The concentration of antimony in nail and hair was determined by thermal neutron activation analysis. Samples were collected from the workers of an antimony refinery, inhabitants near the refinery, and residents in control area. They were irradiated by Kyoto University 5 000 kW Reactor for 1 h, and cooled for 30 to 100 days. After cooling, the concentration of Sb in nail and hair was estimated by measuring the intensity of γ-ray from124Sb of the samples, then the samples were washed by 0.1% aqueous solution of nonionic surface active agent in an ultrasonic cleaner. The γ-ray spectrometry was done again (after washing) . The concentration of Sb in nail before washing was 730 ppm for the workers, 2.46 ppm for habitants near the refinery, and 0.19 ppm for the control; after washing, it became 230 ppm for the workers, 0.63 ppm for habitants, and 0.09 ppm for the control. The concentration of Sb in hair before and after washing was 222 ppm and 196ppm for the workers, and 0.21 ppm and 0.15 ppm for the control, respectively.
The investigations about the radiolysis materials and their quantities, and, anti-microbial activities of γ-irradiated (in the ranges of 0.516-2.064 kC/kg (2-8 MR) ) acrinol on liquid dosage form have been carried out to study the application of radiosterilization. About nine components were found as radiolysis materials. Most of them were also found in the UV irradiated of Fenton's reagent-treated acrinol solution. Increase of anti-microbial activity was observed with γ-irradiated acrinol solutions, but this phenomenon was not long-lasting. The micro-organism such as Pseudomonas aeruginosa or Staphylococcus aureus that infect at the lips of wound are highly sensitive to the γ-irradiation. They are almost sterilized by the irradiation of 10 kGy (1.0 Mrad) . At a low acrinol concentration, the decomposition rate of acrinol by the irradiation was relatively high. When 1.0% of acrinol solution was irradiated at a dose of 10 kGy (1.0 Mrad), the decomposition of the drug was less than 2% and the variation of anti-microbial activity was negligible.
We studied the quantity of thallium-201 myocardial single photon emission CT (SPECT) image with a cardiac phantom. The myocardial SPECT image is influenced by several causes, i.e., the absorption of gamma rays, collimator aperture, statistical noise and limited angle of rotation in data acquisition. The attenuation correction under the assumption of uniform distribution is not sufficient, so we have to consider the actual distribution of absorption. The effects of the nonuniform attenuation are most prominently appeared when we evaluate the quantity by the integral method. The aperture characteristics of a collimator are decided by the distance between the rotational center of the gamma camera and the collimator surface. Simultaneously scattered gamma rays affect the reconstructed image in the low frequency component, so the effective attenuation coefficient varies gradually. The statistical noise intermixed in the projection data generate artifacts like as lumpshaped pattern. The noise are clearly appeared in the spatial frequency upper than 0.25 cycle, so the low-pass filter are required with that of cut-of frequency. Moreover to enhance the details of the radionuelide distribution of cardiac muscle, the Wiener filter should be applied. The scan area also affects the appearance of the artifact in the myocardial SPECT image. The 180-degree scan usually generates false defects just nearby the center of reconstructed cross section. And the positions are changed with the conditions of gamma ray absorber and its relative position to the myocardial area. The 360-degree scan should be used from the standpoint of reconstructing more quantitative image.
(1) Adsorption properties of14C-alanine, 14C-ATP (adenosine triphosphate) and14C-aspartic acid on the metal-chelating resins were determined and found that the Cu (II) -Chelex 100 and Fe (III) -Unicel-lex UR10, Fe (III) -Chelex 100 chelating resins were highly effective for the adsorption of14C-alanine and14C-ATP, respectively. (2) Desorption rate of14C-ATP from the Fe (III) -Unieellex UR10 and Fe (III) -Chelex 100 resins was somewhat higher than the case of14C-alanine, probably because the coordination bonds of Cu-alanine might be stronger than those of Fe-ATP.Thus, 14C-labeled organic compounds such as14C-alanine and14C-ATP of a low activity concentration (3.7 mBq/ml) (1 × 10-7μCi/ml) in aqueous solution may be measured with liquid scintillation counter after pre-concentration by use of the Fe (III) -and Cu (II) -chelating resin columns.
“Dead water”, low level tritiated water is indispensable to measure tritium concentration in environmental waters using a low background liquid scintillation counter. Water produced by combustion of natural gas, or deep sea water etc. are usually used for the above purpose. A new method of reducing tritium concentration in natural water has been introduced for preparation of“dead water”. This method is to combine hydrogen-oxygen mixture produced by water electrolysis with hop calite catalyzer at 700°C. Deep well water was electrolized up to 2/3 volume, and tritium concentration of recombined water was reduced to be about one third of that of the original one.
The highest60Co γ-ray field available in Radiation Center of Osaka Prefecture was determined employing a cylindrical cavity chamber which has been calibrated with the national standard up to 7.7 (C kg-1) /h (30 kR/h) . For higher exposure rate regionn four stage of calibrations were carried out up to 3.7 (kC kg-1) /h (14 MR/h), which is higher than ever reported, based on the additivity of gamma intensity in terms of the source activity. The errors accompanied with the resultant values were estimated as 6% at most. Axial dose rate distributions in the irradiation cans used in the irradiation pool were measured with PMMA dosimeters.
Clinical utility of determination of serum deoxythymidine kinase (TK) activity is described. It is well known that elevated TK level is observed in leukemia and other malignant diseases, or some viral infectious diseases. The TK activity was assayed on normal subjects, hepatitis B virus (HBV) positive liver diseases and various cancer by a newly developed high sensitive method, radio enzyme assay (REA) utilizing125I-iododeoxyuridine as the substrate. Measurement of TK activity by the REA is revealed to be useful for“the marker of DNA metabolism anomaly”in leukemia, etc.