Experimental Verification of Prompt Gamma Imaging Technique during Carbon Ion Radiation Therapy

Prompt Gamma Imaging (PGI) is a technique here considered to verify the range of the particle beams in real-time during Carbon Ion Radiation Therapy (CIRT). In this framework, PGI measurements are strongly affected by the limited number of emitted prompt gammas (PGs) and by the presence of a neutron background. A recent study performed using Monte Carlo simulations demonstrated that, despite these limitations, a prompt-gamma camera based on a knife-edge collimator and a pixelated detector could achieve the required sensitivity to measure a shift of the C-ions range of an energy layer during a clinical treatment. Therefore, a prompt-gamma camera based on this concept was developed in order to experimentally validate the simulation results. The camera is based on a compact scintillation detector composed by a 2"x2" pixelated LYSO crystal (6 mm crystal pitch) coupled 1:1 with an array of SiPMs and by its complete readout electronics, which uses a custom-developed readout ASIC and an FPGA-based DAQ. The spectroscopic and positioning performance of the detector have been characterized, achieving the performance required by the application. An experimental campaign will be carried out in May 2023 at CNAO to demonstrate the system capability to verify the beam range during C-ion treatments. The results of this experimental measurements will be presented at the conference.