Measurement of Neutron Leakage and Facility Survey of a Newly Commissioned Quadruple Photon Energy Medical Linear Accelerator Using a Neutron Survey Meter

This is the authors' abstract. We don't add key points for this paper.

Neutron head leakage and survey measurements at clinical Linear Accelerators (LINAC) for Radiotherapy are aimed at protecting patients, radiation workers, hospital staff, and even the general public.The purpose of this study was to measure neutrons produced via the (γ, n) reaction in the LINAC head for a 15 MV X-ray beam.A functional electron linear accelerator with energy 15 MV was used to measure the neutron leakage along the patient plane and other than the patient plane using a commercially available neutron survey meter (Model 30-7).LINAC collimator was kept in the fully closed position while irradiating radiation and the measurements were taken at various positions.For the facility survey, multiple locations were identified to analyze the neutron existence.Entire measurements were carried out in a dose rate mode and analyzed concerning the maximum allowed tolerance.The survey was carried out using a neutron survey meter.Head leakage along the patient plane at various positions i.e., 1m and 2m from the isocenter, similarly other than the patient plane i.e., 1m at the lateral sides of the LINAC head were analyzed.The maximum & average leakage along the patient plane were 0.005% & 0.0049% and leakage other than the patient plane was 0.0049% & 0.0048% respectively.Survey readings across the facility were below the radiation exposure rate limit set by the regulatory board i.e., less than 10µSv/hr.Institutions which are having LINAC with a photon energy of more than 10MV must carry out the neutron head leakage test and room survey periodically as per the regulatory board and ensure that no excess amount of leakage is evidenced in and around the facility.This study confirmed that there is no harmful neutron leakage at the site and also allows the institute to continue using a 15MV beam and get good clinical outcomes with deep-seated cancer tumors.