Photon dose rate distribution inside and outside a brachytherapy room

Sabri, A. H. A.*; Tajudin, S. M.*; Aziz, M. Z. A.*; Furuta, Takuya   

The spatial distributions of photon dose rates in a brachytherapy room with an Iridium-192 were simulated by using the particle and heavy ion transport code system (PHITS). A geometry of the brachytherapy room with concrete walls and a sliding lead door was reproduced by tracing the existing room in Advanced Medical and Dental Institute at the Universiti Sains Malaysia in Penang. The simulation results were confirmed by comparing to the measured results using a thermoluminescent dosimeter. The simulation study suggested that an additional layer of 3-mm thick lead at the side wall of the entrance will efficiently reduce the dose outside the entrance due to the photons leaked from the edge of the entrance. Simulation with replacing the source with Cobalt-60 was also conducted and revealed the dose level outside the room was too high compared to regulatory value in the current room configuration.