Quantitative organ-uptake measurement with a gamma camera.

A study was carried out to investigate the use of a gamma camera for quantitative measurement of the absolute radioactivity in internal organs. Phantoms simulating different patient conditions were used to derive the attenuation correction factor and the conversion factor which relates a known radioactive dose to organ activity. The delimitation of the source image was established by means of an isocontour of maximum count rate. A mathematical approach was used for achievement of isosensitivity with depth of the organ and for correction for background. The accuracy of the procedure was proven by the recovery over the stomach area of the ingested activity. The method is applied to the quantitative assessment of the splenic red-cell volume.