Radiation protection studies for a new mobile electron accelerator for intra operative radiation therapy (IORT)

A specially constructed highly-mobile electron accelerator for intraoperative radiation therapy (IORT) is under development in Poland. Using an accelerator in a regular operating room (OR) for direct irradiation of surgically exposed organs raises specific questions concerning radiation safety of the patient and medical personnel. Therefore, the aim of this investigation was to optimize the beam forming system and external shields in order to assure radiation safety. The Monte Carlo code BEAMnrc/EGSnrc was used to build and test a model of the accelerator treatment head and beam applicators. We used FLUKA code to study the dose distribution inside and outside the OR. It was determined that dose distribution in the patient plane meets existing radiation protection requirements. It was further found that safe operation of the accelerator in a conventional OR may require some additional light shielding, depending on details of the wall construction, patient workload and occupancy factors. We show that relatively light and mobile lead shielding panels may be successfully used for that purpose. (author)