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Title: Theoretical and observational analysis of individual ionizing particle effects in biological tissue

The microstructural damage to living tissue caused by heavy ion radiation was studied. Preliminary tests on rat corneal tissue, rat cerebellar tissue grown in culture, and rat retinal tissue indicated that the best assay for heavy ion damage is the rat cornea. The corneal tissue of the living rat was exposed to beams of carbon at 474 MeV/amu, neon at 8.5 MeV/amu, argon at 8.5 MeV/amu, silicon at 530 MeV/amu, iron at 500 MeV/amu, and iron at 600 MeV/amu. X-rays were also used on corneas to compare with the heavy ion irradiated corneas. Scanning electron microscopy revealed lesions with circular symmetry on the external plasma membranes of corneal epithelium which were irradiated with heavy ions, but similar lesions were not observed on the plasma membranes of x-ray irradiated or non-irradiated control samples. These data verify the special way in which heavy ions interact with matter: each ion interacts coulombically with electrons all along its trajectory to generate a track. The dose from heavy ion radiation is not distributed homogeneously on a tissue microstructural scale but is concentrated along the individual particle track. Even along a single particle track the dose is discontinuous except at the Bragg peak when the LETmore » is maximum. Micrographs of heavy-ion-irradiated corneas demonstrated two significant correlations with the heavy ion beam: (1) the number of plasma membrane lesions per unit area was correlated with the particle fluence, and (2) the diameter of the lesions were linearly related to the energy loss or LET of the individual particle. These observations corroborate what has already been suggested theoretically about heavy ion tracks and what has been shown experimentally. But the new data indicate that particle tracks occur in biological tissues as well, and that a single heavy ion is responsible for each membrane lesion. (ERB)« less
Authors:
Publication Date:
OSTI Identifier:
6759783
Report Number(s):
LBL-11147
TRN: 81-002086
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Technical Report
Resource Relation:
Other Information: Thesis
Research Org:
California Univ., Berkeley (USA). Lawrence Berkeley Lab.
Country of Publication:
United States
Language:
English
Subject:
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; CORNEA; BIOLOGICAL RADIATION EFFECTS; ARGON 40 BEAMS; CARBON 12 BEAMS; COMPARATIVE EVALUATIONS; ELECTRON MICROSCOPY; EXPERIMENTAL DATA; IRON 56 BEAMS; LET; LOCAL IRRADIATION; MEV RANGE 01-10; MEV RANGE 100-1000; NEON 20 BEAMS; PARTICLE TRACKS; RATS; SILICON 28 BEAMS; SPATIAL DOSE DISTRIBUTIONS; X RADIATION; ANIMALS; BEAMS; BIOLOGICAL EFFECTS; BODY; BODY AREAS; DATA; ELECTROMAGNETIC RADIATION; ENERGY RANGE; ENERGY TRANSFER; EYES; FACE; HEAD; INFORMATION; ION BEAMS; IONIZING RADIATIONS; IRRADIATION; MAMMALS; MEV RANGE; MICROSCOPY; NUMERICAL DATA; ORGANS; RADIATION DOSE DISTRIBUTIONS; RADIATION EFFECTS; RADIATIONS; RODENTS; SENSE ORGANS; VERTEBRATES 560152* -- Radiation Effects on Animals-- Animals