In last report, part (III), of this study, a formula for calculating the optimum radiaton intensity for the detection of small changes in thickness was induced. The formula includes some important factors such as the pulse height spectrum induced in the radiation detector and absorption characteristics of samples. These two factors are discussed minutely in this report. The pulse height spectrum was investigated with β-rays from90Y-90Sr. The β-rays were measured by silicon semiconductor radiation detectors of two different types, i.e. planer type and Li ion drift type. The reason why these two types were picked out is that these two solid state ionization detectors are considered to be similar in the function to the gas ionization chamber. The results are as follows; the shape of spectrum is obviously deformed with the change in thickness of the depletion layer, and the mean value ‹q›, standard deviation σq of the spectrum, and their ratio ‹q›/σq increase along with thickness of the depletion layer. In view of this result, it is hoped that the increasing air pressure in the ionization air chamber will decrease the statistical error of the output. The error, however, scarcely changes. When β-rays decrease by penetrating some absorber, the shape of spectrum changes little, and the same thing is observed with the ionization air chamber. As to the absorption characteristics, the experimental results shown in the part (I) of this study is used. The absorption curves develope various shapes. They can be classified into three types, and are approximated by each formula. Finally, the optimum intensity of radiation is calculated with some examples by putting these results into the formula.
A method has been developed for the determination of trace amounts of chlorine, bromine, and iodine in biological materials. After thermal neutron irradiation of the sample for 20 minutes at a flux of 2×1013n⋅cm-2⋅sec-1, followed by rapid chemical separation, chlorine, bromine and iodine were determined by gamma-ray spectrometry. The sample was transferred to the distillation flask together with 0.2mM each of KCl, KBr and KI carrier. While being heated and made bubbles with the air stream, it was decomposed by the conc. HNO3and conc. H2SO4mixture. Iodine and bromine were distilled at this step. Potassium permanganate solution was then added to the flask to form chlorine. During the process the distillate was absorbed in the Na2SO3solution. Then for the determination of iodine, accurate 0.1 mM of AgNO3was added to the solution and 0.1mM of negatively charged colloidal pure AgI was formed. It was precipitated by Al (NO3) 3 9 H2O and faltrated. Immediately the gamma activity of128I was counted. Then for the determination of others the excess of AgNO3was added to the filtrate, the precipitate containing AgI, AgBr and AgCl was filtrated, immediately the activity of38Cl was counted, and after the38Cl decay, the activity of82Br was counted. The gamma activity of the sample was counted with a 3 in. φ×3 in. NaI (Tl) crystal connected to a TMC 256 channel pulse height analyzer. The chemical yields were about 100 percent with halogens, and the separation time was 30-50 minutes for iodine. The isolated precipitates of AgI were extremely pure.
Res-O-Mat T3 is an in vitro triiodothyronine-131I diagnostic test taken for determining the T3binding capacity of serum. TBC Index (T3-Binding-Capacity Index) is obtained by comparing the quantity of T3bound by the patient serum with that bound by pooled normal sera. TBC Index and resin sponge uptake were measured in a series of 20 hyperthyroid, 4 hypothyroid and 20 euthyroid individuals. The two tests showed comparable results. The TBC Index in euthyroid persons was little variable on incubation time, but in hypertoxic and hypotoxic persons it decreased as the time increased. Errors of several minutes made on incubation time, however, did not make substantial difference when the incubation period was two hours. TBC Index either increased or decreased about 0.004 as the temperature of incubation decreased or increased by 1 °C. In contrast to resin sponge uptake test, Res-O-Mat T3test doesn't require any washing procedure and needes only 0.5ml of serum, though it must be gently incubated with rotator for two hours.
Res-O-Mat T3is an in vitro131I-T3diagnostic test used for determining the T3binding capacity of serum. An index of this binding capacity (TBC Index) is obtained by comparing the quantity of T3bound by the patient serum with that bound by pooled normal standard sera. “Res-O-Mat T3Kit” was used in 108 cases. The test procedure was examined and the following results were obtained. 1) TBC Index: 0.86-1.11 (average 0.972) for 21 normal persons, 0.62-0.9 (average 0.764) for 24 cases with hyperthyroidism, 1.13-1.39 (average 1.215) for 4 cases with hypothyroidism, 0.83-1.13 (average 0.997) for 21 cases of non toxic goiter, and 1.05 and 1.12 for 2 cases of subacute thyroiditis. The test demonstrated that the indices obtained with hyperthyroid, euthyroid, and hypothyroid persons very slightly overlapped. 2) TBC Index decreased as the incubation time increased. 3) TBC Index was influenced by temperature of incubation. Res-O-Mat T3 Kit doesn't need washing process, needs only 0.5ml of sera, and requires extremely simple procedure.
The Res-O-Mat T3 test is based on the principle that the sera bound radioisotope is counted after removing free131I-triiodothyroxine by the adsorption on the ion exchange resin. Therefore the method is antipodal to the131I-T3RSU test. The value is given by the ratio of the incorporation of the patient sera to that of the standard sera. The results obtained by authors are as follows: Dispersions of the TBC Index shown by the same kit for different incubation times and temperatures, periods of aging, and amounts of the sample are negligible. Dispersions of the incorporation into the sera are also negligible. The reproducibility shows SD: 0.02 and CV: 2.0 % (N=10) . This test also shows an appreciable correlation with the triosorb test. The reproducibility and manual process of this test are about the same as the triosorb test. But it is one of the merits of this test method that the different measuring conditions including instruments do not affect ect the results because the TBC Index is obtained from the standard sera of each kit. Thus the comparison of data collected by different institutions can by made without difficulty.