Thyroid radiation absorbed dose from diagnostic procedures in U.S. population.

Area of Science:

• Nuclear medicine
• Radiology
• Medical imaging

Background:

• Thyroid imaging methods, including radionuclide scans and uptake studies, saw a significant increase in utilization in the U.S. from 1966 to 1981.
• This rise in procedures outpaced U.S. population growth during the same period.

Purpose of the Study:

• To analyze trends in thyroid imaging procedures and associated radiation doses.
• To evaluate the impact of changing radioisotope usage on collective absorbed dose.

Main Methods:

• A survey of thyroid imaging methods conducted in the United States in 1981.
• Comparison of data from 1966 and 1981 regarding procedure volumes and radioisotope utilization.
• Calculation of collective absorbed dose based on radioisotope type and study frequency.

Main Results:

• Radionuclide thyroid scans and uptake studies increased by 250%-300% between 1966 and 1981.
• Collective absorbed dose from these procedures decreased from 18 x 10^6 rad in 1966 to 13.9 x 10^6 rad in 1981.
• The reduction in dose was attributed to the increased use of iodine-123 and technetium-99m pertechnetate over iodine-131, and a decrease in standalone uptake studies. Iodine-131, despite reduced use, accounted for 93% of the collective dose in 1981.

Conclusions:

• Shifting to lower-dose radioisotopes like iodine-123 and technetium-99m pertechnetate significantly reduced collective radiation dose from thyroid imaging.
• Further reduction in radiation-induced cancer cases is possible by eliminating iodine-131 from diagnostic procedures.