Uterine radiation dose from open sources: the potential for underestimation.

The evaluation of the risk of radiation damage to the unborn child as the result of the administration of radionuclides remains a subject for discussion (Mountford 1989). Lack of information concerning the biodistribution of radiopharmaceuticals in the early stages of pregnancy, before organogenesis has occurred, has greatly restricted the objective assessment of fetal doses. Recent observations on the biodistribution of a therapeutic dose of sodium iodide 131 in a patient with an unsuspected early pregnancy lead us to suspect that current dose estimates with respect to uterine exposure (ARSAC 1988) may seriously underestimate the actual exposure of the developing fetus.