Radiation-induced chromosomal aberrations in human lymphocytes after partial-body exposure to 60Co gamma-irradiation and in vitro exposure to 230 kV X-irradiation.

Small yields of chromosome aberrations were present in lymphocytes from 12 patients observed at first metaphase in culbure. Blood samples were obtained at various times, up to three days, after single partial-body therapeutic exposure ranging from 75 to 400 rads of 60Co gamma-irradiation. When all patients were considered there was no correlation between treatment dose and aberration frequency, but on subdivision into two groups on the basis of whether the reticuloendothelial system was involved in the cancer, linear regression analysis could be fitted to the data for each group. An in vitro dose response curve for dicentrics induced by 230 kV X rays at a dose rate of 23.3 rads per minute was constructed for use as a standard calibration curve for 48 hour cultures. The yield of dicentric aberrations was best fitted by a power law model, Y = kDn in which k = (1.59 +/- 0.66) 10(-4) and n= 1.49 +/- 0.08, (P =0.96).