COMPARATIVE KINETIC STUDIES OF SIMULTANEOUSLY INJECTED CITRATE-TM-167 AND CITRATE-GA-67 IN NORMAL AND TUMOR BEARING MICE

Thulium-167 was produced by spallation reactions during irradiation of tantalum targets with 680 MeV protons in the Dubna synchrocyclotron. After the chromatographic separation of simultaneously produced radiolanthanides, thulium was available carrier-free and with high radiochemical purity. The kinetics of intravenously injected thulium-citrate were studied in comparison with simultaneously applied gallium-67-citrate in normal and tumour-bearing mice. Scans were performed in mice and rabbits for the visual recording. The very fast clearance from blood of thulium-167 and its good storage in tumour may be considered as important results of the present study. This behaviour of the radiopharmaceutical was demonstrated by an ascent of the tumour to blood ratio of thulium-167 to the tenfold of the initial value whereas the corresponding ratio for 67-gallium is constant within 76 h, remaining at the level of the initial value. According to the kinetic of thulium-167, the tumour can be scanned already 4-6 h after the application of the tracer.