Radiation protection in proton therapy: Insights from a multi-institutional survey and experimental measurements within the SINFONIA project

Purpose: This study, part of the EU-funded SINFONIA project, addresses radiation protection concerns in daily PT practice to study potentially under- or overprotection of staff depending on their working environment and tasks. Methods: A multi-institutional survey was carried out, complemented by specific neutron dose measurements at a PT centre. Besides mono-energetic irradiations, clinical treatments for brain, thorax (Hodgkin's lymphoma — HL) and pelvis (prostate), were investigated with and without range shifter (RS). The Thermo Fisher Scientific WENDI II and Berthold LB6411 ambient neutron monitors and two DIAMON neutron spectrometers were used for H*(10). Furthermore, BTI BD-PND bubble detectors, LANDAUER Neutrak dosimeters and Intercast CR-39 + plastic converters were also tested for Hp(10). Results: Initial survey results suggest no considerable risk for staff, with doses registering below 1 mSv/year. Further, site-specific measurements conducted at the Skandion facility, unveil annual staff doses ranging from 5–10 μSv in the staff control room. Accidental exposure scenarios on the other hand could reach up to 0.26 μSv/Gy in the gantry pit. Notably, H*(10) detectors demonstrated good performance, while H_p(10) dosimeters solely captured doses within the treatment room, yet remaining in agreement with reference values. Conclusion: Findings suggest a minimal neutron exposure risk for staff members within contemporary PT facilities.