Photodynamic therapy (PDT) is a well-established treatment method and has been shown effective for treating a variety of diseases. Translation to the clinical setting however, has largely been inhibited by the limited penetration depth of light in tissue using traditional lasers and LEDs as light sources. Cerenkov luminescence represents a potential solution to this problem and could deliver light noninvasively to deep tissues. Cerenkov luminescence is produced when a charged particle, such as a beta particle emitted from a decaying radionuclide, travels faster than the phase velocity of light in a given material. Thus far it has predominantly been implemented for small animal imaging but we are attempting to use it as a light source for PDT. This work is performed in collaboration with Simon Cherry of Biomedical Engineering and Henry Hirschberg from UC Irvine.