NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 267 (10): 1837-1840 MAY 15 2009
Jing, XG, Chinese Acad Sci, Inst Modern Phys, Lanzhou, Gansu, Peoples R China.
Human hepatoma (SMMC-7721) and normal liver (L02) cells were irradiated with gamma-rays, C-12(6+) and Ar-36(18+) ion beams at the Heavy Ion Research Facility in Lanzhou (HIRFL). By using the Calyculin-A induced premature chromosome condensation technique, chromatid-type breaks and isochromatid-type breaks were scored separately. Tumor cells irradiated with heavy ions produced a majority of isochromatid break, while chromatid breaks were dominant when cells were exposed to gamma-rays. The relative biological effectiveness (RBE) for irradiation-induced chromatid breaks were 3.6 for L02 and 3.5 for SMMC-7721 cell lines at the LET peak of 96 keV mu m(-1) C-12(6+) ions, and 2.9 for both of the two cell lines of 512 keV mu m(-1) Ar-36(18+) ions. It suggested that the RBE of isochromatid-type breaks was pretty high when high-LET radiations were induced. Thus we concluded that the high production of isochromatid-type breaks, induced by the densely ionizing track structure, could be ! regarded as a signature of high-LET radiation exposure.