The development of a treatment control system for a passive scattering proton therapy installation

Ocular melanoma has been treated using proton therapy at the Centre Antoine Lacassagne (CAL) since 1991, following the commissioning of the 65 MeV cyclotron MEDICYC and its associated beam-lines a few years earlier. The dedicated eye-line is optimized for shallow tumors and sharp penumbrae and provides state-of-the-art quality of care. The cyclotron, beam-lines and treatment systems, which are maintained exclusively by the staff at CAL, have proven to be exceptionally robust with up-times consistently above 95%. The systems are however aging and need to be replaced to ensure a continuation of ocular treatments with MEDICYC. This paper describes the development and performance of a new treatment control and dose measurement system for MEDICYC. Software and hardware architectural design choices are discussed in context of the requirements for dose delivery precision, robustness and patient safety. The performance of the treatment delivery, dose monitoring and beam quality assurance systems are presented.