Rodriguez A, Alpen E L, Powers-Risius P
Lawrence Berkeley Laboratory, Cell and Molecular Biology Division, University of California, Berkeley 94720.
Radiat Res. 1992 Nov;132(2):184-92.
This report presents data for survival of mouse intestinal crypt cells, mouse testes weight loss as an indicator of survival of spermatogonial stem cells, and survival of rat 9L spheroid cells after irradiation in the plateau region of unmodified particle beams ranging in mass from 4He to 139La. The LET values range from 1.6 to 953 keV/microns. These studies examine the RBE-LET relationship for two normal tissues and for an in vitro tissue model, multicellular spheroids. When the RBE values are plotted as a function of LET, the resulting curve is characterized by a region in which RBE increases with LET, a peak RBE at an LET value of 100 keV/microns, and a region of decreasing RBE at LETs greater than 100 keV/microns. Inactivation cross sections (sigma) for these three biological systems have been calculated from the exponential terminal slope of the dose-response relationship for each ion. For this determination the dose is expressed as particle fluence and the parameter sigma indicates effect per particle. A plot of sigma versus LET shows that the curve for testes weight loss is shifted to the left, indicating greater radiosensitivity at lower LETs than for crypt cell and spheroid cell survival. The curves for cross section versus LET for all three model systems show similar characteristics with a relatively linear portion below 100 keV/microns and a region of lessened slope in the LET range above 100 keV/microns for testes and spheroids. The data indicate that the effectiveness per particle increases as a function of LET and, to a limited extent, Z, at LET values greater than 100 keV/microns. Previously published results for spread Bragg peaks are also summarized, and they suggest that RBE is dependent on both the LET and the Z of the particle.
本报告展示了在质量范围从4He到139La的未修饰粒子束的坪区进行辐照后，小鼠肠道隐窝细胞的存活数据、作为精原干细胞存活指标的小鼠睾丸重量损失数据以及大鼠9L球状体细胞的存活数据。传能线密度（LET）值范围为1.6至953 keV/微米。这些研究考察了两种正常组织以及一种体外组织模型——多细胞球状体的相对生物效应（RBE）与传能线密度（LET）的关系。当将RBE值绘制为LET的函数时，所得曲线的特征是存在一个RBE随LET增加的区域、在LET值为100 keV/微米时出现RBE峰值以及在LET大于100 keV/微米时RBE下降的区域。已根据每种离子剂量响应关系的指数末端斜率计算了这三种生物系统的失活截面（σ）。对于此测定，剂量表示为粒子注量，参数σ表示每个粒子的效应。σ与LET的关系图表明，睾丸重量损失的曲线向左移动，这表明在较低LET下比隐窝细胞和球状体细胞存活具有更高的放射敏感性。所有三种模型系统的截面与LET的关系曲线都显示出相似的特征，在100 keV/微米以下有一个相对线性的部分，在睾丸和球状体的LET范围高于100 keV/微米时有一个斜率减小的区域。数据表明，在LET值大于100 keV/微米时，每个粒子的有效性随LET以及在有限程度上随Z增加。还总结了先前发表的关于扩展布拉格峰的结果，这些结果表明RBE既取决于粒子的LET也取决于Z。
