Rubach A, Bichsel H
Phys Med Biol. 1982 Oct;27(10):1231-43. doi: 10.1088/0031-9155/27/10/003.
Values are given of the average energy required to produce an ion pair, Wn, and of the dose conversion factor, r, for tissue-equivalent chambers filled with either tissue-equivalent gas or air, irradiated by neutrons. The model for finite spherical cavities previously presented in part I was used for the calculations, which employed the W values and stopping powers of the charged particles produced in the materials described in part II. Neutron energies ranging from 0.4 to 14 MeV were considered: many of these energies were chosen because of their particularly large or small total cross-sections in order to explore the range of fluctuations of r and Wn. The results are therefore not very suitable for spectral averaging. Cavity sizes ranging from the infinitesimal Bragg-Gray to the infinite cavity were studied. It was found that the changes of r with cavity size and with neutron energy are smaller for the TE-TE chamber than for the TE-air chamber, but for Wn they are about equal; the TE-TE chamber should therefore be considered the ionisation chamber of choice but absolute doses cannot be determined with it to better than +/- 8%.
给出了用中子辐照时，充有组织等效气体或空气的组织等效电离室产生一个离子对所需的平均能量(W_n)以及剂量转换因子(r)的值。计算中使用了第一部分中先前提出的有限球形空腔模型，该模型采用了第二部分所述材料中产生的带电粒子的(W)值和阻止本领。考虑了能量范围从(0.4)到(14)兆电子伏的中子：选择这些能量中的许多能量是因为它们的总截面特别大或特别小，以便探索(r)和(W_n)的波动范围。因此，这些结果不太适合进行谱平均。研究了从无限小的布拉格 - 格雷空腔到无限大空腔的空腔尺寸范围。结果发现，对于组织等效 - 组织等效（TE - TE）电离室，(r)随空腔尺寸和中子能量的变化比组织等效 - 空气（TE - 空气）电离室小，但对于(W_n)，它们大致相等；因此，TE - TE电离室应被视为首选电离室，但用它无法将绝对剂量确定到优于±8%的精度。
