Monte Carlo modeling of a 60Co MRI-guided radiotherapy system on Geant4 and experimental verification of dose calculation under a magnetic field of 0.35 T.
Monte Carlo modeling of a 60Co MRI-guided radiotherapy system on Geant4 and experimental verification of dose calculation under a magnetic field of 0.35 T.
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DOI：
10.1093/jrr/rry087
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发表时间：
2019-01-01
影响因子：
2
通讯作者：
Itami J
中科院分区：
文献类型：
--
作者：
Okamoto H;Nishioka S;Iijima K;Nakamura S;Sakasai T;Miura Y;Takemori M;Nakayama H;Morishita Y;Shimizu M;Abe Y;Igaki H;Nakayama Y;Itami J
我们的目的是建立磁共振成像引导放射治疗系统（MRIDian，Viewray Inc.）的Monte Carlo建模调试程序。在0.345T的磁场下，通过实验测量。为此，我们试图（i）使用EBT 3胶片或BJR-25数据评估Geant 4产生的深度剂量和横向分布;（ii）评估0.345 T磁场下的计算精度。用Geant 4方法和理论方法计算了真空中电子返回效应（ERE）引起的电子轨迹半径。计算体模表面剂量，并与胶片测量结果进行比较。用EBT 3胶片计算和测量了具有两个空气间隙的体模中的剂量分布。(i)对于4.5和27.3 cm 2的射野尺寸，Geant 4生成的深度-剂量分布与BJR-25数据的差异分别为0.0 ± 0.8%和0.3 ± 1.5%。Geant 4产生的横向剂量分布与EBT 3胶片数据产生的横向剂量分布一致。(ii)Geant 4产生的电子轨迹半径与理论值吻合得很好。由于消除了由磁场引起的电子污染，在0.345 T的磁场下观察到表面剂量的最大约50%的减少，如通过膜测量和Geant 4所确定的。在Geant 4和薄膜测量中观察到由ERE引起的气隙中剂量分布的变化。伽马分析（3%/3 mm）显示合格率为95.1%。建立了Geant 4上MRI引导放射治疗系统的调试程序，我们得出结论，Geant 4在0.345 T的磁场下提供了较高的计算精度。
Our purpose was to establish the commissioning procedure of Monte Carlo modeling on a magnetic resonance imaging–guided radiotherapy system (MRIdian, Viewray Inc.) under a magnetic field of 0.345 T through experimental measurements. To do this, we sought (i) to assess the depth–dose and lateral profiles generated by the Geant4 using either EBT3 film or the BJR-25 data; (ii) to assess the calculation accuracy under a magnetic field of 0.345 T. The radius of the electron trajectory caused by the electron return effect (ERE) in a vacuum was obtained both by the Geant4 and the theoretical methods. The surface dose on the phantom was calculated and compared with that obtained from the film measurements. The dose distribution in a phantom having two air gaps was calculated and measured with EBT 3 film. (i) The difference of depth–dose profile generated by the Geant4 from the BJR-25 data was 0.0 ± 0.8% and 0.3 ± 1.5% for field sizes of 4.5 and 27.3 cm2, respectively. Lateral dose profiles generated by Geant4 agreed well with those generated from the EBT3 film data. (ii) The radius of the electron trajectory generated by Geant4 agreed well with the theoretical values. A maximum of ~50% reduction of the surface dose under a magnetic field of 0.345 T was observed due to elimination of the electron contamination caused by the magnetic field, as determined by both the film measurements and the Geant4. Changes in the dose distributions in the air gaps caused by the ERE were observed on the Geant4 and in the film measurements. Gamma analysis (3%/3 mm) showed a pass rate of 95.1%. Commissioning procedures for the MRI-guided radiotherapy system on the Geant4 were established, and we concluded that the Geant4 had provided high calculation accuracy under a magnetic field of 0.345 T.
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影响因子：
3.5
作者：
Raaijmakers, A. J. E.;Raaymakers, B. W.;Lagendijk, J. J. W.
通讯作者：
Lagendijk, J. J. W.
影响因子：
3.8
作者：
Malkov, Victor N.;Rogers, D. W. O.
通讯作者：
Rogers, D. W. O.
影响因子：
3.5
作者：
Raaijmakers, A. J. E.;Raaymakers, B. W.;Lagendijk, J. J. W.
通讯作者：
Lagendijk, J. J. W.
影响因子：
3.8
作者：
Chen, Xinfeng;Prior, Phil;Li, X. Allen
通讯作者：
Li, X. Allen
影响因子：
3.5
作者：
Mutic, Sasa;Dempsey, James F.
通讯作者：
Dempsey, James F.