We conducted this study to understand the regional differences of radioactive caesium concentration(134Cs +137Cs) in the first crop of tea in Kanagawa prefecture. No relations were observed between the radioactive caesium concentration(134Cs +137Cs) in the first crop of tea and the sampling point of distance from the Fukushima Daiichi Nuclear Power Plant, altitude, amount of rainfall(March 15 to 31, 2012), and frequency of rainfall(March 15 to 31, 2012). Multiple regression analysis was performed to understand the reduction factor of 137Cs concentration from the second crop of tea. The reduced 137Cs concentration was related to the 137Cs concentration in the first crop of tea(X1) and frequency of plucking and pruning(X2). Multiple correlation coefficients of the analysis with reduced 137Cs concentration as the dependent variable and X1 and X2 as explanatory variables was 0.915(p<0.01), coefficients of determination were 0.838. In the case of the analysis with 137Cs reduction rate as the dependent variable and X2 as the explanatory the variable was 0.755(p<0.01), and the coefficients of determination was 0.570. The regional differences in radioactive caesium concentration did not depend on distance from Fukushima Daiichi Nuclear Power Plant, altitude and precipitation in Kanagawa Prefecture. However, it became clear that the reduction rate of 137Cs concentration from the second crop of tea could be explained to be about 57% by frequency of plucking and pruning.
99mTc-Technegas inhalation scintigraphy is replacing ventilation scintigraphy using radioactive inert gas. 99mTc-Technegas, which is carbon nanoparticles, has a characteristic of a smaller and uniform particle size. When 99mTc-Technegas is inhaled into the lungs of patients, it is promising to perform the inhalation in an additional space because the inhalation procedure probably results in an equipment and floor contamination, which gives radiation exposure to staffs. The method mentioned above needs to measure 99mTc radioactivity in the lungs. The aim of this study was to design simple measurement using phantom study. Radioactivity of a phantom was obtained by using an ionization chamber survey meter. Radioactivity in the lungs of patients who inhaled 99mTc-Technegas was measured by using an ionization chamber survey meter, correlated with the radioactivity of the phantom data. Our established method was able to accurately and simply measure radioactivity of the lungs in all of the patients who underwent 99mTc-Technegas inhalation study.
The radioactivities of 134Cs and 137Cs in grape and peach trees and the soils where these trees were cultivated were measured in Fukushima prefecture. In grape, the radioactivity in trees or soil was very low owing to cultivation in a plastic greenhouse. In peach, though radioactivity in shoots, leaves, fruits or roots was low, that in 3 years-old branches, was high, especially at the bark. The high radioactivity at outer side of the bark could be found by an imaging plate.
Movement and distribution of radiocaesium in peach tree was studied. The radiocaesium distributed on branches most, which branches were 1, 2 or 3 years old. With the observation of tissues of trunk, the highest radiocaesium concentration was measured at the bark, which was higher than that of soil surface. The radiocaesium concentration was drastically low in the wood part. However, the total amount of radiocaesium of wood was as the same level as that of the bark. About 20% of radiocaesium in the tree was estimated to be removed as fruits and leaves.
A questionnaire survey was conducted to evaluate decrease in SPECT studies and its causes after the cessation of long supply shortage of 99Mo/99mTc generators. Of the replies by the chief nuclear medicine technologists, no necessity for 99Mo/99mTc generator use or for domestic supply of 99mTc unexpectedly accounted for 25% and 46%, respectively. Generator use leads to an additional profit by 8654 yen per patient, compared to purchase of commercially available 99mTc-labeled kits. It is essential to install a 99Mo/99mTc generator to perform emergency SPECT studies, increase a profit in hospital management, reduction of financial issues in patients, and pediatric studies. This adverse circumstance, however, may provide a good opportunity to instruct nuclear medicine specialists to be aware of the importance mentioned above in medical meetings.
We designed a new method to produce 99Mo by the 100Mo(n, 2n)99Mo reaction using intense neutrons emitted from an accelerator. About 20% of the demand of 99Mo in Japan is expected to be available reliably by the method we designed. In fact, we have shown that the 99Mo produced contained a very small amount of radionuclides except 99Mo and the radionuclide purity of 99mTc separated from 99Mo by a sublimation method and the efficiency of labeling an MDP kit with the 99mTc fulfilled the United States Pharmacopeia requirements for a fission product, 99Mo. We expect that the present 99Mo production method will be accepted worldwide to ensure a reliable supply of 99Mo.