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An analysis of particle track effects on solid mammalian tissuesRelative biological effectiveness (RBE) and quality factor (Q) at extreme values of linear energy transfer (LET) have been determined on the basis of experiments with single-cell systems and specific tissue responses. In typical single-cell systems, each heavy particle (Ar or Fe) passes through a single cell or no cell. In experiments on animal tissues, however, each heavy particle passes through several cells, and the LET can exceed 200 keV micrometers-1 in every cell. In most laboratory animal tissue systems, however, only a small portion of the hit cells are capable of expressing the end-point being measured, such as cell killing, mutation or carcinogenesis. The following question was therefore addressed: do RBEs and Q factors derived from single-cell experiments properly account for the damage at high LET when multiple cells are hit by HZE tracks? A review is offered in which measured radiation effects and known tissue properties are combined to estimate on the one hand, the number of cells at risk, p3n, per track, where n is the number of cells per track based on tissue and organ geometry, and p3 is the probability that a cell in the track is capable of expressing the experimental end-point. On the other hand, the tissue and single-cell responses are compared by determining the ratio RBE in tissue/RBE in corresponding single cells. Experimental data from the literature indicate that tissue RBEs at very high LET (Fe and Ar ions) are higher than corresponding single-cell RBEs, especially in tissues in which p3n is high.
Document ID
20040088681
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Todd, P.
(2595 Vassar Drive, Boulder, CO 80303, United States)
Clarkson, T. W.
Date Acquired
August 21, 2013
Publication Date
January 1, 1992
Publication Information
Publication: International Journal Of Radiation Applications And Instrumentation. Part D, Nuclear Tracks And Radiation Measurements
Volume: 20
Issue: 1
ISSN: 0735-245X
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
Review, Tutorial
NASA Discipline Environmental Health
Review

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