The determination of trace fluorine in contaminated water has been investigated by combining a concentration technique with the fast neutron activation analysis utiliz-ing the reaction of 19F (n, 2n) 18F. An amount of 1% AgNO3solution was added to one liter of sample water to remove Cl-as AgCl. The filtrate was dropped through a column of 5 ml Dowex-2X anion exchange resin of acetate type. The resin was washed, dried and packed in a polyethylene capsule of 3 ml capacity. Three samples prepared in this way and one monitoring sample (CaF2) were simultaneously irradiated by a neutron beam with the flux of 5×109-1×1010n/sec for 20 min. They were cooled for 100 min and the radioactivity of 0.511 Me V γ-photo peak from each sample was successively counted for 10 min. Fluoride ion at the level of 1 ppm was found to be determined without any interferences due to coexistent ions in water sample by the present analytical procedure.
As previously reported, the electrolysis method is more simple and convenient for labeling of99mTc than the other conventional methods. We further expanded the application of this method to the other compounds and confirmed that this method can be applied for labeling of stannous hydroxide and99mTc-EDTA. We have experimentally determined99mTc-EDTA can be used for the measurement of GFR and99mTc-stannous hydroxide for the liver scanning. By using Pt-Sn electrodes, better result was obtained in labeling efficiency of both99mTc-EDTA and99mTc-stannous hydroxide than by Pt-Zr electrodes. 99mTc-EDTA was prepared by adding99mTcO-4soln. to Sn-EDTA soln. which was preivously produced by electrolysis. The efficiency of chelation averaged more than 94 % by allowing this mixture for about 15 minutes.99mTc-EDTA and169Yb-DTPA were simultaneously injected in an adult rabbit, and almost the same GFR values were obtained as 15.6 mllmin and 16.0 ml/min, respectively. As for99mTc-stannous hydroxide, chromatographic studies have shown that electrolysis with 0.1-0.3 coulomb gives a labeling efficiency of more than 98%. When injected into mice, more than 90% of this compound was taken up by liver. As the results of further investigations, we found this electrolysis method can be applied for labeling of several other compounds such as polyphosphate and bleomycin. When this reaction is aseptically performed in sterile 0.9% NaCl soln., the resulting solution is ready for injection; this is considered to be an advantage for the medical use.
131I-MIAA (Daiichi Radioisotope Labs., Ltd., particle size: 1-3μ) was compared with198Au-colloid using liver and spleen scintigraphy. The disappearance of131I-MIAA was 2.5 hours in liver and 3.5 hours in spleen. Suitable time of scintigraphy was from 10 min to 1 hour after intravenous injection. The radiation dose with131I-MIAA to liver was decreased to 1/40 of that with198Au-colloid and131I-MIAA was more localized to spleen in hepatosplenopathy. Therefore, it is useful for the reagent of scintigraphy for spleen than51Cr or203Hg-MHP, considering radiation dose to spleen and kidney. The spleen-liver RI accumulation ratio calculated with131I-MIAA about various diseases showed more separative values than that with198Au-colloid, so it seemed to be valuable for diagnosis and estimation of disease.
In thyroid scintigraphy, if the thyroid131I uptake measurement is made simultaneously with the scintigram of the thyroid gland using a pinhole scinticamera, it would be very convenient for us. However, the problem is whether correct results can be obtained or not. Then, some experiment has been carried out. The results obtained were compared with the routine thyroid uptake tests (GRINS technique) . The values of uptake were in general low compared with the ORINS technique, when a point source like a capsule is used as a standard source. It is recommended that the thyroid131I uptake measurement is made separately from the scintigraphy by 20-25 cm distance method, or used a standard source similar to a patient's thyroid.