Effects of Radiation on Living Organisms Early and Late Effects of Radiation of Different Project Title: Quality and at Different Dose Rate RX-03-Ol1-(a)| 13. Publicatcions: Tisljar-Lentulis, G. M., Bond, V. P., Robertson, J. S., and Moore, W. H., Jr. The let of 150-MeV protons and 70-MeV negative 7 mesons near the end of the particle tracks in polyethylene. BNL 50306, April 1971, ty 14. State Scope: A) 200 Word Summary: The primary objective of these studies is the accumulation of experimen- tal information fcr the development and evaluation of theories of radiobioclogic action through systematie collection of quantitative data on the effects of radiation on eukaryotic cells and tissues. The effects under study include cell killing, genetic effects, somatic mutation, growth reduction and tumor induction. ' The variation in degree of biological effect as a function of the microscopic distribution of energy deposition represents a principal avenue for the understanding of the biological action of radiation; the influence of radiation quality must be accounted for in any theory of the mechanisms involved. Neutrons provide a convenient and powerful tool for varying radiation quality, particularly for the exposure of mammalian systems. A modified Van de Graaff generator makes possible the production of essentially monoenergetic neutrons over a wide spectrum of energies. 3 Evidence for an association between radiation exposure and breast cancer in the human female continues to accumulate. Data on the neoplastic response of mammary tissue to ionzing radiation in the rat is extensive. The additional research proposed in these studies on the mammary neoplastic response of the rat to ionizing radiation should provide further insight towards an understanding of the qualitative aspects of mammary radiation carcinogenesis in man, B) Supplement to 200 Word Summary: The modified Van de Graaff generator at BNL, used originally as the injector for the Cosmotron, is the main feature of the Medical Department's Radiological Research Accelerator Facility (RARAF). The charged particle beams at the facility are capable of direct employment to investigate radiation damage mechanisms at the cellular and sub-cellular level. Precise dosimeghe and quantitative biological studies, coupled with microdosimetry W@Piated methods of theoretical analysis, provide a powerful approach Ge ing the basic mechanisms of interaction of radiation with biologi- cal systems. However, most of these studies are also pursued with a view for their practical implications to radiation protection and radiation therapy. Careful control of the various radiation environments produced and the high quality of dosimetric techniques utilized provide a facility uniquely suited (See Continuation Sheet) 11719258 RX-165 -