 Meso-tetrahydroxyphenylchlorin mTHPC, Foscan is a photosensitizer for PDT in cholangiocarcinoma. In compared with other agents such as Photofin and Photosan, PDT treatment using temoporfin at a low dose 3 mg per treatment is associated with a deeper tissue penetration 4-6mm and a reduced period of photosensitivity. 