Since 1991 Mr Hopper has been working at UCL Eastman. He has lead a variety of research projects on the use of photodynamic therapy in the treatment of oral squamous cell carcinoma. This program has been extended to work in Bolivia and recently India in a collaborative study with Harvard. He has been the principal investigator on a series of ethically approved projects. His work has resulted in a number of publications and helped establish a clear role for this treatment in a variety of neoplastic conditions in the head and neck. This work has advanced rapidly by the development of interstitial treatment of tumours using image guidance systems developed with the department of imaging and medical physics. PDT for treatment of cancer has been licensed since 2002. Other related areas of research are fluorescence diagnostics, optical coherence tomography (optical techniques for tissue interrogation) and the use of PDT as a primer for chemotherapy treatment.