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Effects of track structure and cell inactivation on the calculation of heavy ion mutation rates in mammalian cellsIt has long been suggested that inactivation severely effects the probability of mutation by heavy ions in mammalian cells. Heavy ions have observed cross sections of inactivation that approach and sometimes exceed the geometric size of the cell nucleus in mammalian cells. In the track structure model of Katz the inactivation cross section is found by summing an inactivation probability over all impact parameters from the ion to the sensitive sites within the cell nucleus. The inactivation probability is evaluated using the dose-response of the system to gamma-rays and the radial dose of the ions and may be equal to unity at small impact parameters for some ions. We show how the effects of inactivation may be taken into account in the evaluation of the mutation cross sections from heavy ions in the track structure model through correlation of sites for gene mutation and cell inactivation. The model is fit to available data for HPRT mutations in Chinese hamster cells and good agreement is found. The resulting calculations qualitatively show that mutation cross sections for heavy ions display minima at velocities where inactivation cross sections display maxima. Also, calculations show the high probability of mutation by relativistic heavy ions due to the radial extension of ions track from delta-rays in agreement with the microlesion concept. The effects of inactivation on mutations rates make it very unlikely that a single parameter such as LET or Z*2/beta(2) can be used to specify radiation quality for heavy ion bombardment.
Document ID
20040173230
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Cucinotta, F. A. (NASA Langley Research Center Hampton, VA United States)
Wilson, J. W.
Shavers, M. R.
Katz, R.
Date Acquired
August 22, 2013
Publication Date
May 1, 1996
Publication Information
Publication: International journal of radiation biology
Volume: 69
Issue: 5
ISSN: 0955-3002
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Number 45-10
NASA Program Radiation Health
NASA Discipline Radiation Health