1. Image-guided photodynamic therapy device for treatment of oral cancer in global health settings System is designed around the chemical properties of PP-IX PP-IX fluoresces when exposed to 409nm PP-IX decomposes to a cytotoxic molecule(s) when exposed to 635nm Patient is given aminolevulinic acid (ALA) which causes PP-IX to build up in tumorous lesions -> photosensitization UV light is applied to mouth, tumors identified/measured via imaging (smartphone assisted), red light applied directly to tumorous lesion for 30-60 min, UV light reapplied to check level of PP-IX activation.

2. Motivation and design criteria for use in resource-limited setting High incidence and mortality of oral cancer in developing countries High prevalence of risk factors, limited access to screening/treatment Low cost of construction Battery powered Light weight Simple to operate interfaces with smartphone app for imaging/screening, calculating dose parameters, switching optical power settings, dose timing

3. Current design Constant current circuit (LM317) driving a high intensity LED or passively cooled laser diode Laser is optically coupled to a fiber bundle which delivers light to treatment region Teensy MCU switches laser power settings, monitor battery, interface with smartphone via BT – optical power settings switchable from android app. Powered with 7.4V LiPo

4. To-do Design and test driver circuit for higher power laser diode with active cooling. Design intra-oral camera with UV LED flash, interface with smartphone via USB video class (UVC). Develop Image processing app to identify tumors and measure their size Implement local and remote database for record keeping and usage tracking