The dosimetry of radioisotopes incorporated in bone using cavity ionization theory

Abstract

Cavity ionization theory is applied to the dosimetry of bones incorporating .beta.- and .gamma.-emitting radioactive isotopes. The assumptions inherent in different theoretical approaches to bone dosimetry are reviewed and compared with those adopted in cavity theory. Attention is given to the effects of electron and photon attenuation and to the absence of electronic equilibrium which may occur in bone. The mean marrow dose is calculated for a range of cavity size and .gamma.-ray energies and for a .beta.-ray emitter. The mean marrow dose and the mean endosteal dose are calculated for a human lumbar vetebra and some comparisons made with the results. Cavity theory provides a useful approach to the dosimetry problems of bone-seeking .beta.- and .gamma.-ray radioactive isotopes.