To find out the possibility producing practical amount of123I for medical use, comparative studies on α and3He bombardment on natural antimony up to 40 MeV were carried out by stacked foil technique. The excitation curves and thick-target yield curves were determined for the formation of123I, and other by-produced nuclides such as121I, 124I and125I. In the case of the3He bombardment, the maximum cross section for the formation of123I was found to be 475 mb at 30 MeV3He particles. After 21 hr cooling, the yield of123I was 180μCi/μAh and the121I/123I ratio was found to be 4.1%, which was fairly large impurity for medical use. In the case of a bombardment, the maximum cross sections for the formation of123I, 124I and125I were found to be 410 mb at 24.5 MeV, 370 mb at 35 MeV and 300 mb at 24 MeV α particles, respectively. These three nuclides were produced with yield of 174, 1.2 and 1.4μCi/μAh at 24.5 MeV a particles. The124I/123I ratio was found to be 0.69%, which was much improved with those reported in literature. 123I can be separated by distillation from dissolved solution of bombarded antimony target with radiochemical yield of 81.1%. It may be said that 24.5 MeV α particles bombardment on natural antimony was superior in giving useful quantities of123I with reasonable high yield of 174μCi/μAh and only accompanied with smallest quantities of124I at the end of bombardment.
Solvent extraction behavior of yttrium was studied in the system of chloroform solution of thenoyltrifluoroacetone (TTA) and 0.1 M aqueous perchlorate solution at 25°C. 88Y was used as the tracer. The variation of distribution coefficients in the concentration range of 10-2-10-1M TTA and pH 3-6 was explained as the extraction of YA3 into the organic phase and the formation of YA2+, YA2+andYA3 (A=anion of TTA) in the aqueous phase. The equilibrium constant for the reaction Y3++3HA(org) _??_ YA3 (org) +3H+ was obtained asK0=2.82×10-9
Heparin is a kind of acidic mucopolysaccharide. Heparin-67Ga complex was prepared to investigate distribution in tumor-bearing rats. This compound was intravenously injected to the rats subcutaneously transplanted Yoshida sarcoma. These rats were sacrificed at 10 minutes, 30 minutes, 1 hour and 3 hours after injection. The radioactivities of the tumor, blood, muscle, liver, kidney, spleen and urine were measured by well-type scintillation counter. The retention values in these organs and the excretion rates in the urine were calculated. Excretion rates (%/dose) of heparin-67Ga in 10 min., 30 min., 1 hours and 3 hours were 38.2%, 67.5%, 79.5% and 78.0%, respectively. From these facts, it was thought that heparin-67Ga complex had not suitable property for tumor scanning, but this compound might be suitable agent for renal function test.