Characterization of a Novel Gamma-Ray Detection System for Tomographic, In-Situ Proton Therapy Quality Assurance

In the field of hadron therapy, quality assurance is vital to ensure the accurate delivery of radiation to the target while minimizing the dose to healthy tissue. In this work, we present the characterization of a novel gamma-ray detection system developed by Terapet SA for in-situ quality assurance in proton therapy. The detector is intended for use with either phantoms or anatomical targets, and operates by reconstruction of the PET activity induced in the target by proton irradiation. The detector is composed of scintillator-based detection modules, each with an area of 60 mm by 60 mm, a spatial resolution for 511 keV gamma ray interactions of approximately 1 mm and depth of interaction resolution of 1.2 mm. The field of view is extended by rotation and displacement of the detector about the target. The proposed use cases for the device are to detect changes in beam delivery or target positioning, and to assess the accuracy of target modelling by the treatment planning system. The results presented assess the performance of the device and its ability to fulfill the stated quality assurance use cases.