为了研究非均匀荷载和切割斑块对眼斑块剂量分布的影响，我们使用EGSnrc蒙特卡洛（MC）模拟在水和解剖学上代表性的眼球模型中研究眼斑块剂量分布。我们按照TG43规范进行模拟，并与完全考虑种子间和不均匀性效应的MC模拟进行比较。对于标准斑块配置，水中均匀和非均匀荷载的斑块剂量分布几乎没有区别。对于标准斑块，与TG43计算相比，平行于斑块的平面的MC计算剂量分布由于在斑块的边缘处被模达屏蔽而变窄。在斑块后面的剂量经过完全衰减。对于切割斑块，结果相似，切割平面上的衰减沿着切割处平面是不对称的。累积剂量体积直方图显示，与TG43计算相比，计算得到的MC剂量对于肿瘤和眼部结构均有显著减少。对于切割斑块，由于包围视神经的模达，MC剂量大大减弱，使视神经D95%从14 Gy降至0.2 Gy，与TG43计算相比。肿瘤D95%分别为89.2 Gy和79.95 Gy，对应于TG43和MC计算。TG43计算高估了靶区和风险器官的绝对剂量和横向剂量分布。对于非均匀荷载的斑块来说，与均匀荷载的斑块沿中心轴线进行剂量匹配足以提供可比较的覆盖率，可在眼科肿瘤繁忙中心进行临床使用。© 2023 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.

To investigate the effect of using non-uniform loading and notched plaques on dose distribution for eye plaques. Using EGSnrc Monte Carlo (MC) simulations, we investigate eye plaque dose distributions in water and in an anatomically representative eye phantom. Simulations were performed in accordance with TG43 formalism and compared against full MC simulations which account for inter-seed and inhomogeneity effects. For standard plaque configurations, uniformly and non-uniformly loaded plaque dose distributions in water showed virtually no difference between each other. For standard plaque, the MC calculated dose distribution in planes parallel to the plaque is narrower than the TG43 calculation due to attenuation at the periphery of the plaque by the modulay. MC calculated the dose behind the plaque is fully attenuated. Similar results were found for the notched plaque, with asymmetric attenuation along the plane of the notch. Cumulative dose volume histograms showed significant reductions in the calculated MC doses for both tumor and eye structures, compared to TG43 calculations. The effect was most pronounced for the notch plaque where the MC dose to the optic nerve was greatly attenuated by the modulay surrounding the optic nerve compared to the TG43. Thus, a reduction of optic nerve D95% from 14 to 0.2 Gy was observed, when comparing the TG43 calculation to the MC result. The tumor D95% reduced from 89.2 to 79.95 Gy for TG43 and MC calculations, respectively. TG43 calculations overestimate the absolute dose and the lateral dose distribution of both standard and notched eye plaques, leading to the dose overestimation for the target and organs at risk. The dose matching along the central axis for the non-uniformly loaded plaques to that of uniformly loaded ones was found to be sufficient for providing comparable coverage and can be clinically used in eye-cancer-busy centers.© 2023 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, LLC on behalf of The American Association of Physicists in Medicine.