No abstract

This paper reports the method and the results of a study on the impact of the detected light intensity on gamma-neutron discrimination. In particular, the minimum number of photons required to achieve a statistically significant separation was measured and shown to be stable against a variation of the Photon Detection Efficiency (PDE) of the system under study. The method, developed using an EJ-276 scintillator bar coupled to a Silicon Photomultiplier (SiPM), is of general interest. For this specific system, the minimum statistics was measured to be 317 ± 16 photons, corresponding to different values of the deposited energy, as the PDE was changed.

The ORIGIN project (Optical Fiber Dose Imaging for Adaptive Brachytherapy) targets the production and qualification of a real-time radiation dose imaging and source localization system for both Low Dose Rate and High Dose Rate brachytherapy treatments. This goal will be achieved through a 16-fibre sensor system. Each fibre tip has been engineered to house a small volume of scintillating material to allow for measurements of the delivered dose. The instrument is based on Silicon Photomultipliers detectors, with a solution fully qualified on a single fibre prototype and currently being scaled up through the use of the CITIROC1A ASIC by WEEROC, embedded in the FERS-DT5202 scalable platform designed by CAEN S.p.A. The key features for a system such as ORIGIN, which aims to perform dose measurements in a clinical environment, are fibre response uniformity, system stability, high sensitivity, and perfect reproducibility. The commissioning of the 16-channel dosimeter system in laboratory conditions, with an X-ray cabinet, demonstrated reproducibility of measurements with deviations below 1% after the equalization procedure of the 16 sensors. Finally, the system performance, evaluated in clinical conditions (High Dose Rate centre, Belfast Hospital), allowed for valuable insight into the possible systematics which are present in the current system while simultaneously corroborating the validity of the equalization procedure.