Abstract
According to thereciprocity law, the total dose absorbed in a specimen irradiated by a point source can be inferred from the reciprocal situation, where the absorber is replaced by a source of the same shape and the radiation is measured at the position of the original point source.
In this paper, for a spherical source of homogeneous radioactive material with absorption coefficient μ1, we calculate the intensity of radiation (or flux) at a pointP, as well as the intensity which would be found at the same point if μ1 were zero. The ratio between these two quantities is denoted byk. We assume throughout that absorption follows the simple exponential law.
Self-absorption can also be characterized by the numberv, which is defined as the ratio between the total radiation current flowing through the surface of the source and the total current obtained if there were no absorption.
For a homogeneous spherical source in a nonabsorbing medium it is shown that the quantityk becomes equal tov if the distance between the pointP and the center of the sphere is sufficiently large. This fact was used by W. K. Sinclair in estimating an absorption coefficient from his experimental results.
We also derive an expression for the self-absorption ratio,v, of acylindrical source. In the limiting case of an infinitely long cylinder our result coincides with an equation previously found by S. Kushneriuk.
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This work was performed under the auspices of the U.S. Atomic Energy Commission.
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Trucco, E. Self-absorption in spheres and cylinders of radioactive material. Bulletin of Mathematical Biophysics 26, 303–325 (1964). https://doi.org/10.1007/BF02484232
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DOI: https://doi.org/10.1007/BF02484232