Facure A, Cardoso S C, da Rosa L A R, da Silva A X
Comissão Nacional de Energia Nuclear, R. Gal. Severiano 90, sala 409, 22294-900 Rio de Janeiro, RJ, Brazil.
Radiat Prot Dosimetry. 2010 Mar;138(3):251-6. doi: 10.1093/rpd/ncp245. Epub 2009 Dec 4.
In this paper, the general-purpose Monte Carlo code MCNP5 was used to study the dose variance due to the position of medical linear accelerators, under unusual conditions, for shielding design of radiotherapy facilities. It was found that the computational methods generally used to estimate the scattered photon doses at the entrance of radiotherapy unit vaults provide conservative results when compared with the MCNP results, considering the standard condition. On the other hand, for the situations where the axis of gantry rotation is redirected at, for example, 45 degrees with respect to the walls of the room, the photon doses at the entrance can reach values up to seven times higher than those obtained under the standard condition, depending on the energy of the primary beam.
在本文中，通用蒙特卡罗代码MCNP5被用于研究在非常规条件下，医用直线加速器位置对剂量方差的影响，以用于放射治疗设施的屏蔽设计。研究发现，与MCNP结果相比，在标准条件下，通常用于估计放射治疗单元机房入口处散射光子剂量的计算方法会得出保守的结果。另一方面，对于龙门架旋转轴相对于房间墙壁例如以45度重新定向的情况，入口处的光子剂量可达标准条件下所获剂量的七倍之高，这取决于初级束的能量。
