Schuhmacher H, Menzel H G, Blattmann H, Muth H
Radiat Res. 1985 Jan;101(1):177-96.
At the Swiss Institute for Nuclear Research (SIN) cancer patients are irradiated with negatively charged pi mesons using a 60-beam medical pion generator, the Piotron. A low-pressure tissue-equivalent proportional counter was used to measure absorbed dose and microdosimetric spectra. A method was developed to allow discrimination of events from different beam components, i.e., beam contamination (electrons and muons), pions in flight, and stopping pions. Measurements were performed along the axis and at lateral distances off one of these identical pion beams. The marked changes of total microdosimetric spectra with depth in phantom detected in earlier measurements are mainly due to large variations in the dose contributions of the beam components and much less to changes in the shapes of the individual microdosimetric spectra. The single beam measurements were used to calculate three-dimensional distributions of absorbed dose and of dose mean lineal energy, yD, for dynamic patient irradiations. Within the whole target volume yD remains nearly constant when irradiated with all 60 beams, whereas considerable changes were found for irradiations with 31 beams coming from a semicircle. Both size and shape of target volumes influence yD, the maximum values ranging from 30 to 45 keV/micron.
在瑞士核研究所（SIN），癌症患者使用60束医用π介子发生器“皮奥创”接受带负电的π介子照射。使用低压组织等效正比计数器来测量吸收剂量和微剂量谱。开发了一种方法，以区分来自不同束流成分的事件，即束流污染（电子和μ子）、飞行中的π介子和停止的π介子。沿着这些相同π介子束之一的轴并在横向距离处进行了测量。早期测量中在体模中检测到的总微剂量谱随深度的显著变化主要是由于束流成分的剂量贡献有很大变化，而单个微剂量谱形状的变化则小得多。单束测量用于计算动态患者照射时吸收剂量和剂量平均线能量yD的三维分布。当用全部60束照射时，在整个靶体积内yD几乎保持恒定，而用来自半圆的31束照射时则发现有相当大的变化。靶体积的大小和形状都会影响yD，最大值范围为30至45keV/微米。
