Dose to Bone from Strontium-90: Implications for the Setting of the Maximum Permissible Body Burden

Abstract

Consideration is given to the choice of critical tissues in bone in relation to the setting of the mpbb [maximum permissible body burden] for Sr90, and the [beta]-particle dose rates to bone marrow and to endosteal tissues in trabecular bone are then calculated. The calculations are based on mensuration of certain bones of the skeleton and on measured distributions of marrow cavity sizes in the trabecular bone. The dose rates for a skeletal burden of the 1 [mu]Ci Sr90 + y90 are 0.55 rad/year to bone marrow and 1.1 rad/year to endosteal tissues. Assigning a bone marrow dose of 5 rem/year would imply a value of the mpbb for Sr90 of 9[mu]Ci. The dose rate to the bone marrow of a child aged 5 years is also calculated to be 4.1 rads/ years for a skeletal burden of 1 [mu]Ci and 0.82 mrad/year for a skeletal contamination of 1 s.u.