Autoradiographic Studies of the Distribution of Radium-226 in Rat Bone: Their Implications for Human Radiation Dosimetry and Toxicity

Abstract

A solution containing 226Ra chloride was injected into young female rats via the saphenous vein. Subsequently, the distribution and retention of the 226Ra in the skeleton was studied. The results show that: 1226Ra is initially deposited in the rat femur as a volume deposit and is fairly evenly distributed throughout the bone matrix. 2 Much of the 226Ra initially deposited in the skeleton is lost within a few days of its administration. 3 During the first week 226Ra gradually accumulates at sites of bone deposition including accreting surfaces. 4 Subsequent bone growth results in the burial of contaminated bone surfaces and 5 Following bone resorption some of the 226Ra released from individual bones is recycled systemically so that all skeletal components tend towards a uniform 226Ra concentration per unit of bone mineral. Of the two models conventionally used for radiation dosimetry purposes, the results reported here for rats suggest that though neither is ideal, the volume distribution model is preferable to the surface model at all times after the uptake of radium by the skeleton.