Schulz R J, Nath R
Med Phys. 1977 Jan-Feb;4(1):42-5. doi: 10.1118/1.594300.
A sensitive and relatively simple method for obtaining an index of the spectral quality of x rays in the 4-15-MV range is presented. The method is based upon the simultaneous production of 115mIn by inelastic scattering of x rays by an indium foil and the production of 116mIn by neutron capture, where the neutrons are obtained from the photodisintegration of deuterium. Since the cross sections for the production of 115mIn and 116mIn have markedly different energy response functions, the ratio of radioactivities is very sensitive to the incident x-ray spectrum. Using a detector consisting of an indium foil sandwiched between two plastic bottles of D2O, photoactivation ratios (PAR) have been measured for 4-, 6-, and 10-MV x rays. It is shown that the PAR method offers a sensitive and practical means for quality control of x-ray spectra and comparison of high-energy accelerators.
本文提出了一种灵敏且相对简单的方法，用于获取4 - 15兆伏范围内X射线光谱质量的指标。该方法基于通过铟箔对X射线的非弹性散射同时产生115mIn以及通过中子俘获产生116mIn，其中中子由氘的光致蜕变获得。由于产生115mIn和116mIn的截面具有明显不同的能量响应函数，放射性之比对入射X射线光谱非常敏感。使用由夹在两个重水塑料瓶之间的铟箔组成的探测器，已测量了4兆伏、6兆伏和10兆伏X射线的光激活比（PAR）。结果表明，PAR方法为X射线光谱的质量控制和高能加速器的比较提供了一种灵敏且实用的手段。
