Irradiation to the thyroid gland at cardiac catheterization and angiocardiography in children.

Irradiation to the thyroid gland was measured during cardiac catheterization in 16 infants and 30 children aged 1 to 13 years. The doses from fluoroscopy, full-scale angiocardiography, and cineradiography were measured separately with thermoluminescent dosimeters and, in addition, the exposure-area product was assessed during fluoroscopy with a transparent ionization chamber. Median value of the absorbed dose to the thyroid from the complete heart investigation was 370 mrad in infants and 260 mrad in children. The highest values and also the greatest range in dosage were observed in infants. The quotient of the thyroid-absorbed dose divided by the integral dose or the dose per exposed film area was also highest in infants, due to anatomical conditions. The absorbed dose to the thyroid during heart catheterization comes almost exclusively from scattered radiation. By appropriate examination technique this dose can be kept within acceptable limits.