Tomo Plan Verification Based on ArcCHECK Phantom and the Effects of Setup Errors on Dose Verification

Yuan Meifang; Yang Yi; Sun Chaoxi

doi:10.3969/j.issn.1004-5775.2024.21.001

Abstract：Objective:To explore the verification of ArcCHECK phantom in Helical Tomotherapy(Tomo)plan and to investigate the effects of setup errors on the pass rate of dose validation.Methods:A total of 45 Tomo plans from Jan.2021 to Feb.2023 in the hospital were randomly collected.The actual dose distribution cloud map measured by ArcCHECK phantom was compared with the optimized results of planning system for their coincidence degree,and quantitatively analyzing the passing rates by Gamma analysis.Sun patient software was used to simulate the setup errors in the rotation direction,X direction and Y direction,respectively.The passing rate of Gamma analysis,ANOVA and LSD analysis were used for these data.Results:When there were no setup errors,the passing rate for breast cancer was(92.83±6.36)%with the threshold at 10%,2%/2 mm by Gamma analysis.The passing rate for the rest of the different tumors was up to or higher than 95%with that three thresholds by Gamma analysis.After simulating setup errors,the passing rate decreased gradually with the increase of the errors.When the rotation error was≥1.0° and the translation errors in X and Y directions were≥3 mm,the passing rate decreased sharply to about 90%or below.The differences were statistically significant(P＜0.05).Conclusion:The results of DQA quality control for Tomo plan by ArcCheck phantom meet the requirements of accurate radiation dose when there are no setup errors.It has great impact on the Gamma passing rate of Tomo plan when the rotation error is≥1.0°,and X direction or Y direction error are≥3 mm.In clinical work,the setup errors in each direction should be reduced as much as possible.