It is important to determine internal exposure dose in the case of accident, and it is usually estimated from intake radioactivity measured by human counter. Its detection efficiency necessary for calculation is determined from the measurement using phantoms or Monte-Carlo calculation, but other important problem arises for difference to actual measuring condition. The γ-ray sum peak method is one of them to resolve this problem, but application in the existence of plural radionuclides is difficult. The γ-γ coincidence measurement using two Ge detectors is another answer, and measurements for24Na, 60Co and134Cs were carried out for the existence of single nuclide or plural nuclides. The results for single nuclide and for plural nuclides showed agreement with disintegration rates determined by 4πβ-γ coincidence within ±10% and ±15%, respectively.
We present a circadian rhythm of water uptake manner in a soybean plant through realtime imaging of water, labeled with15O. Nitrogen gas was irradiated with deuterons accelerated by a cyclotron at Hamamatsu Photonics Co. to produce15O-labeled water. Then the15O-labeled water was supplied to a soybean plant from the root and the realtime water uptake amount was measured for 20 min by Positron Emitting Tracer Imaging System (PETIS) . All the targeting positions for the measurements were stems, two points at an internode between root and the first leaves, between the first leaves and the first trifoliates and between the first trifoliates and the second trifoliates. The water uptake amount was gradually increased and showed its maximum at around 13: 00, especially at the basal part of the stem. Then the water uptake activity was gradually decreased until 17: 00. The water amount taken up by a plant at 13: 00 was about 40% higher than that at 17: 00.
Sorghum has a big potential to be grown and developed in Indonesia. The objective of this research is to produce new sorghum variety to improve sorghum production for supporting the development of sorghum agroindustry in Indonesia. The lethal dose 50% (LD-50) value for sorghum was found to be 0.73 kGy. The dose of 0.4 kGy gave the highest variance for plant height and harvest index. Selection in the generating M2, M3 and M4 populations resulted to some promising lines, especially ET20-B, with desirable agronomic characteristics, big and condense head, high yielding, white and clean color of seeds, and good nutrition values.
Accuracy of left ventricular (LV) volume calculated by Quantitative Gated SPECT (QGS) was studied by using a cardiac phantom with 12 SPECT systems of 10 hospitals. The data were obtained by the same preset time and same preset counts protocols, and also by each hospital's own acquisition protocol. The LV volume calculated by QGS was generally underestimated. The mean errors of the LV volume with each acquisition protocol were 4% in preset time, 5 to 8% in preset counts and greater than 9% in each hospital's own acquisition protocol. To decrease the differences of estimated LV volume among hospitals a uniform protocol for data acquisition should be established.
Uniformity of different types of beta-ray plane sources has been examined. Four types of plane sources, polymer, anodized aluminum, filter and ion exchange membrane, were selected. On estimation of the uniformity, the coefficient of variation with respect to surface emission rate was measured using an imaging plate or a proportional counter. As a result, polymer sources and ion exchange membrane sources showed good uniformity. The area and number of region of interest for estimation of uniformity were discussed.