We have measured pulse shape and pulse height of the promising scintillators, LSO and GSO, and compared with those of BGO. The decay time of the LSO was approximately 40 ns, 1/8 of the BGO, and the light output was approximately 3.8 times of the BGO. The decay time of the GSO was approximately 50 ns, 1/6 of the BGO, and the light output was approximately 1.7 times of the BGO. As the decay time of GSO can be controlled by the concentration of Ce doped in GSO, it was possible to separate two GSOs by using the pulse shape analysis. The possibility of performance improvement of PET by using BGO or GSO was also discussed.
After the Chernobyl nuclear power plant accident, relatively high radioactive cesium levels were detected in various mushrooms produced in many countries. Mushrooms have a high transfer factor, showing a relatively high uptake of cesium from wood and soil from which they grow. In the present investigation, we analysed radioactive cesium concentrations contained in the dried Lentinula edodes (Shiitake) produced in various prefectures all over Japan, and examined the effectiveness of this mushroom as an indicator of radioactive contamination of environment due to nuclear explosion tests and Chernobyl power plant accident. We collected dried Lentinula edodes (Shiitake) grown on the wood from 32 prefectures from north to south, and measured137Cs and134Cs concentrations with high purity Ge-detectors. Levels of137Cs concentration were found to vary from 3.4 to 33.6 Bq/kg, while those of134Cs were less than detectable. 137Cs concentrations in Lentinula edodes (Shiitake) samples showed a statistically significant positive correlation with those in rain and dry fallout at 1% significance level. They also proved to have been inversely correlated with atmospheric temperature at 10% significance level, but it could not be determined whether it was only an apparent correlation or not because no information of137Cs concentrations in wood was available. Multiple correlation coefficient of137Cs concentrations with atmospheric temperatures and fallout levels was 0.54 which was statistically significant at 2.5% level. A variance analysis based on the137Cs concentrations in Lentinula edodes (Shiitake) classified into 7 groups (Hokkaido-Tohoku, Kanto, Chubu, Kinki, Chugoku, Shikoku and Kyushu) showed that the variance between the groups was significantly greater than that within each group, which suggested, together with the above-mentioned information regarding the correlation of137Cs concentration in Lentinula edodes (Shiitake) with average temperatures and fallout levels, that the137Cs levels in Lentinula edodes (Shiitake) are possibly related with these two factors.
Scattering of gaseous125I from a bottle containing Na125I solution for iodination has been measured by distributing active charcoal granule at various heights on the inner surface of a plastic cylinder surrounding the bottle and counting the activities of granule samples. The result shows that about 70% of total scattered125I exist below the level of mouth of the bottle. By drawing the air from the bottle of the cylinder through a tube filled with active charcoal, about 90% of scattered125I collected.
Circumferential profile analysis is one of quantitative analyses in201Tl myocardial scintigraphy. We compared the detectability of coronary artery stenosis between 4 various methods of circumferential profiles (peak point method, all points method, 3 points around the peak method and average method) based on short-axial images of201Tl myocardial single photon emission computed tomography. Diagnostic criteria for coronary artery stenosis was that the circumferential profile curve of a patient was below the normal limit (mean—2SD) obtained from 23 normal volunteers in more than serial 3 profiles. After examining 16 patients with coronary artery stenosis demonstrated by coronary arteriography, it was concluded that both peak point method and 3 points around the peak method surpassed other methods in the detectability of clinically significant coronary artery stenosis.