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Biomedical applications for reflected ultraviolet photography
Slight changes in pigment of the skin, especially those associated with melanin, show more clearly under ultraviolet than with conventional methods. Unpigmented skin reflects ultraviolet strongly, whereas melanin absorbs it very heavily.
The extent of hypo- and hyper-pigmentary conditions is clearly delineated. Applications include vitiligo, pigmented naevi, halo naevi, malignant and benign melanomas, melasma/chloasma, albinism, scleroderma, keratin plugs, moles and freckles. Pigmentary disturbances that will only become evident to the patient in mid-summer when they become tanned, can be "mapped" in mid-winter with this technique.
A recently reported application is the use of reflected ultraviolet to map the changes in the melanin distribution as a result of exposure to sunlight - interpreted by some cosmetic dermatologists as "sun damage." This mapping is then followed by laser treatment or some other intervention: a practice described by Dr Paul Weber on the Cancer Information Web Site as "a scam in the first degree by the dermatologist...a medical, ethical and moral violation." Certainly the reflected ultraviolet technique can be expected to show dramatically any change in pigment distribution.
The method is also very useful for enhancing surface detail of skin. There is virtually no penetration of ultraviolet into the tissues, therefore there is no scattering and sharper pictures result. Disturbances in the skin surface texture as in ichthyosis or poikiloderma, are shown very clearly.
Old traumatic lesions-scars, bruises, bite marks, etc.- may sometimes be revealed by the reflected ultraviolet method months after they have faded visibly, and this has obvious forensic applications. This may be due to some disturbance of the pigment producing cells in the basal cell membrane, or to pigmentation following inflammatory reaction. (For further details see the section on the optical characteristics of the human skin).
Reflected ultraviolet photography maps the surface blood vessels of the sclera and conjunctiva with exceptional clarity.
The technique is reported as being of significant use in the early detection of malignant melanoma of the skin, which has become a major problem worldwide.
Clarity and detail can be restored in old pathological specimens by using the reflected ultraviolet technique. It is also useful in the differentiation between bone and cartilage and has been reported as being useful for examining the surface features of tooth: enamel- cracks and caries.
The gallery of images - Figures 63-80 - demonstrate very clearly the usefulness of the reflected ultraviolet photographic technique.
Some of the more useful biomedical applications along with key references are tabulated on the following pages:
|© 2002 Prof. Robin Williams and Gigi Williams - Disclaimer
Last modified: 3 May 2002