Cyclotron production of medium-lived NCA technetium radiotracers : use for biodistribution studies and setting up new Tc-99m production methods

Medium-lived gamma-emitting Tc RNs are used to optimise radioanalytical methods for the determination of Tc in environmental matrices, for the study of metabolic patterns and the kinetics of uptake and release in living organisms and for simulating the radiochemical processing of biomedical radioisotopes 99mTc and 94mTc. Both 99gTc (T1/2 = 200 ka) and 99mTc (T1/2 = 6.0 h) are not suitable for medium-term experiments onto biological systems. To study the excitation functions for different Tc RNs, "thin" Mo metal targets were irradiated up to 45 MeV. The gamma-decay of the radionuclides was followed for not less than three half-lives. In cases requiring radioactive equilibria (A= 95 and 96) corrections were performed. The experimental data regards 94g,95g,95m,96(g+m)Tc. Besides the Tc RNs, the irradiations induced the direct and indirect production of Mo, Nb, Y and Zr ones.