The dosimetry of bone incorporating alpha-emitting radionuclides.

The previous work on the dosimetry of alpha-emitting radionuclides incorporated in bone is briefly reviewed. The application of cavity ionisation theory to problems of bone dosimetry is propounded and recent developments of the cavity theory for alpha particle fields are applied to bone dosimetry problems. The mean marrow dose over a large range of bone cavity size calculated by a simple theory using a mean chord length to characterise a cavity is compared with results of a more elaborate theory employing the chord length distribution for a sphere. The difference is not great. The influence of the shape of the cavity is explored by considering cylindrical cavities of different elongation. Data are presented for both volume-seeking and surface-seeking radioactive nuclides. The endosteal dose to a 10 mu layer is calculated as a function of cavity size for both volume-seeking and surface-seeking radioactive nuclides. The endosteal dose is also calculated for a surface seeker as a function of endosteal layer thickness. Finally, the results of these calculations are shown to be generally in good agreement with those of the calculations of earlier workers. It is concluded that a simple and reliable method of calculating the mean marrow dose and endosteal dose for both volume- and surface-seeking alpha emitters has been established.