Analysis of Setup Errors in ArcCHECK for dose Verification of SBRT Plans of HT

To explore the impact of introducing setup errors in the phantom positioning on the verification pass rate of body stereotactic helical tomography (HT) radiotherapy plans when using the ArcCHECK system. A total of 25 body stereotactic HT plans from a department, collected between August 2023 and December 2024, were validated using the ArcCHECK system. The plans were analyzed using two methods: the Distance-to-Agreement (DTA) analysis and Gamma analysis, with pass rate criteria set at 3%/3 mm and 2%/2 mm, respectively. The dose distribution maps were recorded under two conditions: with the center location unchanged and after simulating setup errors using software. The pass rates were averaged and compared. Under the 3%/3 mm standard, both RD and AD pass rates for both methods were above 95%. Under the 2%/2 mm standard, both RD and AD pass rates were above 90%, For setup errors under the 3%/3 mm standard: rotation errors within 0.5°, X-axis translation errors within 3 mm, and Y-axis translation errors within -1, 1, and 2 mm maintained RD and AD pass rates above 90%. After introducing ArcCHECK setup errors in three directions, the dose verification pass rate of SBRT to a certain extent, and the higher the error, the lower the pass rate. The positioning errors in the rotational direction and Y-direction of ArcCHECK have a significant impact on the dose verification pass rate of HT plans for the body. Attention should be paid to errors in the rotational direction and Y-direction during both radiotherapy positioning and verification phantom positioning.