[en] A chelating agent-loaded resin consisting of an anion exchange resin (Dowex 1 X-4) and bathocuproine disulfonic acid (BCS-resin) was prepared. The adsorption behavior of some chalcophile elements as a function of pH by the column method was studied, and mercury was shown to be adsorbed selectively to the BCS-resin at the pH region of 0.5 -- 1.0, and the BCS-resin was found to be a specific collector for trace mercury in natural water samples before neutron activation analysis. The molar ratio of BCS to mercury(II) in the resin was confirmed to be 1 : 1 and the resulting chelate was stable at least within a month. The method was applied to the determination of mercury in the Watarase river water sample. The sample solution was adjusted to pH 1.0 with HNO₃, filtered and flown through the column (BCS-resin: 4 x 10^-4 mol.g^-1.resin, 7 mm diameter x 35 mmH) and the resin was then washed and dried in a desiccator. The monitor containing 10 μg of mercury was also prepared according to the above scheme. The samples and the monitor were irradiated together in the pneumatic tube of JRR-3 for 60 min (neutron flux: 2 x 10¹³ n.cm^-2.s^-1). After cooling for 15 days, γ-activity of ²⁰³Hg was measured. The result was 21 +- 3 ppt for mercury, indicating that the method was well applicable to the determination of trace mercury in river water samples. (author)

No abstract available

[en] In the measurements of regional cerebral blood flow (rCBF) using inhalation of ¹³³Xe gas, the activity present is generally limited in lower levels than those of usual brain scintigraphy. Measurements with low count-rate are usually resulted in diminishing the accuracies of results obtained. Therefore, it is necessary to make measurements using a high sensitive collimator for getting as much count-rate as possible when a gamma camera is used. The relationships among sensitivity and structures of multi-parallel collimator were mathematically analyzed. The results of analysis suggested that sensitivity usually increased by using a collimator with holes of reduced height and diameter. A prototype multi-parallel collimator with holes of low height and small diameter was made in our laboratory for testing sensitivity and resolution. The collimator possessing 1141 holes of 6 mmdiameter in hole diameter, 1.5 cm is hole height and septal thickness of 1 mm lead showed 24 times more sensitive than those of a general all purpose collimator supplied by the manufacturer. However, resolution measured in FWHM was of 9 to 14 mm at the collimator face and of 29 to 38 mm at 5 cm from the face. The results indicated that this collimator was useful enough in rCBF measurements with ¹³³Xe inhalation using a gamma camera. The mathematical analysis however, suggested that optimum collimator for rCBF measurements was approximate 4.5 mmdiameter in hole diameter and 1.0 cm in hole height. (author)

[en] Interpretation of spleen size in the liver scintigram was analysed in this study. The spleen size of 325 cases, finally proved of their diseases by autopsies, surgeries, etc., were interpreted by 11 nuclear medicine physicians from 8 institutions. Moderate splenomegaly was suggested when the size of the spleen, expressed by the ratio of longitudinal spleen length to the body width, exceeds 40%. Definite splenomegaly was correctly diagnosed at the ratio of more than 50%. (author)

[en] The dispersal rates of radioisotopes under normal chemical operations were determined with a view to obtaining a fundamental information, which will be applicable to reasonable design of laboratory and safety handling of radioactive materials. A total of 16 samples was selected from widely used radioisotopes. The dispersal rate is defined as the ratio of radioactivity released from the vessel in a unit time to whole radioactivity. The results showed that the dispersal rates varied widely according to nuclide and chemical form. The higher values were obtained from ³H (amino acid mixture), ¹⁴C (amino acid mixture), ³⁵S (cysteine) and ⁷⁵Se (selenomethionine) with average levels ranging from 4 x 10^-5/h to 7 x 10^-4/h. The values of radioiodines such as ¹²⁵I (sodium io dide), ¹²⁵I (triiodothyronine) and ¹³¹I (sodium iodide) ranged between 4 x 10^-6/h and 2 x 10^-5/h. The lower values were observed for ³²P (phosphoric acid), ³⁵S (sodium sulfate), most nuclides of the metallic elements, etc., in which the values lied in less than the order of 10^-7/h. On the basis of these experimental evidences, the relationship between the dispersal rates and the natures of nuclides and of chemical forms is discussed. (author)

No abstract available

[en] In positron emission computed tomographs employing circular ring arrays of detectors, the performance of the imaging device has been specified ultimately by the characteristics of the detector. The responses of NaI detector were studied when detecting positron annihilation photon (511 keV). The study was mainly by using the NaI detector used in hybrid emission computed tomography (CT) ''HEADTOME'' we had developed. A series of measurements were carried out positioning two detectors with 40 cm distance and scanning ²²Na point source in water. Both detectors was inclined from 0⁰ through 30⁰ to change incident angle of positron annihilation toward crystal face. Energy window was set from 100 to 700 keV. The results were presented as follows; 1 Shortening the crystal length from 7 to 5 cm made sensitivity decrease about 10% and resolution deteriorate about 1 mm (FWHM). 2 As the results of varying the width of the crystal, 20 mm width was optimal at any incident angle. 3 The lead septum between the detectors was the thickness of 4 mm enough to reject multiple detector interactions (crosstalk). 4 Beam mask which was made of lead in order to improve spatial resolution and placed on crystal face worked effectively for incident angles from 0⁰ to 15⁰ but degraded uniformity of spatial resolution from 0⁰ to through 30⁰. (author)

[en] Deuterated piperidines with various deuterium contents were obtained by a catalytic reduction of pyridine with deuterium gas (99.0 atom %) on platinum oxide and of pyridine-d₅ (99.0 atom %) with hydrogen gas or deuterium gas. Mass spectrometric analysis of the deuterated piperidines revealed marked scrambling of deuterium label. After methylation of an equal amount of unlabeled piperidine and the deuterated peperidine with diazomethane, the mixture was injected to gas chromatograph/mass spectrometer. Selected ion monitoring was performed by focussing to the m/z values of parent ions of N-methylpiperidine and deuterated N-methylpiperidine to obtain mass fragmentograms. An isotope effect was observed on the gas chromatographic behavior of deuterio and protio variants. Using a 1.5% OV-1 column, the protio variant was eluted faster than the deuterio variant. On the other hand, the latter was eluted faster than the former on a 5% dinonylphthalate column. In both cases, the difference in the retention time between the deuterio and the protio variants was nearly proportional to the number of deuterium atoms in a piperidine molecule. These results suggest that, in a stable isotope tracer technique, it is necessary to consider the scrambling of deuterium label in the labelled compounds obtained by a catalytic reduction. Moreover, it should be noted that ion peak intensities on the mass spectrum measured at one point on the gas chromatogram may give an erroneous ratios of unlabelled and labelled compounds. (author)

[en] Single photon radioisotope computed tomography (RCT) images were obtained using the following devices such as conventional gamma camera, data processer for exclusive use of nuclear medicine (C.D.S.-4096), magnetic tape and medium size electronic computer FACOM 230-28s (48K) for multipurposes, which are routinely used for clinical purpose. To reconstruct the RCT image we made absorption correction by geometric mean of opposing counts considering the thickness of source and used the convolution integral method. The reconstructed images of phantom study resolved one centimeter clearly and were very similar to original. The RCT image of patient was acquired by the rotation of patients using the revolving chair and the handmade implement which settles the center of patient's head. Three dimensional informations were obtained by one examination with a gamma camera which collects two dimensional images. When using a gamma camera, therefore, not only a transaxial but an arbitrary RCT image will be important to contribute for diagnosis. (author)

[en] Myocardial scintigrams with sup(99m)Tc-pyrophosphate (PYP) were performed in 30 patients with acute myocardial infarct (AMI) and positive scintigrams were obtained in the 24 patients. In 12 patients the size of the AMI estimated from the scintigram with sup(99m)Tc-PYP was compared with the pulmonary capillary wedge pressure (PCWP). In the 7 patients with PCWP below 10 mmHg the mean area of the AMIs was 22 +- 5.5 cm² and that of in the 5 patients with PCWP beyond 10 mmHg was 41 +- 12.4 cm². This difference was statistically significant (p lt 0.05). In comparison with chest x-ray findings, the average size of the AMIs among 6 patients with alveolar and/or interstitial edema was 43 +- 11.9 cm² and that of among 8 patients without pulmonary edema was 25 +- 9 cm². The left ventricular ejection fraction (LVEF) was obtained by first pass method. In 12 patients LVEF and PXWP was compared. The 7 patients with PCWP below 10 mmHg did show significantly larger LVEF (49 +- 8.2%) than that of 5 patients with PCWP beyond 10 mmHg (33 +- 6.1%) (p lt 0.01). The mean LVEF in the 7 patients with pulmonary edema was 35 +- 10.2% and that of in the 8 patients without pulmonary was 48 +- 5.3%. Myocardial scintigram and radionuclide angiocardiography with sup(99m)Tc-PYP were useful for evaluation of the left ventricular function as well as detection of the AMI. (author)