The concentrations of238U, 234U, 226Ra and210Pb in 4 crystalline apatlte samples from different localities were determined by means of nondestraetive γ-ray spectrometry and α-ray spectrometry. The data obtained indicate that234U and226Ra are in radioactive equilibrium with the parent238U The210Pb/238U activity ratios are clearly smaller than unity. Release of222Rn from apatites after crystallization was shown to be responsible for the238U-210Pb disequilibrium.
Transmission scanning was proposed to be a useful adjunct to conventional emission scanning for accurately keying radionuclide deposition to radiographic anatomy. After introduction of a scintillation camera, transmission whole-body scintigraphy using a flood source has been performed in a patient with differentiated thyroid carcinoma. In recent immunoscintigraphy with radiolabeled monoclonal anti-tumor antibodies has become popular and transmission whole-body scintigraphy have been re-evaluated to make diagnosis for laterality of metastases. However, there are several problems to handle a flood source for preparation and shielding. We developed a special line source for transmission whole-body scintigraphy. The lane source is composed of a plastic tube (inner diameter: 3 mm) with three-way stop in a U-shaped metal. There are several advantages to use this line source as compared to a flood one; (1) a small volume of radioactive solution (less than 5 ml), (2) easy preparation and setting, and (3) less radiation. Moreover good quality of transmission image is obtained using this line source.
As a new parametric image of cerebral lesions, a map of the ratio between regional cerebral blood flow (rCBF) and the 2nd image of a series of dynamic images was proposed and tested. Three classes (poor, mild and well) were defined based on the degree of coupling between the rCBF and the new parametric image of the affected lesion. In 16 patients with cerebral infarction, those in the acute stage (within 1 week after onset) were found to belong to the poor coupling group, and the subacute group (1 to 4 weeks) showed mild coupling. In the chronic group (over 4 weeks), well coupling was observed. All patients of TIA fell into the mild coupling group. In a stimulation study with 5% CO2mixed air, all of the well or mild-coupled lesions changed to uncoupled. These clinical findings demonstrate the characteristics of the new proposed image.
We developed an automatic kidney detection procedure designed to do away with extraneous margins such as the liver or spleen while leaving the kidney margins intact using Laplacian operations and concurrence calculations. We evaluated the delectability of kidneys using our procedures and found that the renal margins were successfully detected in 84 cases of 100 subjects (84%) including 176 kidneys out of a total of 198 kidneys (89%) . It was shown that as the renal function decreased the detectability of the renal margin decreased. In eight cases (16 kidneys) out of 9 patients who later resultantly received hemodialysis even manual settings of the renal ROI were very difficult. After excluding these 8 cases the detectability was 92% for all the cases and 95% for the kidneys. It was our conclusion that this method is sufficient for clinical application.
In order to evaluate the gastric emptying and postprandial mixing of bile with food, the scintigraphies of hepatobiliary and gastrointestinal tracts by using three different kinds of radioisotopes were performed simultaneously (99mTe-E·HIDA for hepatobiliary scintigraphy, 111In-DTPA containing orange juice and131I-albumin containing scrambled egg for gastrointestinal scintigraphy) . This method was available for observation of gastric emptying of liquid and solid foods and also examination of the mixing effect of bile and food quantitatively.
Activity measurements of3H and14C in several environmental samples around the incinerator for radioactive liquid scintillator waste at the Radioisotope Center, Kyushu University were carried out to estimate their levels. It was indicated that3H and14C concentrations in the atmosphere at 1 m from the outlet were about 0.2% of those estimated at the outlet, respectively. At 6 m away from the outlet, 3H concentration decreased to about one twentieth of that at 1 m and14C concentration to background level. For soils and plants, 14C concentrations showed negligibly low values. The existence of these nuclides in particle form was not confirmed. It is considered that the result of the higher3H concentrations as compared to14C concentrations reflects not only the difference of the waste amounts of their nuclides, but also the discharge of3H as moisture as well as water vapor.