The role of the radiotherapy technician during prostate radiation treatment

Abstract

Introduction: Increasing positioning security is one of the main challenges of radiotherapy. The main movements of the prostate during radiotherapy are as a result of poor positioning of the patient, as well as by bladder and rectum volumes. These movements can be detected using various visualization techniques such as CBCT and radiographic images before each treatment session. Purpose: The purpose of this work is to highlight the role of radiotherapy technician in the management of the patient’s movements during prostate treatment. Methods: 8 patients after customized positioning and immobilization performed the treatment with Varian TrueBeam HD linear accelerator. CBCT’s were performed on different days during the course of treatment as well as radiographic images on other days to verify the position. These positions were compared with the positions planned by the simulation scanner and the daily movements of the patient and the prostate were corrected, thus creating a new isocenter. In cases where and with the new isocenter the prostate and seminal vesicles are located outside the planned PTV, it is performed a new simulation CT scan and a new treatment plan. Results: From 8 patients with primary prostate cancer, 42 CBCT controls and 207 MV-KV controls were considered. Patients required an average movement of 0.27 cm in the vertical direction, 0.28 cm in the longitudinal direction, and a displacement of 0.17 cm in the lateral one. Regarding the rotation of the bed according to the X; Y; Z axes, we have an average Pitch of 1.32°, Roll of 0.5° and Rotation of 0.63°. Conclusions: 50% of these patients, needed a rescanning and replanning of treatment, and 12.5% more than one rescan. Key words: Prostate cancer, Radiotherapy technician, Movement, CBCT, Radiographic imaging.