Effect of different stopping volumes of clinical pion beams at TRIUMF on the mouse small intestine.
Effect of different stopping volumes of clinical pion beams at TRIUMF on the mouse small intestine.
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TRIUMF 临床π介子束不同停止体积对小鼠小肠的影响。
DOI：
10.2307/3577272
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发表时间：
1989
影响因子：
3.4
通讯作者：
L. Skarsgard
中科院分区：
文献类型：
--
作者：
T. Saito;D. Chaplin;G. Lam;L. Skarsgard
用三种不同的pion停止体积中的一种照射后，用微集落试验测定小鼠空肠隐窝细胞的存活率。所有治疗都是使用TRIUMF为临床治疗开发的束点扫描系统进行的。治疗体积很小，使用4个束点的10ml体积，具有狭窄的停止峰；中等，40ml的体积，使用4个束点，峰延长；大，1.2L体积，使用37个峰延长的点。由于扫描过程的原因，剂量率在治疗过程中波动很大。小、中、大剂量的相对生物学效应(RBE)值分别为1.11、1.04和1.16。随着阻止峰宽度的增加，从小体积的4厘米窄峰到中等体积的12厘米峰，介子束的效率降低。这可能反映了在更宽的停止峰中大量通过的介子对能量转移的线性贡献很小。然而，结果表明，大容量比中等容量具有更大的生物学效果。尽管这些场具有相似宽度的停止峰，但场大小和剂量率不同。虽然RBE的增加可能部分是由于较大体积的中子通量增加，但我们的结果表明，这种明显的增加在很大程度上可以用介子与X射线的剂量率随时间的函数关系来解释。
The survival of mouse jejunal crypt cells was measured using a microcolony assay following irradiation with one of three different pion stopping volumes. All treatments were done using the beam spot scanning system developed for clinical therapy at TRIUMF. Treatment volumes were Small, 10 ml of volume using 4 beam spots with a narrow stopping peak; Moderate, 40 ml of volume using 4 beam spots with an extended peak; Large, 1.2 liters of volume using 37 spots with an extended peak. The dose rate fluctuated considerably during treatment because of the scanning procedure. The relative biological effectiveness (RBE) values of pions were 1.11, 1.04, and 1.16 for the small, moderate, and large volumes, respectively. As the width of the stopping peak increased, from the narrow 4-cm peak of the small volume to the 12-cm peak of the moderate volume, the effectiveness of the pion beam decreased. This presumably reflects the low linear energy transfer contribution of the large number of passing pions in the wider stopping peak. The results indicate, however, a greater biological effectiveness for the large volume than for the moderate volume. Even though these fields had stopping peaks of similar width, the field size and dose rate were different. Although the increase in RBE may be partly due to an increased neutron flux from the larger volume, our results suggest that much of this apparent increase could be explained by differences in dose rate as a function of time for pions versus X rays.