Weaver K, Bichsel H, Eenmaa J, Wootton P
Med Phys. 1977 Sep-Oct;4(5):376-86. doi: 10.1118/1.594323.
Photon dose fractions (PDFs) have been measured in and around a neutron radiotherapy beam with a tissue-equivalent proportional counter (TEPC) and with paired ion chambers. The PDFs were found to increase linearly with increasing field size and width depth in phantom. PDFs were shown to decrease with decreasing phantom size and to be larger in the shielded region of the phantom than in the direct beam. Uncertainties in the PDF values were estimated to be 10%-15% for the TEPC measurements but about 50% for the measurement made with ion chambers.
已使用组织等效正比计数器（TEPC）和成对电离室在中子放射治疗束及其周围测量了光子剂量分数（PDF）。发现PDF在模体中随场大小和宽度深度的增加而线性增加。结果表明，PDF随模体尺寸减小而降低，并且在模体的屏蔽区域中比在直射束中更大。TEPC测量的PDF值不确定度估计为10%-15%，但电离室测量的不确定度约为50%。
