Cell cycle progression after heavy-ion irradiation

Abstract

The cell cycle progression in cultured mammalian cells after irradiation with carbon ion beams and X-rays has been studied. The cell population at G(sub 2) and G(sub 2)/M phase measured by flowcytometer increased with the incubation time after irradiation. Accumulation of cells at G(sub 2)/M phase was observed from four hours after irradiation, and lasted for several hours with a peak at around six hours. It was found that accumulation length depended on irradiation dose and LET (Linear Energy Transfer). As for X-rays, the maximum value and the width of the peak increased with irradiation dose. For carbon ion beams with LET of 30 and 77 keV/micrometer, the peak value increased with dose up to 3 Gy.

炭素イオンビームおよびX線照射後の培養ほ乳類細胞の細胞周期の累進を研究した。フローサイトメータで計測したG(sub 2)およびG(sub 2)/M相の細胞集団は照射後の培養時間とともに増加した。細胞の蓄積は照射後4時間目からG(sub 2)/M相に観測され、蓄積は数時間継続し6時間目にはピークを示した。蓄積時間の長さは照射放射線量と線エネルギー付与(LET)に依存することが分かった。X線については、最大値とピーク幅が照射放射線量の増加に伴い増大した。LETが30と77keV/マイクロメートルの炭素イオンビームに対し放射線量が3グレイ以下では放射性量の増加に伴いピーク値は高くなった。