First experimental verification of prompt gamma imaging with carbon ion irradiation

Abstract

Prompt Gamma Imaging (PGI) is a promising technique for range verification in Particle Therapy. This technique was already tested in clinical environment with a knife-edge-collimator camera for proton treatments but remains relatively unexplored for Carbon Ion Radiation Therapy (CIRT). Previous FLUKA simulations suggested that PG profile shifts could be detected in CIRT with a precision of 4 mm ( ) for a particle statistic equal to C-ions using a 10 × 10 cm 2 camera. An experimental campaign was carried out at CNAO (Pavia, Italy) to verify these results, using a knife-edge-collimator camera prototype based on a 5 × 5 cm 2 pixelated LYSO crystal. PG profiles were measured irradiating a plastic phantom with a C-ion pencil beam at clinical energies and intensities, also moving the detector to extend the FOV to 13 × 5 cm 2 . The prototype detected Bragg-peak shifts with 4 mm precision for a statistic of C-ions ( for the extended FOV), slightly larger than expected. Nevertheless, the detector demonstrated significant potential for verifying the precision in dose delivery following a treatment fraction, which remains fundamental in the clinical environment. For the first time to our knowledge, range verification based on PGI was applied to a C-ion beam at clinical energy and intensities.