Impact of statistical uncertainty per control point on dose calculation on VMAT for rectum cancer
10.3969/j.issn.1006-5725.2024.19.004
- VernacularTitle:控制点统计不确定度对直肠癌容积旋转调强放疗剂量计算的影响
- Author:
Weiqiang YE
1
;
Wei ZHANG
;
Bo LI
;
Chaojun YU
;
Zhenzhen WEI
;
Shida SU
;
Wen QIN
;
Dawei ZHANG
Author Information
1. 广西医科大学第一附属医院放疗科(广西南宁 530021)
- Keywords:
statistical uncertainty;
dose calculation;
VMAT;
rectum cancer
- From:
The Journal of Practical Medicine
2024;40(19):2685-2689
- CountryChina
- Language:Chinese
-
Abstract:
Objective To investigate the impact of statistical uncertainty per control point(SUpCP)on dose calculation on volumetric modulated arc therapy(VMAT)for rectum cancer,and to analyze the accuracy and efficiency of calculation.Methods 19 patients with rectum cancer undergoing radiotherapy were selected.The initial VMAT plans were generated on Monaco TPS using SUpCP=3,then changed SUpCP in the dose calculation process as follow:10 SUpCPs(1～10)for each patient,and totally190 VMAT dose distributions were obtained.For plan evaluation,Dmax,Dmean,D95%,V50,homogeneity index(HI),conformity index(CI)of the planning target volume(PTV),dissymmetric variations of bladder,small intestine and femoral head,and time calculation(Time)were analyzed.Patient specific quality assurance(PSQA),dose deviation of isocenter(ΔDISO)and passing rate of three-dimensional dose distribution(γ33,γ32,γ22)between calculated and delivered radiation doses were measured.Results AsSUpC increased,Dmax and HI of PTV,Dmax of bladder were increased,but D95%and V50 of PTV,Time,γ32 and γ22 were decreased(P<0.05).Dmax and CI of PTV,Dmean of bladder,Dmax and Dmean of small intestine and femoral head,ΔDISO and γ33 showed no statistical significance(P>0.05).When ΔDISO<1%,gamma passing rate>90%for all VMAT plan.When SUpCP<6,Dmax of PTV<110%of the prescribed dose was obtained;while SUpCP>2,time for dose calculation was less than 5 min.Conclusion For VMAT plan of rectum cancer on Monaco TPS using XVMC algorithm,3%～5%of statistical uncertainty per control point for dose calculation,and 3%2 mm or 2%2 mm gamma criteria for three-dimensional dose verification is recommended.This study provides clinical application basis for precise dose calculation of VMAT plan of rectum cancer.
