A Study on Workload of a Medical Linear Accelerator at a High Throughput Cancer Treatment Centre in Sri Lanka

Radiotherapy bunker design depends on several factors, and among them, workload is one of the important factors. Workload is calculated from the radiation dose delivered at the isocenter. Due to the introduction of new radiotherapy treatment modalities and an increasing number of new cancer patients, there is a higher possibility to increase the workload. Therefore, this study aims to assess the workload of Varian linear accelerator vault at Apeksha Hospital, Maharagama. Data were collected from 1st of August 2020 to 30th November 2020. Dose delivered at isocenter from the 3D-CRT procedures with 6 MV and 15 MV photon energy, the IMRT procedures with 6 MV photon energy and the quality assurance (QA) procedures were collected from ARIA patient management system and transferred into Excel spread sheet for data analysis. The calculated weekly workload was 2326 Gy/week with a 43% contribution from the IMRT procedures with 6 MV, 39% contribution from the 3D-CDT procedures with 6 MV, 16% contribution from the 3D-CDT procedures with 15 MV and 2% contribution from physics workload (QA procedures). The evaluated workload is higher than the NCRP recommended workload of 1000 Gy/week. This study recommends for at least a one-year survey for more accuracy on workload assessment, and also to evaluate the use factor since most of the advanced radiotherapy treatment techniques use high number of monitor units which will increase the leakage radiation.