Effects of Radiation on Living Organisms Project Title: 17. Early and Late Effects of Radiation of Different Qualityand at Different Dose Rate RX-03-0]-(4) Expected Results in FY 1974: (Conc'd.) these studies extended to include x radiation, (Shellabarger) If collaborative support is continued, the effects of multiple exposures on the visual acuity of monkeys will continue to be studied. It is hoped that techniques of electrophysiological measurements in the elasmobranch brain as a parameter for radiation effects will be perfected, If this is not accomplished, an established technique for specific measure- ments on the olfactory tract will be used after radiation of the olfactory nerves, Lerner Marine Laboratory may install an x-ray machine. It would then be possible to investigate the effects of radiation on a number of marine organisms which are now impossible with the present Co-60 source designed for narrow beam irradiation of specific areas. (Carsten) The high RBE's obtained for mammary gland tumor induction have obvious theoretical importance as well as practical implications. Radiation protection guides for radiation workers and for nuclear medicine procedures in which high LET radiations are used perhaps should be reconsidered in this light. In addition, interpretation of the data from Hiroshima and Nagasaki, in which a part of the exposure was due to neutrons, depends very much on the neutron RBE for tumorogenesis as a function of dose. For these reasons, systems in addition to mammary gland neoplasia will be studied. In particular, efforts will be made to begin experiments on myelocytic leukemia induction in mice. This probably will involve a collaborative program between the Medical Department at Brookhaven and the Medical Center at the State University of New York at Stony Brook (Dr. Arthur Upton). 18. . Expected Results in FY 1975: The sophisticated instrumentation and experimental techniques required for the microbeam experiments will require extensive development work, The LET of the traversing particle will be varied by adjusting particle energy. This approach should allow direct observation of the probability of single cell’ inactivation by particles of different LET, should remove a large area of uncertainty in determining the kinetics of cell inactivation, and should give considerable insight into mechanisms of cell inactivation. It is expected that much progress will be made in perfecting the rather demanding tec of goes required to perform chis type of exposure of sizable population xis. fe. Discussions are being held regarding two types of collaborative studies. These include RBE studies of leukemia induction and research in radiation genetics. It appears probable that both of these efforts will be well under (See Continuation Sheet) 1119269 RX-172