Reflection modeling in ultraviolet phototherapy

Purpose: Ultraviolet phototherapy is a widely used treatment which has exceptional success with a variety of skin conditions. Over-exposure to ultraviolet radiation (UVR) can however be detrimental and cause side effects such as erythema, photokeratisis, and even skin cancer. Quantifying patient dose is therefore imperative to ensure biologically effective treatment while minimizing negative repercussions. A dosemodel for treatment would be valuable in achieving these ends. Methods: Prior work by the authors concentrated on modeling the output of the lamps used in treatment and it was found a line source model described the output from the sources to a high degree. In practice, these lamps are surrounded by reflective anodized aluminum in patient treatment cabins and this work extends the model to quantify specular reflections from these planes on patient dose. Results: The extension of the model to allow for reflected images in addition to tube output shows a remarkably good fit to the actual data measured. Conclusions: The reflection model yields impressive accuracy and is a good basis for full UVR cabin modeling.