Analysis of the Radioactive Content of Tissues by α-Track Autoradiography

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Abstract
An autoradiographic techniques is described based on the measurement of track lengths of [alpha]-paticles emitted from tissue sections recorded in photographic emulsions. The distribution of track lengths from a section of finite thickness is derived, and analysis of this distribution allows determination of the tissue radioactivity. The technique was applied to two practical problems (a) the calculation of tissue dosage from thorotrast introduced into the body as a radiographical contrast medium, and (b) the measurement of the radium content of the bones of a subject who ingested radium. In the thorotrast work analysis provides a measure of the activity of parent thorium relative to that of its decay products RdTh, etc.; the relative content varies according to the age of the thorotrast and the proportion of soluble products retained in the body. In the radium work, the distribution suggested, in addition to radium, the presence of RaD derived from inhaled radon; resolution was not good enough to measure the relative activities of these elements accurately, but did give limits for the radium content of the bone.