Occupational radiation exposure of therapists in clinical use of spot scanning proton-carbon ion synchrotron systems

This study addresses the escalating radiation safety concerns among medical professionals due to the rising application of proton and carbon ion radiotherapy. It evaluates the occupational radiation exposure faced by therapists when utilizing the Siemens IONTRIS Proton-Carbon Ion System. Through random sampling of 80 patients treated between January and June 2024, we recorded particle types and counts and measured dose rates using a photon/neutron radiation dose meter. Notably, 1 min post-treatment, the dose rate peaked at 16.00 μSv/h near the tumor's skin surface, showing a significant correlation with particle count. The therapist's standing position and the surfaces of the range shifter and ripple filter registered average dose rates of 1.25 μSv/h and 3.63 μSv/h, 0.33 μSv/h, respectively. Other points averaged 0.08 μSv/h, with no neutron detection. The study concludes that the annual average occupational exposure for therapists, at ~300 μSv, is significantly below the International Commission on Radiological Protection's recommended dose equivalent limit, confirming the safety of the Siemens IONTRIS device in clinical settings.