Abstract: OBJECTIVE: To study the time-course and dose-response of chromosome aberrations in human blood lymphocyte induced by carbon ion irradiation. METHODS: Peripheral blood samples from volunteers were irradiated with carbon ions with a mean LET of 46 keV/μm. For the time-course study, the irradiation doses were 2 Gy and 4 Gy. First division metaphase cells were collected after different culture times of 48,72 and 84 h, and chromosome aberrations were determined by using sister chromatid differential staining method. For dose-response study, the irradiation doses were 0，0.5，1，2，3and 4 Gy. First division metaphase cells were collected after a culture time of 48 h, and chromosome aberrations were determined by using conventional chromosome technology. RESULTS: There was no significant difference between the frequencies of “dic＋ring” obtained in these three culture times. The frequency of “dic＋ring” increased linearly with doses, with the equation of Y=0.0005＋0.689D. CONCLUSION: In these irradiation conditions, there was no time-course effect in PBL chromosome damage induced by 12C ions. A culture time of 48 h is acceptable for studing the biological effectiveness of carbon ions, and the number of chromosome aberrations increased linearly with dose.

Key words: carbon ion, lymphocytes, chromosome aberrations, time-course effect, dose-response effect