Absolute determination of thyroid activity from profile scans. Description of a correction method for extra-thyroidal activity of the neck. , pt. 2

An absolute method to measure the uptake of radioactive iodide by the thyroid by making a profile scan across the thyroid region with a slit-collimated detector is described. It is well known that the extra-thyroidal activity (ETA) in the neck may constitute a severe hindrance to measure the uptake accurately, especially in cases of hypothyroidism and often during the first few hours after the administration of the traces dose (e.g. orally 0.5 μCiNa131I). The author's approach to the problem is presented. A practical application of the method is discussed in extenso. A comparative evaluation of the usability of 123I and 131I as least-burdening radionuclides for child patients is given at the end