A newly developed charged-particle imaging system was applied to rapid measurements of the distribution of α-and β-emitters. The imaging system consists of a ZnS (Ag) screen, two tapered fibers, an image intensifier, and a Polaroid film. The image obtained with the system shows very good quality, namely, a spatial resolution of more than 6 line pairs (lp) /mm and a distortion of less than 2.5%. As the system is capable of detecting each α-particle separately, the distribution of a-emitters can be quantitatively determined. The autoradiograms of the sections of mice with β-emitters administered can be obtained with an exposure time of only 2 min compared with 2 weeks by a conventional technique.
An anemometer utilizing α-ray ionization was investigated to measure low wind velocity below a few ten centimeters per second. It is based on the decrease of ionic current due to air flow into an anemometer probe. The anemometer consists of the measuring probe fitted with an241Am α-ray source, a picoammeter, and a direct current power source. A parallel plate probe was designed to eliminate the dependence of measurement on two dimensional wind direction. Component parameters of the measuring probe were experimentally optimized by wind tunnel examinations so as to have a good response for wind velocities ranging from 0 to 100 cm/s. The dimensions of the anemometer probe fabricated are as follows; the diameter of collector electrode is 20 mm, and the spacing distance of parallel plate electrodes having a size of 100×100 mm is 25 mm, which corresponds to the range of alpha particles emitted from the241Am source. The most sensitive condition for low wind velocity was achieved when the mean electric field strength between the electrodes was adjusted at 100 V/cm, which is in the region of ion recombination. In the optimized anemometer, the ionic current at a wind velocity of 100 cm/s decreases to about 70% of that at 0 cm/s, regardless of the α-ray source strength. By using a 1.85 MBq (50μCi) α-ray source, the low wind velocity was determined with a precision of 2 cm/s. Since atmospheric pressure is beyond control even in air-conditioned rooms, the influence of that on the ionic current was checked in a range of 96 to 102 kPa It was revealed that the effect of atmospheric pressure on the ionic current was minimized at the electric field strength of 100 V/cm, which corresponded to the ideal condition in the sensitivity for low wind velocity measurement. To compensate other atmospheric conditions a differential probe is useful. The wind velocity distribution in an IC manufacturing clean room measured by the anemometer was finally demonstrated.
In an atmospheric discharge of radioiodines, direct deposition of the nuclides onto leaf surface must be the most significant pathway. However, root uptake is also of importance specifically for129I because of its long half life of 1.57×107years. In order to estimate the amount of the nuclide transferred to the crop plants from contaminated field, the experiments were carried out using solution culture. Rice plant, Oryza sativa cv, koshihikari, spinach, Spinacea oleracea L., radish, Raphanus sativus L., and the other four kinds of crop plants were exposed to culture solution in which Na131I were contained. The transfer rates, defined as the ratio of activity of plant sample per day to the mean activity of culture solution, were calculated. And the differences by the organs of each crop plant and by plant species were discussed in this paper. Temporal critical crop plants for 129I were selected.
The influence of SPECT over the detectability of SOL in the liver was evaluated by the Subcommittee on Efficacy Study, which belongs to Medical and Pharmaceutical Committee of Japan Radioisotope Association, under the participation of 9 hospitals including some university hospitals. In this study segmental reading of the SOL was requested. The film reading was performed twice on the different patient-groups and the results from well-experienced doctors (11 doctors) were summarized, indicating a slight increase in sensitivity as a whole although there were some doctors showing a reverse effect in each performance. Sensitivity was determined in the patient-group without SOL, which showed a slight decrease as a whole, indicating that SPECT had some possibility of increasing false positive cases. In the study of SOL detectability based on its segmental location, a marked positive effect of SPECT was noted in the right anterior and right posterior segments whereas a marked negative effect in the left lateral segment. The left medial segment also showed a slight decrease in the detectability of SOL.
In order to obtain a highly concentrated, pure and super-hot [γ-32P] ATP, we improved the purification method of super-hot [γ-32P] ATP which was synthesized by the method of Johnson and Walseth (1979) . The super-hot [γ-32P] ATP was synthesized in a relatively large volume (2 ml) of reaction mixture and purified using semi-micro scale anion exchange chromatography (Dowex 1×2, 60-70μl column volume) . In combination with washing the reaction product with certain organic solvents, this chromatography technique makes it possible to obtain a highly concentrated and pure super-hot [γ-32P] ATP (approx.7000 Ci/mmol; 20-30 mCi/ml) from [32P] Pi of any commercial source in a good yield.
The effects of higher-energy photon from123I (p, 5n) on the SPECT image quality were evaluated. The quality was evaluated by image contrast and %rms. Image contrast had similar tendency to planar and SPECT FWHM value. %rms was affected by septal penetration. Using 140 keV high resolution collimator (140 keV HR), image contrast was superior to that for 300 keV medium energy collimator (300 keV ME), but septal penetration rate (SPR) was 18% and %rms was 10.5. When quantitation is required, the collimator with less SPR than 18% is recommended for SPECT imaging. Using 300 keV ME, SPR was 0.05%, but spatial resolution and image contrast were inferrior to that for 140 keV HR.
Plasma vasoactive intestinal peptide (VIP) concentrations of normal individuals and patients with pancreatitis were studied using a VIP RIA kit. The inter-assay and intra-assay variation of this kit were between 2.1 and 9.4%. The VIP levels increased in the acute phase of acute pancreatitis and patients with chronic pancreatitis. The VIP concentration increased during the first 30 min of glucose tolerance test, but this increase was much smaller than that in insulin. These results suggest that this kit is useful for physiologic and pathologic changes in the VIP level.