Rikner G, Grusell E
Department of Hospital Physics, University Hospital, Uppsala, Sweden.
Med Phys. 1987 Sep-Oct;14(5):870-3. doi: 10.1118/1.596015.
Semiconductor detectors based on p-type silicon and designed for in vivo measurement of entrance dose at the reference point from photon radiation fields, are described. To estimate the absorbed dose at the reference point from measurements with a thin detector, field-size dependent correction factors must be applied to the reading, as the shape of the dose buildup curve varies with field size. To decrease or avoid field-size dependent correction factors, the detector can be covered with a buildup cap. The presence of such a detector will cause perturbation of the radiation field. Therefore, the design of a detector, irrespective of its type, intended for patient dosimetry involves a compromise between minimizing the radiation field perturbation and minimizing field-size dependent correction factors. Detectors with three different buildup caps were designed to cover the energy range from cobalt-60 to 16-MV x rays. The three different detector types were investigated with respect to their signal dependence on field size, field perturbation, and directional dependence. A summary of radiation damage effects on sensitivity, and of sensitivity variation with temperature is also presented.
描述了基于p型硅且设计用于在体内测量光子辐射场参考点处入射剂量的半导体探测器。为了根据薄探测器的测量结果估算参考点处的吸收剂量，由于剂量积累曲线的形状随射野大小而变化，必须对读数应用与射野大小相关的校正因子。为了减少或避免与射野大小相关的校正因子，可以用一个积累帽覆盖探测器。这种探测器的存在会导致辐射场的扰动。因此，无论探测器类型如何，用于患者剂量测定的探测器设计都需要在最小化辐射场扰动和最小化与射野大小相关的校正因子之间进行权衡。设计了具有三种不同积累帽的探测器，以覆盖从钴-60到16兆伏X射线的能量范围。研究了这三种不同类型的探测器在信号对射野大小的依赖性、射野扰动和方向依赖性方面的情况。还给出了辐射损伤对灵敏度的影响以及灵敏度随温度变化的总结。
