STEREOTACTIC BODY RADIATION THERAPY – DOSIMETRY AND MECHANICAL PREPARATION OF LINEAR ACCELERATOR

The aim of this study is to emphasize the importance of proper dosimetric and mechanical preparation of the linear accelerator and to highlight the significance of this step in ensuring the efficacy and safety of stereotactic body radiation therapy (SBRT). Performance verification of two Varian VitalBeam linear accelerators was executed in order to monitor the output consistency, MLC repeatability and radiation isocenter location and size. Dose output consistency measurements were conducted using phantoms and dosimetric equipment from PTW. The analysis of MLC positioning tests, isocenter size and location were performed by in-house scripts based on pylinac tools. These tests were conducted on a weekly basis. Evaluation of the results of tests performed over a 90-week period showed a positive trend in output consistency. However, no discernible trend or pattern was observed in the other tests. In conclusion, the authors suggest that performing dosimetric and mechanical checks on the linear accelerator before conducting SBRT treatment is an effective way to maintain a safe treatment environment.