Low Dose Suppression of Neoplastic Transformation in Vitro

John Leslie Redpath

关键词: DELTA RAYS;    DOSE RATES;    DOSE-RESPONSE RELATIONSHIPS;    IN VITRO;    IONIZING RADIATIONS;    IRON IONS;    NEOPLASMS;    ONCOGENIC TRANSFORMATIONS;    PHOTONS;    PROTONS;    RADIATIONS;    RISK ASSESSMENT;    SHAPE;    TRANSFORMATIONS Low dose low-LET radiation;    cancer risk;   

DOI  :  10.2172/1039285
RP-ID  :  DOE-ER63648- Final Report
PID  :  OSTI ID: 1039285
Others  :  TRN: US1202644

学科分类：放射科、核医学、医学影像

美国|英语

来源: SciTech Connect

【 摘 要 】

This grant was to study the low dose suppression of neoplastic transformation in vitro and the shape of the dose-response curve at low doses and dose-rates of ionizing radiation. Previous findings had indicated a suppression of transformation at dose <10cGy of low-LET radiation when delivered at high dose-rate. The present study indicates that such suppression extends out to doses in excess of 100cGy when the dose (from I-125 photons) is delivered at dose-rates as low as 0.2 mGy/min and out to in excess of {approx}25cGy the highest dose studied at the very low dose-rate of 0.5 mGy/day. We also examined dose-rate effects for high energy protons (which are a low-LET radiation) and suppression was evident below {approx}10cGy for high dose-rate delivery and at least out to 50cGy for low dose-rate (20cGy/h) delivery. Finally, we also examined the effect of low doses of 1 GeV/n iron ions (a high-LET radiation) delivered at high dose-rate on transformation at low doses and found a suppression below {approx}10cGy that could be attributable to an adaptive response in bystander cells induced by the associated low-LET delta rays. These results have implications for cancer risk assessment at low doses.