Prise K M, Folkard M, Davies S, Michael B D
Grey Laboratory, Mount Vernon Hospital, Northwood, Middlesex, UK.
Int J Radiat Biol. 1990 Aug;58(2):261-77. doi: 10.1080/09553009014551611.
The effectiveness of low-energy (below 2 MeV) protons at inducing DNA damage in the form of single- and double-strand breaks has been determined. Protons with mean energies of 1.90 MeV, 1.15 MeV and 0.76 MeV corresponding to track average LETs of 17 keV/microns, 24 keV/microns and 32 keV/microns, respectively, have been used and compared with 250 kVp X-rays and 3.8 MeV 238Pu alpha-particles. Although there was variation in the RBE for DNA ssb induction with LET, the RBEs for dsb induction at all three proton energies and for 3.8 MeV alpha-particles were all around 1.0. This suggests that, if DNA dsb are important in radiation-induced cell lethality, the probability of an induced dsb leading to a lethal event increases with increasing LET of radiation. Oxygen enhancement ratios were measured for both cell survival and DNA dsb induction, and in both cases a decrease in OER with increasing LET was observed.
已确定低能（低于2兆电子伏特）质子以单链和双链断裂形式诱导DNA损伤的有效性。使用了平均能量为1.90兆电子伏特、1.15兆电子伏特和0.76兆电子伏特的质子，其对应的径迹平均传能线密度分别为17千电子伏特/微米、24千电子伏特/微米和32千电子伏特/微米，并与250千伏峰值X射线和3.8兆电子伏特的238钚α粒子进行了比较。尽管随着传能线密度，DNA单链断裂诱导的相对生物效应存在变化，但在所有三个质子能量以及3.8兆电子伏特α粒子下双链断裂诱导的相对生物效应均约为1.0。这表明，如果DNA双链断裂在辐射诱导的细胞致死性中很重要，那么诱导的双链断裂导致致死事件的概率会随着辐射传能线密度的增加而增加。对细胞存活和DNA双链断裂诱导都测量了氧增强比，并且在两种情况下都观察到随着传能线密度增加氧增强比降低。
