Ratio of peak to total efficiencies for Ge detectors with six different relative efficiencies (εr) to a 3 in×3 in NaI (Tl) detector has been measured as functions of gamma-ray energy and of source-detector distance. The ratio is simply fitted to a linear equation of In εrin the range of 200 to 2000 keV gammaray energy. The parametric coefficients of the equation are also found to have a simple relation against gamma-ray energy.
We have reported fundamental studies on the TSH immunoradiometric assay, using TSH RIABEAD II kit (Dainabot) . The sensitivity of the assay was 0.03μIU/ml and its C. V. was 27.2%. Intra-and inter-assay C. V. were less than 5%. Dilution test and recovery test were good. Serum TSH level was 0.3-4.0μIU/ml in normal subjects, less than 0.03μIU/ml in untreated Graves' disease and subacute thyroiditis. Therefore, it was found that the clear difference exist in serum TSH levels between normal subjects and patients with untreated Graves' disease. There was a well correlation on the serum TSH levels between this method and TSH radioimmunoassay kit (Amerlex TSH, r=0.983) . Especially, the measurement of serum TSH levels, using Immunoradiometric assay kit, was useful for the diagnosis of patients with Graves' disease.
We have measured serum ferritin level using double antibody radioimmunoassay kit (Eiken ICL) and evaluated the characteristics of the kit and clinical usefulness. Satisfactory results were observed in standard curve, reproducibility, dilution and recovery test. In clinical evaluation, we have measured in normal subjects and patients with various diseases. The range in normal males and females were 13.0-158.7 ng/ml and 7.3-73.0 ng/ml, respectively. Serum ferritin level was elevated in patients with hepatoma, biliary cancer, lung cancer and other malignant diseases. Measurement of serum ferritin value would be useful in the monitoring of cancer patients.
In order to reduce radiation dose to the hands of examiners who prepare and aspirate radiopharmaceuticals, we made a prototype of simplified manually-operated dispense system, which the syringe and the vial shield with lead were set in the small box made of lead and lead glass. The result showed that our dispense system allowed substantial reduction of radiation dose to the hands and rapid preparation of radiopharmaceuticals compard with the conventional lead shield syringe system, and allowed closer operation, smaller dead volume and lower cost compared with the conventional automatic system.