eeeSounded by a low photon flux. Most of these studies were performed : presence of this equipment in combination with the use of iodine-123 makes such a study possible with a high degree of accuracy. Our method of 99m. uptake has been previously presented (20). now been utilized for early iodine-123 uptakes as well. It has The pin-hole collimator is positioned 19cm above the surface of the neck and sequential images are obtained over the next half-hour following intravenous administration of the radiopharmaceutical. technetium-99m. A 4.75 om pinhole is used with For the dynamic part of the study, a 10 mm pinhole is used with iodine-123 because of the relatively low level of activity per patient available to us with this radionuclide (~90,Ci). study with fodine-123 the smaller pinhole is For detailed anatomical used. The radioiodine studies were performed on each patient the day following the technetium study. Following field correction of the pinhole images, curves were generated of counts per minute over the thyroid area and a background area just The background curve was subtracted from the thyroid beneath the thyroid. area curve to obtain a net thyroid uptake curve. The results were converted to percent uptake in the thyroid by comparison of a standard in a neck phantom counted with the Same geometry and corrected for radioactive decay. The results were then submitted to a larger computer facility for processing using the Berman and Weiss SAAM program (30). This program smoothed the curves by least squares fitting and gave the slopes and intercepts for a \ two component: solution. At the time of this writing 26 patients have been studied by this Procedure. was Of these, three were hyperthyroid and 23 euthyroid. \ thought to have Hashimotos thyroiditis. 50071354 One patient A comparison of the