the measured beam dose profile for the filter of Figure 6A; Figure 7A illustrates an example embodiment of a uniform beam path filter; Figure 7B illustrates a magnified portion of Figure 7A; Figure 70 illustrates the measured beam dose profile for the filter of Figure 7A Figure BA illustrates an example embodiment of a uniform beam path filter; Figure SB illustrates a magnified portion of Figure 8A; Figure 80 illustrates the measured beam dose profile for the filter of Figure 8A; Figure 9 illustrates an example embodiment of an X-ray applicator; Figure 10 illustrates a second example embodiment of an X-ray applicator; Figure 11 illustrates an X-ray tube head in different orientations; Figure 12 illustrates a ball joint; Figure 13 illustrates an example embodiment of an X-ray support structure; Figure 14A illustrates an example embodiment of a lighting ring; Figure 14B illustrates the lighting ring of Figure 14A from the side; Figure 140 illustrates a printed circuit board for use in a light ring; Figure 14D illustrates another example embodiment of a lighting ring; Figure 14E illustrates the lighting ring of Figure 140 from the side; Figure 15A illustrates an example embodiment of a filter carrier; Figure 15B illustrates the filter carrier of Figure ISA from below; Figure 16A illustrates an example embodiment of a dual axis joint; Figure 16B illustrates an alternative example embodiment of a dual axis joint; Figure 17A illustrates another example embodiment of an applicator; Figure 17B illustrates the applicator of Figure 17A from above; and Figure 170 illustrates the applicator of Figure 1 7A from below.

DETAILED DESCRIPTION OF THE INVENTION

Referring to Figure 1, an example embodiment of an X-ray apparatus for radiotherapy will now be described. Figure 1 show an X-ray tube head 100 comprising an X-ray tube 110 for generating X-ray radiation. The X-ray tube 110 is surrounded by a tube housing 112 and attached to a supply cable 114 and a support 116.

Advantageously, the presently described X-ray apparatus is small in size (for example the X-ray tube outer cover has a 76mm) and lightweight (the X-ray tube head weighs approximately 2kg). The supply cable 114 can be used for supplying electricity for X-ray generation. The cable could also be used to supply air or water for cooling the X-ray tube head 100, or a separate cable could be used for this purpose. Although in this embodiment the supply cable 114 exits the X-ray tube head IOU atan angle of -45°, other angles are also possible; for example in another embodiment the supply cable 114 exits the tube head 100 from the top of the X-ray tube head 100.

X-ray tubes produce X-rays by accelerating electrons from a cathode to collide with an anode (i.e. an X-ray target) by a high voltage electrical field. Xrays are generated when the high-energy electrons collide with the anode. The X-ray tube 110 has a 50W power supply, generates an X-ray beam with a maximum power of 50kV and weighs 1.2- 1.3kg. However, more powerful tubes (e.g. 80kV, lOOWtube, which may weigh slightly more) would also be suitable. The X-ray tube 110 has an end-window 118 for emitting an X-ray beam. Inside the X-ray tube 100 is an X-ray target 120 for generating an X-ray beam, positioned at the focal spot of the X-ray tube 110, approximately 6mm from the end-window 118 of the X-ray tube 110. Positioning the focal spot so close to the end of the end-window X-Ray tube 110 and the tube end-window 118 makes it possible to get a very wide beam angle from the X-Ray source. In this embodiment, the maximum beam angle is approximately 80° (or ±40° from the normal to the end of the tube), and the end-window 118 has a diameter of about 8mm. However, the diameter may be greater than 6mm or greater than 7mm, and less than 9mm, or less than 10mm.

Covering the end of the X-ray tube 110 is a primary collimator 130 formed of tungsten, which absorbs X-rays. Lead could be used as an alternative to tungsten; generally a only very thin piece of tungsten or lead (-1 -2mm) is required to block the X-rays emitted by an X-ray tube 110 such as that shown in Figure 1. The primary collimator 130 has a cap" shape, so that the side walls extend up the sides of the X-ray tube 110 to surround the X-ray target 120 from all but one direction (the top). The primary collimator 130 has an aperture positioned below the X-ray target 120 for allowing the X-ray beam through. Providing the primary collimator 130 in such a cap" shape also allows for very accurate alignment of the aperture with the X-ray target 120.

Below the primary collimator 130 is an X-ray filter 140 for filtering the X-ray beam.

The filter 140 has a diameter of approximately 20mm and is up to 2mm thick. The filter can be easily removed from the apparatus, and normally a plurality of interchangeable filters are provided with such an X-ray apparatus to allow the system to work at different energies, with different beam qualities and different depth and dose profiles. The filter 140 can also be used for flattening the X-ray beam. The filter 140 is made of aluminium of -1mm thickness.

Below the filter 140 is a secondary collimator 150 for further collimating the X-ray beam. This secondary collimator 150 is removable and, like with the filter, several different sized secondary collimators may be used with the system for providing different degrees of collimation. The secondary collimator 150 is about 23mm in diameter and also formed from tungsten.

Extending from the front of the X-ray tube 110 is an applicator 160 for making contact with the patient's skin, to ensure the correct distance and size of the X-ray treatment area. The applicator 160 is removable and interchangeable in order to allow different X-ray treatment field sizes and different working distances. In this embodiment, the working distance or focus skin distance (FSD), i.e. the distance between the focus (or X-ray target 120) and the surface of incidence on a patient, which is normally measured along the axis of the X-ray beam, is 5cm. At Scm FSD, the applicator 160 defines an X-ray treatment field with a 6cm diameter, as shown in Figure 1. The applicator 160 is transparent to allow the operator to see the X-ray treatment area clearly and can be made, for example, of Perspex (i.e. Poly(methyl methacrylate) or PMMA).

The applicator 160 is cone-shaped, with side walls that extend from the end of the X-ray tube 110 to the X-ray treatment area. Perspex allows good oxygenation of the X-ray treatment area and is also good for absorption of the X-ray beam. This is useful, as the side walls of the applicator 160 can provide a final level of collimation for the beam.

Polystyrene could be used, but has a much lower X-ray absorption than Perspex. Lead crystal glass is also another alternative, but can be dangerous if broken.

The secondary collimator 150 can also be integrated into the applicator 160, to allow quick and simple insertion and removal of both components. The applicator 160 defines the distance between the X-ray target and treatment surface, and also the area of the X-ray treatment surface. Since different distances and areas require different beam collimation, it is useful to combine the applicator 160 and secondary collimator into one removable component.

Figure 2 shows a portion of a second embodiment of an X-ray apparatus for radiotherapy, similar to that of Figure 1. Like reference numerals have been used to denote like components. The X-ray system of Figure 2 has a tube head 100' with an applicator 160'. The applicator 160' is smaller than the applicator 160 in Figure 1, in that the side walls of the applicator 160' are at an angle of ±16.7° to the normal to the end of the tube head 100', and the side walls define an area with a 3cm diameter at Scm FSD, as shown in Figure 2. The applicator 160' of Figure 2 is also transparent to visible light.

Thus a secondary collimator 150' is provided, which differs from the secondary collimator of Figure 1 in that it provides more collimation and narrows the X-ray beam further.

The X-ray system of Figure 2 also includes an integrated LED lighting ring 170' for illuminating the treatment field and surrounding area, which helps the operator to place the applicator in the correct position. Providing illumination from inside the tube head 100' is very efficient as it is unlikely that other components can obstruct the light or cast shadows over the treatment area, as may happen when a separate illumination device is used. It also means that the operator does not have to adjust the positioning of a separate lighting device every time the tube head 100' is moved, which saves the operator time. As the applicator 160' is transparent, the operator is able to see the X-ray treatment field, which helps in positioning. The LED lighting ring 170' is positioned above the transparent applicator 160', so that the walls of the applicator 160' act as a "light pipe" or "light tube" by channelling the light to the ends of the side walls that are for making contact with the patient treatment area. When the applicator makes good contact with a surface (i.e. the patient's skin), a ring of light ("halo" ring) appears on the surface of the skin, directly outside the treatment area. When the applicator moves away slightly from the skin surface, the light of the "halo" ring disperses very quickly, so that the ring appears broken. This provides an instantaneous indication to the operator of that the applicator is in good and even contact with the skin (i.e. there will be no "stand off" -a reduction in dose provided to the treatment area due to improper positioning).

Figure 3 provides a more detailed view of another embodiment of an X-ray tube head 100", where like reference numerals have also been used to denote the same or similar components to those in Figures 1 and 2.

The supply cable 114" differs from the previous embodiment in that it extends from one end of the X-ray tube 110'. The X-ray tube 110" has a connection for the supply cable 114", in this case a High Tension (HT) cable, already built in. The X-ray tube 110" is supplied with a fixed length HT cable integrated and pre-connected. This allows notable space to be saved at the top of the X-Ray tube 110", and ensures the X-ray tube head 100" can be kept as small as possible.

The X-ray tube head 100" of Figure 3 also incorporates a water cooling jacket 180" for cooling the X-ray tube 110", which has water cooling pipes 182" surrounding the X-ray tube 110". Such a small X-Ray tube 110" would typically be air cooled and not water cooled. However, water provides more efficient cooling, which means the size can be reduced, allowing a more compact tube head 100". Water cooling systems also require less maintenance than air-cooled systems, which can become blocked with dust which has to be removed.

Figure 4 is an enlarged view of the area marked "B" in Figure 3. Some of the dimensions are marked in mm, showing the FSD to be 50mm, and a treatment area defined by the applicator of a 54.1mm diameter. The widest angle beam which can pass through the primary collimator 130" is shown, and marked as 56.82° (i.e. ±28.41°).

The primary collimator 130" is formed of a single piece of metal -normally Tungsten, but lead and copper are suitable alternatives. If tungsten, a 1cm thickness is enough to absorb the X-rays not intended for the X-ray beam. The primary collimator 130" is located a very short distance (less than 1 cm) from the X-ray target 120". This provides less backscatter than if it was placed further from the X-ray source. The primary collimator 130" comprises an aperture 132" for allowing X-ray beams through. The aperture 132" is cone-shaped, with the width of the aperture 132" increasing with distance from the target, along the line of the widest angle X-ray beam. This helps to provide a better collimation than if the aperture was of a constant size, because less diffraction of the beam occurs.

The X-ray filter 140" is supported by a filter carrier 142", which allows quick and easy insertion/removal of the filter 140" into/from the X-ray apparatus. The system will generally be provided with several interchangeable filters like the filter 140" shown in Figure 4. Each filter can allow different X-ray beam filtration, and therefore allow the system to work at different energies with different beam quality and different depth and dose profiles. By manipulating the shape, or profile, of the filter 140" it is possible to differentially manipulate the X-Ray beam. For example, this permits beam manipulation for beam flattening (for a uniform dose field for a flat field treatment applicator), beam manipulation to create a uniform dose field for a convex field treatment applicator or for a concave treatment applicator. VVhen the filter 140" is fitted onto the X-ray tube head, the pin makes electrical contact so the system can automatically determine which type of filter is fitted. This information can be determined, for example, by the control system of the X-ray tube.

The applicator 160" is configured for easy attachment and removal to the X-ray tube head 100". The system would normally be provided with several interchangeable applicators, where each applicator can allow a different field sizes at different working distances. The applicator 160" shown in Figure 4 has side walls 164" extending from the front of the X-ray tube head 100". The side walls 164" are generally circular (not shown), which make the applicator 160" cone-shaped. The applicator 160" has a circular, flat treatment face 162". However, interchangeable applicators of different shapes may also be provided for use with the apparatus, e.g. an applicator with a circular, convex (i.e. spherical) treatment face, or with a circular, concave treatment face. There could also be provided non-circular variants of these (e.g. elliptical, square, rectangular). Different shaped applicator faces are useful for tailoring X-ray treatment to different parts of the human body, e.g. nose or chin, which do not form a continuous flat surface. The applicator 160' is made of transparent Perspex to allow the operator a clear view of the X-ray treatment area. The applicator 160" has an encoder pin, which stores information about the type and/or dimensions of the applicator 160". When the applicator 160" is fitted onto the X-ray tube head, the pin makes electrical contact so the system can automatically determine which type of applicator is fitted. This information can be determined, for example, by the control system of the X-ray tube. Safety settings can be configured to ensure that X-rays of certain energies are only emitted when the correct applicator (or correct combination of filter and applicator) is fitted and to ensure no X-rays are emitted when no applicator and/or filter installed.

Integrated into the applicator 160" is a secondary collimator 150", formed of tungsten, and includes an aperture 152" for allowing the X-ray beam to pass through.

Lead could also be used for the collimator. Generally a very thin thickness of tungsten or lead (-1-2mm) is required to block the X-rays emitted by an X-ray tube 110" such as that shown in Figure 4. As shown, the secondary collimator 152" provides slightly more collimation than the primary collimator 130", since the aperture 152" of the secondary collimator 150" is set to allow a narrower widest beam angle.

Generally, the secondary collimator 150" provides sufficient collimation for the X-ray treatment field required with each applicator. However, the applicator 160" can provide further collimation for the X-ray beam. The widest beam angle which can pass through the primary collimator 130 is shown in Figure 4 passing through the side walls 164" of the applicator 160". By the time the X-ray beam reaches the side walls 164" of the applicator 160', it has been collimated sufficiently, so that any rays enter the side walls 160" only propagate at a very small angle with respect to the angle of the side walls 160". Therefore the outer edge of the X-ray beam must pass a fairly long distance (several cm -e.g. 2 to 4cm at 5cm FSD) through the side walls 160" before being emitted at the treatment face 162". Although Perspex is much less efficient at blocking X-rays than the material used in the collimators (e.g. tungsten or lead), the Perspex side walls 162 can provide sufficient X-ray attenuation at the outer edges of the beam due to the distance the X-rays must travel through the side walls.

The LED lighting ring 170' includes LEDS 172" for illuminating the X-ray treatment surface and surrounding area. The LEDs 172" are located inside the X-ray tube head 110". The transparent applicator 160" allows full visibility of the treatment area both within and around the X-ray treatment field when aligning X-Ray treatment field, which is improved by illumination trom the LED lighting ring 170". The lighting ring 170" may comprise several (e.g. 4, 6 or 8) LEDs 172', although only two are visible in Figure 4. Although LED5 have been used in the lighting ring in this embodiment, other light sources could also be used. LED5 with different wavelengths can be used for e.g. white, one or more of red, green or blue light, or light outside the visible spectrum. The lighting ring 170" is arranged to contact the transparent applicator 160", which can act as a light tube to create a ring of light ("halo" ring) on the skin surface just outside the X-ray field (as described above) in order to provide a further indication in the form of visual feedback that the X-ray applicator 160" is correctly positioned.

The X-ray systems such as those described above in relation to Figures 1-4 have many advantages due to the X-ray target (i.e. the focal spot, from which X-rays are emitted) being positioned so close (i.e. 6mm) to the end of the tube end-window. The beam angle obtained can be very wide (e.g. 800 or ±40°). This design also saves space, as it makes it possible to miniaturize any support components (i.e. metalwork such as beam collimator(s), and beam filter(s) placed in the X-Ray beam for providing the required X-Ray beam quality and beam size for treatment). This is because these components can be placed closer to the X-Ray target where the beam has a smaller diameter, and therefore the supporting components can be smaller in diameter. This results in a smaller, lighter and more compact X-ray tube head compared to when the X-ray target is positioned further from the end of the X-ray tube.

When the support components are designed to be so compact, it is possible to provide an X-ray treatment field at a very short working distance (i.e. FSD) that wasn't possible with previous X-ray tube heads. At shorter working distances, beams have a greater intensity compared to beams produced with the same input energy at a longer working distance. The increase in intensity is significant due to the inverse-square law (which can be applied as the X-ray focal point can be modelled as a point source), because the intensity is inversely proportional to the square of the distance from a point source.

Previously X-Ray systems for skin (e.g. the XSTRAHL 100 or XSTRAHL 150) operated at a shortest FSD working distance of 15cm or 20cm due to the X-Ray source used and requirements for the support components and metalwork. For example, the XSTRAHL 100 and XSTRAHL 150 were supplied with standard applicators with shortest FSD of 15cm, and the XSTRAHL 200 with shortest FSD of 20cm. The bulk and size of the metalwork surrounding the larger X-Ray tubes in previous systems make providing a considerably shorter FSD impractical, as it would then be difficult to access and view the treatment site on a patient (the metalwork would get in the way and be invasive to the patient). By taking into account the inverse-square law, by operating at Scm FSD instead of 15cm, the dose output would be approximately 9 times higher from the same X-Ray source. Therefore reducing the FSD significantly reduces the input power required to achieve the same X-ray dose output. Compared to an X-Ray system operating at 15cm FSD, you can achieve the same treatment dose at 5cm FSD with an X-Ray source and X-Ray generator requiring approximately 1/9th of the power. Compared to an X-Ray system operating at 20cm FSD, you can achieve the same treatment dose at 5cm FSD with an X-Ray source and X-Ray generator requiring approximately 1/16th of the power.

Generating X-rays is a very inefficient process, with somewhere in the region of 99% of the energy being dissipated as heat. Effective cooling of an X-Ray source is therefore an integral and critical part of X-Ray radiotherapy system design, which must be provided for cooling the X-ray tube. When the required treatment dose can be provided with a lower power system, the cooling system required can also be smaller.

This further reduces the size and weight of the X-ray tube head and improves the manoeuvrability of the apparatus. For example, in the embodiment shown in Figure 3 a relatively small water cooling jacket is used. However, air cooling could also be used with an X-ray tube of this size and power.

The wide beam angle, smaller X-ray support components and short working distance allows a large field size with a high dose output while working at short working distance (i.e. an X-ray beam field up to 5cm diameter at Scm FSD). This combination meets the clinical requirements (for field size and dose) for treating the most common skin cancers (Basal Cell Carcinoma, BCC, and Squamous Cell Carcinoma, SCC, etc.) as well as intraoperative X-Ray radiotherapy.

With the radiotherapy system designed as described herein only requiring 1/9th or 1/16th of the power of previous systems, instead of requiring a large 1kW or 3kW X-ray source and cooling system, it is possible to achieve a treatment field size and dose which is sufficient for clinical application with a very small and lightweight 50W to 100W X-ray source, with a maximum voltage of -50kV -100kV. Typically a 50kV tube can be run at energies of 5kV to 50kV, but clinically a range of 10kV to 50kV would be typical, with the majority of use at 30kV to 50kV. An X-ray tube with a maximum power of SOW would produce a maximum current of I mA at 50kV. A 50W X-ray tube could be capable of running at a range of 0.01 mA to 5mA.

For example, a 50kV end-window X-ray tube with a maximum power of 50W could be used in the embodiments described above to provide an X-ray beam of sufficient power and diameter for clinical treatment. The X-ray tube may have a diameter of 50-60mm, a length of 100-140mm and weigh 1.2-1.3kg.

It is also possible to use slightly more powerful X-ray tubes, using the same design principles. For example an 80kV, 100W system with end-window X-Ray tube, may be similar in size to a 50kV, 50W tube, for example having a 60-70mm diameter. An 80kV tube would have a 5kV to 80kV energy range, but would probably be used clinically in the lOkv-8OkV or 3OkV-80kV range. The 80kW X-ray tube could also be capable of running at a range of 0.01 mA to 5mA. By providing a higher-powered X-ray tube, a more powerful X-ray beam which can penetrate deeper can be generated. This can be more appropriate for treating skin conditions, such as skin cancers than lower power X-ray tubes. For example the treatment time could be reduced.

It is the X-ray tube head (which incorporate the X-ray tube) that the operator needs to position by the patient, adjacent to the treatment area. Using some or all of the design principles described herein, it is possible to produce an X-Ray radiotherapy solution with a tube head that is about the size of a medium coffee cup and which weighs less than 2kg. Such a tube head can easily be supported on the end of a lightweight support arm. It can also easily be gripped and manoeuvred by the operator, so that it can be quickly positioned on a patient for treatment.

Furthermore, with a 50 or 100W X-ray source, the supporting high voltage (HV) generator and cooler can be cheaper than those required for previous X-ray systems.

The HV generator and the cooling solution required for these lower-powered X-ray tubes can also be more compact. For example, with an 80kV X-ray tube, it is possible to utilise an 80kV 100W HV generator which measures nominally 7" x 3" x 11" (180mm x 80mm x 270mm), and weighs just bIbs (4.6kg). For comparison the generator utilised in the previous XSTRAHL 100 system (100kV, 1kV measures nominally 340mm x475mm x 440mm, and weighs 98kg. Preferably an HV generator of less than 300mm cubed and weighing less than 10kg would be provided. More preferably, an HV generator of less than 5kg. A 50kV, 50W solution would be even smaller and lighter than the stated 80kV solution.

A very small water cooling jacket is fitted around the top of the X-ray tube housing and supplied by water pipes connected to the X-Ray tube, and a heat exchanger and water pump located in the base unit. The cooling requirement for the X-ray tubes is just SOW to 100W (e.g. for a 50W or 80W tube), which permits a very small and compact cooling solution. At this wattage a chiller solution can be readily and cheaply implemented with a small heat exchanger and a peltier cooler, permitting a simple and very compact cooling solution (with a cooling fluid at well below ambient, and therefore can be utilised for a solution in high ambient temperatures). The water cooler includes an integrated closed circuit cooling system, water pump, heat exchanger, with integrated heat exchanger cooling fans. An example is the Corsair HlOOi water cooler, which integrates a 120mm x 275mm x 27mm radiator, two 120mm cooling fans (fan speed 2700 RPM, fan airflow 77 CFM). Other examples include Zalman Reserator 3 MAX, which integrates a 145 x 79 x 120 mm (WxHxD) circular dual radiator heat exchanger, 120mm cooling fan (fan speed 1000 to 2200 RPM), with 90 litres/hr (1.5 L/min) integrated water pump. Water cooling, which is cooling by conduction, is a considerably more efficient process than cooling by convection (i.e. air blower). Water cooling permits rapid and efficient cooling, and to be achieved in a comparatively small and compact space (for the localised cooling). Forced air cooling and convection is limited by the fact that you can never cool below ambient temperature, and when the temperature of the cooled object approaches ambient temperature the efficiency of the cooling (and ability to remove the heat) drops off rapidly. Most air cooling solutions typically therefore work on specified cooling capacity with a temperature differential of 20°C above ambient for target cooling. As a cooling differential of less than 20°C is normally required for such an X-ray system, there is clear merit in considering a water-cooled rather than direct air-cooled solution.

Generating X-Rays is an inefficient process and somewhere in the region of 99% of the energy put into the X-ray system is often dissipated as heat. It is important the heat can be efficiently taken away from the X-ray tube (which is important for the long-term reliability of the X-ray tube). With an air cooled solution on the tube-head it means positioning both a noise and a vibration source close to patient during treatment. By putting a water cooling jacket it is possible to move the "air cooling" away from the tube-head and into the base unit (which can be placed remotely from the patient).

A water cooling solution, which utilises a significantly larger area air cooled radiator (normally positioned in the base) than would be possible on the tube-head, could be incorporated into any of the embodiments described herein. This permits a lower air-flow and quieter (virtually silent) cooling solution to be possible. As the tube heads described herein generally have a small surface area, it would require high rate or airflow in a compact space, which would generate more noise.

A water cooled solution, as a result also permits a slightly smaller tube-head solution to be possible, which is desirable.

One specific embodiment uses a cooling radiator with an ultra-quiet cooling fan, which of 150-200mm diameter. This cooling solution has been found to be virtually silent, e.g. it has been found to be quieter than the background noise level measured with an office air conditioning unit, and similarly for a hospital treatment room air conditioning. This has many benefits as a quite cooling solution is non-invasive to the patient during treatment. It means a quiet and compact cooling solution can be designed into the X-ray system.

For larger, more powerful systems, an XSTRAHL 150 and XSTRAHL 200 system, for example, the cooling solution needed is such that a water/air, or water/water cooling solution commonly has to be located outside the patient treatment room (due to noise emission).

As the beam angle from the vertical (0°) is increased, the beam path from the X-ray target (point source) to a flat surface will increase, so at larger angles (e.g. ±20° or ±30°) the X-ray beam will have to travel further. Taking into account the inverse-square law (as described above), the result is that when the X-Ray beam is projected onto a flat surface, as the beam angle increased the X-ray dose decreases.

Figure 5 shows the output measured at a flat surface by an imaging panel for an end-window X-ray tube operating at 25kV at O.2mA. The graph of Figure 5 shows the normalised intensity at different beam angles (normalised so that the intensity at 00 is 100%). Two plots are shown; one is across the width (W) of the beam, and the other is taken at 90°, along the length (L) of the beam, however the results are very similar for the two plots. The intensity drops as the angle increases, to -95% at ±100, to -80% at ±200, to -60% at ±30° and to below 50% at ±40°. This shows the problem with providing a wide angle X-ray beam with a consistent intensity. When using an end-window X-ray tube with an X-ray target placed close to the end (as described above), a wide angle beam can be emitted from the X-ray tube, and thus it becomes necessary to provide correction or compensation for the non-homogeneous intensity of the beam at wide angles.

Filters can be used in X-ray apparatus to change the beam quality and increase the half-value layer (HVL) and Depth Dose Performance. The normalised intensity of an X-ray beam varies with beam angle, and this effect is particularly pronounced when using wide-angled X-ray beams; therefore filtration to change the beam shape can be required e.g. to produce a uniform intensity across a treatment surface.

Consider a filter material which is flat and of uniform thickness across the beam angle (e.g. 1mm thickness of aluminium). In the centre of the beam the X-rays will pass through a thickness of 1mm aluminium, however as the beam angle is increased (i.e. further from the centre of the beam), the beam path through the filter material will increase due to the angle. This would result in the X-rays in the outer part of the beam experiencing a higher level of filtration. (e.g. the beam would pass through 1.064mm of filter material at2O°, 1.103mm at 25° and 1.155mm at 30°).

In order to reduce this variation in beam intensity, the primary tungsten collimator can be designed to cap the output from the X-ray tube at large angles (e.g. in one embodiment at 56.82°, i.e. ±28.41°). This ensures the X-Ray beam output is within the central beam region in the plot of Figure 5.

The dose penetration can be altered by changing the tilter thickness. For example, increasing the filter thickness can increase the dose depth penetration.

The thickness and surface profile of the X-ray beam filter material can also be adjusted to compensate for beam position (and angle) within the field. Depending on the desired treatment area, the filter can be designed to compensate for the beam path through the filter and/or the inverse square law in a number of ways, for example: a) to provide a uniform X-Ray dose profile across the surface of a flat treatment

field

b) to provide a uniform dose can across the surface of spherical faced convex applicator and treatment surface; c) to provide a uniform dose across the surface of spherical faced concave applicator and treatment surface.

Traditionally it has been common for treatment applicators to have a flat treatment area. However it is common to have to treat areas of a patient where the skin surface is not flat, such as the end of a patient's nose, under a patients chin, on the side of a patient's nose etc. By changing the filter thickness or profile, it is not just possible to compensate the X-Ray beam to achieve a uniform dose across the treatment field with a flat face applicator, but also to permit convex and concave faced applicators to be used, with a uniform dose across the treatment face. This offers new opportunities for treatments, with improved accuracy and uniformity of treatment dose.

In some embodiments of the system, both the treatment applicators and the treatment filters are interchangeable, which allows considerable flexibility in the treatment field and application of the system for a range of treatments. For example, the filter would need to be changed if a different beam quality is required for a treatment (i.e. a higher level or lower level of filtration to change the nominal half value layer, HVL, or penetration of the beam). A beam flattening filter profile would also need to be changed, if for example a different beam profile applicator was used (say a flat field applicator, or a spherical faced Convex or Concave applicator).

However, it is also possible to integrate an applicator and filter into one interchangeable component, for ease of operator use. For example, operator errors from using an inappropriate filter and applicator combination could be prevented. If a range of beam qualities need to be used, then this approach could quickly become more complex (i.e. if there are 3 beam qualities used then there would need to be 3 times as many applicators, with an applicator needed tor every beam quality and tilter variant), and it may be easier to provide the filter and applicator as separate, removable, interchangeable components.

It is also possible to include identification means on the filter and applicator attachment mechanisms, so the system can automatically detect which filter and applicator have been fitted. Thus in the event of an unsuitable combination, the system could automatically disable X-ray production and/or inform the operator. Automatic identification of which interchangeable filter and applicator are installed can also make providing an automatic record of patient treatment easier, which can be useful for traceability and for collecting data on the efficacy of treatment methods.

The design of an example set of filters comprising a flat filter, uniform beam path filter and a uniform beam path inverse square compensation filter will now be described in relation to Figures 6A & 6C, 7A-7C and OA-8C. The filters described herein would normally be formed of aluminium, but copper or tin are also suitable materials.

Figure 6A shows the profile of a uniform, flat filter 640, which is formed of aluminium of uniform thickness 1±0.05 mm.

Figure 7A shows the profile of a uniform beam path filter 740, and Figure 7B shows a magnified view of the section of the uniform beam path filter 740 marked "A' in Figure 7A. The profile of the filter material in the uniform beam path filter 740 is arranged to compensate for the increased path of the X-rays through the filter 740 at larger angles. The uniform beam path filter 740 shown in Figures 7A & 7B is formed of aluminium of maximum thickness 1±0.05 mm, as marked in Figure 7B. The uniform beam path filter 740 is thickest at the centre point 742, which when installed in the X-ray tube head would be at the centre of the X-ray beam (i.e. 00). The thickness of the filter material in the uniform beam path filter 740 decreases with distance from the centre point 742, so that the filter material is thinnest at an outer edge 744, where the widest angle part of the X-ray beam hits the filter material. The thickness of the filter material does not decrease linearly with distance from the centre point 742. Instead, the thickness is dependent on the angle the X-ray beam would make with the normal to the filter material and the thickness of the filter material, so that wherever the X-ray beam hits the uniform beam path filter 740 between the centre point 742 and the outer edge 744, the beam will pass through the same thickness of filter material. This means that the beam will receive the same amount of attenuation across all beam angles, and the intensity of the X-ray beam will be constant across a spherical surface centred on the X-ray target.

However, it is sometimes necessary to provide an X-ray beam which has a uniform intensity across a flat treatment surface. Figure 8A shows the profile of a uniform beam path inverse square compensation filter 840, and Figure 8B shows a magnified view of the section of the uniform beam path inverse square compensation filter 840 marked "A' in Figure 8A. The profile of the filter material in the uniform beam path inverse square compensation filter 840 is arranged to compensate for the increased path of the X-rays through the filter at larger angles and to compensate for the reduction in intensity due to the beams at larger angles being further from the X-ray source (inverse-square law intensity reduction as discussed above). The uniform beam path inverse square compensation filter 840 shown in Figures BA & 8B is formed of aluminium of maximum thickness 1±0.05 mm, as marked in Figure 8B. The uniform beam path inverse square compensation filter 840 is thickest at the centre point 842, which when installed in the X-ray tube head would be at the centre of the X-ray beam (i.e. 00). The thickness of the filter material in the uniform beam path inverse square compensation filter 840 decreases with distance from the centre point 842, so that the filter material is thinnest at an outer edge 844, where the widest angle part of the X-ray beam hits the filter material. As with the uniform beam path filter 740, the thickness of the filter material does not decrease linearly with distance from the centre point 842.

Instead, the thickness is dependent on the angle the X-ray beam would make with the normal to the filter material and the thickness of the filter material, as well as the square of the distance between the X-ray source and the desired X-ray treatment area.

Therefore, wherever the X-ray beam hits the uniform beam path inverse square compensation filter 840 between the centre point 842 and the outer edge 844, the increased distance travelled at greater angles is compensated for by a reduced filter thickness. This means that the filter attenuation, or filtration, received by the beam will vary across all beam angles to compensate for the longer distance that beams at wider angles will travel before reaching the X-ray treatment surface and the longer distance the beam will travel through the filter. Therefore the intensity of the X-ray beam will be constant across a flat treatment surface.

Any of the filters (640, 740, 840) shown in Figures 6A, 7A-7B and 8A-BB could be used for the filters (140, 140', 140") shown in Figures 1 -4.

Figures 60, 70 and 80 show the measured beam dose profile for an X-ray beam that uses the filters (640, 740, 840) shown in Figures 6A, 7A and 8A respectively. The plots shown are from exposures with EBT2 Gafchromic Dosimetry film exposed to X-Rays, which has been digitally scanned EBT2 with different profile filters. The scale on the plots is a "Gray Value" which is measuring the exposure of the film, namely how light or how dark the exposure is. The results show how the X-ray dose varies across the beam with a flat filter, and how non-flat "Beam Flattening" or "Compensating Profile" filters selectively manipulate the X-ray beam to provide a uniform dose profile. A low Gray value (i.e. 15000 -20000) indicates maximum X-ray exposure and therefore high X-ray intensity, where a high Gray value (i.e. 40,000+) indicates very little or no X-ray exposure and therefore low or non-existent X-ray intensity.

The graph of Figure 60 shows that the intensity of the X-ray beam is fairly high at the centre point 642, but reduces fairly rapidly with distance from the centre point 642 and towards the outer edge. This is because at larger angles (i.e. further from the centre point 642) the beam passes through a longer distance of filter material and has travelled a longer distance before reaching the film, so the intensity has dropped due to more filtration and the inverse-square relationship.

The graph of Figure 70 shows that the intensity of the X-ray beam reduces slightly less rapidly from the centre point 742 of the filter 740 than in Figure 60. The intensity of the beam is therefore more consistent across a wider angle for the uniform beam path filter 740 than for the flat filter 640. This is because at larger angles (i.e. further from the centre point 742) the beam passes through the same distance of filter material, but the longer distance travelled before reaching the film has not been compensated for, so the intensity has dropped only due to the inverse-square relationship.

The graph of Figure 80 shows that the intensity of the X-ray beam is fairly uniform across the entire width of the beam. This is because at larger angles (i.e. further from the centre point 842) the beam passes through a shorter distance of filter material to compensate for the longer distance travelled by the beam before reaching the film.

Thus the uniform beam path inverse square compensation filter 840 can be used to provide an X-ray treatment beam of uniform intensity across a flat surface.

Although only filters with a maximum thickness of 1mm have been described above, other thicknesses of filter are also possible. For example, it is sometimes desirable to filter the X-ray beam more to provide a lower intensity treatment dose (e.g. to target cells closer to the surface of the skin). In such cases, thicker filters (e.g. 1.5mm or 2mm maximum) would be used, and can be shaped to compensate in a similar way.

It is also possible to provide filters in which the thickness varies to provide a uniform intensity across surfaces other than a flat surface, e.g. a spherical concave or convex surface, particularly when the X-ray treatment surface on the patient is not flat.

Figure iSA illustrates a top side view of a filter carrier 1500, which may be used to support, or hold, the filter material of any of the filters described herein. The filter carrier 1500 has an aperture 1510 for the filter material, in which the filter material can be secured. A grip 1520 is provided so that a user (i.e. system operator) can hold the filter carrier 1500 and remove/insert it into a slot, or hole, in the housing of an X-ray tube head. When the filter carrier 1500 is correctly installed in the slot or hole in the housing, the filter material would be placed in the path of the X-ray beam. This filter carrier 1500 provides a quick and efficient means for replacing interchangeable filters.

The filter carrier 1500 also includes encoder pins 1530 for selective encoding and identification of the filter. These encoder pins 1530 are arranged to operate one or more electrical switches provided in the X-ray tube housing in the slot for receiving the filter carrier 1500. This allows the X-ray system to identify the type of filter that has been inserted.

The filter carrier 1500 also includes a ball-plunger locating hole 1540, which is for engaging with a ball-plunger provided in the slot for receiving the filter carrier in the housing. This ensured accurate alignment of the filter material in the centre of the X-ray field. In some embodiments, another ball-plunger locating hole would be located on the other side of the filter carrier 1500.

Figure 1SB is a bottom side view of the filter carrier 1500 illustrated in Figure iSA.

The underside of the filter carrier 1500 has a step 1550 on the side closest to the grip 1520. This mechanically prevents the filter carrier 1500 and therefore the filter material being inserted in the X-ray tube the wrong way up.

When the treatment surface is not flat (e.g. nose, chin), it may also be useful to provide an applicator that can fit the profile of the X-ray treatment surface. Figure 9 shows an applicator 960 with cone-shaped side walls 964 for extending towards the treatment surface and a spherical-shaped curved convex treatment face 962 for making contact with a concave treatment area. It may be advantageous to use an applicator 960 with a curved treatment face 962 in combination with a filter which provides a beam of uniform intensity across a curved surface. In some systems these can be provided as separate removable components, which allows for more combinations of applicators and filters. In other systems it is preferred to integrate the filter into the top of the applicator, to prevent the applicator being used with the wrong filter.

Figure 10 shows an applicator 1060 with cone-shaped side walls 1064 for extending towards the treatment surface and a flat convex treatment face 1062 for making contact with a flat treatment area.

Applicators can be provided in several sizes and for working at several distances.

For example, common applicators for use with this system are applicators with 1.5cm, 3cm and Scm treatment surface diameters and a working distance of 6cm FSD.

However, in practice, applicators could be produced in the range 0.5cm to 6cm diameter treatment surface. Non-circular applicators (e.g. square, rectangular, elliptical) could also be provided.

The diameter of the treatment surface could also be increased by increasing the FSD. For example, a 10cm diameter can be achieved at a 10cm FSD.

Figure 17A shows an example applicator 1760. The applicator 1760 has a Perspex (a transparent plastic is preferred) cone 1710 -i.e. the side walls of the applicator. A tungsten secondary collimator 1750 is inserted in the centre at the top of the applicator 1760. A transparent ring 1780 at the top allows the light from an LED lighting ring to optically couple into the applicator 1760, providing illumination both inside and outside the applicator cone 1710 (i.e. across the treatment area and around the treatment area). This allows coupling the light into the cone 1710 of the plastic applicator 1760, so that it acts as a light pipe. As a result this enables a "halo" lighting ring (on the skin surface) when the applicator 1760 face is in good contact with the skin. As a result this provides visual feedback to the operator to assist with optimal applicator placement and minimising "stand-off".

The applicator 1760 has a stainless steel applicator fitting (or retaining "shoe" or mounting portion), 1790 for accurate applicator alignment in the centre of the X-ray field.

The applicator fitting or mounting portion 1790 is arranged to slot into a fitting on an X-ray tube housing. The stainless steel is hard-wearing for routine interchanging of the applicators for different field sizes and different treatments. The applicator 1760 has a treatment face, or front window, 1762 for contacting a treatment surface on a patient. In this example, the treatment face 1762 is flat. However, in alternative embodiments, a concave or convex face could also be used. This is useful when treating non-flat areas on a patient. The treatment face is formed of transparent polystyrene, which has significantly lower X-ray absorption, as well as well as significantly better stability when exposed to X-rays for a prolonged period compared to Perspex (i.e. prolonged exposure to X-rays does not change the structure of the polystyrene, nor will it discolour).

The applicator 1760 also has encoder pins 1720 for selective encoding and identification of the applicator 1760 when fitted. These encoder pins 1720 are arranged to operate one or more electrical switches provided in the X-ray tube housing in the slot for receiving an applicator. This allows the X-ray system to identify the type of applicator that has been inserted.

The applicator 1760 also has a ball-plunger locating hole 1730 on the top face, close to the encoding pins 1720. This is for engaging with a ball-plunger provided in the slot for receiving the applicator fitting in the housing. This ensures accurate alignment of the applicator in the centre of the X-ray field,as well as retaining the applicator in place once it is fitted. It can also serve as a safety feature, e.g. the X-ray system may be provided with logic for determining whether the ball-plunger in received in a ball-plunger locating hole and disable X-ray generation in response to detecting that no ball-plunger has been received.

The applicator 1760 and tungsten collimator 1750 shown in Figure 17A is for a

5cm diameter field at 5cm FSD.

Figures 17B shows the applicator 1760 from above, and Figure 170 shows the applicator 1760 from a side orientation.

Any of the applicators described herein may be formed of transparent material, e.g. Perspex. When an LED lighting ring is installed on the tube head, this can be coupled with the applicator when installed, so that the treatment area, and the area outside is clearly illuminated, with the side walls of the applicators acting as a light pipe, or light tube, which, when the applicator makes good contact with the skin, gives visual feedback with a "halo" ring which lights up on the skin surface directly around the treatment zone. Vvhen the applicator moves away from the skin the light of the "halo" ring disperses very quickly, and so offers a very good visual indicator to an operator, confirming if they have made a good & even contact with the patients skin, (i.e. no stand-off).

Figure 14A shows an example embodiment of the underside face of an LED lighting ring 1470, which may be installed in any of the tube heads described herein. The LED lighting ring 1470 including eight LEDs 1472. There are other light sources that could be readily used instead of LED5 (such as a tungsten bulb), however the advantage of using small surface-mounted LEDs are their very small size, and ease of integration meaning, they can be positioned and coupled to the applicator (for illumination in and around the treatment site as well as coupling into the applicator cone to form a light pipe).

In this example, the LED ring is formed of a printed circuit board (PCB) with a thickness of 0.8mm. A thickness of 0.6-1 mm is preferred. LED5 as thin as 0.2mm are used, which means that the LED lighting solution can be integrated into the X-Ray tube-head metalwork and it only requires a height of 1 to 2mm to accommodate. With this arrangement the LED5 1472 can be positioned and aligned immediately above a light coupling ring on the Perspex applicators, allowing the light of the LEDs 1472 to be directly coupled to the applicator cone.

The LEDs of Figure 14A are placed in a circular arrangement at 45° steps.

Various LED5 are available with different light emission patterns, which would be suitable for any lighting ring described herein; in this example LED5 with a very disperse 120° light emission pattern have been used. The PCB is also included with individual resistors for each individual LED. It is also possible to use a single resistor for all or more than one LED. However, by providing individual resistors, this biases the LED and controls the light emission level from the LED for an applied voltage.

Figure 14B shows the LED lighting ring 1470 of Figure 14A from a side orientation, showing how the LED5 1472 protrude slightly from the surface of the lighting ring 1470.

Figure 14C shows a circular ring Printed Circuit Board (PCB) 1471" (of thickness typically 0.8mm) for use in e.g. the LED ring 1470 of Figure 14A. Electrical connectors 1474" are provided on one side. The edge of the PCB 1471" holding the electrical connectors 1474" is extended, so that when the LED ring is fitted, it protrudes outside the tube-head metalwork, so as to allow an electrical connection.

Figure 14D shows the underside face of an LED ring 1470", which is an alternative to that of Figure 14A. The LED ring 1470" has more than one set of LED5, which can be controlled independently. A first set ot LED5 1472" is spaced radially around the ring 1470" every 45°, with a second set of LED5 1473" spaced between. For example, any of White LED, and Intra Red. Alternatively RGB LED5 and UV LED5 etc. could be used for each of the sets. The additional set of LED5 can be used for enhanced visual identification of the treatment site, or could be used for visual tube status indication.

Figure 14E shows the LED lighting ring 1470" of Figure 14D from a side orientation, showing how the LED5 1472" protrude slightly from the surface of the lighting ring 1470".

When used in conjunction with an imaging camera (digital or video) there are additional benefits of being able to control the light source, and being able to apply and view light of differing wavelength or polarisation.

When an LED lighting ring (such as one shown in Figures 14A-E) is combined with a video or digital camera, in particular, there are advantages to also utilise different wavelengths ot light (other than just a white light source). This allows one or more images to be taken at different wavelengths of light, or with polarised light, and allows an image to be captured and recorded of the treatment site, as well improving contrast and definition of a skin lesion (for example), this allows the features and functionality of a dermatoscope to be incorporated into the X-Ray system, allowing a visual record and traceability of the treatment, and it's effectiveness, to be recorded through a patient treatment.

The length of the applicator cone sets the precise FSD (focal spot distance) from the X-ray tube focal spot, or X-ray target, and the inside face of the applicator's conical side walls define the edge of the skin surface X-ray beam (i.e. the largest-angled beam).

The "halo" ring provides a visual lighting ring immediately outside the treatment field, as well as providing visual feedback to the operator, that allows the operator to position the applicator more precisely (minimising skin surface stand-off, and therefore providing more accurate treatment dose and treatment dose reproducibility). The visual feedback provided to the operator for applicator alignment also allow the operator to set up a patient treatment more quickly and efficiently, and therefore to treat a patient more quickly, and to treat more patients in a day.

There are several ways for integrated video to be offered with any of the tube head designs described herein.

A camera and/or video recorder can be integrated inside the tube head, within the zone of the X-ray field. This allows photos and imaging of the patient treatment area with clear visibility of the applicator positioned around skin lesion I treatment site, which can help the operator to position the applicator correctly and quickly. These images can also be stored and used for patient treatment records and traceability. When a camera is provided within the X-ray field zone, it must be removed from the apparatus during X-ray production to prevent it from being damaged by the X-ray beam. The camera could, for example, be integrated into a slide that fits into the filter receiving section. This is very space-efficient, as it means a separate camera-receiving porbon does not need to be added to the tube head. The filter and camera would not need to be installed in the tube head at the same time, as the filter is only required to filter the X-ray beam, and the X-ray beam should not be used when the camera is installed. The camera slide could also be fitted with one or more identification encoding pins (like the applicator and filter), so that the system can detect when it is installed.

In another arrangement, a camera and/or video recorder is integrated inside the tube head covers, but outside the zone of the X-ray field. This has the advantage that it can remain in positioning and functioning while X-rays are being applied to the treatment area, which allows live photos and video of the applicator positioned on the patient.

These can be used to help the operation position the applicator initially, and for patient treatment records and traceability. However, these images can also be viewed by the operator during treatment to confirm if a patient moves (and if the treatment needs to be paused and the patient settled & X-ray head reset before completing treatment dose).

This can enhance patient safety during operation. It is particularly advantageous when the operator has to leave the treatment room during X-ray treatment (to minimise their exposure to ionising X-ray radiation), as normally they would not have a clear view of the applicator positioned on the treatment area.

Yet another possible camera arrangement comprises two cameras and/or video recorders integrated inside the tube head. By combining the images from two cameras, set slightly apart from each other, 3D images can be constructed, allowing depth imaging of the treatment site and skin lesion.

By illuminating the treatment area with different wavelengths of light (both in and outside the visual spectrum) and/or polarised light, it is possible to enhance the imaging contrast and minimise surface deflections. This provides a clearer image and therefore easier identification of the skin lesion. This allows a trained medical professional to more easily identify between a cancerous and non-cancerous lesion than when viewed with just visible light. The different types of light may be provided, for example, by LED5 integrated into the light ring. When polarised light is used, a polarising filter should be placed in front of the camera so that the camera only picks up light of a single polarisation and light that has been multiply scattered is not included in the images.

When light outside the visual spectrum (e.g. infrared or ultraviolet) is used, a camera for detecting these types of light should be installed in any of the arrangements described above.

One or more of the above-described camera and/or lighting arrangements could be incorporated into an X-ray tube. When the camera is positioned outside the X-ray beam, it can be used to provide an automatic indication when the applicator moves in relation to the patient treatment surface during treatment (or before treatment, but after the applicator has been deemed to be set up). For example, the images can be sent to a processor for motion detection analysis. Alternatively, a separate IR, UV or laser distance measuring device can be installed outside the X-ray beam for determining whether the applicator has moved in relation to the applicator. When motion of more than a certain threshold is detected (either by motion detection software or distance measurement), the operator can be informed and/or the X-ray production automatically halted (e.g. by drawing a shutter across the X-ray window and/or turning off power to the X-ray tube).

A laser beam could also be incorporated into the device for checking the applicator has been set up correctly. For example, a laser could be provided on a slide to slide into the filter receiving means on the X-ray tube. The laser could be used to measure the distance to the X-ray treatment area. The operator could be informed if this distance was incorrect for the planned treatment. Once it had been confirmed that the setup was correct, the operator could slide the laser out of the filter receiving means and slide the correct filter in. As with the camera arrangement, this is very space-efficient, as it means a separate camera-receiving portion does not need to be added to the tube head.

A visual indication of correct/incorrect positioning of the applicator could be provided on the exterior of the X-ray head. For example, the LED lighting ring could be programmed to display different coloured light to indicate that the detected distance to the patient's skin is (in)correct, or that the applicator has been moved. Alternatively, a separate light source could be provided on the X-ray tube head for this indication, or an indication provided on the control panel.

An X-ray tube head as described above requires a stable support structure that allows a wide range of movement, so that the X-ray tube head can be easily placed in the correct position for treatment. Normally the tube head is attached to a support arm or tube stand, which allows some flexibility in the placement of the X-ray head, but the means for attaching the tube head to the arm or stand should be carefully designed to allow the tube head to be placed in different orientations (i.e. rotated with respect to the end of the arm). For example, Figure 11 shows the X-ray tube head 100 of Figure 1 in different orientations with respect to the tube support 116. The tube head 100 has been rotated with respect to a horizontal axis (i.e. one going into the page), to show the tube head in a horizontal position, a position rotated up by 30° and a position rotated down by 30°.

Figure 13 shows a support structure 1316 for an X-ray tube, as described above.

An X-ray tube head 1300, with an applicator 1360 and supply cable 1314 attached. The tube head 1300 is joined to the support structure 1316 by a joint 1390. The support structure 1316 comprises a first elongate section 1340 and a second elongate section 1350 for supporting the tube head 1300.

One end of the first section 1340 is attached to a base unit 1370 via a joint 1372.

The other end of the first section 1340 is attached to one end of the second section 1350 via a hinge joint 1380. The hinge joint 1380 allows the second section 1350 to pivot. The friction, or torque, in the hinge joint 1380 would normally be set so that it allows rotation when pushed or pulled by an operator, but remains stable when left in position. Gas springs 1342, 1344 are provided, which aid in maintaining the position of the support structure 1316, e.g. by balancingtheweightofthetube head l300andweightofthefirst and second support sections 1340, 1350. The second section 1350 is formed of two parallel, elongate members 1352, 1354, which form a parallelogram linkage. The support structure 1316 may be formed primarily of stainless steel or aluminium, or a combination of the two.

In one specific embodiment, the elongate sections are formed from extruded aluminium section. Aluminium allowing a lighter support arm than, for example, steel, which could also be used.

In alternative embodiments, one or more of these support sections or members can instead be formed with a metal C-section. In a preferred embodiment the lower elongate support section is replaced with two "C-sections". Advantageously, this incorporates both the functionality of the arm frame as well as mechanical and/or cosmetic covers for the lower sections of the arm. The lower 2 C-sections of the upper and lower arm can be interleaved, so that when the X-ray system is not in use, (e.g. it is in a "parked" position), the lower part of the arm, or support structure, can allow the at least a part of upper arm section, or strut, to collapse inside the lower section, allowing a very small footprint for the stored system.

The hinge joint 1380 in this embodiment is a friction joint to allow for a level of flexibility and fine adjustment of the support structure balancing (along with the gas springs 1342, 1344). Gas springs are generally available in a limited range of values, e.g. 40N/m, 5ONIm, 70M/m, 100N/m. By adding one or more controlled levels of friction to one or more of the joints on the arm or support structure, we are able to achieve better control for finely balancing the arm and X-ray tube-head. By using this combination of gas springs and one or more friction joints, it is possible to finely balance the support sections. This ensures the arm sections and tube head move smoothly.

When the tube head (and applicator) is placed in position on the patient, the applicator can be fixed and retained in the set position.

In some embodiments, it is preferable that an additional electronically controlled, or manually controlled braking system is not necessary to retain the applicator in the set position, when the joint 1390 fixing the tube head to the support arm is adjusted, or the vertical position of the tube head is adjusted. The provision of a friction joint in conjunction with the gas springs offer a solution to make this possible.

An alternative to the friction joint is to consider using gas springs with an integrated braking mechanism. The braking gas springs option adds more weight and size to the support structure.

In certain embodiments, one or more of the other joints in the structure may also be friction joints. The hinge joint attaching the first section 1340 to the second section 1350 may not be a friction joint in some embodiments.

The one or more friction joints (e.g. joint 1380) can be implemented with a fixing bolt, with a nylock fixing nut on the end. An improvement is to use the same arrangement, but with a plastic, partially compressible washer. The preferred solution is to apply a controllable friction (or torque), by means of using a "Spring Washer'. This permits a more controlled and more consistent friction to be applied. There are various types of spring washer available, which have various performance features and benefits/limitation, depending how they are applied and the range of force that is optimal, e.g. a Conical Spring Washer, Disc Spring Washer, Cupped spring washer, Belleville washer, Wave washer or Finger Spring Washer.

Various arrangements are possible for fixing the tube head to a support arm via joint 1390, e.g. a ball joint, as this will offer a high range of movement, while minimising the size, weight, and complexity of the tube head mechanics. A ball joint permits the range of movement required with the tube head to permit the operator to readily align and place the applicator on the patient treatment site.

A friction ball head joint would offer an optimal and elegant solution as a tube head fixation method for retaining or attaching the tube head to a support arm or stand, whilst allowing 3 ranges of movement (i.e. 3 degrees of freedom): (1) Nodding (vertical) (2) Side to side (horizontal) (3) Rotation (around tube head fixing axis).

Figure 12 shows a ball 190" from a ball joint attached to a tube head support 116", such as the support 116 shown in Figure 1. The directions of three movements allowed by the ball joint are marked. A vertical (i.e. "nodding") movement 192", which is perpendicular to a horizontal ("side-to-side") movement 194", and a rotational movement 196" around the tube head support fixing are all possible when using a ball joint.

The tube head should be fixed to the support in so that the operator can easily adjust its position, but also so the tube head remains securely in place once in position.

A ball joint must use friction to retain its position. Even the compact and lightweight tube heads described above weigh about 2kg, and thus a fairly large ball head must be used to allow sufficiently sized contact surface area to generate enough friction. For example, for a 2kg tube head, a ball joint of 38mm diameter, with a retaining cap permitting a range of movement of around ±300 in the vertical and horizontal directions is required, which balances the need for ease of movement with sufficient friction to retain the tube head in place once positioned. Limiting the range of movement of the ball joint to ±30° offers the right balance of surface area and retention force with the ball joint.

The ball joint movement in the 3rd axis, namely rotation about the fixing axis, is unrestricted, and the ball joint can permit up to 360° rotation movement. When considering the tube head design, it is the length and range of movement of the HT cable that will determine the chosen "permitted" maximum range of movement in this axis. Limiting to a maximum of ±90° rotation movement for the tube head would be required, and if this range of movement is not essential, reducing this to somewhere in the region of ±30° to ±60° would keep the HT cable length to a minimum, permit the HI cable to be routed within the covers of the support arm or stand (offering optimum cosmetic appearance for the product), as well reducing HT cable flexing (minimising risk of HI cable damage and failure).

However, the friction required to retain the tube head in position is different in each direction. In particular, the vertical "nodding" direction 192" requires the most friction, or torque, in order to balance the weight of the tube head. In comparison, the horizontal direction 194" requires least friction. The size of the frictional force required in the vertical direction 192" means that the range and ease of movement in the other directions must be reduced. Furthermore, the size of the ball joint required is fairly large and unwieldy.

Therefore, a dual-axis joint that fixes and supports the X-Ray tube head can be preferable (e.g. the joint 1390 of Figure 13). By providing a joint in which the rotation about two different axes is independent, the friction in each movement can be better adjusted.

Figure 16A shows an example embodiment of a dual axis joint 1600, which may for example be used as the joint 1390 of Figure 13 for fixing and supporting the X-ray tube head to the support arm or structure.

The dual axis joint 1600 comprises a base for fixing the dual axis joint 1600 to the second section of the support structure. The base has two flanges, or support struts 1612, 1613. The support struts 1612, 1613 in this embodiment each contain two screw holes for attaching to the support structure.

A first rotating section 1630 is attached to the base of the dual axis joint via a first washer 1640. The first washer 1640 may be, for example, a Conical Spring Washer, Disc Spring Washer, Cupped spring washer, Belleville washer, Wave washer or Finger Spring Washer. The first washer 1640 allows the first rotating section to rotate about a first axis, as shown by arrow 1642. For example, this first axis may be in the plane of the elongate arm/support sections.

The dual axis joint also has two further flanges or support struts 1610, 1611 for fixing to the X-ray tube, or X-ray tube housing. These also contain screw holes. Each of the two further flanges or support struts 1610, 1611 is secured to the first rotating section 1630 via a second washer 1650, and a third washer 1651, respectively. These washers 1650, 1651 may be of the same, or of a different type from the first washer 1640. The second washer 1650 and third washer 1651 allow rotation of the two further flanges or support struts 1610, 1611 with respect to the first rotating section 1630, about a second axis. The rotation of the two further flanges or support struts 1610, 1611 about the second axis is shown by two arrows 1652, 1653.

Figure 16B shows an alternative embodiment of a dual axis joint 1600'. It is similar to the embodiment shown in Figure 16A, but shows an alternative arrangement forflangesorsupportstruts 1620', 1621', 1622', 1623'.

For example, in one embodiment using a 2kg tube head, it has been found that, with some adjustment a dual axis friction joint with a torque of 13 lbs/in (approximately 1.5N/m) for the rotation axis and of 26.Slbs/in (approximately 3N/m) for the nodding axis was found to offer a good balance of performance for easy movement of the X-ray tube head, and for the tube to accurately remain in position after placed on a patient treatment site.

These figures are close to optimal for an X-ray tube and supporting metalwork and cosmetic outer covers weighing approximately 2kg, and at the distance set from the fixing joints (the distance from the centre of the vertical "nodding" joint to the centre of the X-Ray tube is approximately 60mm, however distances of between 55mm and 65mm are preferable and distances of between 50mm and 70mm are also possible). If the weight is increased or reduced (or the X-Ray tube positioned closer or further away from the fixing joints -therefore changing the mechanical leverage) then the frictions, or torques, must be scaled accordingly. Torque joints have the advantage that they are relatively simple mechanically, remain very static when in position and have a long working life, allowing many adjustments before they wear and require replacement.

Preferably, a support arm or tube stand would provide a range of movement needed for positioning the tube head of about 2ft cubed (i.e. 60cm x 60cm x 60cm). In terms of treatment, a patient would typically be lying on a couch, or occasionally sitting upright on a chair for treatment. A treatment couch would be approximately I.8m (long) x 0.7m (wide), with the surface of the couch around 0.7 meters off the ground. The range of movement of the support arm and the dual axis joint, should be arranged such that the tube-head has the range of movement necessary to be able to position the applicator on the patient in the critical treatment areas. The most common skin cancer treatment areas are the nose and round the head and ears. Typically the most difficult (and challenging) to access to access for an X-ray radiotherapy system are under the chin, around the nose, the ears and around the side of the head.

By providing a system with a small X-Ray tube-head size (such as the ones described herein), and the range of movement of the arm and the dual axis joint, these normally difficult to reach treatment areas are easier to access and placement of a treatment applicator is easier than in earlier systems (e.g. XSTRAHL 100, XSTRAHL 150, XSTRAHL 200, XSTRAHL 300).

In most hospitals and treatment facilities the treatment couch will be mobile and height adjustable. In one embodiment, the base unit can be moveable (within the treatment room). This can allowing the treatment couch to remain fixed, and the tube-head able to be moved around the treatment couch, which replicates what was previously facilitated within a treatment room with a ceiling mounted tube-head.

In one example embodiment, the prototype support arm can extend horizontally out to about 850mm and vertically to about 550mm. This can be achieved with upper and lower arm support sections which are approximately 500mm long. A range of horizontal movement of between 500mm and 1000mm and of vertical movement of between 300mm and 800mm is preferred. Support sections of between 250mm and 750mm are preferred.

It is useful to provide a support arm that can be locked in position to prevent movement during X-ray application. In one embodiment, the locking means is electrical, which has the advantage that a single button can be provided to actuate the locking system, and there is some flexibility in where this button can be placed. When the locking mechanism is mechanical, the position of the locking actuation means is normally less user-friendly, for example when mechanical locking handles are provided.

In one specific embodiment, a 50W X-ray generation tube is surrounded by sub-tube metalwork to form a tube head and the tube head is mounted on a dual-axis torque joint, fixed on the end of a support arm. The support arm is formed of elongated metal sections (e.g. aluminium or steel) and is provided with gas springs for support. A heat exchanger coil is located around tube head for cooling, which is supplied by a connecting cooling pipe. The cooling pipe could contain air for cooling, but water cooling is preferred, as has been described above. The connecting cooling pipe, filament cable and HT cable all routed through the support arm.

Using smaller, less powerful X-ray tubes reduces the size of the cabling needed.

This also helps to make the tube head more manoeuvrable. For example, the HT cable of a 50kV X-Ray tube is small, lightweight and fairly flexible compared to the HI cables on previous X-ray apparatus (e.g. XSTRAHL 100 or 150 systems). The 50kV or 80kV tubes require an HI cable of roughly a 12mm diameter, with a minimum bend radius of 22mm. This compares very favourably to the HI cables used with tubes capable of providing higher energy X-rays, such as the XSIRAHL 100 which has a 20mm diameter with a minimum bend radius of 102mm. Lower energy (e.g. 50kV or 80kV) X-ray tubes can be supplied with grounded-filament HT cables (unlike higher energy X-ray tubes).

This means the filament wires aren't held at a high voltage, and therefore don't have to be passed through the centre of the HV cable and therefore the HV cable used can be vastly smaller in size, weight and outside diameter than for higher energy tubes. Having a smaller, light weight HI cable significantly improves the ease of movement, and ease of range of movement, of the X-ray tube-head for placement on a patient treatment site.

A preferred embodiment of this system positions the filament wires (for the X-ray tube filament biasing and control, which allow a user to adjust the dose output of the X-ray tube), along with the water cooling hoses (for the X-ray tube cooling), through cosmetic covers on the support arm. This permits an optimal solution, with just a small lightweight HI cable passing outside, which may be visible at the top (non-X-ray emitting end) of the X-ray tube-head. This offers notable advantages and benefits over other X-Ray radiotherapy solutions.

An LED lighting ring along with filter and applicator recognition printed circuit boards (PCB5) are fitted onto the tube head. The system is also provided with operator interchangeable filters and applicators, which can be easily fitted onto the X-ray tube for changing the properties of the X-ray treatment beam. Each applicator and filter comprises a pin, which is unique to each specification of applicator or filter, for making an electrical connection with the recognition PCBs. The recognition POBs and pins allow the system to determine which type of applicator or filter is installed. The support arm may be mounted on a desktop base unit, or on a mobile base unit.

A controller is provided for controlling the X-ray tube; the controller is fixed to the wall of the treatment room and may comprise, for example, a computer memory, processor, user interface. The user interface may also be placed outside the treatment room, so the operator can control the X-ray apparatus when they have left the room (to reduce X-ray exposure) during the X-ray application. The controller is separate to the X-ray tube-head base unit, being fixed to the wall of the facility, and hard-wired into local power system and safety interlocks of the treatment room. It has been found that it is more efficient to install the system controller in the treatment room, rather than to provide it on a mobile base unit that also supports the X-ray tube head support arm.

It may be possible to provide an X-ray solution with this system that can be fitted in a vehicle for a transportable solution (allowing on-vehicle treatment of patients in remote communities). However in this case the system architecture still replicates the arrangement detailed above, but the medical controller is in the vehicle, being hard-wired into a local or on-vehicle (24Vdc or mains ac) power source, and hardwired into warning lights and door safety interlocks of the treatment room in the vehicle Any system feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.

Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to system aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination.

It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.

Claims

CLAIMS: 1. A radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, corn pri sing: an X-ray generator cornprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of the one or more collimator(s) allows through an X-ray beam with a beam angle of at least 35° in at least one plane; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; and at least one removable filter having a filtering region with a non-uniform thickness for adjusting the X-ray beam intensity profile based on the X-ray beam profile from the X-ray tube; wherein the filter is arranged for use with at least one applicator.
2. A radiotherapy X-ray system according to claim 1, wherein the at least one removable filter arranged for use with at least one applicator is configured for filtering said X-ray beam dependent on the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface defined by said applicator.
3. A radiotherapy X-ray system according to claim 1 or 2, wherein the at least one applicator comprises an applicator treatment face for defining the X-ray treatment surface; and wherein the at least one removable filter arranged for use with at least one applicator is configured for filtering said X-ray beam dependent on said applicator treatment face.
4. A radiotherapy X-ray system according to claim 3, wherein said applicator treatment face is flat, concave or convex.
5. A radiotherapy X-ray system according to any preceding claim, wherein the provision for receiving an exchangeable X-ray filter comprises integrating the at least one filter into the at least one removable applicator.
6. A radiotherapy X-ray system according to any of claims 1 to 4, wherein the provision for receiving a removable X-ray filter comprises an aperture in the housing for engaging the filter; and wherein the at least one X-ray filter comprises a securing portion for attaching directly to the aperture in the housing for engaging the filter.
7. A radiotherapy X-ray system according to claim 6, wherein the securing portion of the filter comprises a filter identifier encoding portion for storing the filter identifier; and the aperture in the housing for engaging the filter comprises a filter identifier slot for receiving said filter identifier encoding portion and for obtaining said filter identifier.
8. A radiotherapy X-ray system according to claim 7, wherein the filter identifier encoding portion comprises: optical encoding means; a magnetic stripe; a barcode; one or more mechanical formations; and/or mechanical means to operate an electrical switch.
9. A radiotherapy X-ray system according to any preceding claim, wherein the thickness of the filtering region decreases towards the outer edges, such that the filter is configured to adjust the X-ray beam intensity profile to achieve a substantially uniform X-ray dose intensity across the surface of the X-ray treatment surface.
10. A radiotherapy X-ray system according to any preceding claim, wherein the thickness of the filtering region varies across its surface to compensate for difference in X-ray intensity across the X-ray beam due to the difference in distance travelled between the X-ray target and the X-ray treatment surface by the beam at different beam angles.
11. A radiotherapy X-ray system according to any preceding claim, wherein the thickness of the filtering region is based on the X-ray energy.
12. A radiotherapy X-ray system according to any preceding claim, wherein the filtering region is formed of aluminium, copper, or tin.
13. A radiotherapy X-ray system according to any preceding claim, comprising at least two non-uniform removable filters, each filter having a filtering region with a different thickness profile, such that each filter provides a corresponding adjustment to the beam intensity profile.
14. A radiotherapy X-ray system according to any preceding claim, wherein the removable filter adjusts the X-ray beam field such that for an X-ray beam having an angle of at least 36°, the variation of the X-ray dose across a substantially flat treatment surface is less than 5% within at least 80% of the X-ray beam field.
15. A radiotherapy X-ray system according to any preceding claim, wherein the X-ray beam controller is configured for controlling the beam to at least two X-ray beam qualities, each X-ray beam quality corresponding to the half value layer, HVL, of the beam in the centre of the X-ray beam field at the treatment surface; wherein each of the at least two X-ray beam qualities may be selected by a user; and wherein the at least two X-ray beam qualities have an HVL of between 0.5mm Aluminium and 3mm Aluminium.
16. A radiotherapy X-ray system according to any preceding claim, wherein the X-ray beam controller is operable to select at least one X-ray beam energy greater than 70kV.
17. A radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; two or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the two or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the distance between the X-ray target and the aperture of each of the two or more collimator(s) is less than 35mm; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; and at least one removable filter.
18. A radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, corn pri sing: an X-ray generator cornprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube cornprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; wherein the at least one removable applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface and wherein the side walls are formed substantially of a material that is transparent, such that a user can view the treatment surface through the applicator side walls; and at least one removable filter.
19. A radiotherapy X-ray system according to claim 18, wherein said transparent material is a plastic, preferably Perspex or Acrylic.
20. A radiotherapy X-ray system according to any preceding claim, comprising two or more collimator(s) provided in the housing between the end-window X-ray tube and the treatment surface, the two or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the distance between the X-ray target and the aperture of each of the two or more collimator(s) is less than 35mm.
21. A radiotherapy X-ray system according to any preceding claim, wherein the system is operable to provide an X-ray beam for a treatment surface having a maximum diameter of at least 35mm; and wherein said treatment surface is at a distance of 3cm to 5.5cm from the X-ray target.
22. A radiotherapy X-ray system according to any preceding claim, wherein the generator is arranged to operate with at least one removable applicator which defines an X-ray treatment surface with a maximum diameter of at least 4-6cm at a distance of 3- 7cm from the X-ray target.
23. A radiotherapy X-ray system according to any preceding claim, wherein a collimator is integrated with the mounting portion of the at least one removable applicator, such that the applicator comprises a mounting portion with an aperture for allowing X-rays to pass through and an absorbing portion tor absorbing X-ray radiation outside the aperture.
24. A radiotherapy X-ray system according to claim 23, wherein when the removable applicator is received in the housing, the distance between the X-ray target and the aperture of the collimator integrated with the mounting portion of the removable applicator is less than 35mm.
25. A radiotherapy X-ray system according to claim 23 or 24, wherein the absorbing portion of the applicator is formed of tungsten.
26. A radiotherapy X-ray system according to any preceding claim, further comprising: one or more light sources for coupling to the at least one applicator for illuminating at least a portion of the X-ray treatment surface.
27. A radiotherapy X-ray system according to any preceding claim, further corn pri sing: at least one camera for coupling to the X-ray housing for irnaging the X-ray treatment surface.
28. A radiotherapy X-ray systern for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray bearn and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of the one or more collirnator(s) allows through an X-ray beam with a bearn angle of at least 35° in at least one plane; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; control apparatus for the X-ray generator comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the cornbination of filter identifier, go applicator identifier and selected X-ray energy corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm; at least one removable filter; an electronic distance measuring device coupled to the X-ray tube housing for measuring the distance between the X-ray target and the X-ray treatment surface; and at least one of: means for providing an indication to an operator in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than 5mm during treatment; and means for disabling the X-ray beam in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than 5mm during treatment.
29. A radiotherapy X-ray system according to any preceding claim, wherein the control apparatus comprises: a memory for storing a set of approved X-ray treatment plans; wherein each treatment plan comprises a combination of parameters for the treatment plan, the parameters including one or more of: an X-ray beam energy; an applicator identifier; a filter identifier; and a treatment time or treatment dose.
30. A radiotherapy system or control apparatus according to claim 29, further comprising: a user interface, comprising user input means for allowing a user to select a desired X-ray treatment plan from the set of approved X-ray treatment plans; and control logic for receiving an indication of the selected desired X-ray treatment plan; wherein the control logic determines at least one combination of an applicator and a filter based on the selected X-ray treatment plan compatible with the selected X-ray treatment plan; wherein the user interface further comprises display means for displaying to a user an indication of said at least one combination of an applicator and a filter.
31. A radiotherapy X-ray system or control apparatus according to any preceding claim, wherein the user interface further comprises: a display for displaying to a user a menu comprising at least a portion of the set of approved X-ray treatment plans.
32. A radiotherapy X-ray system or control apparatus according to claim 30 or 31, wherein the user input means allows the user to input an indication of at least one treatment option, the treatment options comprising: the size of the X-ray treatment surface; the profile of the X-ray treatment surface defined by an applicator, wherein said profile is chosen from a list comprising at least one of: a flat treatment surface, a concave treatment surface and a convex treatment surface; and the desired beam quality; and wherein the control logic is configured to determine at least one suitable approved X-ray treatment plan based on said indication of the at least one treatment option.
33. A radiotherapy X-ray system according to any preceding claim, further comprising: a removable collimator associated with the at least one removable applicator for collimating said X-ray beam dependent on the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface defined by the applicator; said removable collimator comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the housing has provision for receiving the removable collimator.
34. A radiotherapy X-ray system according to claim 33, wherein the removable collimator is integrated with the mounting portion of the at least one removable applicator, such that the applicator comprises: a mounting portion with an aperture for allowing X-rays to pass through and an absorbing portion for absorbing X-ray radiation outside the aperture; and conical side walls arranged to extend from the X-ray tube housing such that the diameter of the applicator increases with distance from the X-ray target.
35. A radiotherapy X-ray system according to claim 34, wherein when the removable applicator is received in the housing, the distance between the X-ray target and the aperture of the removable collimator is less than 40mm.
36. A radiotherapy X-ray system according to any preceding claim, wherein the aperture of at least one collimator is conical, such that the diameter of the aperture increases with distance from the X-ray target.
37. A radiotherapy X-ray system according to any preceding claim, wherein at least one of the collimators is formed predominantly of tungsten or lead.
38. A radiotherapy X-ray system according to any preceding claim, wherein the portion of one of the one or more collimator(s) for absorbing X-rays comprises a recess complementary with the end-face of the X-ray tube and dimensioned to locate and receive the end of the X-ray tube, and wherein said collimator is further positioned for collimation of the X-ray beam and absorption of X-rays.
39. A radiotherapy X-ray system according to any preceding claim, wherein the portion of at least one of the one or more collimator(s) for absorbing X-rays extends around the X-ray target in a direction substantially perpendicular to the end-window of the tube for absorbing X-rays that propagate from the target towards the side of the X-ray tube.
40. A radiotherapy X-ray according to any preceding claim, wherein one of the one or more collimator(s) comprises a shield comprising: a recess dimensioned for receiving and locating the X-ray emitting end of the elongate end-window X-ray tube, the recess having a portion arranged to extend around the sides of the X-ray tube to surround the X-ray target radially and absorb a portion of the X-ray radiation that does not pass through the end-window end of the X-ray tube; and an aperture arranged to align with the end-window for allowing an X-ray beam emitted from the end-window of the X-ray tube through the shield; wherein the aperture is shaped and dimensioned for collimating the X-ray beam to provide a beam angle of between 35° and 90° and narrower than the beam emerging from the X-ray tube window.
41. A radiotherapy X-ray according to any preceding claim, wherein the distance between the X-ray target and the aperture of one or more collimator(s) is less than 35mm.
42. A radiotherapy X-ray system according to any preceding claim, wherein the distance between the X-ray target and the aperture of one or more collimator(s) is greater than 6mm.
43. A radiotherapy X-ray system according to any preceding claim, wherein the at least one removable applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface and wherein the side walls are formed substantially of material that is transparent to at least a portion of the frequencies of electromagnetic light.
44. A radiotherapy X-ray system according to claim 43, wherein said material is transparent to visible light.
45. A radiotherapy X-ray system according to any preceding claim, wherein said applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface and wherein the side walls are formed substantially of Perspex or Acrylic.
46. A radiotherapy X-ray system according to any preceding claim wherein said applicator comprises an X-ray treatment face for contacting the X-ray treatment surface and wherein said X-ray treatment face is formed substantially of Polystyrene.
47. A radiotherapy X-ray system according to any preceding claim, wherein: the securing portion of the applicator comprises an applicator identifier encoding portion for storing the applicator identifier; and the fitting for receiving a removable applicator comprises an applicator identifier slot for receiving said applicator identifier encoding portion and for obtaining said identifier code.
48. A radiotherapy X-ray system according to claim 47, wherein the applicator identifier encoding portion comprises: optical encoding means; a magnetic stripe; a barcode; one or more mechanical formations; or mechanical means to operate an electrical switch.
49. A radiotherapy X-ray system according to any preceding claim, wherein the applicator comprises conical side walls arranged to extend from the housing at an angle of less than 31° to the normal to the X-ray generation tube end-window.
50. A radiotherapy X-ray system according to any preceding claim, further comprising: one or more light sources for coupling to the at least one applicator for illuminating at least a portion of the X-ray treatment surface.
51. A radiotherapy X-ray system according to claim 50, wherein the one or more light sources are integrated in the housing and provided with a light pipe for coupling to the at least one applicator.
52. A radiotherapy X-ray system according to claim 50, wherein the one or more light sources are integrated into the at least one applicator.
53. A radiotherapy X-ray system according to any of claims 50 to 52, wherein the one or more light sources are configured to illuminate an area inside and outside the X-ray treatment surface.
54. A radiotherapy X-ray system according to any of claims 50 to 53, wherein the at least one applicator comprises side walls arranged to extend from the X-ray tube housing for contacting the X-ray treatment surface; wherein the side walls are formed substantially of material that is transparent to at least a portion of the frequencies of light emitted from said one or more light sources; and wherein the applicator is arranged such that when coupled to the light sources, the applicator transmits light from the light sources through the applicator side walls to the X-ray treatment surface.
55. A radiotherapy X-ray system for delivering X-ray radiation to a patient's skin, comprising: an X-ray generator comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the end-window X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; and a moveable support structure for the X-ray tube; at least one removable applicator for defining an X-ray treatment surface on the patient; the applicator having a mounting portion for engaging with the fitting for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; and one or more light sources for coupling to the at least one applicator for illuminating at least a portion of the X-ray treatment surface; wherein the at least one applicator comprises side walls arranged to extend from the X-ray tube housing for contacting the X-ray treatment surface; wherein the side walls are formed substantially of material that is transparent to at least a portion of the frequencies light emitted from said one or more light sources; and wherein the applicator is arranged such that when coupled to the light sources, the applicator transmits light from the light sources through the applicator walls to the X-ray treatment surface.
56. A radiotherapy X-ray system according to claim 54 or 55, wherein the transmitted light is visible when the emitting surface of the applicator walls is in contact with the edge of the X-ray treatment surface; and the light disperses within a small distance when the emitting surface of the applicator walls is a small distance from the target X-ray surface.
57. A radiotherapy X-ray system according to any of claim 26, claims 27 to 49 when dependent on claim 26, or claims 50 to 56, wherein said light sources emit one or more of: visible light; ultraviolet light; infrared light; and polarised light.
58. A radiotherapy X-ray system according to any of claim 26, claims 27 to 49 when dependent on claim 26, or claims 50 to 57, wherein the light sources are light-emitting diodes, LED5.
59. A radiotherapy X-ray system according to any of claim 26, claims 27 to 49 when dependent on claim 26, or claims 50 to 58, wherein the one or more light sources are arranged in a ring surrounding the X-ray beam zone at the X-ray emitting end of the X-ray tube housing.
60. A radiotherapy X-ray system according to any preceding claim, further comprising: at least one camera for coupling to the X-ray housing for imaging the X-ray treatment surface.
61. A radiotherapy X-ray system according to any of claim 27, claims 28 to 59 when dependent on claim 27, or claim 60, wherein at least one camera is configured to be removably fitted to the housing within an X-ray beam zone.
62. A radiotherapy X-ray system according to claim 61, wherein the X-ray generator is configured such that X-ray generation tube is disabled while the camera is positioned within the X-ray beam zone.
63. A radiotherapy X-ray system according to any of claims to any of claim 27, claims 28 to 59 when dependent on claim 27, or claims 60 to 62, wherein at least one camera is fitted to the X-ray housing outside an X-ray beam zone.
64. A radiotherapy X-ray system according to claim 63, wherein the X-ray applicator is formed substantially of material that is transparent to at least a portion of the frequencies of light which the camera fitted outside the X-ray beam zone is operable to detect.
65. A radiotherapy X-ray system according to any of claim 27, claims 28 to 59 when dependent on claim 27, or claims 60 to 64, further comprising: a computer program, computer program product or non-transitory computer-readable storage medium storing one or more instructions which, when executed by one or more processors, cause the one or more processors to detect motion from the output of the at least one camera; and a processor for executing said instructions for detecting motion from images of the target X-ray area.
66. A radiotherapy X-ray system according to any of claims any of claim 27, claims 28 to 59 when dependent on claim 27, or claims 60 to 65, comprising: at least two cameras for imaging the target X-ray area and arranged such that images from the at least two cameras can be combined to produce 3-dimensional imaging of the treatment surface.
67. A radiotherapy X-ray system according to claim 66, wherein the 3-dimensional imaging of the treatment surface provides an indication of one or more of: the height of a skin abnormality above the skin surface; and the depth of a skin abnormality below the skin surface.
68. A radiotherapy X-ray system according to any preceding claim, further comprising: an electronic distance measuring device coupled to the X-ray tube housing for measuring the distance between the X-ray target and the X-ray treatment surface.
69. A radiotherapy X-ray system according to any of claim 28, claims 29 to 67 when dependent on claim 28, or claim 68, wherein the distance measuring device obtains a measure of distance using one or more of: an infrared, IR, sensor; one or more lasers; and ultrasound.
70. A radiotherapy X-ray system according any of claim 28, claims 29 to 67 when dependent on claim 28, or claim 68 or 69, further comprising: means for providing an indication to an operator in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.
71. A radiotherapy X-ray system to any of claim 28, claims 29 to 67 when dependent on claim 28, or claim 68 to 70, further comprising: means for disabling the X-ray beam in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.
72. A radiotherapy X-ray system according to any of claim 28, claims 29 to 67 when dependent on claim 28, or claim 68 tor 71, wherein the predetermined threshold value is smaller than or equal to 6mm; preferably wherein the predetermined threshold value is smaller than or equal to 4mm; preferably wherein the predetermined threshold value is smaller than or equal to 3mm; or preferably wherein the predetermined threshold value is smaller than or equal to 2mm.
73. A radiotherapy X-ray system for delivering X-ray radiation to a patient, comprising: a housing for receiving an X-ray tube, the housing having a fluid pipe or an air pipe for fluid or air cooling the X-ray tube and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; one or more collimator(s) integrated into the housing, the one or more collimator(s) for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering said X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, one or more collimator(s), X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the moveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a joint and a distal end; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein at least one of the first and second elongate sections comprises a parallelogram linkage; wherein the X-ray tube housing is attached to the second elongate section via at least one joint which permits movement of the X-ray housing relative to the second elongate section; and a biasing arrangement and maintaining arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.
74. A radiotherapy X-ray system according to claim 73, wherein the biasing arrangement comprises one or more of: one or more gas springs; one or more tension springs; one or more compression springs; one or more coil springs; one or more torsion springs; and one or more weights.
75. A radiotherapy X-ray system according to claim 73 or 74, wherein the maintaining arrangement comprises one or more of: friction of one or more joints; electronic braking; and manual braking.
76. A radiotherapy X-ray system according to any of claims 73 to 75, wherein both of the first and second elongate sections comprise a parallelogram linkage.
77. A radiotherapy X-ray tube support arm for supporting an X-ray tube head of mass 1kg to 15kg, the support arm comprising: a first elongate section for connecting to a base support unit; and a second elongate section, movably coupled to the first elongate section, the second elongate section for attaching to the X-ray tube head; wherein the first and second elongate sections each comprise at least one parallelogram linkage.
78. A radiotherapy X-ray system according to any of claims 73 to 77, wherein each parallelogram linkage comprises: a first elongate substantially rigid member having a first end and a second end; a second elongate substantially rigid member having a first end and a second end; a first substantially rigid linkage member fixed to the first end of each elongate member by a pivot joint, such that the second ends of the elongate members are maintained at a constant separation distance; wherein the second ends of each elongate member are pivotably fixed such that the second ends of the elongate members are maintained at a constant separation distance, equal to the separation distance of the first ends of the elongate members; such that the two elongate members are configured to rotate in an arc while remaining parallel.
79. A radiotherapy X-ray system according to claim 78, further comprising: a second substantially rigid linkage member fixed to the second end of each elongate member by a pivot joint the second ends of each elongate member for maintaining the second ends of the elongate members at said constant separation distance.
80. A radiotherapy X-ray system according to any of claims 73 to 79, wherein the maintaining arrangement comprises at least one friction component for applying friction to one or more of: the hinged joint coupling the first and second elongate sections; the joint attaching the X-ray tube housing to the second elongate section; and the joint fixing the first elongate section to the base support arrangement; wherein the level of friction applied by the friction component is adjustable.
81. A radiotherapy X-ray system according to claim 80, wherein the degree of applied friction is adjustable by means of a spring washer.
82. A radiotherapy X-ray system according to claim 80 or 81, wherein the degree of applied friction is adjustable by means of a Belleville washer.
83. A radiotherapy X-ray system according to any of claims 80 or 81, wherein the degree of applied friction is adjustable by means of a Wave washer.
84. A radiotherapy X-ray system according to claim 80 or 81, wherein the degree of applied friction is adjustable by means of a compressible plastic component.
85. A radiotherapy X-ray system according to any of claims 73 to 84, wherein the joint attaching the X-ray tube housing to the second elongate section comprises: a dual axis joint configured to allow rotation about at least a first axis and a second axis.
86. A radiotherapy X-ray system for delivering X-ray radiation to a patient, corn pri sing: a housing for receiving an X-ray tube, the housing having a fluid pipe or an air pipe for fluid or air cooling the X-ray tube and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; one or more collimator(s) integrated into the housing, the one or more collimator(s) for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering said X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, one or more collimator(s), X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the moveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a joint and a distal end; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein the X-ray tube housing is attached to the second elongate section via a dual axis joint configured to allow rotation about at least a first axis and a second axis which permits two degrees of freedom in the movement of the X-ray housing relative to the second elongate section; and a biasing arrangement and maintaining arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.
87. A radiotherapy X-ray system according to claim 85 or 86, wherein the dual axis joint comprises a friction joint.
88. A radiotherapy X-ray system according to claim 87, wherein: the first axis is in the plane containing the first and second elongate sections; the second axis is perpendicular to the plane containing the first and second elongate sections; and the dual axis friction joint is configured such that the friction about the second axis is greater than the friction about the first axis.
89. A radiotherapy system according to claim 87 or 88, wherein the dual axis joint is configured such that: the torque required for rotation about the first axis is greater than 1 Nm, preferably greater than I.25Nm1 and/or less than 2.5Nm1, preferably less than 2Nm1, more preferably less than 1.75Nm1; and/or the torque required for rotation about the second axis is greater than 2Nm, preferably greater than 2.5 Nm, more preferably greater than 2.75Nm and/or less than 10Nm1, preferably less than 5 Nm and/or more preferably less than 3.25Nm*
90. A radiotherapy X-ray system according to any of claims 73 to 89, wherein the joint for fixing the proximal end of the first elongate section to the base support arrangement comprises a rotation joint.
91. A radiotherapy X-ray system according to claim 90, wherein the maintaining arrangement comprises a braking mechanism for locking said rotation joint.
92. A radiotherapy X-ray system for delivering X-ray radiation to a patient, comprising: a housing for receiving an X-ray tube, the housing having a fluid pipe or an air pipe for fluid or air cooling the X-ray tube and a power supply; an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X-ray beam and an X-ray target adjacent to the end-window within the tube; the X-ray tube being installed in the housing; one or more collimator(s) integrated into the housing, the one or more collimator(s) for collimating said X-ray beam; an X-ray filter secured to the X-ray housing, the X-ray filter for filtering said X-ray beam; a removable applicator fitted to the X-ray housing, the applicator for defining an X-ray treatment surface on the patient, the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; wherein the combined mass of the X-ray housing with the X-ray tube, one or more collimator(s), X-ray filter and applicator does not exceed 2.5kg; and a moveable support structure for supporting the X-ray housing, the moveable support structure comprising: a base support arrangement with a mass of more than 5kg; a first elongate section having a length of at least 25cm and having a proximal end fixed to the base support arrangement via a rotation joint and a distal end; a braking mechanism for inhibiting movement of said rotation joint; a second elongate section having a length of at least 25cm and having a proximal end coupled to the distal end of the first elongate section and a distal end attached to the X-ray housing; wherein the first and second elongate sections are coupled via a hinged joint, such that the second elongate section can be moved relative to the first elongate section, allowing at least two degrees of freedom in the movement of the X-ray housing; wherein the X-ray tube housing is attached to the second elongate section via at least one joint which permits movement of the X-ray housing relative to the second elongate section; and a biasing arrangement for balancing the forces on the first and second elongate sections such that the X-ray housing is configured to move in response to manual manipulation by a user applied to at least one point on the X-ray housing or X-ray support structure, and configured to remain in a static position when no force is applied.
93. A radiotherapy X-ray system according to claim 91 or 92, wherein said braking mechanism comprises a mechanical braking mechanism.
94. A radiotherapy X-ray system according to claim 91 or 92, wherein said braking mechanism comprises an electronic braking mechanism.
95. A radiotherapy X-ray system according to any of claims 91 to 94, wherein the braking mechanism is operable from the X-ray tube housing.
96. A radiotherapy X-ray system according to any of claims 73 to 95, wherein the moveable support structure further comprises: one or more cosmetic covers for covering one or more of the elongate sections; wherein the fluid pipe or air pipe and a power supply cable are routed through at least a part of said one or more cosmetic covers.
97. A support structure for a radiotherapy X-ray generation tube head, comprising: at least two elongate sections for securing the X-ray generation tube head to a base support unit; and a plurality of joints for allowing the X-ray generation tube to move with multiple degrees of freedom; wherein the plurality of joints includes: at least one passive joint; and at least one actively controlled joint.
98. A support structure according to claim 97, wherein the movement of the at least one passive joint is dependent on friction in the joint.
99. An X-ray generator, preferably for use in the radiotherapy system of any of claims Ito 96, comprising: an end-window X-ray tube for generating an X-ray beam, the end-window X-ray tube comprising an elongate tube having an end-window at one end for emitting said X- ray beam and an X-ray target adjacent to the end-window within the tube, wherein the X-ray tube provides an X-ray beam having a beam angle of at least 35°; a housing for receiving the X-ray tube, the housing having: provision for receiving a removable X-ray filter for filtering said X-ray beam; a fitting for receiving a removable applicator; one or more collimator(s) provided in the housing between the X-ray tube and a treatment surface, the one or more collimator(s) for collimating said X-ray beam and comprising an aperture for allowing X-rays to pass through and a portion for absorbing X-ray radiation outside the aperture; wherein the aperture of one or more collimator(s) allows through an X-ray beam with a beam angle of at least 35° in at least one plane; and a moveable support structure for supporting the X-ray tube; provision for a cooling means to cool the X-ray tube and a power supply to power the X-ray tube; wherein the generator is arranged to operate with at least one removable applicator which defines an X-ray treatment surface with a 4-6cm diameter at a distance of 4-6cm from the X-ray target.
100. An X-ray generator control apparatus, preferably for use with the system or generator of any preceding claim, the control apparatus comprising: filter detection logic for detecting an inserted filter and receiving a filter identifier; applicator detection logic for detecting an inserted applicator and receiving an applicator identifier; an X-ray beam controller for controlling the beam to at least one selected X-ray energy; and validation logic for determining whether the combination of filter identifier, applicator identifier and selected power level corresponds to an allowable combination and selectively enabling the X-ray treatment only when the combination is allowable; wherein at least a portion of the control apparatus housing is provided in a housing, said housing configured to be positioned remotely from the generator.
101. An X-ray applicator, preferably for use with the radiotherapy system or X-ray generator according to any preceding claim, the applicator defining an X-ray treatment surface on a patient; the applicator having a mounting portion for engaging with a fitting in an X-ray tube housing for receiving the applicator; the applicator being dimensioned for defining the area of the X-ray treatment surface and the distance between an X-ray target and the X-ray treatment surface; wherein the applicator is arranged to transmit light from one or more light sources provided on the X-ray tube housing to the X-ray treatment surface.
102. An applicator according to claim 101, wherein the applicator defines the distance between the X-ray target and the treatment surface as less than 12cm.
103. An applicator according to claim 101 or 102, wherein the mounting portion comprises a portion for absorbing X-ray radiation and an aperture for providing secondary collimation for an X-ray beam.
104. An applicator according to any of claims 101 to 103, wherein the applicator comprises side walls arranged to extend from the X-ray tube housing towards the X-ray treatment surface for contacting the X-ray treatment surface to define the area of the X-ray treatment surface and the distance between the X-ray target and the X-ray treatment surface; and wherein the side walls are formed substantially of material that is transparent.
105. An applicator according to any of claims 101 to 104, wherein the applicator comprises a light pipe for extending through the mounting portion and coupling the transparent side walls of the applicator to one or more light sources provided in the X-ray tube housing; and wherein the applicator side walls acts as a light pipe for channelling light from the light sources towards an X-ray treatment surface and emitting light from the end of the side walls for contacting the X-ray treatment surface, such that the edge of the treatment surface is illuminated when the applicator makes contact with said treatment surface.
106. A plurality of interchangeable X-ray filters for a radiotherapy X-ray system, preferably for use with the radiotherapy system or the X-ray generator according to any preceding claim, wherein the thickness of each filter varies across the filtering region to alter the shape of the X-ray beam dose intensity in a different way to compensate for variation in X-ray beam intensity caused by the non-uniform output of an X-ray tube.
107. An X-ray filter according to claim 106, wherein at least one of the plurality of filters has a thickness that varies across the filtering region to compensate for variation in X-ray beam intensity due to the difference in distance travelled between an X-ray target and an X-ray treatment surface by the beam at different beam angles.
108. A shield for an elongate end-window X-ray tube having a tube diameter of between 20mm and 75mm, the tube comprising an X-ray target for generating an X-ray beam positioned adjacent the end window, the shield comprising: a recess dimensioned for receiving and locating the X-ray emitting end of the elongate end-window X-ray tube, the recess having a portion arranged to extend around the sides of the X-ray tube to surround the X-ray target radially and absorb a portion of the X-ray radiation that does not pass through the end-window end of the X-ray tube; and an aperture arranged to align with the end-window for allowing an X-ray beam emitted from the end-window of the X-ray tube through the shield; wherein the aperture is shaped and dimensioned for collimating the X-ray beam to provide a beam angle of between 35° and 90° and narrower than the beam emerging from the X-ray tube window.
109. A shield according to claim 108, wherein the shield is formed substantially of tungsten.
110. A shield according to claim 108 or 109, wherein the recess is dimensioned for positioning the aperture between 8mm and 30mm from the X-ray target.
111. A shield according to any of claims 108 to 110, wherein the recess is dimensioned for positioning the aperture less than 10mm from the X-ray target.
112. A radiotherapy X-ray tube head, preferably for use with the radiotherapy system or X-ray generator according to any preceding claim, the tube head comprising a housing for an end-window X-ray tube, the housing having provision for attaching an applicator for defining an X-ray treatment surface and an X-ray treatment beam zone, the tube head further comprising: provision for attaching a camera within the X-ray beam zone for imaging the X-ray treatment surface; and means for disabling the X-ray tube while the camera is positioned within the X-ray beam zone.
113. A radiotherapy X-ray tube head, preferably for use with the radiotherapy system or X-ray generator according to any preceding claim, the tube head comprising a housing for an end-window X-ray tube, the housing having: provision for attaching an applicator for defining an X-ray treatment surface and X-ray treatment beam zone; and a camera for imaging the X-ray treatment surface fitted to the X-ray housing outside the X-ray beam zone.
114. A radiotherapy X-ray tube head according to claim 112 or 113, the housing further having provision for attaching at least two cameras for imaging the X-ray treatment surface and arranged such that images from the two cameras can be combined to produce 3-dimensional imaging.
115. A radiotherapy X-ray tube head comprising a housing for an end-window X-ray tube, preferably for use with the radiotherapy system or X-ray generator according to any preceding claim, the housing having provision for attaching an applicator for defining an X-ray treatment surface and an electronic distance measuring device coupled to the X-ray housing for measuring the distance between the X-ray target and the X-ray treatment surface.
116. A radiotherapy X-ray tube according to claim 115, further comprising: means for providing an indication to an operator in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.
117. A radiotherapy X-ray tube head according to claim 115 or 116, further comprising: means for disabling the X-ray beam in response to the distance measuring device detecting a change in the distance between the X-ray target and the X-ray treatment surface of more than a predetermined threshold value.
118. A radiotherapy X-ray tube head according to claim 116 or 117, wherein the predetermined threshold value is smaller than or equal to 6mm; preferably wherein the predetermined threshold value is smaller than or equal to 4mm; preferably wherein the predetermined threshold value is smaller than or equal to 3mm;or preferably wherein the predetermined threshold value is smaller than or equal to 2mm.
119. A method of configuring an X-ray filter for use with an X-ray apparatus including an end-window X-ray tube for generating an X-ray beam, means for supporting a filter in a plane across the path of the X-ray beam, and an applicator defining a patient treatment surface, the method comprising the steps of: determining the divergence of the X-ray beam at a plurality of points in the plane across the path of the X-ray beam; calculating the variation in beam intensity across the treatment surface based on the variation with beam angle of X-rays emitted by the X-ray apparatus and the variation of path length from the X-ray apparatus to points on the treatment surface; and calculating a filter profile based on the attenuation of the filter material, the divergence of the X-ray beam in the plane and the calculated variation in beam intensity to give a desired intensity profile across the treatment surface.
120. A method of configuring an X-ray filter according to claim 119, wherein the desired intensity profile is of substantially uniform intensity across the treatment surface.
121. A method of configuring an X-ray filter according to claim 119 or 120, wherein the treatment surface is concave, convex or flat.
122. A method for cosmetically treating a non-malignant skin condition, comprising: providing an X-ray generation tube comprising an X-ray target and an end-window at one end of the tube for emitting said X-ray beam, the X-ray tube providing a beam having a beam angle of at least 35°; positioning the X-ray generation tube such that the distance between the X-ray target and an X-ray treatment surface on a patient is less than 10cm, preferably less than 7cm, preferably between 4.5cm and 5.5cm; and generating an X-ray beam using the X-ray generation tube; wherein said X-ray treatment surface contains at least a portion skin affected by said non-malignant skin condition.
123. A method according to claim 122, wherein the X-ray beam generated has an energy of between 5kV and 100kV, preferably an energy greater than 50kV, more preferably greater than 65kV, or more preferably greater than 75kV.
124. A system, method, generator or control apparatus according to any preceding claim, wherein the X-ray tube is operable to deliver a dose at the treatment surface of greater than 1 Gy/min with a half-value layer of 0.9mm Aluminium or greater.
125. A radiotherapy X-ray system, method, generator or control apparatus according to any preceding claim, wherein the X-ray tube provides a beam having a normalised intensity on a flat surface of at least 70% across a beam angle of at least 50°.
126. A radiotherapy X-ray system, generator or control apparatus according to any preceding claim, wherein the X-ray beam controller is operable to select at least one X-ray beam energy between 5kV and 100kV.
127. A radiotherapy X-ray system, generator or control apparatus according to any preceding claim, wherein the X-ray beam controller is operable to select at least one X-ray beam energy greater than 70kV.
128. A radiotherapy X-ray system, method, generator or control apparatus according to any preceding claim, wherein the distance between the X-ray target and the end-window of the X-ray tube is less than 25mm, preferably less than 15mm, more preferably less than 10mm, more preferably less than 8mm and/or greater than 4mm.
129. An apparatus substantially as hereinbefore described in relation to the Figures.
130. A method substantially as hereinbefore described in relation to the Figures.