Takiguchi Yasuo, Miyamoto Tadaaki, Nagao Keiichi, Kuriyama Takayuki
Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, Anagawa, 4-9-1, Inage-ku, Chiba, 263-8555, Japan.
Radiat Med. 2007 Jul;25(6):272-7. doi: 10.1007/s11604-007-0134-6. Epub 2007 Jul 27.
The aim of this study was to assess the radiosensitivities and homogeneous efficacy in the spread-out Bragg peak (SOBP) for lung cancer cell lines exposed to carbon ions.
The dose-dependent survival rates of seven cell lines exposed to carbon ions, fast neutrons, and photons were obtained using colony-forming assays in vitro. The relative biological effectiveness (RBE) of carbon ions and fast neutrons to photons was determined by comparing the doses at the 10% and 1% survival levels.
The RBEs at 13, 40, 50, and 80 keV/microm were 1.20-1.29, 1.55-1.80, 1.57-2.00, and 1.69-2.58, respectively, at the 10% survival level. The RBE of 290 MeV carbon ions increased with increasing linear energy transfer. The biological dose (relative physical dose x RBE) distributions in the SOBP did not statistically differ at the proximal, mid, or distal points at the 10% (p = 0.945) and 1% (p = 0.211) survival levels, respectively; however, deviation of the biological dose at 10% and 1% survival were 3%-16% and 6%-24%, respectively. Furthermore, 290 MeV carbon ions at 80 keV/microm in the SOBP were nearly equivalent to 30 MeV fast neutrons.
Our results demonstrate nearly homogeneous effectiveness in the SOBP, although we are aware of the deviation in some cell lines.
本研究旨在评估暴露于碳离子的肺癌细胞系在扩展布拉格峰（SOBP）中的放射敏感性和均匀疗效。
使用体外集落形成试验获得七种暴露于碳离子、快中子和光子的细胞系的剂量依赖性存活率。通过比较10%和1%存活水平下的剂量来确定碳离子和快中子对光子的相对生物效能（RBE）。
在10%存活水平下，13、40、50和80 keV/μm处的RBE分别为1.20 - 1.29、1.55 - 1.80、1.57 - 2.00和1.69 - 2.58。290 MeV碳离子的RBE随线能量转移增加而增加。在10%（p = 0.945）和1%（p = 0.211）存活水平下，SOBP中生物剂量（相对物理剂量×RBE）分布在近端、中部或远端点分别无统计学差异；然而，10%和1%存活时生物剂量的偏差分别为3% - 16%和6% - 24%。此外，SOBP中80 keV/μm的290 MeV碳离子几乎等同于30 MeV快中子。
我们的结果表明，尽管我们意识到某些细胞系存在偏差，但SOBP中的疗效几乎是均匀的。
