Analysis of the CT-linear accelerator output stability

Abstract

Purpose

The URT-Linac 506C integrates a diagnostic helical CT scanner into a linear accelerator, enabling the use of CT scanning data for radiation therapy planning. This innovative design facilitates online adaptive radiotherapy. This study aims to report the findings of a two-year quality control program assessing the physical stability and reliability of this advanced radiation treatment unit.

Methods

Absolute dose, flatness, and symmetry of 6 MV photon beams were analyzed using SPSS 23.0 from October 2022 to June 2024 to evaluate the stability of the dose output of the linear accelerator. The relative dose values are measured weekly for the same nasopharyngeal carcinoma patient, and the pass rates for criteria of 3% and 3 mm are evaluated.

Results

The absorbed dose was within 102%. The flatness of the 10 cm × 10 cm field was within 105%, the symmetry was within 102%, the flatness of the 20 cm × 20 cm field was within 103%, and the symmetry was within 102%. The long-term patient dose verification results ranging between 99.6% and 100%.

Conclusion

The URT-Linac 506C linear accelerator demonstrates high-dose stability. Routine quality assurance ensures the accuracy and reliability of the equipment, which is crucial for precise treatment delivery.