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Our modification of a method for the absolute quantification of gallium-67 uptake in lungs with a scintillation camera and computer is described. The uptake of 67Ga in lungs, expressed in percentage of administered radioactivity, was determined by the transmission-emission method. We proved theoretically and experimentally that a 67Ga planar source could be replaced with a 57Co planar source. The performance of lung perfusion scans allows a more accurate delineation of the regions of interest on gallium scans. The method was applied to control subjects (n = 27) and to patients (n = 114) suffering from biopsy-proven pulmonary sarcoidosis (28 with inactive and 86 with active disease). The obtained results were compared with chest X-ray findings, the percentage of lymphocytes in the bronchoalveolar fluid (BAF-ly%), and serum angiotensin-converting enzyme (SACE) values. The method seems suitable for the assessment of disease activity in sarcoidosis. It is more accurate in detecting parenchymal involvement in lung sarcoidosis than the commonly used X-ray criteria. No correlation was found between 67Ga uptake and the BAF-ly% and SACE values.

A total of 39 99mTc eluates obtained from 9 99Mo--99mTc generators delivered by The Radiochemical Centre Amersham during one year was studied with regard to their radionuclide purity. Using a Ge(Li) spectrometer the contaminants 60Co, 103Ru, 131I, 134Cs, 140Ba, 140La and 188Re were found in 99mTc-eluates with average levels ranging from 2.9 X 10(-3) to 2.8 X 10(-1) per cent of 99mTc activity. The additional total body absorbed dose caused by these contaminants, as calculated from their average content in 99mTc eluates, was less than 1% of the dose due to 99mTc pertechnetate.

Several methods for the measurement of dead time and for evaluation of the dependencies required to correct dynamic studies for dead-time losses are described. Two program variants were written to produce time-activity curves in the selected areas of interest of the dynamic studies with computer's correction of dead-time losses; these variants are part of the system of programs for complex processing of scintigraphic studies set up for a Clincom instrument. The first variant performs correction on the basis of the registered count rate in the whole image, while the second variant makes us of the additional reference source positioned on the periphery of the camera visual field.

Using the specific absorbed fractions reported by Smith and Warner, the radiation doses absorbed by the embryo in early pregnancy were calculated for various radiopharmaceuticals used in the diagnostic procedures of nuclear medicine. Radiopharmaceuticals are considered which are excreted predominantly through urine and cause the doses to the embryo to be 40%--90% higher than gonad doses. Also discussed are large differences of doses reported by various authors to the embryo by 99mTc-pertechnetate.