CA1101133A - Arrangement for the reproduction of a planar slice of a body with the aid of gamma or x-radiation - Google Patents
Arrangement for the reproduction of a planar slice of a body with the aid of gamma or x-radiationInfo
- Publication number
- CA1101133A CA1101133A CA299,716A CA299716A CA1101133A CA 1101133 A CA1101133 A CA 1101133A CA 299716 A CA299716 A CA 299716A CA 1101133 A CA1101133 A CA 1101133A
- Authority
- CA
- Canada
- Prior art keywords
- primary beam
- detectors
- detector
- arrangement
- radiation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/48—Diagnostic techniques
- A61B6/483—Diagnostic techniques involving scattered radiation
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/02—Devices for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computerised tomographs
- A61B6/032—Transmission computed tomography [CT]
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment
- A61B6/42—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with arrangements for detecting radiation specially adapted for radiation diagnosis
- A61B6/4208—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector
- A61B6/4258—Apparatus for radiation diagnosis, e.g. combined with radiation therapy equipment with arrangements for detecting radiation specially adapted for radiation diagnosis characterised by using a particular type of detector for detecting non x-ray radiation, e.g. gamma radiation
Abstract
PHD. 77-023 8.3.78 ABSTRACT:
The invention enables the density distribution in a plane, in particular in a planar slice of a body, to be reproduced with the aid of scattered radiation.
A narrow X-ray beam is then passed through the body to be examined. The scattered radiation produced in the path of said primary beam through the body reaches an array of detectors through a slot diaphragm which is disposed outside the primary beam, the slot diaphragm and the detectors being arranged so that each detector can only measure a spatially limited part of the scattered radiation originating from the primary beam.
Thus, at the end of a measurement the detector output signals represent a qualitative image of the density distribution inthe body along the primary beam.
Subsequently, the body is moved by approximately the width of the primary beam normal to the direction of said beam, thus enabling line scanning to be realised.
The invention enables the density distribution in a plane, in particular in a planar slice of a body, to be reproduced with the aid of scattered radiation.
A narrow X-ray beam is then passed through the body to be examined. The scattered radiation produced in the path of said primary beam through the body reaches an array of detectors through a slot diaphragm which is disposed outside the primary beam, the slot diaphragm and the detectors being arranged so that each detector can only measure a spatially limited part of the scattered radiation originating from the primary beam.
Thus, at the end of a measurement the detector output signals represent a qualitative image of the density distribution inthe body along the primary beam.
Subsequently, the body is moved by approximately the width of the primary beam normal to the direction of said beam, thus enabling line scanning to be realised.
Description
11~1133 ~ -023 VMI AVDV
~ 8-3-78 "Arrangement for the reproduction of a planar ~slice of a body with the aid of gamma or X-radiation"
The invention relates to an arrangement for the reproduction of a planar slice of a body with at least one gamma or X-radiation source for ge~erating a primary beam of` small cross-section which is passed through the body, with a detector array which is disposed outside the primary beam and which receives a part of the scattered radiation produced in the body by the primary beam, and with a diaphragm device between the body and the detector array.
The magazine "Phys. rned. Biol.~' 1959 ~4), pages 159 to 166 describes an arrangement in which a gamma or X-ray beam of small cross-section is passed through the body to be examined. The scattered radiation then produced is measured by a scintillator crystal , in conjunction with a photomultiplier, which is arranged behind a collimator, which is focussed at a point in the primary radiation beam, so that only the scattered radiation originating from this point, which is dependent on the object density in said point, is received.
~ 20 Thls arraneement enables the density of the ; ~ objèct in a planar slice to be measured when first of all the object (or the collin1ator with the photomultiplier) is moved in the direction of the radiation beam, so that ' : :
~ 8-3-78 "Arrangement for the reproduction of a planar ~slice of a body with the aid of gamma or X-radiation"
The invention relates to an arrangement for the reproduction of a planar slice of a body with at least one gamma or X-radiation source for ge~erating a primary beam of` small cross-section which is passed through the body, with a detector array which is disposed outside the primary beam and which receives a part of the scattered radiation produced in the body by the primary beam, and with a diaphragm device between the body and the detector array.
The magazine "Phys. rned. Biol.~' 1959 ~4), pages 159 to 166 describes an arrangement in which a gamma or X-ray beam of small cross-section is passed through the body to be examined. The scattered radiation then produced is measured by a scintillator crystal , in conjunction with a photomultiplier, which is arranged behind a collimator, which is focussed at a point in the primary radiation beam, so that only the scattered radiation originating from this point, which is dependent on the object density in said point, is received.
~ 20 Thls arraneement enables the density of the ; ~ objèct in a planar slice to be measured when first of all the object (or the collin1ator with the photomultiplier) is moved in the direction of the radiation beam, so that ' : :
-2-' ` ' .
.
1101~33 PIID.77-023 8.3.78 the scintillator with the photomultiplier scans the density distribution in the radiation beam.
Subsequently, the body and radiator are shifted relabive to each other, so that the radiation is passed through a different cross-section of the object, the described scanning operation being repeated.
This arrangement demands much time for measuring the intensity distribution in a planar slice.
The magazine "Phys. med. Biol." 1974, Vol.19, No.6, pages 808 and further also describes an arrangement in which the scattered radiation produced in the primary beam is measured by a crystal which supplies an output signal which is dependent on the energy of the incident radiation. As is known, the energy of the incldent scattered radiation depends on the angle between the scattered radiation and the primary radiation (compton effect). Any arbitrary amplitude of the crystal detector, which corresponds to a specific ; energy, consequently also corresponds to a specific angle or to a specific point along the primary beam.
, By means of a pulse height analyser and a suitable computer it is thus possible to reconstruct the density distribution along the primary beam in a single measurement.
This arrangement is therefore highly comple~. It has a limited spatial resolution and requires the use of a radiation source which generates monoenergetlc radiation~ i.e. for example an isotope; X-radiators cal~not be employed as .ad-ation sources.
:::
,, , , ' .
` 1~01~33 PHD.77-023 Finally, i* is known to emplOy a gamma camera for the detection of the scattered radiation, spatial.
al~cation being obtained by means of a collimator having a corresponding number of apertures which are directed at; dif`~erent points of the primary beam. The spatial resolution of such a collimeter is very low and the complete arrangement is-comparatively insensiti~e, so that relati~ely high doses are necessary for an examination.
~ 10 It is the object of the invention to provide ; an arrangement for the reproduction of a planar slice (or also a non-planar slice) of a body, having an improved spatial resolution and a satisfactory sensitivity.
Starting -~rom an arrangement of the type ~- mentioned i.n the preamble this object is achieved `~ in that the diaphragm device is constitutecd by a slot diaphragm having a slotted aperture, whose principal dimension extends in a direction which is substantially normal to the primary beam, behind which the detector-array9 which comprises a pl.urality of detectors, is arranged in such a way that the scattered beam produced by the primary beam in the area to be exami.ned and passing through the slotted aperture is incident on the detectors.
The slot diaphragm between the detectors and the body to be examined ensures that each detector ~ 33 PI~D 77-023 can only receive scattered radiation produced in a spccific section of` the primary beam, in such a way that each detector corresponds to a diff`erent section and all detectors together cover the part o~ the primary beam which passes througll the area to be exarnined.
; In accordance with a further embodiment of the invention the detectors are strip shaped, the principal dimension of a detector and the principal dimension of the slotted aperture each time being co-planr. As a result of this the sensitiv:ity of the arrangement is increased substantially, without loss - o~ spatial resolution, because the spatial resolution only depends on the dimensions of the aperture and of` the detectors in a direction parallel to the primary beam.
In the extreme case each detec-tor could concentrically surround the primary beam, yielding the additional advantage that the detector output signal would become highly independent of the position of` the primary beam relative to the body being e~amined.
In accordance with a f`urther embodiment of` the invention the last-mentioned effect can also be obtained in that a plurality of groups of detectors are each provided with a slot diaphragm and that the output s~gnals of the detectors of different groups which are disposed in the same plane normal to the primary beam are superimposed on each other.
~5- ~
~ 33 , PHD;77-023 In the body under examination the primary beam is attenuated both by scattering and by absorption, so that - for the same density of the tissue through which the primary beam is passed - the intensi-ty of the scattered radiation on the side which faces the - radiation source is higher than on the side which is remote from the radiation source. In accordance with a further embodiment of the invention this can be avoided in that two radiators are arranged on both sides of the area to be e~amined in such a way that their stopped, down beams coincide.
A different further embodiment of the invention is characterized by a detector which'is disposed in the primary beam for measuring the intensity of the beam which has been attenuàted by the ~ody and which has been stopped-down by the facing radiation source. The output signal of the detector which is disposed in the primary beam can be employed for correcting ::
the output signals of the detectors used for measuring the scattered radiation.
The invention will be described in more detail with re~erence to the drawing which shows an embodiment~
In the drawing.
~ig. 1 schematically shows a perspective vlew - 25 of an embodiment of the invention, Fig. 2 schematically shows a plan view of the ar~angement which is shown in persepective in Fig.1~arld -6_ ' 1101~33 PHD.77-023 Fig. 3 schematically shows a circuit arrangement which enables the output signals obtained by means of the detectors to be converted directly into a visible irnage.
The body 1 to be examined is located on a table top 2 and a horizontal priMary ~eam 3 is passed through it, which beam is produced by two-X-radiators 4a and 4b arranged on both sides of the body 1 and is stopped down by a diaphragm device 5a and 5b respectively (~ig.2). The dimensions of the stopped-down primary beam determine the resolution of -the arrangement; the resolution increases as the beam cross-section decreases.
The voltage applied to the X-ray tube during the examination is approximately 350 kV Thus, the radiation dose administered to the patient is minimized, whilst the attenuation o~ the primary beam as a result of (photo) absorption is low in comparison with the attenuation by (~ompton) scattering.
The scattered radiation produced in the body area through which the primary beam 3 is passed reaches a detectorgroup D and D' which, respectively comprise a plurality of detectors dl, d2, d3 and d1~, d2', d3' which are arranged in line adjacent each other parallel to the primary bearn via the slotted, preferably adjus-table~
`~ apertures 7 and 7' of a slot diaphragm 6 and 6' respectlvely disposed undernea-th and above the body -7-~
to be examined. As is shown in Fig. 1 the surface area of the detectors which serves as measuring surface, has the shape of an oblong rectangle, whose long sides are disposed in a plane which is normal to the primary beam. The slotted aperture 7 or 7' of the respective slotted diaphragm 6 or 6' has a corresponding shape, its dimensions in both directions being smaller according as their distance from the primary beam is smaller than that of the detectors.
The detectors may for example be chambers filled with a pressurized highly radiation-absorbing inert gas ~xenon) in which two parallel electrodes are arranged, which carry off the charge carriers which have been ionized by the scattered radiation.
Owing to the slot diaphragm and unambiguous relationship is obtain-ed between a point on the primary beam and a detector within the detector group D or D'. As is shown in Fig. 2, the cone of scattered radiation which is produced in the body in point 8 on the primary beam and which is stopped down by the respective slot diaphragm 6 or 6' is incident on the respective detector di or di' and accordingly each point within the limits of the primary beam represented by the dashed lines 10 corresponds to a detector in the two detector groups, both detectors being disposed on the same plane normal PMD.77_023 8,3.78 to the primary beam. The output signals of the detectors dl, d2, d3 and dl', d2', d3' respectively are a measure of the density of the area of the body 1 to be examined through which the primary beam 3 is passed.
The output signals supplied by the detectors increase according as the width of the slotted apertures 7 and 7' onthe slotted diaphragms~6 and 6~ respectively increases. On the other hand the spatial resolution improves according as the width of the slot decreases.
A satisfactory compromise is obtained when the width s of the slotted apertures 7 and 7' ~i.e. the dimension in a plane which contains the primary beam) satisfies the equation s = wb/(a ~ b)~ ^
where w represents the width of a detector (i.e. its dimension in a direction parallel to the primary beam), a the distance from the detector group D or d' to the slot diaphragm 6 and 6' respectively, and b the distance ::
from the slot diaphragm 6 and 6' respectively to the primary beam 3. The spatial resolution is then sub-; stantially in conformity with the expression wb/a.
As previously stated, i-t suffice in principle to employ only one radiation source ~or generating a primary beam, but in the case of generation by two .-:
radiation sources which are arranged as show~ a more uniform intensity distribution in ~le direction of the primary beam is obtained. Similarly, :Lt would also suffice - . - .
1101~33 PlID,77-023 8.3.78 to use a single detector group for measuring the cattered radiation produced in the primary beam between the ~-imits 10; however, when two detector groups are employed an improved signal-to-noise ratio is obtained and moreover the sum of the output signals of a detector pair (for example d3, d3') is less dependent on the position of the primary beam in the object than in the case that only one detector group is used.
It is not absolutely necessary that the connecting lines between the centre of the slot and the centre of the detectors form a right angles with the primary beam, as is shown in Fig. Z. The detector groups and associated slots may rather be shifted in a horizontal direction in comparison with the arrangemrlnt in accordance with Fig. 2. Neither is it ~: .
- necessary that the plane which is formed by the detector ~;~ arrays D and D' respectively e~tends parallel to the primary beam 3. - It is merely important that the ; dimension 6 of the slot in the plane containing the one primary beam is sm~lland that the detectors are arranged so that they can measure the scattered radiation which is produced by the primary beam in the ~;~ area to be e~amined-10 - 101 and which passes through theslot.
As previously stated, each detector group provides information on the scattering properties of the 1101133 PHD.77-023 8.3-78 object (i.e. in particular the average elec-tron density) along the line which is defined by the position of the primary beam in the object. The individual detector groups provide information on individual sections (cells) o-~ these lines.
By means of a relative displacement between the primary beam together with the detectors and on the one hand the slot diaphragm and on the other hand, the body to be e~amined, the density distribution along a different line 13 or 14 (represented by an inter-rupted line) in the body can be scanned, and Irom a multitude of such measurements the density distri-bution in a planar slice or in a dif~erent area o~ the body can be determined. In between two measurements the output signals o~ the detectors should either be stored or applied to a disp]ay device.
The relative displacement betwenn the primary beam and the body 1 to be examined can be obtained in that the table top 2 is moved by approximately 2 mm, i.e. a travel corre6ponding to the width of the primary beam and the spatial resolution, in a perpéndicular ;~ dlrection~ i.e. perpendicular to the primary beam.
Patient examination tables, whose table top can be moved through a defined path by means of a motor drive, are generally known in X-ray technology, in particular tomography so that these need not be shown in further detail. After the nex-t line, which i5 thus adjusted, l~V1133 PHD.77-023 8-3.78 has been measured and the mea~uring values have been stored or applied to a display device, the table top is moved again by the same amount in the same direction etc.
It is alternatively possible to move the table top in one direction with constant speed and to sample the signals -from the detectors at constant time intervals. The speed of movement should then substantially correspond to the quotient of the width of the primary beam and the measuring time necessary per measurement. In comparison with the stepwise movement this continuous movement has -the advantage that accelerations of the body, which may give rise to blurring and thus to an unsharp reproduction are avoided.
The relative movement between the primary beam and the bodytobe examined can be performed in any arbitrary direction perpendicular to the primary beam. For example (when the force of gravity is detected normal to the plane of the drawing~, the table top 2 may be disposed parallel to the plane of drawing and may be moved normal thereto.
Fig. 3 schematically shows a simple embodiment of a reproduction arrangement, For each detector pair (for example, d1 and d1' or d3 and d~') there is provided a so-called sample-alld-hold circuif S1~ S2; S3 which stores the sum of the -two output signals or the .
:. :
~ -12-: , ~ , . .
1101133 PHD.77-023 8.3.7~
ge~metric mean or roat mean square of a detector pair at the end of the measuring time. The stored signals are consecutively applied to the Wehnelt cylinder 111 of an image .storage tube 11, as is schematically indicated by the change~over switch 112 which consecutively connects the outputsof the sample-and-hold circuits to the Wehnelt cy~nder 111, ~ deflection generator 113, which feeds the horizontal deflection coil 114, supplies a deflection signal which changes stepwise in synchronism with the switching operation, so that a line is displayed on the image storage tube 11 when the density distri-bution of the next line is being measured. The cross-section of the electron beam of the image storage tube 11 should then correspond to the dimensions of a cell 1~ on the target of the image-storage tube. Before the next line begins the current which flows through the vertical deflection coil 115 of the ima~e s-torage tube .
is also varied by one step by the vertical deflection generator 116, in such a way that the electron beam is moved in a vertical direction by the width of one cell.
Thus, the density dis-tribution measured in the object 1 ;~ ~ being examined is stored on the target in the image storage tube 11. Subseq1lently7 it can then be read out and displayed on a display tube.
.
Instead of an lmage storage tube which has a very li~ited gray scale, it is also possible -to make direct use~of a display tube, in which the density .
::
: , .
: , . , ' : ~ : :
~1~1133 distribution is written time-sequentially. By means of a photographic camera, whose shutter is open during the time needed for writing all the lines~ a ~photographic) image of the density distribution in the planar slice being scanned can be produced.
In this respect it is to be noted that apparatus for so-called computer tomography are known (see for example Canadian application 949,233), which also enable a reconstruction of the density distribution in a planar slice of a body to be obtained. In such apparatus the scattered radiation is not measured, but the primary radiation behind the object. Such apparatus require the use of an expensive computer, which calculates the density distribution from the detector output signals, because a detector output signal does not represent the density in a specific point in the planar slice, but the integral along a straight line in said plane. In accordance with ; the invention such a computer is not necessary.
The dose which is administered to the patient during an examination with the arrangement in accordance with the invention and with the known arrangement is of approximately the same order of magnitude. In computer tomograph apparatus the primary beam is measured directly, whereas in accord-ance with the present invention only a small portion of the emergent scattered radiation is measured, so that - in order to obtain : 1101133 I'~ID 77-023 equal detector output signals - the intensity of the primar-y beam would have to be increased substan~i-ally in the case of the present inven-tion, but this is compensated for because in the case of the present invention the body must be exposed only once (wi-th.
the known arrangement the planar slice is to be exposed approximately 1~0 times from different directions) and because the invention enables the use of substantially harder radiation, which is hardly attenuated by photoabsorption.
An advantage of the known arrangement is that it enables a quan-titative representation of the density distribution in the planar slice to be obtained, whilst in the case of the invention - if no additional ~: 15 correction steps are taken - only one qualitative ~ , .
i representation is possible, which however in most cases is absolutely satisfactory. The deviation from the exact values of the detector output signals ~ has causes which depend on the geometry of the : 20 measurin.g arrangement and causes which may be attri-, buted to the different attenuation of the primary radiation and the scattered radiation in the objec-t and to the fact that the scattered radlat:ion on its : ~ way to the detector may be scattered several times under certain conditions, so that the relat:ionship . : between the pOiIlt from which the ecattered radiation origlrlates and the detector which receives th.e measuring signal is disturbed.
. ~ .
' :: .- .. . . . : ... , .. ~ ... . .... .
1101133 PI~D.77-023 8.3-78 However, it is possible to correct the measuring vallles obtained ~ith an arrangement in accordance with the inYention by means of a digital computer, which enables -the geometric factors to be corrected by suitable wei.ghting of the detector output signals~ which is dependent on the geometry of the arrangement but not on the body to be examincd.
Measuring erro:rs as a result of the attenuation of the primary and the scattered radiation in the body can also be corrected if allowance is made for the attenuation'of the radiation along the path ~ollowed by the primary beam and the scattered radiation respectively.
If it is for example assumed that first of.`
all the line of the planar body-slice is scanned from which scatterd radiation originates which reaches the detector array without attenuation by interposed tissue, the scatterd radiation originating ~rom the ~irst cell of said line is not yet subJect to any attenuation and may therefore be used directly as a measure of the . density in this cell. The primary beam which reaches the second cell of said line is attanuated by the amount which has been converted into scattered radiation in the .~irst cell, and because this amount is known Z5 from -the mcasurement of the :~irst cell allowance can be made for this by accordingly increasing the output signal o~ the detector associal;ed with the second cell -i6-' ~ llQ1133 P~D.77-02~
~-3-78 in comparison wi-th the output signal of the detector associated with the first cell. For the third ce]l of said line allowance should then be made for the - attenuation by the two first cells etc. - It is true that for the first cell of the next line the primary ; beam is not attenuated ei-ther, but the scattered radiation from said cell is attanuated by the cells of the preceding line disposed between the slot andsaid cell. As the attenuation of the radiation through these cells has already been determined during the preceding measurement, the measuring value corres-ponding to the first cell of the second line can be corrected accordingly. With the output signal of the detector which measures th.e scattered radiation obtained from the second cell of the second line allowance is to be made for both the attenuation of the primary ~ beam by the adjacent first cell and the attenuation of the ~scattered radiation by the cells of the line situated above it.
If the attenuation of the primary beam ~ in one lin.e has been assessed correctly with this - : - correction, the attenuation factor for the primary ~ : radiation which has been measured indirectly by :~ ~. measurement of the scatter.ed radiation should be - 25 in conformity wi.th the a-ttenuation factor which is obtained when the intensity of` the primary beam before entrance into the body (f`or e~ample known by means of .
. -17 ' ,, a measurement) is compared with its intensity measured by a detector after pasaage through the body. In the event of deviations the attenuation values deternlined for the individual cells should then be changed accordingly. Such a detector for measuring the primary beam which has been attenuated by -the body is also necessary in the case of an arrangement with two radiation sources. This detector is designated. ~2 in ~ig.2 and has a bore through which the beam produced by the radiation source 4a, 5a is passed~
without giving rise to an output signal of the detector 12, whilst the beam wh~ch h.as been stopped down by the : ra.diation source 4b, 5b is also incident on the active - measuring surface of the detector, because this beam is inevitably widened on its way through the body.
:~ Errors in the measuring result as a result o~
. multiple scattering can be avoided in the case o~
: :
: radiation sources producing mainly monoenergetic~
radiatlon (radio isitopes), in that each detector onl.y measures that part of the incident radiation whose wavelength has thë value to be anticipated for the wavelength of the primary beam and the given scatter angle. This can be ef~ected in k:nown manner in that the (crystal) detectors are followed by suitable amplitude ; 25 discrimillators.
In the case of an X-radiator the errors as : a result o~ multiple scatterin.g can be reduced in that , ~ . -. . ;,: . . . .
11~1133 PHD.77-023 8.3.78 .
the average va]ue of the output signals of additional detectors~ not shown, is subtracted from the detector output signals, which additional detectors are arranged in such a way that they cannot recei~e the scattered radiation produced in theprimary beam 3 between the limits 10, lO~ but only the scattered radiation produced in other areas of the body by multiple scattering.
.
~ .
' ~ ~ .
' . .
.
1101~33 PIID.77-023 8.3.78 the scintillator with the photomultiplier scans the density distribution in the radiation beam.
Subsequently, the body and radiator are shifted relabive to each other, so that the radiation is passed through a different cross-section of the object, the described scanning operation being repeated.
This arrangement demands much time for measuring the intensity distribution in a planar slice.
The magazine "Phys. med. Biol." 1974, Vol.19, No.6, pages 808 and further also describes an arrangement in which the scattered radiation produced in the primary beam is measured by a crystal which supplies an output signal which is dependent on the energy of the incident radiation. As is known, the energy of the incldent scattered radiation depends on the angle between the scattered radiation and the primary radiation (compton effect). Any arbitrary amplitude of the crystal detector, which corresponds to a specific ; energy, consequently also corresponds to a specific angle or to a specific point along the primary beam.
, By means of a pulse height analyser and a suitable computer it is thus possible to reconstruct the density distribution along the primary beam in a single measurement.
This arrangement is therefore highly comple~. It has a limited spatial resolution and requires the use of a radiation source which generates monoenergetlc radiation~ i.e. for example an isotope; X-radiators cal~not be employed as .ad-ation sources.
:::
,, , , ' .
` 1~01~33 PHD.77-023 Finally, i* is known to emplOy a gamma camera for the detection of the scattered radiation, spatial.
al~cation being obtained by means of a collimator having a corresponding number of apertures which are directed at; dif`~erent points of the primary beam. The spatial resolution of such a collimeter is very low and the complete arrangement is-comparatively insensiti~e, so that relati~ely high doses are necessary for an examination.
~ 10 It is the object of the invention to provide ; an arrangement for the reproduction of a planar slice (or also a non-planar slice) of a body, having an improved spatial resolution and a satisfactory sensitivity.
Starting -~rom an arrangement of the type ~- mentioned i.n the preamble this object is achieved `~ in that the diaphragm device is constitutecd by a slot diaphragm having a slotted aperture, whose principal dimension extends in a direction which is substantially normal to the primary beam, behind which the detector-array9 which comprises a pl.urality of detectors, is arranged in such a way that the scattered beam produced by the primary beam in the area to be exami.ned and passing through the slotted aperture is incident on the detectors.
The slot diaphragm between the detectors and the body to be examined ensures that each detector ~ 33 PI~D 77-023 can only receive scattered radiation produced in a spccific section of` the primary beam, in such a way that each detector corresponds to a diff`erent section and all detectors together cover the part o~ the primary beam which passes througll the area to be exarnined.
; In accordance with a further embodiment of the invention the detectors are strip shaped, the principal dimension of a detector and the principal dimension of the slotted aperture each time being co-planr. As a result of this the sensitiv:ity of the arrangement is increased substantially, without loss - o~ spatial resolution, because the spatial resolution only depends on the dimensions of the aperture and of` the detectors in a direction parallel to the primary beam.
In the extreme case each detec-tor could concentrically surround the primary beam, yielding the additional advantage that the detector output signal would become highly independent of the position of` the primary beam relative to the body being e~amined.
In accordance with a f`urther embodiment of` the invention the last-mentioned effect can also be obtained in that a plurality of groups of detectors are each provided with a slot diaphragm and that the output s~gnals of the detectors of different groups which are disposed in the same plane normal to the primary beam are superimposed on each other.
~5- ~
~ 33 , PHD;77-023 In the body under examination the primary beam is attenuated both by scattering and by absorption, so that - for the same density of the tissue through which the primary beam is passed - the intensi-ty of the scattered radiation on the side which faces the - radiation source is higher than on the side which is remote from the radiation source. In accordance with a further embodiment of the invention this can be avoided in that two radiators are arranged on both sides of the area to be e~amined in such a way that their stopped, down beams coincide.
A different further embodiment of the invention is characterized by a detector which'is disposed in the primary beam for measuring the intensity of the beam which has been attenuàted by the ~ody and which has been stopped-down by the facing radiation source. The output signal of the detector which is disposed in the primary beam can be employed for correcting ::
the output signals of the detectors used for measuring the scattered radiation.
The invention will be described in more detail with re~erence to the drawing which shows an embodiment~
In the drawing.
~ig. 1 schematically shows a perspective vlew - 25 of an embodiment of the invention, Fig. 2 schematically shows a plan view of the ar~angement which is shown in persepective in Fig.1~arld -6_ ' 1101~33 PHD.77-023 Fig. 3 schematically shows a circuit arrangement which enables the output signals obtained by means of the detectors to be converted directly into a visible irnage.
The body 1 to be examined is located on a table top 2 and a horizontal priMary ~eam 3 is passed through it, which beam is produced by two-X-radiators 4a and 4b arranged on both sides of the body 1 and is stopped down by a diaphragm device 5a and 5b respectively (~ig.2). The dimensions of the stopped-down primary beam determine the resolution of -the arrangement; the resolution increases as the beam cross-section decreases.
The voltage applied to the X-ray tube during the examination is approximately 350 kV Thus, the radiation dose administered to the patient is minimized, whilst the attenuation o~ the primary beam as a result of (photo) absorption is low in comparison with the attenuation by (~ompton) scattering.
The scattered radiation produced in the body area through which the primary beam 3 is passed reaches a detectorgroup D and D' which, respectively comprise a plurality of detectors dl, d2, d3 and d1~, d2', d3' which are arranged in line adjacent each other parallel to the primary bearn via the slotted, preferably adjus-table~
`~ apertures 7 and 7' of a slot diaphragm 6 and 6' respectlvely disposed undernea-th and above the body -7-~
to be examined. As is shown in Fig. 1 the surface area of the detectors which serves as measuring surface, has the shape of an oblong rectangle, whose long sides are disposed in a plane which is normal to the primary beam. The slotted aperture 7 or 7' of the respective slotted diaphragm 6 or 6' has a corresponding shape, its dimensions in both directions being smaller according as their distance from the primary beam is smaller than that of the detectors.
The detectors may for example be chambers filled with a pressurized highly radiation-absorbing inert gas ~xenon) in which two parallel electrodes are arranged, which carry off the charge carriers which have been ionized by the scattered radiation.
Owing to the slot diaphragm and unambiguous relationship is obtain-ed between a point on the primary beam and a detector within the detector group D or D'. As is shown in Fig. 2, the cone of scattered radiation which is produced in the body in point 8 on the primary beam and which is stopped down by the respective slot diaphragm 6 or 6' is incident on the respective detector di or di' and accordingly each point within the limits of the primary beam represented by the dashed lines 10 corresponds to a detector in the two detector groups, both detectors being disposed on the same plane normal PMD.77_023 8,3.78 to the primary beam. The output signals of the detectors dl, d2, d3 and dl', d2', d3' respectively are a measure of the density of the area of the body 1 to be examined through which the primary beam 3 is passed.
The output signals supplied by the detectors increase according as the width of the slotted apertures 7 and 7' onthe slotted diaphragms~6 and 6~ respectively increases. On the other hand the spatial resolution improves according as the width of the slot decreases.
A satisfactory compromise is obtained when the width s of the slotted apertures 7 and 7' ~i.e. the dimension in a plane which contains the primary beam) satisfies the equation s = wb/(a ~ b)~ ^
where w represents the width of a detector (i.e. its dimension in a direction parallel to the primary beam), a the distance from the detector group D or d' to the slot diaphragm 6 and 6' respectively, and b the distance ::
from the slot diaphragm 6 and 6' respectively to the primary beam 3. The spatial resolution is then sub-; stantially in conformity with the expression wb/a.
As previously stated, i-t suffice in principle to employ only one radiation source ~or generating a primary beam, but in the case of generation by two .-:
radiation sources which are arranged as show~ a more uniform intensity distribution in ~le direction of the primary beam is obtained. Similarly, :Lt would also suffice - . - .
1101~33 PlID,77-023 8.3.78 to use a single detector group for measuring the cattered radiation produced in the primary beam between the ~-imits 10; however, when two detector groups are employed an improved signal-to-noise ratio is obtained and moreover the sum of the output signals of a detector pair (for example d3, d3') is less dependent on the position of the primary beam in the object than in the case that only one detector group is used.
It is not absolutely necessary that the connecting lines between the centre of the slot and the centre of the detectors form a right angles with the primary beam, as is shown in Fig. Z. The detector groups and associated slots may rather be shifted in a horizontal direction in comparison with the arrangemrlnt in accordance with Fig. 2. Neither is it ~: .
- necessary that the plane which is formed by the detector ~;~ arrays D and D' respectively e~tends parallel to the primary beam 3. - It is merely important that the ; dimension 6 of the slot in the plane containing the one primary beam is sm~lland that the detectors are arranged so that they can measure the scattered radiation which is produced by the primary beam in the ~;~ area to be e~amined-10 - 101 and which passes through theslot.
As previously stated, each detector group provides information on the scattering properties of the 1101133 PHD.77-023 8.3-78 object (i.e. in particular the average elec-tron density) along the line which is defined by the position of the primary beam in the object. The individual detector groups provide information on individual sections (cells) o-~ these lines.
By means of a relative displacement between the primary beam together with the detectors and on the one hand the slot diaphragm and on the other hand, the body to be e~amined, the density distribution along a different line 13 or 14 (represented by an inter-rupted line) in the body can be scanned, and Irom a multitude of such measurements the density distri-bution in a planar slice or in a dif~erent area o~ the body can be determined. In between two measurements the output signals o~ the detectors should either be stored or applied to a disp]ay device.
The relative displacement betwenn the primary beam and the body 1 to be examined can be obtained in that the table top 2 is moved by approximately 2 mm, i.e. a travel corre6ponding to the width of the primary beam and the spatial resolution, in a perpéndicular ;~ dlrection~ i.e. perpendicular to the primary beam.
Patient examination tables, whose table top can be moved through a defined path by means of a motor drive, are generally known in X-ray technology, in particular tomography so that these need not be shown in further detail. After the nex-t line, which i5 thus adjusted, l~V1133 PHD.77-023 8-3.78 has been measured and the mea~uring values have been stored or applied to a display device, the table top is moved again by the same amount in the same direction etc.
It is alternatively possible to move the table top in one direction with constant speed and to sample the signals -from the detectors at constant time intervals. The speed of movement should then substantially correspond to the quotient of the width of the primary beam and the measuring time necessary per measurement. In comparison with the stepwise movement this continuous movement has -the advantage that accelerations of the body, which may give rise to blurring and thus to an unsharp reproduction are avoided.
The relative movement between the primary beam and the bodytobe examined can be performed in any arbitrary direction perpendicular to the primary beam. For example (when the force of gravity is detected normal to the plane of the drawing~, the table top 2 may be disposed parallel to the plane of drawing and may be moved normal thereto.
Fig. 3 schematically shows a simple embodiment of a reproduction arrangement, For each detector pair (for example, d1 and d1' or d3 and d~') there is provided a so-called sample-alld-hold circuif S1~ S2; S3 which stores the sum of the -two output signals or the .
:. :
~ -12-: , ~ , . .
1101133 PHD.77-023 8.3.7~
ge~metric mean or roat mean square of a detector pair at the end of the measuring time. The stored signals are consecutively applied to the Wehnelt cylinder 111 of an image .storage tube 11, as is schematically indicated by the change~over switch 112 which consecutively connects the outputsof the sample-and-hold circuits to the Wehnelt cy~nder 111, ~ deflection generator 113, which feeds the horizontal deflection coil 114, supplies a deflection signal which changes stepwise in synchronism with the switching operation, so that a line is displayed on the image storage tube 11 when the density distri-bution of the next line is being measured. The cross-section of the electron beam of the image storage tube 11 should then correspond to the dimensions of a cell 1~ on the target of the image-storage tube. Before the next line begins the current which flows through the vertical deflection coil 115 of the ima~e s-torage tube .
is also varied by one step by the vertical deflection generator 116, in such a way that the electron beam is moved in a vertical direction by the width of one cell.
Thus, the density dis-tribution measured in the object 1 ;~ ~ being examined is stored on the target in the image storage tube 11. Subseq1lently7 it can then be read out and displayed on a display tube.
.
Instead of an lmage storage tube which has a very li~ited gray scale, it is also possible -to make direct use~of a display tube, in which the density .
::
: , .
: , . , ' : ~ : :
~1~1133 distribution is written time-sequentially. By means of a photographic camera, whose shutter is open during the time needed for writing all the lines~ a ~photographic) image of the density distribution in the planar slice being scanned can be produced.
In this respect it is to be noted that apparatus for so-called computer tomography are known (see for example Canadian application 949,233), which also enable a reconstruction of the density distribution in a planar slice of a body to be obtained. In such apparatus the scattered radiation is not measured, but the primary radiation behind the object. Such apparatus require the use of an expensive computer, which calculates the density distribution from the detector output signals, because a detector output signal does not represent the density in a specific point in the planar slice, but the integral along a straight line in said plane. In accordance with ; the invention such a computer is not necessary.
The dose which is administered to the patient during an examination with the arrangement in accordance with the invention and with the known arrangement is of approximately the same order of magnitude. In computer tomograph apparatus the primary beam is measured directly, whereas in accord-ance with the present invention only a small portion of the emergent scattered radiation is measured, so that - in order to obtain : 1101133 I'~ID 77-023 equal detector output signals - the intensity of the primar-y beam would have to be increased substan~i-ally in the case of the present inven-tion, but this is compensated for because in the case of the present invention the body must be exposed only once (wi-th.
the known arrangement the planar slice is to be exposed approximately 1~0 times from different directions) and because the invention enables the use of substantially harder radiation, which is hardly attenuated by photoabsorption.
An advantage of the known arrangement is that it enables a quan-titative representation of the density distribution in the planar slice to be obtained, whilst in the case of the invention - if no additional ~: 15 correction steps are taken - only one qualitative ~ , .
i representation is possible, which however in most cases is absolutely satisfactory. The deviation from the exact values of the detector output signals ~ has causes which depend on the geometry of the : 20 measurin.g arrangement and causes which may be attri-, buted to the different attenuation of the primary radiation and the scattered radiation in the objec-t and to the fact that the scattered radlat:ion on its : ~ way to the detector may be scattered several times under certain conditions, so that the relat:ionship . : between the pOiIlt from which the ecattered radiation origlrlates and the detector which receives th.e measuring signal is disturbed.
. ~ .
' :: .- .. . . . : ... , .. ~ ... . .... .
1101133 PI~D.77-023 8.3-78 However, it is possible to correct the measuring vallles obtained ~ith an arrangement in accordance with the inYention by means of a digital computer, which enables -the geometric factors to be corrected by suitable wei.ghting of the detector output signals~ which is dependent on the geometry of the arrangement but not on the body to be examincd.
Measuring erro:rs as a result of the attenuation of the primary and the scattered radiation in the body can also be corrected if allowance is made for the attenuation'of the radiation along the path ~ollowed by the primary beam and the scattered radiation respectively.
If it is for example assumed that first of.`
all the line of the planar body-slice is scanned from which scatterd radiation originates which reaches the detector array without attenuation by interposed tissue, the scatterd radiation originating ~rom the ~irst cell of said line is not yet subJect to any attenuation and may therefore be used directly as a measure of the . density in this cell. The primary beam which reaches the second cell of said line is attanuated by the amount which has been converted into scattered radiation in the .~irst cell, and because this amount is known Z5 from -the mcasurement of the :~irst cell allowance can be made for this by accordingly increasing the output signal o~ the detector associal;ed with the second cell -i6-' ~ llQ1133 P~D.77-02~
~-3-78 in comparison wi-th the output signal of the detector associated with the first cell. For the third ce]l of said line allowance should then be made for the - attenuation by the two first cells etc. - It is true that for the first cell of the next line the primary ; beam is not attenuated ei-ther, but the scattered radiation from said cell is attanuated by the cells of the preceding line disposed between the slot andsaid cell. As the attenuation of the radiation through these cells has already been determined during the preceding measurement, the measuring value corres-ponding to the first cell of the second line can be corrected accordingly. With the output signal of the detector which measures th.e scattered radiation obtained from the second cell of the second line allowance is to be made for both the attenuation of the primary ~ beam by the adjacent first cell and the attenuation of the ~scattered radiation by the cells of the line situated above it.
If the attenuation of the primary beam ~ in one lin.e has been assessed correctly with this - : - correction, the attenuation factor for the primary ~ : radiation which has been measured indirectly by :~ ~. measurement of the scatter.ed radiation should be - 25 in conformity wi.th the a-ttenuation factor which is obtained when the intensity of` the primary beam before entrance into the body (f`or e~ample known by means of .
. -17 ' ,, a measurement) is compared with its intensity measured by a detector after pasaage through the body. In the event of deviations the attenuation values deternlined for the individual cells should then be changed accordingly. Such a detector for measuring the primary beam which has been attenuated by -the body is also necessary in the case of an arrangement with two radiation sources. This detector is designated. ~2 in ~ig.2 and has a bore through which the beam produced by the radiation source 4a, 5a is passed~
without giving rise to an output signal of the detector 12, whilst the beam wh~ch h.as been stopped down by the : ra.diation source 4b, 5b is also incident on the active - measuring surface of the detector, because this beam is inevitably widened on its way through the body.
:~ Errors in the measuring result as a result o~
. multiple scattering can be avoided in the case o~
: :
: radiation sources producing mainly monoenergetic~
radiatlon (radio isitopes), in that each detector onl.y measures that part of the incident radiation whose wavelength has thë value to be anticipated for the wavelength of the primary beam and the given scatter angle. This can be ef~ected in k:nown manner in that the (crystal) detectors are followed by suitable amplitude ; 25 discrimillators.
In the case of an X-radiator the errors as : a result o~ multiple scatterin.g can be reduced in that , ~ . -. . ;,: . . . .
11~1133 PHD.77-023 8.3.78 .
the average va]ue of the output signals of additional detectors~ not shown, is subtracted from the detector output signals, which additional detectors are arranged in such a way that they cannot recei~e the scattered radiation produced in theprimary beam 3 between the limits 10, lO~ but only the scattered radiation produced in other areas of the body by multiple scattering.
.
~ .
' ~ ~ .
' . .
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS
1. An arrangement for the reproduction of a planar slice of a body with at least one gamma or X-radiation source for generating a primary beam of small cross-section which is passed through the body, with a detector array which is disposed outside the primary beam and which receives a part of the scattered radiation produced in the body by the primary beam, and with a diaphragm device between the body and the detector array, characterized in that the diaphragm device is constituted by a slot diaphragm (6 and 6' respectively) having a slotted aperture (7 and 7' respectively), whose principal dimension extends in a direction which is substantially normal to the primary beam, behind which the detector array (D and D' respectively), which comprises a plurality of detectors (d1, d2, d3,... and d1 ', d2 ', d3' ...),is arranged in such a way that the scattered radiation produced by the primary beam (3) in the area to be examined (10 - 10') and passing through the slotted aperture (7, 7') is incident on the detectors.
2. An arrangement as claimed in Claim 1, characterized in that the detectors (d1, d2, d3 ...
and d1', d2', d3' ... respectively) are strip-shaped, the principal dimension of a detector and the principal dimension Or the slot-ted aperture each time being co-planar.
and d1', d2', d3' ... respectively) are strip-shaped, the principal dimension of a detector and the principal dimension Or the slot-ted aperture each time being co-planar.
3. An arrangement as claimed in Claim 1 or 2, characterized in that a plurality of groups of detectors are each provided with a slot diaphragm and that the output signals of the detectors of different groups which are disposed in the same plane normal to the primary beam are superimposed on each other.
4. An arrangement as claimed in Claim 1, characterized in that two radiators are arranged on both sides of the area to be examined in such a way that their stopped- down beam coincide.
5. An arrangement as claimed in Claim 1, characterized by a detector which is disposed in the primary beam for measuring the intensity of the beam which has been attenuated by the body and which has been stopped down by the facing radiation source.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2713581A DE2713581C2 (en) | 1977-03-28 | 1977-03-28 | Arrangement for the representation of a plane of a body with gamma or X-rays |
| DEP2713581.5 | 1977-03-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1101133A true CA1101133A (en) | 1981-05-12 |
Family
ID=6004858
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA299,716A Expired CA1101133A (en) | 1977-03-28 | 1978-03-23 | Arrangement for the reproduction of a planar slice of a body with the aid of gamma or x-radiation |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS53120294A (en) |
| AU (2) | AU513395B2 (en) |
| BE (1) | BE865386A (en) |
| BR (1) | BR7801844A (en) |
| CA (1) | CA1101133A (en) |
| DE (1) | DE2713581C2 (en) |
| ES (1) | ES468229A1 (en) |
| FR (1) | FR2386055A1 (en) |
| GB (1) | GB1602521A (en) |
| IT (1) | IT1093720B (en) |
| NL (1) | NL7803229A (en) |
| SE (1) | SE7803371L (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6556653B2 (en) | 2000-05-25 | 2003-04-29 | University Of New Brunswick | Non-rotating X-ray system for three-dimensional, three-parameter imaging |
| US6563906B2 (en) | 2000-08-28 | 2003-05-13 | University Of New Brunswick | X-ray compton scattering density measurement at a point within an object |
| US7203276B2 (en) | 2004-08-27 | 2007-04-10 | University Of New Brunswick | X-ray scatter image reconstruction by balancing of discrepancies between detector responses, and apparatus therefor |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3032801A1 (en) * | 1977-03-28 | 1982-04-22 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Internal structure display unit - with scanning device for primary beam of radiation |
| DE2757320C2 (en) * | 1977-12-22 | 1984-06-20 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Arrangement for the representation of a plane of a body with gamma or X-rays |
| DE2831311C2 (en) * | 1978-07-17 | 1986-10-30 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Device for determining internal body structures by means of scattered radiation |
| FR2442042A1 (en) * | 1978-11-27 | 1980-06-20 | Labo Electronique Physique | METHOD AND APPARATUS FOR TOMOGRAPHIC EXAMINATION BY EXPLORATION OF X-RAY OR GAMMA MEDIA |
| DE2939146A1 (en) * | 1979-09-27 | 1981-04-16 | Philips Patentverwaltung Gmbh, 2000 Hamburg | METHOD FOR EXAMINING A BODY WITH Pervasive RADIATION |
| DE2944147A1 (en) * | 1979-11-02 | 1981-05-14 | Philips Patentverwaltung Gmbh, 2000 Hamburg | ARRANGEMENT FOR DETERMINING THE SPREAD DENSITY DISTRIBUTION IN A LEVEL EXAMINATION AREA |
| DE3007456A1 (en) * | 1980-02-28 | 1981-09-10 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Tomographic appts. for heart examination - has individual secondary radiation sources between collimator plates for each detector array |
| DE3023263C2 (en) * | 1980-06-21 | 1986-08-14 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Arrangement for determining the internal structure of a body by means of monoenergetic radiation |
| DE3031949A1 (en) * | 1980-08-25 | 1982-04-01 | Philips Patentverwaltung Gmbh, 2000 Hamburg | SCREEN EXAMINATION ARRANGEMENT FOR DETERMINING THE INNER STRUCTURE OF A BODY |
| JPS5770432A (en) * | 1980-10-20 | 1982-04-30 | Deiemuetsukusu Asoshieetsusu | Radiation scanning method and apparatus |
| DE3120567A1 (en) * | 1981-05-23 | 1983-01-20 | Philips Patentverwaltung Gmbh, 2000 Hamburg | SCREEN BEAM EXAMINATION ARRANGEMENT |
| US4809312A (en) * | 1986-07-22 | 1989-02-28 | American Science And Engineering, Inc. | Method and apparatus for producing tomographic images |
| DE4000507A1 (en) * | 1990-01-10 | 1991-07-11 | Philips Patentverwaltung | ARRANGEMENT FOR EXAMINING A TEST OBJECT WITH GAMMA OR X-RAY RADIATION |
| KR20090046849A (en) * | 2006-08-23 | 2009-05-11 | 아메리칸 사이언스 앤 엔지니어링, 인크. | Scatter attenuation tomography |
| DK176823B1 (en) | 2006-11-22 | 2009-11-02 | Force Technology | Method for providing the density profile of a plate-shaped body |
| DE102007045798B4 (en) * | 2007-09-25 | 2010-12-02 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Arrangement and method for recording X-ray scattering images |
| DE102009012233B4 (en) * | 2009-03-07 | 2011-06-16 | Zap Systemkomponenten Gmbh & Co. Kg | Device for minimizing positional measurement errors in a contactless mass determination |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3101407A (en) * | 1959-04-09 | 1963-08-20 | Jr John Daniel Shipman | Fluoroscope system utilizing an image storage tube |
| BE647073A (en) * | 1964-04-24 | 1964-10-26 | ||
| US3936638A (en) * | 1973-07-06 | 1976-02-03 | Emi Limited | Radiology |
| US3927318A (en) * | 1974-05-06 | 1975-12-16 | Albert Macovski | Cross-sectional fluorescent imaging system |
| DE2461877A1 (en) * | 1974-12-30 | 1976-07-01 | Alexander Dipl Phys Dr R Krebs | X-ray or gamma radio diagnostic scattered radiation appts - for medical radiodiagnosis or investigating internal organ structures |
| JPS5269287A (en) * | 1975-12-06 | 1977-06-08 | Shimadzu Corp | Tomography equipment |
-
1977
- 1977-03-28 DE DE2713581A patent/DE2713581C2/en not_active Expired
-
1978
- 1978-03-23 CA CA299,716A patent/CA1101133A/en not_active Expired
- 1978-03-23 GB GB11670/78A patent/GB1602521A/en not_active Expired
- 1978-03-23 SE SE7803371A patent/SE7803371L/en unknown
- 1978-03-24 IT IT21630/78A patent/IT1093720B/en active
- 1978-03-25 ES ES468229A patent/ES468229A1/en not_active Expired
- 1978-03-27 BR BR7801844A patent/BR7801844A/en unknown
- 1978-03-27 JP JP3428478A patent/JPS53120294A/en active Pending
- 1978-03-28 BE BE186331A patent/BE865386A/en unknown
- 1978-03-28 FR FR7808900A patent/FR2386055A1/en active Granted
- 1978-03-28 NL NL7803229A patent/NL7803229A/en not_active Application Discontinuation
- 1978-03-31 AU AU34662/78A patent/AU513395B2/en not_active Expired
- 1978-12-19 AU AU42722/78A patent/AU526138B2/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6556653B2 (en) | 2000-05-25 | 2003-04-29 | University Of New Brunswick | Non-rotating X-ray system for three-dimensional, three-parameter imaging |
| US6563906B2 (en) | 2000-08-28 | 2003-05-13 | University Of New Brunswick | X-ray compton scattering density measurement at a point within an object |
| US7203276B2 (en) | 2004-08-27 | 2007-04-10 | University Of New Brunswick | X-ray scatter image reconstruction by balancing of discrepancies between detector responses, and apparatus therefor |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2386055A1 (en) | 1978-10-27 |
| IT7821630A0 (en) | 1978-03-24 |
| GB1602521A (en) | 1981-11-11 |
| AU526138B2 (en) | 1982-12-16 |
| FR2386055B1 (en) | 1983-03-25 |
| DE2713581C2 (en) | 1983-04-14 |
| IT1093720B (en) | 1985-07-26 |
| AU513395B2 (en) | 1980-11-27 |
| ES468229A1 (en) | 1979-04-01 |
| BE865386A (en) | 1978-09-28 |
| DE2713581A1 (en) | 1978-10-05 |
| BR7801844A (en) | 1978-11-07 |
| JPS53120294A (en) | 1978-10-20 |
| NL7803229A (en) | 1978-10-02 |
| AU4272278A (en) | 1979-05-10 |
| AU3466278A (en) | 1979-10-04 |
| SE7803371L (en) | 1978-09-29 |
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