Radiation protection for an intraoperative X-ray source compared to C-arm fluoroscopy

Background: Intraoperative radiotherapy (IORT) using the INTRABEAM (R) system promises a flexible use regarding radiation protection compared to other approaches such as electron treatment or HDR brachytherapy with Ir-192 or Co-60. In this study we compared dose rate measurements of breast- and Kypho-IORT with C-arm fluoroscopy which is needed to estimate radiation protection areas. Materials and Methods: C-arm fluoroscopy, breast- and Kypho-IORTs were performed using phantoms (silicon breast or bucket of water). Dose rates were measured at the phantom's surface, at 30 cm, 100 cm and 200 cm distance. Those measurements were confirmed during 10 Kypho-IORT and 10 breast-IORT patient treatments. Results: The measured dose rates were in the same magnitude for all three paradigms and ranges from 20 mu Sv/h during a simulated breast-IORT at two meter distance up to 64 mSv/h directly at the surface of a simulated Kypho-IORT. Those measurements result in a circle of controlled area (yearly doses >6 mSv) for each paradigm of about 4 m +/- 2 m. Discussion/Conclusions: All three paradigms show comparable dose rates which implies that the radiation protection is straight forward and confirms the flexible use of the INTRABEAM (R) system.