AU2002242490A1 - Disposable calibrated camera for skin lesion examination - Google Patents

Description

Disposable calibrated camera for skin lesion examination

Field of the Invention

The present invention relates to a camera assembly and, in particular, to a camera assembly for taking calibrated images of skin lesions and skin cancers, including melanoma. Background of the Invention

Malignant melanoma is a form of cancer due to the uncontrolled growth of melanocytic cells just under the surface of the skin. These pigmented cells are responsible for the brown colour in skin and freckles. Malignant melanoma is one of the most aggressive forms of cancer known. The interval between a melanoma site becoming malignant or active and the probable death of the patient in the absence of treatment may be short, of the order of only six months. Death occurs due to the spread of the malignant melanoma cells beyond the original site through the blood stream into other parts of the body. Early diagnosis and treatment is essential for a favourable prognosis.

However, the majority of medical practitioners are not expert in the area of dermatology and each one might see only a few melanoma lesions in a year. In consequence, the ordinary medical practitioner has difficulty in assessing a lesion properly. (See, e.g., Early detection of Skin Cancer: Knowledge, Perceptions and Practices of General Practitioners in Victoria, Paine et al, Med J Aust, vol 161 , pp. 188-195, 1994 and General Practitioner and Patient Response During a Public Education Program to Encourage Skin Examinations, Lowe et al, Med J Aust, vol 161 , pp. 195-198, 1994). There is therefore a strong tendency for the ordinary medical practitioner to remove a lesion if it is at all suspect for the purpose of obtaining a histopathological diagnosis.

Medical statistics show that this tendency means that malignant melanomas form a very small fraction of the lesions being surgically excised, with the rest being harmless. A figure of 3% has been quoted by one authority (see Melanocytic Lesions Excised from the Skin: What Percentage are Malignant? Del-Mar, et al Aust J Public Health, vol 18, pp. 221-223). This excess of surgical procedures leads to significant wasted expense to the community, and risks of scarring and infection. Most of these problems could be avoided if the ordinary medical practitioner had access to the knowledge of the expert dermatologist. A significant improvement in diagnosis would come from encapsulating the expert knowledge of a skilled dermatologist and making this knowledge more widely available.

Examination of skin lesions and the identification of skin cancers such as melanoma have traditionally been done with the naked eye. More recently dermatologists have used a hand-held optical magnification device generally known as a dermatoscope (or Episcope) (see, e.g., Skin surface microscopy. Stoltz et al., Lancet vol. 2, pp. 864-5, 1989). In essence, this device consists of a source of light to illuminate the area under examination and a lens or combination of lenses for magnifying the area of skin under examination. Typically, this instrument has a flat glass window at the front which is pressed against the skin in order to flatten the skin and maximise the area in focus. The physician-user looks through the instrument to see a magnified and illuminated image of the lesion. An expert dermatologist can identify over 70 different morphological characteristics of a pigmented lesion. (See, e.g., Automated Instrumentation for the Diagnosis of Invasive Melanoma: Image Analysis of Oil Epiluminescence Microscopy, Menzies, et al., Skin Cancer and UV Radiation, Springer Verlag, 1997.) These instruments are now available commercially (see, e.g., the Episcope™ by Welch-Allyn, Inc., 4341 State Street Rd, Skaneateles Falls, NY 13153-0220). The dermatoscope is used with an "index matching" liquid between the window and the patient's skin. The purpose of this "index matching" liquid as it is known in the literature is to eliminate from the image the reflected light which is due to the step or "mismatch" in refractive index between skin and air. Reflected light contains little information about the skin. Information about the skin and the sub-surface melanoma cells is contained in the reradiated light. By limiting the light reaching the observer to just reradiated light, the best possible image of the medically important subsurface details is obtained. The user sees more of that part of the skin where the malignant melanoma cells are initially located. This method is known as epiluminescence microscopy or ELM. (See, e.g., In Vivo Epiluminescence Microscopy of Pigmented Skin Lesions. II: Diagnosis of Small Pigmented Skin Lesions and Early Detection of Malignant Melanoma, Steiner, et al., Am Acad. Dermat, 1987, vol. 17, pp. 584-591 ; Trends in Dermatology: Differential Diagnosis of Pigmented Lesions Using Epiluminescence Microscopy, in Sober et al., Eds, 1992 Year Book of Dermatology, St Louis, Mo.; Clinical Diagnosis of Pigmented Lesions Using Digital Epiluminescence Microscopy: Grading Protocol and Atlas, Kenet et al., Arch. Derm, Feb. 1993, pp. 157-174; and U.S. Patent No. 5,836,872 in the name of Kenet et al.).

Polarised light may also be used for the purpose of eliminating reflections, and its use is well known in the scientific and medical literature (for medical examples in this area see, e.g., Computerised evaluation of pigmented skin lesion images recorded by a video microscope: comparison between polarising mode observation and oil/slide mode observation. Seidenari et al., Skin Research and Technology, pp. 187-191. 1995 and publication WO 96/16698). The use of polarised light in this context has been shown to produce lower contrast inside the lesion borders than is observed with ELM.

We have found that due to total internal reflection (TIR) in the glass window, ELM images are subject to a self-illuminating effect. The perceived brightness of the object can increase almost twofold when the brightness of the background increases. The effect is independent for each colour channel which makes colour of the object depend on the colour of the background. This introduces errors into colour analysis of the ELM images as well as reducing the image contrast.

In view of the complications introduced by the use of a window, the advantages of designing the system without a window have been considered. Two approaches are possible - either a cone may be placed on the camera and used without a window, or the camera may be operated without any sort of cone whatsoever. The second approach is shown in International Patent Publication No WO 97/47235. The absence of a cone means that the image scale is essentially uncontrolled. The influence of unknown external lighting prevents the production of an image which is colour-calibrated across its whole region. Use of a cone without a window is shown in U.S. Patent No. 4,930,872. This has proven to have a significant disadvantage in that the unsupported skin is allowed to bulge inwards towards the camera. This means that any optical system involving lenses must have a significant depth of focus, which requires a smaller aperture and hence a higher level of illumination than would otherwise be needed. It also means that the shape of the lesion may vary from inspection to inspection due to varying amounts of bulge, and the colour appearance of the lesion will vary due to the varying angle the lesion surface presents to the observer. This bulge may be reduced by reducing the unsupported area, but this is not a realistic approach with a large lesion. Embodiments of the present invention may overcome these problems by means disclosed later in this patent application.

Some dermatologists have used film-based cameras to photograph skin lesions, both as a way of magnifying the image of the lesion and as a way of recording the image. However, skill is required in using such photographs as the repeatability of the images and hence the range of recognisable features can be affected by a range of factors in the photographic process. Attempts have been made to convert these photographic images to digital form and to locate the skin lesion border (see, e.g., Unsupervised Colour Image Segmentation, with Application to Skin Tumor Borders, Hance, et al., IEEE Eng in Med & Biol, Jan/Feb 1996, pp. 104-111 ). Attempts in this direction have highlighted the fact that a skilled dermatologist sees and uses detail in the image down to a very small size, meaning that both high quality colour and high resolution imaging are required for this task. A number of other medical instruments exist for the direct illuminated optical inspection of parts of the human body, e.g., the ophthalmoscope and the otoscope. In these instruments, a miniature TV camera is added to a standard medical instrument or even substituted for the user's eyes. This has created a range of video microscopes of various forms (see, e.g., U.S. Patent No. 4,905,702 in the name of Foss, U.S. Patent No. 4,930,872 in the name of Convery, U.S. Patent No. 4,947,245 in the name of Ogawa, et al., U.S. Patent No. 5,363,854 in the name of Martens et al., U.S. Patent No. 5,442,489 in the name of Yamamoto et al., U.S. Patent No. 5,527,261 in the name of Monroe et al., U.S. Patent 5,662,586 in the name of Monroe et al., U.S. Patent No. 5,745,165 in the name of Atsuta et al., U.S. Patent No. 5,836,872 in the name of Kenet et al., International Patent Publication No WO 96/16698 in the name of Binder and International Patent Publication No WO 98/37811 in the name of Gutkowicz-Krusin et al.). It is also known to save such images of the skin in a computer database (see, e.g., U.S. Patent No. 4,315,309 in the name of Coli and U.S. Patent No. 5,016,173 in the name of Kenet, et al.), although computer databases came into existence with the first computers, and medical researchers have in fact been using computers for many years to store and analyse digital images of melanoma lesions (see, e.g., A Possible New Tool for Clinical Diagnosis of Melanoma: the Computer. Cascinelli, et al., J Am Acad Dermat, 1987, Feb, vol. 16/2 pt 1 , pp. 361 -367 ). It is known that a melanoma lesion will have a complex geometry and this may serve as an indication of malignant melanoma (see, e.g., Shape analysis for classification of malignant melanoma, Claridge et al., J Biomed Eng, vol. 14, pp. 229-234, 1992). However, the complexity of a lesion makes the identification of even the boundaries between the lesion and the surrounding skin difficult. (See, e.g., Unsupervised Color Image Segmentation with Application to Skin Tumor Borders, Hance, et al., IEEE Eng in Med and Biol, Jan/Feb 1996, pp. 104-111.) This problem is compounded by the obvious fact that human skin colour is widely variable between different individuals and across different races. It is also found that skin colour can vary significantly across the body on any individual, due to effects such as sun tan, skin thickness and capillary density. Thus it is not possible to specify any particular colour as being "always skin".

Identification of the fine details within a lesion by computer image analysis of directly recorded colour video images is a problem whose solution has been attempted by some researchers (see, e.g., Computer image analysis of pigmented skin lesions, Green et al., Melanoma Research, vol. 1 , pp. 231-6, 1991 , and Computer Image Analysis in the Diagnosis of Melanoma, Green, et al., J Am Acad Dermal, 1994, vol. 31 , pp. 958-964) but with limited success. Some work has been done with medium resolution grey-scale images but mainly with the borders of the lesion. (See, e.g., Early Diagnosis of Melanoma using Image Analysis Technigues, Ng, et al., Melanoma Research, 1993, vol.3, p. 81 ). It is generally true that the specification and measurement of lesion geometries has not been achieved in a systematic and reproducible manner suitable for widespread use, although descriptive broad rules have been developed and are generally accepted as being useful (see, e.g., The ABCD rule of dermatoscopy, Nachtbar et al., J Am Acad Dermat., pp. 551-59, April 1994).

The analysis problem is compounded by the fact that the resolution of the images taken with common single-CCD miniature colour TV cameras is not very high (typically, poorer than 0.1 mm on the lesion with a 25mm field of view), which limits the ability to discriminate fine detail during either on-screen inspection or software-driven image analysis of geometrical features. Such cameras are used in both International Patent Publication No WO 96/16698 and U.S. Patent No. 4,930,872. Resolution of fine colour detail requires the use of high performance TV cameras such as the type known in the industry as "3-CCD". Full use of such cameras also requires the use of a lens of matching quality. The alternate approach to the generation of high resolution colour images is to use a high resolution monochrome camera, sequentially illuminate the skin area of interest with light in three different colour bands such as red, green and blue, and to take an image under each colour of illumination. Such coloured light may be generated from white light with a set of filters in the illumination path. This generates essentially the same red/green/blue (RGB) set of colour images as is obtained from a 3-CCD camera, and is used in International Patent Publication No WO 98/37811. However, this technique suffers from a disadvantage in comparison to the use of a 3-CCD camera. The process of changing filters takes time, and this permits movement of the skin area of interest during the process. Should this happen there would be a loss of colour registration within the composite image. Times of up to three minutes are quoted in International Patent Publication No WO 98/37811. This problem is exacerbated by the use of an index matching liquid between the skin and the front window since such liquid also serves as a lubricant. The problem may be reduced by applying pressure between the window and the skin, but this compresses the skin, excludes blood from the underlying dermal layers and changes the skin colour in an unacceptable manner. This whole problem may be largely eliminated by using a high resolution 3-CCD video camera, a digital still camera of equivalent or higher resolution, or a film-based camera, each with a short exposure time.

It is also known that a melanoma will feature a range of colours with the range being created by the depth of pigment within the lesion. This is illustrated in An Atlas of Surface Microscopy of Pigmented Skin Lesions, Menzies et al., McGraw-Hill, Sydney, 1996. These colours are typically classified by expert dermatologists with a small set of common names such as light brown, dark red, black, etc. Some attempts have been made to measure these colours. (See, e.g., Marshall op cit). However, the specification and the measurement of these colours has not been achieved in a systematic and reproducible manner, with current research publications still focusing on very simple measurements of lesion colour. (See, e.g., Reliability of Computer Image Analysis of Pigmented Skin lesions of Australian Adolescents. Aitken, et al., Cancer, 1996, vol. 78, pp. 252-257). The ordinary medical practitioner does not have sufficiently frequent contact with malignant melanomas to retain familiarity with these colours. An added complication lies in the way a typical colour TV-based image analysis system measures colour using red, green and blue channels, each measured nominally to 1 part in 256. Typically, there is the potential for up to 16 million different colours (256³) to be recorded. To allow any sort of analysis it is necessary to condense this enormous range down to a small number of medically significant colours. This is done by a process commonly known as colour binning. In this process, all colours within a certain range are given one name, such as red or brown. Defining the boundaries of these bins in a useful manner is a difficult task. It also requires that the imaging system be colour stable. The system shown in International Patent Publication No WO 96/16698 reduces the image intensity to 10 shades of grey but does not provide colour binning. Since a skilled dermatologist relies heavily on the range of colours present in forming a diagnosis, this approach is not adequate. Furthermore, it is done in an ad hoc manner as the system does not provide any stability in either illumination intensity or illumination colour temperature (lamp brightness can be varied by the user at will). Hance et al. (op cit) were only able to reduce images to skin plus 2 (or 3 in one case) lesion colours. Again, there was no attempt to stabilise the illumination.

It may therefore be seen that some form of stabilisation of the illumination is essential. This may be done in two main ways - by driving the illuminator with a stable source of power or by feedback. The latter may be done by sensing the lamp brightness in standard ways, and is used in U.S. Patent No. 4,930,872, although it has been found that a stable voltage source driving a high quality quartz iodine (Ql) lamp provides basic stability. However, further compensation for brightness variations both in time and across the image may still be required to ensure that each individual image can be appropriately calibrated to an international colour standard.

Given that a high stability illumination field has been generated, that provision has been made for monitoring it over time, and that a high resolution 3-CCD camera and lens are used to take images rapidly to avoid colour registration problems, compensation may then be profitably applied to correct for any other imaging problems encountered.

As mentioned above, a significant problem not previously reported which may be encountered with the use of ELM is a variation in apparent image brightness and colour due to total internal reflection in the window otherwise used to keep the skin flat. Prior art calibration means and techniques, e.g., as disclosed in International Patent Publication No WO 98/3781 1 , virtually ignored the existence of the glass surface adjacent to the skin by putting the reference strip of diffusely reflecting grey material on the observer side of the glass surface. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The present invention is directed to a system for recording calibrated images of a viewing area, such as an area of a patient's skin. Summary of the Invention

According to a first aspect, the present invention is a camera assembly for generating images of a viewing area, the assembly comprising a case, an imaging means, and an optical assembly for transmitting light from the viewing area through the case to the imaging means, the imaging means having a first image recording means for recording at least one image of the viewing area and at least a second image recording means for recording at least one calibration image.

In a preferred embodiment, the camera assembly is adapted to image an area of a patient's skin. In particular, the camera assembly is adapted to image skin lesions, such as melanomas. In this case, the camera is preferably operated by a medical practitioner or other health care professional. It can, however, be envisaged that the camera could be utilised by patients themselves or a non-medically trained individual. Hereafter, the camera assembly is described with reference to its application in imaging patient's skin and skin lesions. It should, however, be appreciated that the camera assembly could be adapted to take images other than that of patient's skin. In a preferred embodiment, the camera is a single-use camera. The camera is preferably disposed of after retrieval of at least one image of the viewing area from the first image recording means and at least one calibration image from the second image recording means. In another embodiment, the camera is rendered inoperative by retrieval of the at least one image of the viewing area and/or the at least one calibration image. In a preferred embodiment, the camera assembly further comprises an activation means that must be activated before the second image recording means can record said at least one calibration image. In a further embodiment, the activation means incorporates a locking means that prevents unauthorised activation. This feature allows the calibration image or images to be only taken under controlled conditions with appropriate calibration reference standards. In one embodiment, the locking means can be unlocked by a key.

In one embodiment, the activation means is not operable until after the images of the patient's skin have been taken by the camera.

In a further embodiment, the at least one calibration image is taken before the images of the viewing area are taken. For example, the calibration images can be taken prior to delivery of the camera assembly to a user.

The activation means can comprise a switch which, once activated, allows operation of the second image recording means. The switch is preferably locked while ever the camera assembly is being used to record images of the patient's skin. The activation means preferably can only be unlocked by an authorised user.

In a further embodiment, the camera can be a video camera or a still camera. The camera can be custom-designed or be of a presently available commercial camera design. The camera can be a compact camera. In one embodiment, the video or still camera can be a digital camera. In one embodiment, the camera can rely on a charge coupled device (CCD) array or similar technology to digitally record the image of the patient's skin. The camera can digitally store the at least one image of the patient's skin. The digital storage can be provided wholly or in part by a memory means, such as a memory chip, disk, cartridge or other device suitable for digital storage. Use of a memory means for digital storage of the images allows for the ready transference of image files from the camera assembly to another computer- based system for image processing. In this embodiment, the first and second image recording means can comprise respective portions of the storage capacity of the memory means. In another embodiment, the video or still camera can utilise conventional film imaging. The film is preferably colour film. Film imaging currently has the advantage of higher resolution compared to digital imaging. One disadvantage is that transfer of recorded images from the film to a computer requires a film processing step followed by a scanning step. In this embodiment, the first and second image recording means comprise respective first and second portions of the film loaded within the camera. For a still camera, the film can be wound through the camera by a winding means. The winding means can be manually or mechanically operated after recording of each image of the viewing area. The film stored in the camera preferably allows recording of a plurality of images of the viewing area in the first portion of the film. The film stored in the camera also preferably allows recording of a plurality of calibration images in the second portion of the film. In one embodiment, the winding means can be locked once a certain pre-determined number of viewing area images have been taken. This ensures that sufficient unexposed film is left in the camera to allow the taking of an image of at least one calibration image.

Following exposure of the film it can be removed from the camera. Where the camera is designed to be a single-use camera, the film is preferably only removable by breaking open the camera case to allow removal of the film therefrom. The damage to the camera case preferably renders the camera assembly inoperable so preventing its re-use.

In a further embodiment, the camera assembly may comprise an illumination system. In one embodiment, the illumination system can provide illumination in the visible spectrum and/or in the near infrared portion of the spectrum. The illumination system preferably provides relatively even and stable illumination of the viewing area. The illumination system can comprise a source of light inside the case for directing light towards the viewing area. The light source can be selected from a group comprising a xenon flash tube, an incandescent bulb, a quartz halogen bulb, and a 'white' light emitting diode (LED). In another embodiment, the light source can be a combination of illumination sources of a plurality of colours which when combined provide an illumination source which has a known and even distribution across the visible spectrum which can approximate or simulate white light. In a still further embodiment, the illumination system preferably illuminates the viewing area with polarised light. In one embodiment, the source of light can comprise a plurality of individual light sources. In a further embodiment, the camera can have four individual light sources arranged at the corners of a nominal square.

In a further embodiment, the camera assembly may comprise a means of conveying the light source to the viewing area. The conveying means may comprise a plurality of light conduits, such as one or more optical fibres or rods. If used, the individual optical fibres are preferably randomised before being split and directed into output ports in the case of the assembly.

In another embodiment, the conveying means can comprise a cavity with a plurality of passages and chambers, the purpose of which is to channel and diffuse the light such that the light conveyed from a single source provides a relatively even illumination across the 2-dimensional area comprising the viewing area. Further, the illumination system may comprise one or more holographic diffusers positioned between a light source and a window of the optical assembly, in order to evenly scatter light without absorbing the light.

In a preferred embodiment, the illumination system can comprise at least one light source, a triggering system, and a mounting means. The mounting means preferably provides accurate positioning of the illumination system. The triggering system can be used to activate the light source at the moment of exposure of the imaging means. Where there is a plurality of light sources, the light sources can be linked by a common electronic switching system such that on activation of the triggering system all of the illumination sources are triggered to provide illumination of the viewing area.

In one embodiment, the optical assembly comprises a lens. The optical assembly can have a fixed focus. It can, however, be envisaged that the optical assembly could have a variable focus. The optical assembly can also, in a further embodiment, have a means for registration of image size.

The camera assembly further comprises an optical unit that is mountable to the case of the camera. The optical unit can be removably mounted to the camera case. The optical unit preferably has a first end mounted to the case and an elongate body. At the second distal end, the body can have a window. The window is preferably flat and made from an optically transparent material, such as a glass or plastics material. The window can during use be coated with an index matching liquid. In a further embodiment, the camera assembly can comprise a reservoir for the index matching liquid. The reservoir can be adapted to direct the liquid onto the outside surface of the window on manipulation by a user of the camera assembly.

As noted in the present applicant's co-pending patent application number

WO 01/35827, the contents of which are hereby incorporated by reference, problems associated with total internal reflection in the window can be alleviated by use of a window having a thickness greater than 5mm, and by placement of a target on an external side of the window.

A calibration target can be mounted outside the window prior to the taking of a calibration image. The calibration target can comprise a reference- white or grey material. The reference-white or grey calibration target can take the form of a glazed ceramic tile or card with a very flat surface. In use, the tile or card can be supplied with the camera. When a user is required to take a calibration image, the tile or card can be placed against the window of the body, preferably with a standard index-matching liquid between the two. In another embodiment, one or more calibration targets can be mounted within the optical unit or the camera assembly. In this embodiment, the one or more targets can be slid into place in front of the imaging means whenever a calibration image is required.

In another embodiment, the calibration target can take the form of a thin film which is attached to the window. The thin film is preferably attached to the window prior to delivery of the camera to the user. The thin film can be formed from a suitable white or grey material or be a clear material that has been coated with a layer of suitable white or grey paint. The thin film may be attached to the window with a layer of adhesive. The adhesive should serve to both retain the film in place and to act as an air-excluding mechanism. Once a calibration image has been taken, the thin film calibration target can be removed from the window. The act of removing the target from the window preferably damages the target sufficiently that it cannot be reused. This ensures that no attempt is made to re-adhere the thin film target to the window. Any attempt would likely result in air bubbles being trapped beneath the film so preventing the taking of an appropriate calibration image. Once the target is removed, the camera with the optical unit in place can take one or more images of the patient's skin.

In another embodiment, the elongate body of the optical unit can have a mounting means at its second distal end. The mounting means is preferably removably mounted to the body. The mounting means preferably can hold a window, such as the optically transparent window described above. A calibration target can be mounted to the window of the mounting means. The calibration target can be a film layer that is removably adhered to the window such as was described above. The act of removing the target preferably damages it sufficiently so as to prevent its reuse. Since a calibration image is always required for each patient examination, a new sterile mounting means (with target attached) is required for each use of the camera.

While a reference-white or grey material is described above as the preferred calibration target, it should be appreciated that any reference material of known stable colour can be used. In particular, it is preferred that the calibration target be of a similar brightness to human skin, to enable a full exposure of the skin to be obtained without under-exposing or over-exposing the calibration target.

In another embodiment, the camera can be supplied with more than one calibration target to provide suitable colour and grey scale calibration of the camera assembly. It is preferred that such targets, which may be in the form of tiles or cards, are allocated a calibration card batch number. This batch number can be registered against a serial number allocated to the camera to allow cross-checking of calibration accuracy and quality control. In another embodiment, a peripheral band of the window can be coated with opaque paint or another coloured material of suitable form. This band is preferably visible in the viewing area when an image is taken by the camera assembly. The band can be later used during image analysis to check on the stability of the lighting and the colour calibration. The band can also aid in compensating for the effects of total internal reflection (TIR). The band is preferably formed from a range of colours. The band can be all white or white, light grey, dark grey and black, or some other combination.

In a further embodiment, the camera assembly can comprise a means of indelibly recording the patient's unique identifiers, eg. patient's name or other details, to ensure later accurate matching of medical test results to the appropriate patient. In another embodiment, the camera assembly can comprise a means of affixing a coded patient identification label to the camera assembly to ensure later accurate matching of medical test results to the appropriate patient. In one example of a potential normal use for the present invention, a physician, such as a general practitioner, will order a camera assembly according to the present invention. The supplied camera for the purposes of this description will be a single-use disposable film camera having sufficient film to allow a number of images of one or more suspect lesions to be taken. It is envisaged that the camera assembly may allow up to 12 skin lesion images to be taken. As the practitioner obtains images of lesions, a record is preferably made of a location where each lesion occurs on the body of the patient. For example, the practitioner may indicate on a diagram of a human body where the lesion occurs on the patient. Once all film in the camera available for the taking of images of skin lesions is utilised, the winding means locks preventing further winding of the film in either direction. Once the images are taken, the patient's details are recorded on the camera before it is forwarded to an appropriate film processing facility. The camera may be forwarded by mail or hand delivered by the physician or another person. The record of the location of each lesion is preferably also forwarded with the images of the lesions. Once delivered, an operator at the facility may mount an optical unit to the front of the camera that has an appropriate calibration target mounted thereto. The optical unit incorporates a key that unlocks the winding mechanism on mounting of the optical unit to the camera assembly. The unlocking of the winding mechanism allows the operator to wind the film through the camera. The camera assembly is then able to take at least one further image of a calibration target. The result is a roll of film that in each case has a common test standard that can be used for image calibration. The film is then preferably removed from the camera assembly by breaking open the camera case. The act of breaking the case ensures that the camera assembly cannot be re-used.

Once the film is processed, each image can be scanned to convert it into a digital image. Once a series of digital images is obtained, the calibration target image can be analysed to determine if it is has been reproduced accurately. If it has not, then software tools and algorithms can be utilised to match the calibration target image with the reference targets held in the computer memory. This matching is then used to provide appropriate compensation to the images taken of the skin lesions with the result that the image file has been adjusted to produce true colours of the skin lesion.

The images of the lesion can then be provided to one or more qualified dermatologists for analysis, preferably along with the record of where each lesion occurs on the body of the patient. The one or more dermatologists would then provide their findings to the referring physician. In an alternative embodiment, the calibrated and compensated software image files can be analysed by a software system, such as the Polartechnics Skin Analysis Software which can determine whether the imaged lesion is a melanoma and/or compare the image with one or more previous images of the same lesion to determine if there has been any changes in the lesion indicative of malignant melanoma. Again, the results of this analysis can be provided to the referring physician.

According to a second aspect, the present invention provides a method of recording images of a viewing area, the method comprising the steps of: recording at least one image of the viewing area on a first image recording means; and recording at least one calibration image on a second image recording means. The method of the second aspect of the invention may be particularly suited to recording images of an area of a patient's skin. In particular, the method of the present invention may be used in recording images of skin lesions. In such embodiments, the step of recording at least one image of the viewing area is preferably carried out by a medical practitioner or other health care professional. The step of recording the calibration image may be performed remotely from the medical practitioner or health care professional, for example at an image processing facility.

The step of recording at least one calibration image may be performed after the step of recording at least one image of the viewing area. For example, where the method further comprises the step of retrieving images recorded in the first and second storage means, the step of recording at least one calibration image may be performed immediately prior to the step of retrieving. In such embodiments, the method may comprise the further step of activating the second storage means, wherein recordal of the at least one calibration image cannot occur until after the step of activating. The step of activating may be prevented from occurring until the step of recording the at least one image of the viewing area has occurred.

Alternatively, the step of recording the at least one calibration image may be performed prior to or substantially contemporaneously with the step of recording the at least one image of the viewing area. The method of the present invention may further comprise the step of disposing of the first and second storage means after retrieval. Additionally or alternatively, the step of retrieving images recorded in the first and second storage means may render the first and second storage means inoperative. The method of the present invention preferably further comprises the step of illuminating the viewing area to facilitate the recordal of the at least one image of the viewing area. The step of illuminating preferably comprises providing illumination in the near infrared and/or visible spectrum, and preferably comprises providing a relatively even and stable illumination of the viewing area. The step of illuminating may comprise illuminating the viewing area with polarised light.

In embodiments where the first and second storage means do not record images in digital form, the method of the present invention preferably further comprises the step of converting the images recorded in the first and second storage means into digital images. In such embodiments, the method of the present invention preferably further comprises matching the calibrating image with reference targets stored in a computer memory. Further, the method preferably comprises the step of compensating the at least one recorded image of the viewing area based on said step of matching. Subsequent to matching the at least one calibration image and compensating the at least one image of the viewing area, the at least one image of the viewing area may be provided to one or more qualified dermatologists for analysis, who may then forward their findings to the physician who recorded the at least one image of the viewing area. Alternatively, the at least one compensated image of the viewing area may be provided to a software system for analysis.

US Provisional application No. 60/165072 describes systems and methods that are useful in performing this invention and the entire document is incorporated herein by reference. Brief Description of the Drawings By way of example only, preferred embodiments of the invention are now described with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of one embodiment of a camera assembly according to the present invention;

Fig. 2 is a rear view looking outwardly of one embodiment of a focusing cone for a camera assembly as depicted in Fig. 1 ; Figs. 3a and 3b are side elevational and cross-sectional views, respectively, of a window mounted to a focusing cone as depicted in Fig. 2;

Fig. 4 is a view of an alternative embodiment for a window for a focusing cone to that depicted in Fig. 3; Fig. 5 is a perspective view of another embodiment of a focusing cone for a camera assembly according to the present invention depicting the position of a concealed switch;

Fig. 6 depicts the camera assembly positioned so as to take an image of a calibration target; Fig. 7 depicts another embodiment of a camera assembly positioned so as to take an image of a calibration target; and

Figs. 8a and 8b are perspective and cross-sectional views, respectively, of another embodiment of a window for a focusing cone according to the present invention having a removable calibration target mounted thereto. Preferred Mode of Carrying out the Invention

One embodiment of a single-use camera assembly for generating images of an area of a patient's skin according to the present invention is depicted generally as 100 in the drawings.

The depicted single-use camera 100 uses colour film to record still images of the area of the patient's skin and images of one or more calibration targets. In particular, the camera 100 is adapted to image skin lesions, such as melanomas. In this case, the camera 100 is preferably operated by a medical practitioner or other health care professional. It can, however, be envisaged that the camera 100 could be utilised by patients themselves or a non- medically trained individual. While the operation of the camera 100 is described hereafter with reference to its application in imaging patient's skin and skin lesions, it should, however, be appreciated that the camera 100 could be adapted to take images other than that of patient's skin.

As shown in Figure 1 , the depicted camera 100 comprises a case 102, a focusing cone 104 and a lens 106. In this embodiment, the first and second image recording means described above comprise respective first and second portions of the film loaded within the camera 100. The film can be wound through the camera by a winding means (not depicted). The winding means can be manually operated or motor driven after recording of each image of the viewing area. The film stored in the camera preferably allows recording of a plurality of images of the viewing area in the first portion of the film. The film stored in the camera also preferably allows recording of a plurality of calibration images in the second portion of the film. In the depicted embodiment, the winding means locks once a certain pre-determined number of viewing area images have been taken. This ensures that sufficient unexposed film is left in the camera to allow the taking of an image of at least one calibration target.

As depicted in Figs. 5 and 7, the camera 100 comprises an activation device that must be activated before the camera 100 can be used to take images of one or more calibration targets. In the embodiment depicted in Fig. 5, the activation means comprises a switch 182 concealed behind a removable panel 180. In Fig. 7, the activation means comprises a switch positioned at the base of a hole 198 formed in the focusing cone 104. In the embodiment depicted in Fig. 7, the switch is activated by a rod 196 mounted on the calibration target 190 that can enter the hole 198.

The provision of an activation means, such as is depicted in Figs. 5 and 7, allows the calibration image or images to be only taken by the camera 100 under controlled conditions with appropriate calibration reference standards.

In the depicted embodiment, the activation means within the camera is not operable until after the images of the patient's skin have been taken by the camera 100. It can, however, be envisaged that the at least one calibration image is taken before the images of the viewing area are taken. For example, the calibration images can be taken prior to delivery of the camera 100 to a user.

In a further embodiment, and as shown in figure 2, the camera 100 comprises an illumination system comprised of four light sources 108 arranged at the corners of a square around the camera lens 106 inside the focusing cone 104. The light sources need not, however, be arranged symmetrically around the lens 106. Each light source 108 casts rays of light 124 onto the front window 110 or onto the patient's skin to create a light field depicted symbolically as 126. The overlapping light fields 126 are adapted to provide relatively uniform and stable illumination of the viewing area or field of view 112 of the camera lens 106. One or more holographic diffusers may be positioned between the light sources 108 and the window 110 in order to evenly scatter the light without absorbing the light.

The camera 100 comprises a triggering system that is used to activate the light sources 108 at the moment of exposure of the film within the camera 100. As there is a plurality of light sources, the light sources 108 are linked by a common electronic switching system such that on activation of the triggering system all of the light sources are triggered to provide illumination of the viewing area 112.

The focusing cone 104 of the camera 100 is removably mountable to the case 102. At an end of the cone 104 distal the case 102, the cone 104 can have sidewalls 128 supporting a square window 110. As depicted in Figs. 3 and 4, the window 110 can also be round. Other suitable shapes can also be envisaged. The depicted window 110 is flat and made from an optically transparent material, such as a glass or plastics material. The depicted window has a thickness of about 5-6mm. Other window thicknesses could, however, be utilised.

In Fig. 3, colour reference targets are provided on the outer surface of the window and so come into contact with the skin of the patient in normal use. The targets may be one of several colours. In the embodiment depicted in Fig. 3, four different coloured targets (140, 142, 144 and 146) are provided. The colours can be, for example, white, light grey, dark grey and black. Each target extends slightly into the field of view 112 of the camera 100, such that a subsequent analysis of any taken image includes the colours for reference or checking. Fig. 4 illustrates a different arrangement for the reference targets to that depicted in Fig. 3. In this embodiment, six different coloured targets are generally depicted as 152, 154, 156. These colours can be representative of the typical colours encountered during analysis of a melanoma lesion. Such colours might include pink, red, tan, light and dark brown and blue. Figs. 6 and 7 depict one example of how the camera 100 can be used to take one or more calibration images. As depicted, the window 110 can be brought into contact with calibration area 194 on the top surface 192 of a calibration target 190 in order that a calibration image may be taken. Such an image would normally be taken once the pre-determined number of images of the patient's skin have been taken. Further, in the embodiment depicted in Fig. 6, the winding means would only allow the film to be advanced to allow taking of the calibration image once the switch 182 had been activated following removal of panel 180.

In Fig. 7, the calibration image is taken in a similar fashion to that depicted in Fig. 6 except that the winding means only allows the film to be advanced to allow taking of the calibration image when the switch inside hole 198 is activated.

The depicted calibration target 190 is a reference-grey material. The reference-grey calibration target 190 can take the form of a ceramic tile or card with a very flat surface.

As depicted in Figs. 8a and 8b, the calibration target can take other forms. For example, as shown in Figure 8b the target 202 can comprise a thin film 206 which is adhered to the window 200 by an adhesive layer 204. In this case, the window 200 is essentially identical to the window 110 described above. The thin film 206 has a fragile paint layer 208 which flakes off when the film 206 is removed from the window 200. The paint layer 208 is formed from a suitable grey material or may be a clear material that has been coated with a layer of suitable grey paint. The act of removing the target 202 from the window 200 damages the target such that it cannot be reused. This ensures that no attempt is made to re-adhere the thin film target 202 to the window 200. Once the target 202 is removed, the camera 100 can take one or more images of the patient's skin. Target 202 would typically be used in the instance where a calibration image is to be taken prior to imaging of the patient's skin.

While a reference-grey material is described above as the preferred calibration target, it should be appreciated that the reference material must be of known stable colour and precisely defined to suit this present application.

In another embodiment, the camera 100 can be supplied with more than one calibration target to provide suitable colour and grey scale calibration of the camera 100. It is preferred that such targets, which may be in the form of tiles or cards, are allocated a calibration card batch number. This batch number can be registered against a serial number allocated to the camera 100 to allow cross-checking of calibration accuracy and quality control.

The camera 100 can further comprise a means of indelibly recording the patient's name or other details to ensure later accurate matching of medical test results to the appropriate patient. The camera 100 can also comprise a means of affixing a coded patient identification label to the case 102 to ensure later accurate matching of medical test results to the appropriate patient.

In one example of a potential normal use for the present invention, a physician, such as a general practitioner, will order a camera 100. The supplied camera 100 for the purposes of this description is a single-use film camera having sufficient film to allow a number of images of one or more suspect lesions to be taken. It is envisaged that the camera 100 may allow up to 12 skin lesion images to be taken. Once all film in the camera available for the taking of images of skin lesions is utilised, the winding means locks preventing further winding of the film in either direction. Once the images are taken, the patient's details are recorded on the camera 100 before it is forwarded to an appropriate film processing facility. The camera 100 may be forwarded by mail or hand delivered by the physician or another person.

Once delivered, an operator at the facility may, either activate switch 182 behind panel 180 or mount the hole 198 in cone 104 over rod 196, to activate the winding mechanism that advances film to allow the taking of an image of one or more calibration targets that are positioned before the camera 100. The result is a roll of film that in each case has a common test standard that can be used for image calibration. The film is then removed from the camera assembly by breaking open the camera case. The act of breaking the case ensures that the camera assembly cannot be re-used.

Once the film is processed, each image can be scanned to convert it into a digital image. Once a series of digital images is obtained, the calibration target image can be analysed to determine if it is has been reproduced accurately. If it has not, then software tools and algorithms can be utilised to match the calibration target image with the reference targets held in the computer memory. This matching is then used to provide appropriate compensation to the images taken of the skin lesions with the result that the image file has been adjusted to produce true colours of the skin lesion.

The images of the lesion can then be provided to one or more qualified dermatologists for analysis. The one or more dermatologists would then provide their findings to the referring physician. In an alternative embodiment, the calibrated and compensated software image files can be analysed by a software system, such as the Polartechnics Skin Analysis Software which can determine whether the imaged lesion is a melanoma and/or compare the image with one or more previous images of the same lesion to determine if there has been any changes in the lesion indicative of malignant melanoma. Again, the results of this analysis can be provided to the referring physician.

A camera that relied upon digital storage of recorded images instead of film can also be envisaged. While a camera 100 that takes still images is depicted, the present invention also can be used in association with a video or digital still camera. Such digital cameras can rely on the use of charge coupled device (CCD) arrays or similar technology to digitally record the image of the patient's skin. Such cameras can digitally store the at least one image of the patient's skin. The digital storage can be provided wholly or in part by a memory means, such as a memory chip, disk, cartridge or other device suitable for digital storage. Use of a memory means for digital storage of the images allows for the ready transference of image files from the camera assembly to another computer-based system for image processing. In this case, the first and second image recording means can comprise respective portions of the storage capacity of the memory means. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (113)

CLAIMS:

1. A camera assembly for generating images of a viewing area, the assembly comprising a case, an imaging means, and an optical assembly for transmitting light from the viewing area through the case to the imaging means, the imaging means having a first image recording means for recording at least one image of the viewing area and at least a second image recording means for recording at least one calibration image.

2. The camera assembly of claim 1 , wherein the camera assembly is adapted to image an area of a patient's skin.

3. The camera assembly of claim 2, wherein the camera assembly is adapted to image skin lesions.

4. The camera assembly of any one of the preceding claims, wherein the camera assembly is a single-use camera assembly.

5. The camera assembly of claim 4 wherein the camera assembly is rendered inoperative by retrieval of at least one image of the viewing area from the first recording means, and/or by retrieval of at least one calibration image from the second image recording means.

6. The camera assembly of any one of the preceding claims further comprising an activation means that must be activated before the second image recording means can record said at least one calibration image.

7. The camera assembly of claim 6 wherein the activation means incorporates a locking means that prevents unauthorised activation.

8. The camera assembly of claim 7 wherein the locking means can be unlocked by a key.

9. The camera assembly of claim 7 or claim 8 wherein the activation means can only be unlocked by an authorised user.

10. The camera assembly of any one of claims 6 to 9 wherein the activation means is inoperable until after images of a patient's skin have been taken by the camera.

11. The camera assembly of any one of claims 6 to 10 wherein the activation means comprises a switch which, once activated, allows operation of the second image recording means.

12. The camera assembly of claim 11 wherein the switch is locked while ever the camera assembly is being used to record images of the patient's skin.

13. The camera assembly of any one of the preceding claims wherein at least one calibration image is taken before the images of the viewing area are taken.

14. The camera assembly of claim 13 wherein the at least one calibration image is taken prior to delivery of the camera assembly to a user.

15. The camera assembly of any one of the preceding claims, wherein the camera assembly comprises a video camera.

16. The camera assembly of any one of the preceding claims, wherein the camera assembly comprises a still camera.

17. The camera assembly of any one of the preceding claims, wherein the camera assembly is custom-designed.

18. The camera assembly of any one of the preceding claims, wherein the camera assembly is of a presently available commercial camera design.

19. The camera assembly of any one of the preceding claims, wherein the camera assembly is a compact camera.

20. The camera assembly of any one of the preceding claims, wherein the camera assembly comprises a digital camera.

21. The camera assembly of claim 20, wherein the camera assembly uses a charge coupled device (CCD) array to digitally record the image of the viewing area.

22. The camera assembly of claim 20 or claim 21 , wherein the camera assembly digitally stores the at least one image of the viewing area.

23. The camera assembly of claim 22, wherein the digital storage is provided wholly or in part by a memory means.

24. The camera assembly of claim 23 wherein the memory means is selected from a memory chip, a disk, or a cartridge.

25. The camera assembly of claim 23 or claim 24, wherein the first and second image recording means comprise respective portions of the storage capacity of the memory means.

26. The camera assembly of any one of the preceding claims wherein the camera assembly utilises conventional film imaging.

27. The camera assembly of claim 26 wherein a film loaded within the camera is colour film.

28. The camera assembly of claim 26 or claim 27 wherein the first and second image recording means comprise respective first and second portions of a film loaded within the camera.

29. The camera assembly of any one of claims 26 to 28 further comprising a manual winding means enabling the film to be manually wound through the camera.

30. The camera assembly of any one of claims 26 to 28 further comprising a motor-driven winding means enabling the film to be motor wound through the camera.

31. The camera assembly of claim 29 or 30 wherein the winding means can be locked once a certain pre-determined number of viewing area images have been taken.

32. The camera assembly of any one of the preceding claims wherein the first image recording means allows recording of a plurality of images of the viewing area.

33. The camera assembly of any one of the preceding claims wherein the second image recording means allows recording of a plurality of calibration images.

34. The camera assembly of any one of claims 26 to 31 wherein the camera assembly is a single use camera assembly and wherein the film is only removable by breaking open the camera assembly to allow removal of the film therefrom, so as to render the camera assembly inoperable.

35. The camera assembly of any one of the preceding claims, and further comprising an illumination system for illuminating the viewing area.

36. The camera assembly of claim 35 wherein the illumination system can provide illumination in the visible spectrum and/or in the near infrared portion of the spectrum.

37. The camera assembly of claim 35 or claim 36 wherein the illumination system provides relatively even and stable illumination of the viewing area.

38. The camera assembly of any one of claims 35 to 37 wherein the illumination system comprises a source of light inside the case for directing light towards the viewing area.

39. The camera assembly of any one of claims 35 to 38 wherein the illumination system comprises a light source selected from a xenon flash tube, an incandescent bulb, a quartz halogen bulb, and a 'white' light emitting diode

(LED).

40. The camera assembly of any one of claims 35 to 39 wherein the illumination system comprises a light source comprising a combination of illumination sources of a plurality of colours which when combined provide an illumination source which has a known and even distribution across the visible spectrum which approximates white light.

41. The camera assembly of any one of claims 35 to 40 wherein the illumination system illuminates the viewing area with polarised light.

42. The camera assembly of any one of claims 35 to 41 wherein the illumination system comprises a plurality of individual light sources.

43. The camera assembly of claims 42 wherein the illumination system comprises four individual light sources arranged at the corners of a nominal square.

44. The camera assembly of any one of claims 35 to 43 wherein the illumination system further comprises a means of conveying the light source to the viewing area.

45. The camera assembly of claim 44 wherein the conveying means comprises a plurality of light conduits.

46. The camera assembly of claim 45 wherein the light conduits comprise optical fibres or rods.

47. The camera assembly of claim 46 wherein each of the optical fibres are randomised before being split and directed into output ports in the case of the assembly.

48. The camera assembly of claim 44 wherein the conveying means comprises a cavity with a plurality of passages and chambers for channelling and diffusing the light such that the light conveyed from a single source provides a relatively even illumination across the 2-dimensional area comprising the viewing area.

49. The camera assembly of any one of claims 35 to 48 wherein the illumination system comprises at least one light source, a triggering system to activate the light source at the moment of exposure of the imaging means, and a mounting means to provide accurate positioning of the illumination system.

50. The camera assembly of claim 49 wherein the illumination system comprises a plurality of light sources, and wherein the light sources are linked by a common electronic switching system such that on activation of the triggering system all of the illumination sources are triggered to provide illumination of the viewing area.

51. The camera assembly of any one of the preceding claims wherein the optical assembly comprises a lens.

52. The camera assembly of any one of the preceding claims wherein the optical assembly has a fixed focus.

53. The camera assembly of any one of claims 1 to 51 wherein the optical assembly has a variable focus.

54. The camera assembly of any one of the preceding claims wherein the optical assembly has a means for registration of image size.

55. The camera assembly of any one of the preceding claims wherein the optical assembly is removably mounted to the camera case.

56. The camera assembly of any one of the preceding claims wherein the optical assembly has a first end mounted to the case, an elongate body, and a window at the second distal end of the optical assembly.

57. The camera assembly of claim 56 wherein the window is flat and made from an optically transparent material.

58. The camera assembly of claim 57 wherein the window is made from a glass or plastics material.

59. The camera assembly of claim 57 or 58 wherein the window during use is coated with an index matching liquid.

60. The camera assembly of claim 59 wherein the camera assembly comprises a reservoir of index matching liquid.

61. The camera assembly of claim 60 wherein the reservoir is adapted to direct the liquid onto the outside surface of the window on manipulation by a user of the camera assembly.

62. The camera assembly of any one of claims 56 to 61 wherein a calibration target is mounted outside the window prior to the taking of a calibration image.

63. The camera assembly of claim 62 wherein the calibration target comprises a reference-white or grey material.

64. The camera assembly of claim 63 wherein the calibration target is a glazed ceramic tile.

65. The camera assembly of claim 63 wherein the calibration target is a card with a very flat surface.

66. The camera assembly of any one of claims 56 to 61 wherein one or more calibration targets are mounted within the camera assembly.

67. The camera assembly of claim 66 wherein the one or more calibration targets are mounted within the optical assembly.

68. The camera assembly of any one of claims 62 to 67 wherein the calibration target takes the form of a thin film attached to the window.

69. The camera assembly of claim 68 wherein the thin film is attached to the window prior to delivery of the camera to the user.

70. The camera assembly of claim 68 or claim 69 wherein the thin film is formed from a reference-white or grey material.

71. The camera assembly of claim 68 or claim 69 wherein the thin film is formed from a clear material that has been coated with a layer of reference- white or grey paint.

72. The camera assembly of any one of claims 68 to 71 wherein the thin film is attached to the window with a layer of adhesive serving to retain the film in place and acting as an air-excluding mechanism.

73. The camera assembly of any one of claims 56 to 72 wherein the elongate body of the optical unit comprises a mounting means at its second distal end.

74. The camera assembly of claim 73 wherein the mounting means is removably mounted to the body.

75. The camera assembly of claim 73 or claim 74 wherein the mounting holds the window.

76. The camera assembly of claim 62 wherein the calibration target is formed of a reference material of known stable colour.

77. The camera assembly of any one of claims 56 to 76 comprising more than one calibration target to provide suitable colour and grey scale calibration of the camera assembly.

78. The camera assembly of claim 77 wherein each of the said calibration targets are allocated a calibration target batch number.

79. The camera assembly of any one of claims 56 to 78 wherein a peripheral band of the window is coated with opaque paint.

80. The camera assembly of any one of claims 56 to 79 wherein a peripheral band of the window is coated with coloured material.

81. The camera assembly of claim 79 or claim 80 wherein the band is visible in the viewing area when an image is taken by the camera assembly.

82. The camera assembly of any one of claims 79 to 81 wherein the band is adapted to be used during image analysis to check stability of lighting and colour calibration.

83. The camera assembly of any one of claims 79 to 82 wherein the band is adapted to be used in compensating for the effects of total internal reflection.

84. The camera assembly of any one of claims 79 to 83 wherein the band is formed from a plurality of colours.

85. The camera assembly of any one of the preceding claims wherein the camera assembly comprises a means to indelibly record a patient's unique identifiers.

86. The camera assembly of any one of the preceding claims wherein the camera assembly comprises a means for affixing a coded patient identification label to the camera assembly.

87. A method of recording images of a viewing area, the method comprising the steps of: recording at least one image of the viewing area on a first image recording means; and recording at least one calibration image on a second image recording means.

88. The method of claim 87 wherein the viewing area comprises an area of a patient's skin.

89. The method of claim 88 wherein the at least one image of the viewing area comprises an image of a skin lesion.

90. The method of any one of claims 87 to 89 wherein the step of recording at least one image of the viewing area is carried out by a medical practitioner or other health care professional.

91. The method of any one of claims 87 to 90 wherein the step of recording the calibration image is performed remotely from a site at which the step of recording the at least one image of the viewing area is performed.

92. The method of claim 91 wherein the step of recording the calibration image is performed at an image processing facility.

93. The method of any one of claims 87 to 92 wherein the step of recording the at least one calibration image is performed after the step of recording the at least one image of the viewing area.

94. The method of any one of claims 87 to 93 further comprising the step of retrieving images recorded in the first and second storage means.

95. The method of claim 94 wherein the step of recording at least one calibration image is performed immediately prior to the step of retrieving.

96. The method of claim 93 or claim 95 further comprising the step of activating the second storage means, wherein recordal of the at least one calibration image cannot occur until after the step of activating.

97. The method of claim 96 wherein the step of activating is prevented from occurring until the step of recording the at least one image of the viewing area has occurred.

98. The method of any one of claims 87 to 92 wherein the step of recording the at least one calibration image is performed prior to or substantially contemporaneously with the step of recording the at least one image of the viewing area.

99. The method of any one of claims 87 to 98 further comprising the step of disposing of the first and second storage means after retrieval of images stored therein.

100. The method of any one of claims 87 to 99 wherein the step of retrieving images recorded in the first and second storage means renders the first and second storage means inoperative.

101. The method of any one of claims 87 to 100, further comprising the step of illuminating the viewing area to facilitate the recordal of the at least one image of the viewing area.

102. The method of claim 101 wherein the step of illuminating comprises providing illumination in the near infrared and/or visible spectrum.

103. The method of claim 101 or claim 102 wherein the step of illuminating comprises providing a relatively even and stable illumination of the viewing area.

104. The method of any one of claims 101 to 103 wherein the step of illuminating comprises illuminating the viewing area with polarised light.

105. The method of any one of claims 87 to 104 wherein the first and second storage means record images on conventional film.

106. The method of claim 105 further comprising the step of converting the images recorded in the first and second storage means into digital images.

107. The method of any one of claims 87 to 104 wherein the first and second storage means record images in digital form.

108. The method of claim 106 or claim 107 further comprising the step of matching the calibrating image with reference targets stored in a computer memory.

109. The method of claim 108 further comprising the step of compensating the at least one recorded image of the viewing area based on said step of matching.

110. The method of claim 109 wherein, subsequent to said step of compensating, the at least one image of the viewing area is provided to one or more qualified dermatologists for analysis.

111. The method of claim 109 wherein, subsequent to said step of compensating, the at least one image of the viewing area is provided to a software system for analysis.

112. The camera assembly of claim 37 wherein at least one holographic diffuser is positioned so as to evenly scatter light from the illumination system towards the viewing area without absorbing the light.

113. The method of claim 103 wherein the step of illuminating comprises positioning at least one holographic diffuser in a path of the illumination.