The scintillation counter in clinical studies of human thyroid physiology using I131.

Abstract

DIRECTIONAL and wide-angle scintillation counters have been employed in various clinical studies of human thyroid physiology using eight-day radioiodine. These studies have evolved the precise delineation of the area covered by the thyroid and measurements of the rate of uptake and the total uptake of I131 by the thyroid gland, using doses of 10 microcuries. These studies have been possible because the scintillation counters employed are more efficient detectors of the gamma radiation from eight-day radioiodine than the Geiger-Muller tubes now in general use. Even specially designed Geiger tubes respond to about 2 per cent of the total gamma ray emission from a radioactive source (1). Thus, up until this time the intrinsic insensitivity of the Geiger-Muller tube has limited progress in the in vivo studies of thyroid physiology and therapy in human beings.