Galbraith D M, Rawlinson J A
Med Phys. 1985 May-Jun;12(3):273-80. doi: 10.1118/1.595719.
A method is described in some detail for measuring the magnitude and penetration of the electron contamination in photon beams using a pancake charge detector. It is shown that the response of the detector to a photon beam can be separated from the component due to the electron contamination. In the present work, the detector is used to measure the electron fluence in a 60Co photon beam. This fluence is subsequently converted to dose by comparison with the fluence and dose measured from a pure electron beam (90Sr). This study proves, within experimental error, that the observed changes in the buildup region, with the collimator opening for both filtered and unfiltered 60Co beams, are due to electron, rather than photon, contamination.
详细描述了一种使用薄饼式电荷探测器测量光子束中电子污染的大小和穿透深度的方法。结果表明，探测器对光子束的响应可以与电子污染产生的分量区分开来。在本工作中，该探测器用于测量60Co光子束中的电子注量。随后，通过与从纯电子束（90Sr）测量得到的注量和剂量进行比较，将该注量转换为剂量。本研究在实验误差范围内证明，对于滤波和未滤波的60Co束，随着准直器开口大小变化，在积累区观察到的变化是由电子污染而非光子污染引起的。
