The use of radiation therapy to treat cancer has improved the long-term outcome of thousands of patients but is associated with serious side effects. Photodynamic therapy (PDT), a targeted light-based technique, has been approved as an effective treatment for some forms of cancer with fewer side effects than radiotherapy. However, the effectiveness of this technique depends on fine-tuning its application to the patient. Simphotek, a US-based company founded by world leaders in biophysics and computer modelling, together with its collaborative partners at Roswell Park Comprehensive Cancer Center and the Hospital of the University of Pennsylvania, is focused on expanding novel technologies of PDT as a cancer treatment for solid tumours.