Beddar A S, Mackie T R, Attix F H
Department of Medical Physics, University of Wisconsin Medical School, WI 53706.
Phys Med Biol. 1992 Oct;37(10):1883-900. doi: 10.1088/0031-9155/37/10/006.
A minimally perturbing plastic scintillation detector has been developed for the dosimetry of high-energy beams in radiotherapy. The detector system consists of two identical parallel sets of radiation-resistant optical fibre bundles, each connected to independent photomultiplier tubes (PMTs). One fibre bundle is connected to a miniature water equivalent plastic scintillator and so scintillation as well as Cerenkov light generated in the fibres is detected at its PMT. The other 'background' bundle is not connected to the scintillator and so only Cerenkov light is detected by its PMT. The background signal is subtracted to yield only the signal from the scintillator. The water-equivalence of plastic scintillation detectors is studied for photon and electron beams in the radiotherapy range. Application of Burlin cavity theory shows that the energy dependence of such detectors is expected to be better than the commonly used systems (ionization chambers, LiF thermoluminescent dosimeters, film and Si diodes). It is also shown that they are not affected by temperature variations and exhibit much less radiation damage than either photon or electron diode detectors.
一种用于放射治疗中高能束剂量测定的微扰塑料闪烁探测器已被研制出来。该探测器系统由两组相同的平行抗辐射光纤束组成，每组都连接到独立的光电倍增管（PMT）。一束光纤连接到一个微型水等效塑料闪烁体，因此在其光电倍增管处既检测到光纤中产生的闪烁光也检测到切伦科夫光。另一束“本底”光纤未连接到闪烁体，因此其光电倍增管仅检测到切伦科夫光。减去本底信号后仅得到来自闪烁体的信号。研究了塑料闪烁探测器在放射治疗范围内对光子束和电子束的水等效性。伯林空腔理论的应用表明，预计此类探测器的能量依赖性优于常用系统（电离室、LiF热释光剂量计、胶片和硅二极管）。还表明它们不受温度变化的影响，并且与光子或电子二极管探测器相比，辐射损伤要小得多。
