Preliminary application of volumetric-modulated arc therapy dosimetry verification system based on three-dimensional dose reconstruction of patient anatomical structures
10.3760/cma.j.cn113030-20200703-00341
- VernacularTitle:基于患者解剖结构三维剂量重建进行容积调强弧形治疗剂量验证初探
- Author:
Yangguang MA
1
;
Rizhen MAI
;
Yuntong PEI
;
Yuexin GUO
Author Information
1. 郑州大学第一附属医院放射治疗部，郑州 450052
- Keywords:
Three-dimensional dose reconstruction;
Three-dimensional γ analysis;
Dosimetry verification
- From:
Chinese Journal of Radiation Oncology
2022;31(2):170-175
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To perform testing and clinical application of a volumetric-modulated arc therapy (VMAT) dosimetry verification system based on three-dimensional dose reconstruction of patient anatomical structures.Methods:ArcCheck array calibration was performed. Then, 200 MU was delivered with a 10 cm×10 cm field when the source to center of ArcCheck was 100 cm to calibrate the absolute dose and the dose was simultaneously measured by a FC65-G detector in the center of the ArcCheck. The absolute dose calibration value or the CT value of ArcCheck was adjusted to minimize the differences between the planning and measurement values of FC65-G, reconstructed value by 3DVH and reconstructed percent depth dose by 3DVH. 10 lung and 10 cervical cancer VMAT cases were selected and measured by ArcCheck and FC65-G under the delivery of a TrueBeam LINAC. The three-dimensional doses of all cases were reconstructed by 3DVH and compared with the planning and measurement values.Results:Different array calibration files of ArcCheck exerted different effect upon the two-dimensional dose measured by ArcCheck and three-dimensional dose reconstructed by 3DVH. The optimal reconstructed dose was obtained when self-calibration file was adopted and 249.96 cGy was regarded as the absolute dose calibration value. The deviations of the mean dose (D mean) and D 95% of the target were within ±4.2% and parameters of some organs at risk significantly differed compared with the reconstructed and planning dose for all cases. A negative mean point dose difference was obtained and the reconstructed dose was closer to the measured value. The γ-passing rate of the target for some cases was low, the proportion of regions irradiated by 50% prescription dose was slightly higher and the proportion of other organs was relatively high. Conclusion:The 3DVH model can be accurately established and tested with the acceptance test method in the present study, which can provide detailed information for dose verification.
