The imperfections and defects are well known to form in the alkaline metal sulfates after X-ray irradiation. The Gd ion-doped K3Na (SO4) 2had high susceptibility to X-ray irradiation. The ESR signal of SO3-radical was isotropic and thermally stable in Gd ion-doped K3Na (SO4) 2irradiated by X-ray. The result described is the application of the Gd ion-doped K3Na (SO4) 2to the ESR imaging method which can monitor both absorbed dose and irradiation direction. Zupancic-typed coils were used, to produce the magnetic field gradient with a direction for ESR imaging The parallel wires of Zupancic-typed coils were connected to each other and to the current sources, forming four independent current loops to change the direction of magnetic field. The ESR spectra were measured using an X-band ESR spectrometer with a 100 kHz magnetic field modulator and a phase-sensitive detector. The current values of the four loops were controlled by using four regulated DC power supplies controlled by 12 bit D/A converters. A two-dimensional image was reconstructed using a filtered back projection method from the projection data of 180 directions (1-degree steps), which were obtained by using a field gradient of 1.05mT mm-1. The obtained results suggest that the Gd-doped K3Na (SO4) 2sample can be utilized as the ESR-CT image and the ESR dosimeter in the range from 20μGy to 100 Gy.
In our previous paper, we demonstrated a new method for renal uptake rate measurement with99mTc-dimercaptosuccinic acid (DMSA) which required no background and kidney depth corrections and only 20 min for examination. In this study, we developed a simple and practical alternative approach using graphical analysis. The net uptake rate of DMSA by tubular cells (K) calculated using graphical analysis correlated well with the renal uptake rates measured two hours after DMSA administration (r=0.918 for the 3-parameter model and r=0.924 for the 4-parameter model), and agreed well with the K values obtained using the previous method (r=0.997 for the 3-parameter model and r=0.998 for the 4-parameter model) . These results indicate that the present method can be an alternative approach to our previous method. We believe that this method will facilitate even more widespread utilization of the quantitative assessment of DMSA uptake by planar scintigraphy, because it is much simpler for practical use as compared to the previous method.
We studied the left ventricular (LV) contraction kinetics in patients with hypertrophic cardiomyopathy (HCM) by ECG gated myocardial tomography (gated-SPECT) with99mTc-methoxyisobutylisonitrile (MIBI) . These findings were compared with thoses obtained by123I-metaiodobenzylguanidine (MIBG) myocardial imaging to clarify the effect of myocardial sympathetic integrity. We performed gated-SPELT on 11 patients with HCM and 13 normal subjects. In order to assess myocardial contraction kinetics in various LV parts, we constructed multi-plane long axial tomograms and divided the left ventricle into 17 segments. Myocardial count change during systole (%CC) was calculated in each segment, and compared with %CC in normal subjects in the corresponding segments. As an index of systolic asynchrony we calculated the standard deviation (SD) of R-wave to peak systolic interval among 17 segments in each patient. In patients with HCM we performed MIBG imaging (initial and delayed imaging) and myocardial201Tl imaging at rest. As the indexes of myocardial sympathetic activity we calculated the following parameters ; (1) Uptake Ratio which is the ratio of %uptake of MIBG (delayed image) to %uptake of201Tl, (2) %Washout (% WO) which is the percent decrease of myocardial MIBG activity from initial to delayed image, (3) Unhomogeneity of myocardial MIBG distribution which is coefficient of variance (CV) of myocardial MIBG in delayed image, and (4) Defect Score, which is extent of the defect in MIBG delayed image. Decreased %CC was observed in 87 of 187 HCM segments (47%) and they were mainly distributed in the hypertrophic regions (apex, septum and anterior wall) . Systolic asynchrony (SD) in HCM was greater than that in the normal subjects (5.4±1.4 vs. 3.5±0.6, p<0.01) . In patients with HCM, Uptake Ratio and %WO did not correlate with the number of segments with abnormal %CC, but CV and Defect Score correlated well with the number of segments with decreased %CC (r=0.56, r=0.63, p<0.05 each) . Although abnormal %CC was observed chiefly in the apex, septum and anterior myocardium, defects of MIBG were observed mainly in inferior segments. On the other hand SD correlated well with all MIBG indexes (r=-0.68 with Uptake Ratio p<0.05, r=0.78 with %WO p<0.01, r=0.63 with CV p<0, 05, r=0.78 with Defect Score p<0.01) . SD correlated inversely with the index of LV early diastolic filling (r=-0.79, p<0.01) . These findings suggested that systolic asynchrony in patients with HCM was closely related to myocardial sympathetic integrity and it was one of the causes of abnormal diastolic filling observed frequently in patients with HCM. Gated-SPELT gave important information on the pathophysiology of HCM.
The radioactivities of the naturally occurring radionuclides (226Ra, 228Ra, 228Th and40K) and a fallout nuclide (137Cs) in newspapers issued during 1990s in Japan and information business papers were determined by gamma-ray spectrometry to obtain information on radioactivity level of papers and the sources of radionuclides contained in papers. The concentrations of the naturally occurring radionuclides in the newspapers were low, whereas the228Ra and228Th contents of an information business paper were as high as 30 Bq kg-1. Perhaps the thorium series nuclides contained in this information business paper was present in the kaolinite filler used in the paper. 137Cs was detected in all the newspapers, while the radionuclide was not detected in the information business papers. The137Cs concentration in the newspaper ranged from 0.1 to 0.2 Bq kg-1. Mechanical pulp was the main constituent of the newspapers, and137Cs in the newspapers was maybe brought with the mechanical pulp which kept a part of fallout137Cs contained in the material wood. The data obtained in this work may be useful to estimate radioactivity released from incinerators to the environment by burning waste paper.