Microscopic dose distributions due to iodine isotopes in thyroid.

Microscopic electron dose distributions inside and outside the colloid spheres of thyroid tissue of radii 15-150 micron containing 1.5 muCi/g 123I, 125I, 131I, and 132I uniformly distributed have been calculated by the application of Berger's scaled absorbed dose functions approximately standard polynomial regression techniques. For 131I, 123I and 132I whose electron or effective beta energy ranges are at least few times more than the sphere sizes considered the contributions of energy emitted from neighbouring follicles have been included into the dose calculations. Additionally, the frequency mean and energy mean of microscopic event-size distributions in small spherical 125I sources have been computed in rad per one 125I disintegration.