Author: Liang-Hsin Chen, Li-Chien Wei 👨🔬
Affiliation: National Taiwan University Cancer Center 🌍
Purpose: For proton therapy treatment, it is essential to ensure that the treatments are delivered safely and accurately. Quality assurance (QA) programs of proton treatment system is needed and proton daily QA is an important part of these QA programs. Therefore, the study aims to perform and analyze daily quality assurance of proton treatment system by in-house software with customized phantom more efficiently and monitor the stability of its performance.
Methods: We used Winston Lutz cube phantom (IMT) and MatriXX PT with customized phantom to execute daily QA items. Through executing daily QA items, we confirmed coincidence between kV/CBCT image isocenter and laser isocenter, beam output dose, beam range (162 MeV only), spot size and spot position. After acquiring these data, we used in-house software to analyze and check each daily QA item. Besides, we also verified the stability of proton machine performance by monitoring the daily QA results within 30 days.
Results: We used in-house software to analyze and confirm daily QA results. The coincidence between kV/CBCT image isocenter and laser isocenter are all within 1.5 mm. The average proton beam output dose and range difference are -0.11% and -0.04 mm, respectively. When we compared to baseline of spot size for 80, 100, 130, 160, 180, 210, and 230 MeV, the spot size varied within -5.5 and 11% in x and y directions. The accuracy of spot positions is almost within 1mm for 80, 100, 130, 160, 180, 210, and 230 MeV in x and y directions.
Conclusion: We analyze and check daily QA results through our in-house software more efficiently. Besides, we also check and verify the stability of proton treatment system performance.