Estimation of Absorbed Doses in the Cell Nucleus after Incorporation of 3 H- or 14 C-Labeled Thymidine

The estimation of absorbed doses in cellular and subcellular structures after incorporation of radionuclides is especially difficult if these radionuclides are distributed inhomogeneously. Such inhomogeneous distributions can be the result of an incorporation into specific parts of the structure (for example, incorporation of labeled thymidine into DNA). This directed incorporation of thymidine during and after the pulse labeling was traced by liquid scintillation counting. Besides the activity change of labeled cell nuclei, that of the cytoplasm was studied also. The data obtained allow a good estimation of the absorbed dose in the nucleus after pulse labeling with tritium- and carbon- 14-labeled thymidine as well. For the calculation of the dose, procedures known from the literature are available. They are compared in this paper.