The study objectives were to simulate a 6 MV flattening filter-free (FFF) photon beam of a TrueBeam Varian LINAC, using the PRIMO code. The depth-dose profiles for various jaw open fields and cross-beam profiles for various depths inside water phantoms were determined using PRIMO simulations and were compared with the EGSnrc simulation results. A 93% match between both codes has generally been obtained, with a systematic variation in agreement between the two models that increases with field size. The closest agreement, to within 94%, was obtained for a 6 × 6 cm2 jaw open field at 5.0 cm and 10.0 cm depths, better at 10- than at 5.0 cm depth. The effects of how scatter is modelled has been shown to result in the differences.

中文翻译：

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Varian True Beam 直线加速器的 PRIMO 和 EGSnrc Monte Carlo 模型的比较

研究目标是使用 PRIMO 代码模拟 TrueBeam Varian LINAC 的 6 MV 平坦化无滤波器 (FFF) 光子束。使用 PRIMO 模拟确定各种下颌张开场的深度剂量分布和水体模型内部各种深度的横梁分布，并与 EGSnrc 模拟结果进行比较。两种代码之间的匹配度通常为 93%，随着字段大小的增加，两种模型之间的一致性存在系统性变化。在 5.0 cm 和 10.0 cm 深度处的 6 × 6 cm2 下颌开放视野获得了最接近的一致性，在 94% 以内，在 10- 比在 5.0 cm 深度更好。已显示如何对散射进行建模的效果会导致差异。