Estimation of absorbed dose in cell nuclei due to DNA-bound 3H

The average absorbed dose due to DNA-bound 3H in a cell nucleus was estimated by a Monte Carlo simulation for a model nucleus which was assumed to be spheroidal. The shape of the cell nucleus was found to be of minor importance in determining the average absorbed dose. The volume of the cell nucleus was the major dose-determining factor for cell nuclei which have the same DNA content and the same specific activity of DNA. This result was applied to estimating the accumulated dose in the cell nuclei of organs of young mice born from mother mice which ingested 3H-thymidine with drinking water during pregnancy. The values of dose-modifying factors for the accumulated dose due to DNA-bound 3H compared to the dose due to an assumed homogenous distribution of 3H in organ were found to be between about 2 and 6 for the various organs.