High-LET-induced chromosomal damage: time-dependent expression.
Chromosome aberrations are routinely analysed in metaphase cells at one sampling time post-irradiation. Yet, accumulating evidence shows that radiation-induced cycle perturbations and mitotic delay influence the yield of aberrations detectable in mitosis. In extended time-course studies a drastic increase in the number of aberrations with sampling time has been observed after particle irradiation, while after the exposure to sparsely ionizing radiation a less pronounced effect has been found. This difference in the time-course of chromosomal damage is particularly important for the determination of accurate RBE values. As will be discussed, meaningful RBE values for particles can only be obtained, if cells are analysed at multiple sampling times and the complete time-course of aberrations is considered. Otherwise, particle-induced damage will be over- or underestimated. Moreover, depending on the cell system chosen for the analysis, factors like the loss of damaged cells due to apoptosis or a permanent cell cycle arrest complicate the determination of accurate RBE values based on chromosome data.
Nasonova
E
E
GSI, D-64291 Darmstad, Germany.
Ritter
S
S
Gudowska-Nowak
E
E
Kraft
G
G
D000818:Animals; D017209:Apoptosis / Q000528:radiation effects; D002453:Cell Cycle / Q000528:radiation effects; D002460:Cell Line; D002869:Chromosome Aberrations; D006224:Cricetinae; D003412:Cricetulus; D004307:Dose-Response Relationship, Radiation; D020450:Heavy Ions; D006801:Humans; D018499:Linear Energy Transfer; D008677:Metaphase / Q000528:radiation effects*; D008938:Mitosis / Q000528:radiation effects*; D012062:Relative Biological Effectiveness; D012867:Skin / Q000166:cytology / Q000528:radiation effects; D013997:Time Factors; D014965:X-Rays