Fast Neutron Dose Mapping in a Linac Radiotherapy Facility

CR-39 plastic detectors were used for fast neutron dose mapping in the radiotherapy facility at King AbdulAziz University Hospital (KAUH). Detectors were calibrated using a Cf neutron source and a neutron dosimeter. After exposure chemical etching was performed using 6N NaOH solution at 70 C. Tracks were counted using an optical microscope and the number of tracks/cm was converted to a neutron dose. 15 track detectors were distributed inside and outside the therapy room and were left for 32 days. The average neutron doses were 142.3 mSv on the accelerator head, 28.5 mSv on inside walls, 1.4 mSv beyond the beam shield, and 1 mSv in the control room.