CHROMOSOMAL DAMAGES IN CIRCULATING LYMPHOCYTES INDUCED BY THERAPEUTIC IRRADIATION

The dose-response relationship of the chromosomal damage to the blood lymphocytes was obtained from the in vitro experiment, and an attempt of its use was made to evaluate possible clinical meanings of the chromosomal damages to the lymphocytes in patients given radiation therapy for malignant diseases. In the patients given single dose of gamma-ray exposure, the chromosome analysis of the circulating lymphocytes showed that the production of chromosome aberrations in the irradiated region was grossly analogous to that of the in vitro exposure and that the overall frequency of the chromosome aberrations was determined by the irradiated volume, body weight and radiation dose. After repeated doses of therapeutic radiation, it was found that the irradiated volume, body weight and radiation dose were also among the important factors influencing the level of chromosome aberrations in the circulating lymphocytes. From the data obtained, other factors such as loss of lymphocytes due to death and recovery of the lymphocyte system were shown to play an important part in the determination of the level of chromosome aberrations in the blood lymphocytes, especially in the long term fractionated radiation therapy