A large area CMOS Active Pixel Sensor for imaging in proton therapy

There is an increased interest in developing imaging systems in proton therapy, with the aim of reducing range uncertainty in treatment planning, assisting in patient positioning and verifying anatomical changes at the time of the treatment. Recently, the PRaVDA collaboration has developed two different solid-state detector technologies for imaging in proton therapy: Silicon Strip Detectors and CMOS Active Pixel Sensors (APSs). This paper reports on the design and optimisation process of the PRaVDA CMOS APSs. Optimisation of parameters, such as epitaxial thickness and resistivity, and performance for individual proton detection and proton radiography are reported.