Determination of the average uranium contents in several fossil bones was carried out using an improved fission track method. Four standard samples were prepared from silica-gel powder containing known amounts of natural uranium. The powdered fossil bones was fixed on a muscovite detector as well as the standard samples and followed by the neutron irradiation. After cooling, the muscovites were chemically etched with HF-solution to develop the fission tracks. By using standard samples, it was found that a reliable track counting is impossible through the transmission optical microscope in the region over track density of 5×105cm-2 because of overlap of fission tracks in each other. In order to improve this situation bearing most of the present muscovites, the observation using the reflection microscope was applied after coating the muscovite surface with the vacuum-evaporated gold film and verified to be extremely efficient to the counting of high track density up to 5×107cm-2, which could be no longer to distinguish intrinsic tracks through ordinary microscope. All of the fossil samples were subjected to the track counting through the reflection microscope and after correcting the estimated difference of track ranges between the standard and fossil bone samples the experimental uranium contents were evaluated. The uranium contents in the fossil bones were in the range of 30-460 ppm.
S2-gated (the second heart sound) method was designed by authors. In 6 normal subjects and 16 patients (old myocardial infarction 12 cases, hypertension 2 cases and aortic regurgitation 2 cases), radioisotope (RI) angiography using S2-gated equilibrium method was performed. In RI angiography, 99mTe-human serum albumin (HSA) 555MBq (15mCi) as tracer, PDP11/34 as minicomputer and PCG/ECG synchronizer (Metro Inst.) were used. Then left ventricular (LV) volume curve by S2-gated and electrocardiogram (EGG) R wave-gated method were obtained. Using LV volume curve, left ventricular ejection fraction (EF), mean ejection rate (mER, s-1), mean filling rate (mFR, s-1) and rapid filling fraction (RFF) were calculated. mFR indicated mean filling rate during rapid filling phase. RFF was defined as the filling fraction during rapid filling phase among stroke volume. S2-gated method was reliable in evaluation of early diastolic phase, compared with ECG-gated method. There was the difference between RFF in normal group and myocardial infarction (MI) group (p<0.005) . RFF in 2 groups were correlated with EF (r=0.82, p<0.01) . RFF was useful in evaluating MI cases who had normal EF values. The comparison with mER by ECG-gated and mFR by S2-gated was useful in evaluating MI cases who had normal mER values. mFR was remarkably lower than mER in MI group, but was equal to mER in normal group approximately. In conclusion, the evaluation using RFF and mFR by S2-gated method was useful in MI cases who had normal systolic phase indices.
Single photon emission computed tomography using newly designed whole body imaging system which was composed of opposing dual gamma cameras, a rotating gantry and a sliding table was clinically evaluated for bone imaging. Two hundred and seventeen portions of various bone diseases were performed single photon emission computed tomography following conventional bone imaging with99mTc-MDP (methylen diphosphonate) or -HMDP (hydroxymethylene diphosphonate) and the results were discussed. Transaxial images were sometimes superior than conventional images in the diagnosis of the tumor localization and extension of the facial bone. Combination of emission computed tomography to conventional methods also presented more exact inf ormations for the diagnosis of the vertebral change. Separation of the overlapped radioactivities of the bone and the soft tissue is another advantage of the tomographic image, and cross-sectional images with enoughly high qualities were available in early time after administration of99mTc-phosphate compounds. Useful diagnostic inf ormations could be obtained by tomographic bone imaging combined with conventional imagings.
It is almost impossible to estimate statistically reliable values of within-assay variability only from a few control samples in duplicate because of low number of degree of freedom. In this sense, the method D. Rodbard, et al. developed for estimation of within-assay variability would be the most desirable, reasonable and convenient one in routine quality control. The only problem in this method is that no one has clarified what is the true relationship between the response (y) and the error (σy2or σy) . In order to reveal the true relationship between the two, it is necessary to get the most precise estimate of variance (sy2) based on a great number of degree of freedom. Then, we combined the data from different assays, sample by sample, by using the equation below, to increase the number of degree of freedom and to make the estimate of variance as precisely as possible. Sy2=nΣi=1S′yi2/n(r-1) [sy2: total (combined) within-assay variance s'yi2: within-assay variance of assay no. i n: number of assays performed r: number of replicate] Using the variances so calculated for each sample, relationship between the mean of y and sy2were investigated. In this investigation, competitive radioimmunoassay kits were evaluated, and in every case bound fraction was counted. As the result, we confirmed that there is a clear relationship between the response (y) —B% or B/B0%— and the error (σy2or σy) as shown below. σy=a+by or σy2= (a+by) 2or σy2=aybNaturally, the equation of linear regression should be the choice of use for response error relationship (RER) because of simplicity. In routine assays which are run in duplicate, we confirmed that the same method can be applied using information from all of the samples in the assay which have been analyzed in duplicate. Precision profile obtained from the RER thus calculated has various advantages as D. Rodbard, et al. indicated.