State-of-the-art γ -ray assay of Y86 for medical imaging

An emerging direction in nuclear medicine is the coupling of a therapeutic isotope with an imaging isotope to form a so-called theranostic pair, which allows one to quantitatively track and image the delivery of the therapeutic isotope. $^{90}\mathrm{Y}$ is used in several therapy applications and a convenient candidate imaging partner is the positron emitter $^{86}\mathrm{Y}$. A 27.6 MBq source of $^{86}\mathrm{Y}$ was produced at the University of Wisconsin and assayed with the Gammasphere array at Argonne National Laboratory. Over 200 $\ensuremath{\gamma}$-ray transitions were identified, more than double that which was previously known. The positron emission probability inferred from the present level scheme leads to 27.9(12)%, an important $(\ensuremath{\approx}14%)$ reduction with respect to the previously recommended value.