Pla C, Podgorsak E B, el-Khatib E
McGill University, Department of Radiation Oncology, Montréal, Québec, Canada.
Med Phys. 1988 Jul-Aug;15(4):511-6. doi: 10.1118/1.596202.
Measured and calculated dose profiles under partial attenuators which cover only part of the radiation beam are presented. The study was performed for x-ray beams generated with a 4-MV linear accelerator at a source-surface distance of 120 cm in a water phantom for lead attenuators of arbitrary shape but constant thickness. Dose correction factors, which are used to multiply the open beam data to predict doses under partial attenuators, depend strongly on attenuator parameters, such as its thickness, lateral dimensions, and distance from phantom or patient surface, in addition to depending on depths in the phantom. The dose correction factors are calculated with Clarkson sector integration techniques, and the results, in spite of the simplifying assumptions used in the algorithm, generally agree with measured data to within 3%. The calculational method therefore may be applied to general clinical situations in which partial attenuators are used.
给出了在仅覆盖部分辐射束的部分衰减器下测量和计算的剂量分布。该研究是针对在水模体中源皮距为120 cm的4-MV直线加速器产生的X射线束进行的，用于任意形状但厚度恒定的铅衰减器。剂量校正因子用于乘以开束数据以预测部分衰减器下的剂量，除了取决于模体中的深度外，还强烈依赖于衰减器参数，如其厚度、横向尺寸以及距模体或患者表面的距离。剂量校正因子采用克拉克森扇形积分技术计算，尽管算法中使用了简化假设，但结果与测量数据总体上在3%以内相符。因此，该计算方法可应用于使用部分衰减器的一般临床情况。
