Influence of the phantom shape (slab, cylinder or Alderson) on the performance of an Hp(3) eye dosemeter
Abstract
In the past, the operational quantity Hp(3) was defined for calibration purposes in a slab phantom. Recently, an additional phantom in the form of a cylinder has been suggested for eye lens dosimetry, as a cylinder much better approximates the shape of a human head. Therefore, this work investigates which of the two phantoms, slab or cylinder, is more suitable for calibrations and type tests of eye dosemeters. For that purpose, a typical Hp(3) eye dosemeter was irradiated on a slab, a cylinder and on a human-like Alderson phantom（阿尔德森(Alderson) 放射治疗体模）. It turned out that the response on the three phantoms is nearly equal for angles of radiation incidence up to 45° and deviates only at larger angles of incidence. Thus, calibrations (usually performed at 0° radiation incidence) are practically equivalent on both the slab and the cylinder phantoms. However, type tests (up to 75° or even 90° radiation incidence) should be carried out on a cylinder phantom, as also for large angles of incidence the response on the cylinder and the Alderson phantoms is rather similar, whereas the response on the slab significantly deviates from the one on the Alderson phantom.
本文是对运行使用量——眼晶体个人剂量的定值的讲述。说了传统的平板体模是过去用来校准眼晶体个人剂量的，但是最近圆柱形体模被推荐用来眼晶体剂量的定值。原因是圆柱形更好的近似了人体的头部。文章使用了一种眼晶体剂量计和三种体模在辐射场中进行测试。
结果表明，在0度到45度范围内，三者相差不大。在大角度情况下，圆柱形体模和仿真人体模型差别还是最小的，但是平板体摸显然差别很大。
通过文章的结果，我们可以推断，大角度的角响应，平板体摸已经不能满足要求。因此圆柱形体模是必须的。但是尺寸如何确定，是不是要多算一些不同尺寸，或者加工生产不同尺寸，来进行试验测试，从而挑选出合理的尺寸来。当然着一些之前先要计算时经济合理的方案。