Positron emission intensities in the decay of 64Cu, 76Br and 124I

The relatively long-lived positron emitters Cu-64 (t(1/2) = 12.7 h), Br-76 (t(1/2) = 16.2 h) and I-124 (t(1/2) = 4.18 d) are finding increasing applications in positron emission tomography (PET). For precise determination of their positron emission intensities, each radionuclide was prepared via a charged particle induced reaction in a "no-carrier-added" form and with high radionuclidic purity. It was then subjected to gamma-ray and X-ray spectroscopy as well as to anticoincidence beta and gamma gamma-coincidence counting. The positron emission intensities measured were: Cu-64 (17.8 +/- 0.4)%, (76)'Br (58.2 +/- 1.9)% and I-124 (22.0 +/- 0.5)%. The intensity of the weak 1346 keV gamma-ray emitted in the decay of Cu-64 was determined as (0.54 +/- 0.03)%. Some implications of the precisely determined nuclear data are discussed