Retrospective analysis and evaluation of patient-specific intensity-moduled radiotherapy plan verification data in the radiation oncology department

Objective: This thesis aimed to statistically analyze and classify the data obtained from the quality-control forms of patients treated with various Intensity-Modulated Radiotherapy techniques, such as Intensity-Modulated Radiotherapy(IMRT) and Volumetric Modulated Arc Therapy(VMAT), with a focus on dose and dose distributions at Akdeniz University Department of Radiation Oncology between 2017 and 2023. Method: Quality-control forms of patients whose treatment plans were made with IMRT and VMAT techniques during the specified years were examined. It was defined that the dosimetric calculations and treatment applications were performed by two different treatment planning systems(TPS) and linear accelerator(LINAC) devices. Dose-dose distributions were measured using the MatriXX device for quality-control, and the Gamma index evaluation was performed according to the clinic's accepted criteria. Data were classified and statistically analyzed based on various factors such as disease types, treatment devices, TPSs, etc. using "Google Sheets" and "Google Looker Studio" software. Visuals were created using summary analysis data. Results: A total of 1574 treatment plans for 1078 patients were examined in terms of Gamma index quality-control data during the study period. Due to the update of the treatment device in 2021, plans like IMRT and VMAT were not performed, no Gamma index data were available. The distribution of plans by region was 496-head-neck, 492-pelvis, 542-thoracic, 31-abdomen, 10-vertebra, and 2-femur. The most applied techniques were as follows: 9-field IMRT(31.9%), dual-arc VMAT(23.3%), and single-arc VMAT(19.4%). Conclusion: In patient-specific quality-controls, plans were created using PRECISE-TPS for Static-IMRT technique and MONACO-TPS for Dynamic-IMRT/VMAT technique. The average and standard-deviation of the Gamma index data(%3/3 mm criterion) were found to be 97.29%+1.60(356 plans) and 99.13%+1.10(1012 plans), respectively. No significant differences were observed between the TPSs. The frequent use of the VMAT-technique in subsequent years, along with high Gamma index data, indicated that plans could be applied with high accuracy, worked harmoniously with treatment device, and thus enhanced treatment reliability. Keywords: Radiotherapy, IMRT (Intensity Modulated Radiotherapy), VMAT (Volumetric Modulated Arc Therapy), Quality-control (QC), Gamma Analysis method