| Objective To compare the effects of parameters,such as planning target volume (PTV),calculation grid size,and dose threshold,on the dosimetric verification result of three dosimetric verification systems ArcCHECK,SRS MapCHECK,and 3DMap for stereotactic body radiation therapy (SBRT).Methods Based on the dosimetric verification result of the SBRT plans of 50 patients,this study compared the effects of PTV (<25 cm3 and ≥ 25 cm3),calculation grid size (1.0,1.5,and 2.0 mm),and dose threshold (5%,10%,and 15%) on the γ passing rates of the three dosimetric verification systems at five criteria,i.e.,3 mm/3%,3 mm/2%,3 mm/1%,2 mm/3%,and 2 mm/2%.Results The changes in PTV affected 3DMap more significantly.With an increase in PTV,the γ passing rates of 3DMap at the criteria of 3 mm/3%,3 mm/2%,2 mm/3%,and 2 mm/2% increased by 2.2%,2.2%,4.4%,and 4.7%(t=-2.76,-2.17,-4.72,-3.86,P<0.05),respectively.The increase in the calculation grid from 1.0 mm to 1.5 mm had greater effect on MapCHECK,with the γ passing rates at the criteria of 3 mm/3%,3 mm/2%,3 mm/1%,2 mm/3% and 2 mm/2% decreased by 0.7%,1.1%,1.7%,0.9%,1.5%(t=-6.15,-6.23,-5.98,-5.11,-8.34,P<0.05),respectively.The increases in the calculation grid from 1.0 mm to 2.0 mm had greater impact on ArcCHECK,with the γ passing rates at the criteria of 3 mm/3%,3 mm/2%,3 mm/1%,2 mm/3%,2 mm/2% decreased by 1.0%,1.7%,2.4%,1.7%,2.7%(t=-4.75,-7.3,-8.63,-7.11,-8.26,P<0.05),respectively.The increase in the dose threshold from 5% to 10% had greater impact on ArcCHECK,with the γ passing rates at the criteria of 3 mm/3%,3 mm/2%,2 mm/3% and 2 mm/2% decreased by 1.1%,1.4%,2.5%,and 3.0%(t=5.20,5.68,8.17,9.99,P<0.05),respectively.Moreover,the increase in the dose threshold from 5% to 15% had more impact on 3DMap,with the γ passing rates at the criteria of 3 mm/3%,3 mm/2%,2 mm/3%,and 2 mm/2% decreased by 1.6%,1.7%,2.8%,and 3.2%(t=3.25,2.98,4.40,4.21,P<0.05),respectively.Conclusions Target volume,calculation grid,and dose threshold are influencing factors in the dosimetric verification of three dosimetric verification systems for SBRT.Therefore,the effects of these parameters should be considered for different verification systems in clinical applications. |
