Application of Photometric Stereo in Dermatology (PhotoDerm)

PhotoDerm has been concerned with the deveopment of innovative imaging and modelling techniques for the capture, visualisation and analysis of skin features with unprecedented realism in 3D. A particular area of application has been in the detection and visualisation of skin cancers, such as melanoma. Malignant melanoma is a life-threatening disease, the early detection of which can have a critical impact on the patient’s prognosis. Consequently, there has been increasing interest in methodologies for establishing new indicators for melanoma. PhotoDerm uses a novel application of a technique known as photometric stereo to generate such indicators in the form of observable disruptions to the natural skin-line-patterns we all have. The device, known as the “Skin Analyser” (SA), is thought to be unique in being able to recover detailed 3D colour textures from pigmented lesions in vivo. Photometric stereo uses a sequence of controlled illuminations to recover accurate colour and extremely detailed 3D surface topography. This allows highly realistic virtual reality models to be generated, free from artefacts (such as highlights and shadows), with application in tele-dermatology, where a remote viewer may interact to alter the pose and lighting of the skin model, as though interacting with the real patient, and extract a range of skin feature measurements, useful in diagnosis. The SA has been successfully employed within the North Bristol NHS Trust Pigmented Lesion Clinic. The plan is to now explore its use in primary healthcare by means of a focused follow-on project. Aralia Systems Ltd, the lead company in PhotoDerm, also intends to develop a lower-cost version of the SA in collaboration with UWE, for the cosmetics market. As well as the working device, PhotoDerm has resulted in numerous technical papers that have been published in international journals.