Jones M R, Peet D J, Horton P W
Medical Physics Department, Royal Surrey County Hospital, Egerton Road, Guildford, GU2 7XX, UK.
Health Phys. 2009 Jan;96(1):67-75. doi: 10.1097/01.HP.0000327660.36130.ee.
The attenuation characteristics of MagnaDense high-density concrete are measured using the x-ray beams from two Varian linear accelerators at nominal 6, 10, and 15 megavolt energies. The tenth value layers for the primary beam are evaluated under broad- and narrow-beam conditions. The attenuation of secondary radiation is also investigated. Measured data are compared with existing data used in radiotherapy bunker design, derived from the scaling of published tenth value layers for ordinary concrete according to physical density. Instantaneous dose rates around an existing bunker with MagnaDense concrete walls and a conventional concrete roof are predicted using the various different data and compared to actual dose-rate measurements. Primary beam tenth value layer values derived from the broad-beam measurements are found to represent the attenuation properties of the MagnaDense more accurately than those produced by density-based scaling or from narrow-beam measurements.
使用两台瓦里安直线加速器在标称6兆伏、10兆伏和15兆伏能量下产生的X射线束，测量了MagnaDense高密度混凝土的衰减特性。在宽束和窄束条件下评估了原射线的十分之一值层。还研究了二次辐射的衰减。将测量数据与放射治疗掩体设计中使用的现有数据进行比较，这些现有数据是根据已发表的普通混凝土十分之一值层按物理密度进行缩放得出的。使用各种不同数据预测了现有一个带有MagnaDense混凝土墙和传统混凝土屋顶的掩体周围的瞬时剂量率，并与实际剂量率测量值进行比较。发现从宽束测量得出的原射线十分之一值层数值比基于密度缩放或窄束测量得出的数值更准确地代表了MagnaDense的衰减特性。
