Radiation risk of thyroid scintigraphy in newborns.

Tumor risk factors were calculated for newborns who were investigated for congenital hypothyroidism (CHT) with radionuclides by thyroid scintigraphy. Figures for three radiopharmaceuticals, 99mTc-pertechnetate, 123I-and 131I-sodium iodide for adults were extrapolated to newborns. The radiation dose to the normal thyroid gland in newborns was seven times higher for 123I-NaI than for 99mTcO-4, the somatically effective total body dose was two times higher for 123I-NaI than for 99mTcO-4. The use of 123I-NaI was preferred because of better scintigraphic results. Risk estimates for thyroid scintigraphy in newborns in the diagnostic work-up of CHT are given using published age-dependent tumor induction figures derived from atomic bomb survivors.