RADIOBIOLOGICAL EFFECTIVENESS (RBE) OF MEGAVOLTAGE X-RAY AND ELECTRON-BEAMS IN RADIOTHERAPY
RADIOBIOLOGICAL EFFECTIVENESS (RBE) OF MEGAVOLTAGE X-RAY AND ELECTRON-BEAMS IN RADIOTHERAPY
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DOI：
10.2307/3576725
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发表时间：
1986-01-01
影响因子：
3.4
通讯作者：
CAGNA, D
中科院分区：
文献类型：
--
作者：
AMOLS, HI;LAGUEUX, B;CAGNA, D
最近的实验表明，放射治疗中使用的兆伏 X 射线和电子束的微剂量特性（即线性能量分布）存在显着差异。特别是，18 MeV 电子的线能剂量平均值比 10 MeV 轫致辐射 X 射线低 10-30%，而 10 MeV 轫致辐射 X 射线又比 250 kVp X 射线低 30-60%。这种程度的差异可能表现为这些辐射之间可观察到的放射生物学有效性（RBE）差异。已获得 DLD-1 人类肿瘤细胞系在上述所有三种辐射源上的细胞存活数据。结果清楚地表明了正电压辐射和兆电压辐射之间的 RBE 差异 (P = 0.001)。兆伏级光子和兆伏级电子之间的 RBE 也存在微小差异，但差异不具有统计显着性 (P = 0.25)。所有生物学、剂量学和微剂量学数据都是在几乎相同的几何条件下获得的。这些数据提出了关于微剂量理论在解释生物效应中的适用性的有趣问题。
Recent experiments indicate that significant differences exist in the microdosimetric properties (i.e., linear energy distributions) of megavoltage X-ray and electron beams used in radiation therapy. In particular, dose averaged values of lineal energy for 18 MeV electrons are 10-30% lower than for 10 MeV bremsstrahlung X rays, which in turn are 30-60% lower than for 250 kVp X rays. Differences of this magnitude may manifest themselves in observable radiobiological effectiveness (RBE) differences between these radiations. Cell survival data have been obtained for line DLD-1 human tumor cells on all three of the above radiation sources. Results clearly demonstrate an RBE difference between orthovoltage and megavoltage radiation (P = 0.001). A small difference is also measured in RBE between megavoltage photons and megavoltage electrons, but the difference is not statistically significant (P = 0.25). All biological, dosimetric, and microdosimetric data were obtained under nearly identical geometric conditions. These data raise interesting questions vis a vis the applicability of microdosimetric theories in the interpretation of biological effects.