Secondary dose exposures during 200 MeV proton therapy
Secondary dose exposures during 200 MeV proton therapy
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DOI：
10.1093/oxfordjournals.rpd.a031993
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发表时间：
1997-01-01
影响因子：
1
通讯作者：
Hough, JH
中科院分区：
文献类型：
--
作者：
Binns, PJ;Hough, JH
在一个新的200 MeV质子治疗设施进行第一次预定治疗之前，委托进行了一项研究，以确定束流中辅助部件产生的外来辐射的性质。使用组织等效正比计数器获得等中心附近的剂量和剂量当量的估计值。根据测量的单粒子分布推断了散射辐射的性质，并随主光束中心横向位移的变化而变化。在患者位置发现了一个快中子剂量成分，该成分随着侧向位移和与最终准直器的径向距离而递减。从患者准直器的外围向外延伸，可以明显地看到一个由散布的高能质子组成的前向尖锥。在患者位置确定的可归因于射束输送系统散射的剂量当量在每个治疗灰度计33×10(-3)至80×10(-3)Sv之间变化。
Prior to the first scheduled treatments at a new 200 MeV proton therapy facility a study was commissioned to ascertain the nature of extraneous radiations produced by ancillary components in the beam line. Estimates of the dose and dose equivalent were obtained in the vicinity of the isocentre using a tissue-equivalent proportional counter. The character of the scattered radiation was deduced from the measured single-event distributions and varied with lateral displacement from central axis of the primary beam. A fast neutron dose component was identified at the patient position that decreased progressively with lateral displacement and radial distance from the final collimator. Extending beyond the periphery of the patient collimator a forward peaked cone of scattered high energy protons was evident. Dose equivalents determined at the patient position and attributable to scattering from the beam delivery system varied between 33 x 10(-3) and 80 X 10(-3) Sv per treatment gray.