Positron Emission Intensity in the Decay of (86g)Y for Use in Dosimetry Studies

The β(+)-emitting radionuclide (86g)Y (t(1/2) = 14.7 h) forms a matched-pair with the β(−)-emitting therapeutic radionuclide (90)Y (t(1/2) = 2.7 d) for theranostic application in medicine. This approach demands a precise knowledge of the positron emission probability of the PET nuclide which was until recently rather uncertain for (86g)Y. In this work, an (86g)Y source of high radionuclidic purity was prepared and a direct measurement of the positron emission intensity per 100 decay of the parent (hereafter “positron emission intensity”) was performed using high-resolution HPGe detector γ-ray spectroscopy. The electron capture intensity was also determined as an additional check by measuring the K(α) and K(β) X-rays of energies 14.1 and 15.8 keV, respectively, using a low energy HPGe detector. From those measurements, normalized values of 27.2 ± 2.0% for β(+)-emission and 72.8 ± 2.0% for EC were obtained. These results are in excellent agreement with values recently reported in the literature based on a detailed decay scheme study.