No abstract available

[en] Experiments reported here were conducted with carbon ions, neon ions, and argon ions using rat brain gliosarcoma (9L) and Chinese hamster lung V79 cells grown as multicellular spheroids. Our studies were designed to evaluate high-LET radiation survival characteristics of cells grown in this relatively organized tissue-like environment. Our primary objectives were to determine the RBE values in plateau and spread Bragg peak regions of the carbon, neon, and argon beams, and evaluate with high and low LET radiation, the role of spheroid architecture in postirradiation survival of cells grown in this format

[en] In this historic overview of the role of the Lawrence Berkeley Laboratory in the development of accelerator technology, the advantages of charged particle radiotherapy are emphasized. These include the precise delivery of radiation dose to the tumor with a concomitantly low dose to surrounding tissues; the depth dose distributions and the reduction of the oxygen effect by heavy ions

[en] A knowledge of both physics and biology is required to understand how radiation can cause cell damage or death. This book focuses on the following topics: atomic physics and radiation chemistry; cell killing as an endpoint of radiation; radiation carcinogenesis, genetic effects and risk assessment; the basis of the enhanced biological effects of high linear-energy-transfer radiation; and sources of ionizing radiation in our environment

[en] The effects of high LET radiations produced with accelerated heavy-ion beams on weight loss of the mouse testes have been examined. It is assumed that weight loss is due primarily to cell death in the germinal epithelium. Results indicate that little or no recovery of sublethal injury occurs in this cell renewal system. Generally, the RBE rises continuously and monotonically for all LET values associated with helium and carbon from 6 to 100 keV/μm. On the other hand, the data for neon and argon do not appear to fit. From the standpoint of the radiobiology of heavy ions, the most significant observation is that LET alone does not account for variation in radiation response of the spermatogonial population

[en] Our studies using the sandwich system consists of developing the system as a tumor analogue; characterizing the diffusion limitations and cell kinetics of the system; using the system in radiation experiments; analyzing the effect of varying the oxygen and glucose concentrations in the system; and developing an oxygen-glucose model for growth and necrosis and applying it to the system

[en] Biological investigations with accelerated heavy ions have been carried out regularly at the Lawrence Berkeley Laboratory Bevalac for the past four years. Most of the cellular investigations have been conducted on cell monolayer and suspension culture systems. The studies to date suggest that heavy charged particle beams may offer some radiotherapeutic advantages over conventional radiotherapy sources. The advantages are thought to lie primarily in an increased relative biological effectiveness (RBE), a decrease in the oxygen enhancement ratio (OER), and better tissue distribution dose. Experiments reported here were conducted with 400 MeV/amu carbon ions and 425 MeV/amu neon ions, using a rat brain gliosarcoma cell line grown as multicellular spheroids. Studies have been carried out with x-rays and high-energy carbon and neon ion beams. These studies evaluate high-LET (linear energy transfer) cell survival in terms of RBE and the possible contributions of intercellular communication. Comparisons were made of the post-irradiation survival characteristics for cells irradiated as multicellular spheroids (approximately 100 μm and 300 μm diameters) and for cells irradiated in suspension. These comparisons were made between 225-kVp x-rays, 400 MeV/amu carbon ions, and 425 MeV/amu neon ions

[en] This study was undertaken to determine the degree of interaction between the feeder cell concentration and the spheroid cell and conventional cell culture survival curves using the 9L cell line and 9L-cell spheroids

[en] To set the background for a meaningful discussion of population exposure from the nuclear fuel cycle, it is necessary to examine the competing contributors to radiation exposure for the human population. There is extensive documentation in various sources of the elements which make up the exposure of human beings to naturally occurring radiation. However, there are 3 draft documents of the National Council for Radiation Protection and Measurements which are soon to be published, and which cover, in detail, the three important aspects of this question. The three reports are those of Scientific Committee 43, Exposure to the Population in the US and Canada from natural Background; Scientific Committee 28; Radiation Exposure from Consumer Products and Miscellaneous Sources; and Scientific Committee 44, Exposure of the US Population to Diagnostic Medical Radiation. It is the purpose of this contribution to review and highlight the contacts of these documents. The dose from the first two of these sources is highly dependent upon location and other factors, but the general range of doses from natural radiation sources in the US is about 70-110 mrem/y. (0.7-1.10 mSv/y). Within recent years there has been a sharp increase in public awareness of the importance of the contribution of naturally occurring radon to exposure. Background radiation is well understood by the audience of this conference, therefore emphasis will be placed on the newer contributions relative to Quality Factor. There will be some discussion of the role of consumer products and technological enhancement of the natural contribution, as well as on the medical diagnostic exposure, which typically in advanced countries will range from 100-150 mrem/y (1.0-1.5 mSy/y). Exposure from technological enhancement and from consumer products contributes less than 10% to the total, but both are the result of human activity, and should be well understood and controlled

[en] We will obtain RBE estimates and alpha:beta ratios for the induction of heavy ion-radiation myelopathy in the rat after single doses and multiple fractions. We are examining the hypothesis that the multifraction linear-quadratic model predicts a higher relative biological effectiveness (RBE) for late tissue damage and a higher alpha-beta ratio after heavy-ion irradiation. We will also determine the repair potential of the spinal cord after fractionated doses of neon ions (670 MeV) in the plateau region of ionization. 5 refs., 4 figs., 1 tab