A study on 99mTc by means of HP Ge-spectrometer

The radioactive decay of 99mTc has been measured using a HP Ge-spectrometer with active volume 69.4 cm3 and EG and G ORTEC model 7050 Data Acquisition and Analysis System. The energies and intensities of very weak 321.99keV and 232.01keV gamma rays were obtained. Energy levels of 99Ru were found with the energy value of 321.99keV (5/2+) and 89.98keV(3/2+). The beta branches to 99Ru ground, 89.98keV and 321.99KeV states were respectively determined with the intensities per decay of 1.0 x10-5, 2.6x10-5 and 0.7742x10-6. And also log ft-values of 9.32, 8.63, and 7.82 were respectively derived. The decay scheme of 99mTc were finally presented. Intensity ratios of 321.99keV, 232.01keV and 140.13 keV gammas were calculated through several corrections; I321.99 : I232.01 : I140.13 = 0.8087x10-6 : 0.6963x10-7 : 1. The total gamma emission following 99mTc beta decay results in a negligible effects to dosage calculations in the use of 99mTc for nuclear medicine. (Author)