Evaluation of Shielding Design for A Linear Accelerator (Linac) Facility

Abstract

The main goal of this work is to assess the adequacy of the structural shielding design for the linear accelerator at the Mauritania Oncology Center to protect occupationally exposed workers, and general public due to the anticipated increased workload. A retrospective evaluation was done to verify whether those occupationally exposed and the public are adequately protected from the harmful effect of radiation exposure during the treatment procedures at the facility. National Council on Radiation Protection and Measurements (NCRP) Report No. 151 methodology was used for the evaluation of structural shielding adequacy for a LINAC. The thickness of the primary barrier was calculated to be 168 cm and that of secondary barrier was 82 cm. the existing thickness were 305 cm and 165 cm respectively for the primary barrier and secondary barrier respectively. The existing thickness (primary and secondary) provide adequate protection for the occupationally exposed workers and the public. The total dose equivalent at the door is 2.02 mSv week-1, of which ≈ 86 % is from neutrons, 6 % from low-energy scattered and transmitted leakage photons, and 8 % from neutron capture gamma rays. The dose rate measurement shows that the shielding provided by the entrance door is not adequate so an additional shielding is required for the door or the workload should be constrained to a value that will enable compliance with the designed goal.