The full energy peak efficiencies (FEPE) to Ge (Li) detectors with three different radius rD have been measured by using point sources of24Na, 54Mn, 57Co, 60Co, 133Ba and137Cs, as functions of source-detector distance d and of distance L from the center axis of the detector. Using the reduced distance l which is L/rd, all measured FEPE distributions for d and gamma-ray energy E are found to be scaled approximately to an universal curve. This curve is simply fitted to a quadratic equation of l for each d and E. The coefficient of a squared term is also found to have a simple relation against d and E. The correction factor Kc (r, d, E) of FEPE to disc sources with reduced radius r, using the same notation as 1, is easily calculated by these equations. The calculated Kc (r, d, E) values are in good agreement with measured ones by using a disc source of24Na.
Adsorption behavior of radiogallium (67Ga, 68Ga) on non-ionic MR resin (XAD-7) from hydrochloric acid, lithium chloride and other metal chloride solutions, and purification of68Ga by this resin were studied. Radiogallium was adsorbed on XAD-7 rapidly and quantitatively from the solution of higher chloride concentration than 6M. The adsorption behavior is similar to that obtained with59Fe and195Au previously. Based on adsorption data, elimination of trace amount of68Ge commonly contained in68Ga milked from a68Ge/88Ga generator was tried. When68Ga-6M hydrochloric acid solution containing68Ge was passed through a XAD-7 column, all the activity was transferred on the column. After eliminating68Ge fraction with 3M hydrochloric acid, 68Ga was obtained in high purity by eluting with 0.1M hydrochloric acid.
Splenectomy is known to increase the risk of bacterial infection. Recently splenic autotrans-plantation has been suggested as a method of preserving splenic function. In order to demonstrate the viability of transplanted tissue, spleen scintigraphy using99mTc labeled heat damaged erythrocytes were carried out. So far 21 studies have done in 12 patients. Spleen scans were positive 1 month after surgery, though images showed poor contrast against considerable background of bone marrow and blood pool. The quality of the images much improved five to twelve months after surgery. Functioning splenic autografts could be also shown by scintigraphy using99mTc sulfur colloid, but the image quality was poorer, particularly within the early stage after operation. Labeling yields were 79.8% on the average, ranging from 45.6-92.3%, that affected little the quality of images. Important techniques in the splenic autotransplantation imaging include a thorough elimination of free99mTcO4-before injection and to use comparatively small volume of damaged erythrocytes.