Dosimetry of alpha-emitting radionuclides in bone--a practical approach.

The stopping power of bone and bone marrow as a function of alpha energy up to 10 MeV has been approximated in an integrable mathematical expression. Integration of the stopping power yields the particle path as a function of the particle energy. These two expressions have been used to calculate the stopping power and the dose rate for a planar bone-bone marrow interface. The calculations have been performed for four different bone marrow layers of 10 microns width as a function of the depth of burial in bone of a thin contaminated layer; five different alpha energies between 4 and 8 MeV have been considered. In addition, the stopping power and the dose rate have been calculated for various distances in marrow from the bone surface for a constant volume contamination. In both cases, most of the marrow lies in the range between 100 and 200 keV/micron, where most of the cell killing, mutation and transformation occurs.