Preliminary dosimetric analysis of DOTA-folate radiopharmaceutical radiolabelled with <sup>47</sup> Sc produced through <sup>nat</sup> V(p,x) <sup>47</sup> Sc cyclotron irradiation
Laura De Nardo, Gaia Pupillo, Liliana Mou, D Furlanetto, Antonio Rosato, Juan Esposito, Laura Meléndez‐Alafort
Abstract
Abstract 47 Sc is one of the most promising theranostic radionuclides, thanks to its low energy γ -ray emission (159 keV), suitable for single photon emission computed tomography imaging and its intense β − emission, useful for tumour treatment. Despite promising preclinical results, the translation of 47 Sc-therapeutic agents to the clinic is hampered by its limited availability. Among different 47 Sc-production routes currently being investigated, the nat V(p,x) 47 Sc reaction has proved to be of particular interest, thanks to the low-cost and easy availability on the market of nat V material and the diffusion of medium energy proton cyclotrons. However, the cross section of this specific nuclear reaction is quite low and small amounts of Sc-contaminants are co-produced at energies E P ≤ 45 MeV, namely 48 Sc and 46 Sc. The main concern with these Sc-contaminants is their contribution to the patient absorbed dose. For such a reason, the absorbed dose contributions to healthy organs and the effective dose contributions by the three radioisotopes, 48 Sc, 47 Sc and 46 Sc, were evaluated using DOTA-folate conjugate (cm10) as an example of radiopharmaceutical product. Considering as acceptable the limits of 99% for the radionuclidic purity and 10% for the contribution of radioactive Sc-contaminants to the total effective dose after 47 Sc-cm10 injection, it was obtained that proton beam energies below 35 MeV must be used to produce 47 Sc through irradiation of a nat V target.