The use of theranostic agents in nuclear medicine allow for patient-specific treatment that combines diagnosis and therapy. Recently, increased development of receptor-targeted therapies has highlighted the need for understanding the pharmacokinetic profile of these agents. Imaging with a chemically identical diagnostic agent affords the truest picture of in vivo distribution. Therefore, the development of matched radionuclide pairs for use in receptor targeted therapies and imaging is an emerging area of research. One promising radionuclide pair is the positron-emitting 44Sc (β+avg = 632.0 keV, t1/2 = 3.97 h) and beta-emitting 47Sc (βavg = 162.0 keV, t1/2 = 3.35 d). To determine the feasibility of producing 44,47Sc using titanium targets via the 47Ti(p,α)44Sc and 50Ti(p,α)47Sc reaction, preliminary work was carried out to investigate yield, targetry, and purification chemistry. In this work, published nuclear reaction data were used to predict optimal bombardment energies of 13.0 and 17.5 MeV for 44Sc and 47Sc production, respectively, providing a starting point for our experiments. Radioscandium was produced by the natTi(p,x)43,44,47Sc reaction, using high-purity natural Ti irradiated on a TR-24 cyclotron at the University of Alabama at Birmingham. A typical bombardment at 24 MeV led to 71 MBq, 370 MBq, and 12 MBq of 43Sc, 44Sc, and 47Sc, respectively. Irradiated targets were acid digested in 1.0 M NH4HF2 dissolved in 12.1 M HCl. After digestion, 43,44,47Sc was isolated and purified by cation exchange chromatography using branched DGA resin (N,N,N’,N’-tetrakis-2-ethylhexyl-diglycolamide) in 3.0 mL of 0.1 M HCl. The mean recovery was 90 ± 3%. Data from these experiments show that 44Sc/47Sc can be produced, separated, and purified using natural Ti. These results support further investigation of 44Sc/47Sc production using enriched 47Ti/50Ti targets. Importantly, production of 44Sc/47Sc by this route is advantageous, requiring the optimization of a single process for production and purification of this matched radionuclide pair.

Production of theranostic radioscandium for nuclear imaging and radiotherapy

255th National Meeting (2018)

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