Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195, Warsaw, Poland.
Synektik S.A., Research and Development Center, Warsaw, Poland.
EJNMMI Phys. 2015 Dec;2(1):33. doi: 10.1186/s40658-015-0136-x. Epub 2015 Dec 4.
Recently, significant interest in (44)Sc as a tracer for positron emission tomography (PET) imaging has been observed. Unfortunately, the co-emission by (44)Sc of high-energy γ rays (E γ = 1157, 1499 keV) causes a dangerous increase of the radiation dose to the patients and clinical staff. However, it is possible to produce another radionuclide of scandium-(43)Sc-having properties similar to (44)Sc but is characterized by much lower energy of the concurrent gamma emissions. This work presents the production route of (43)Sc by α irradiation of natural calcium, its separation and purification processes, and the labeling of [DOTA,Tyr3] octreotate (DOTATATE) bioconjugate.
Natural CaCO3 and enriched [(40)Ca]CaCO3 were irradiated with alpha particles for 1 h in an energy range of 14.8-30 MeV at a beam current of 0.5 or 0.25 μA. In order to find the optimum method for the separation of (43)Sc from irradiated calcium targets, three processes previously developed for (44)Sc were tested. Radiolabeling experiments were performed with DOTATATE radiobioconjugate, and the stability of the obtained (43)Sc-DOTATATE was tested in human serum.
Studies of (nat)CaCO3 target irradiation by alpha particles show that the optimum alpha particle energies are in the range of 24-27 MeV, giving 102 MBq/μA/h of (43)Sc radioactivity which creates the opportunity to produce several GBq of (43)Sc. The separation experiments performed indicate that, as with (44)Sc, due to the simplicity of the operations and because of the chemical purity of the (43)Sc obtained, the best separation process is when UTEVA resin is used. The DOTATATE conjugate was labeled by the obtained (43)Sc with a yield >98 % at elevated temperature.
Tens of GBq activities of (43)Sc of high radionuclidic purity can be obtainable for clinical applications by irradiation of natural calcium with an alpha beam.
最近，人们对作为正电子发射断层扫描（PET）成像示踪剂的 44Sc 产生了浓厚的兴趣。不幸的是，44Sc 同时发射的高能γ射线（Eγ=1157、1499keV）会对患者和临床医护人员造成危险的辐射剂量增加。然而，通过对天然钙进行α辐照，可以产生另一种钪放射性核素- 43Sc，它具有与 44Sc 相似的性质，但同时γ射线的能量要低得多。本工作介绍了通过α辐照天然钙生产 43Sc 的途径、其分离和纯化过程以及 DOTA-Tyr3 奥曲肽（DOTATATE）生物缀合物的标记。
用α粒子辐照天然 CaCO3 和富集的[(40)Ca]CaCO3，在 14.8-30MeV 的能量范围内，束流为 0.5 或 0.25μA，辐照 1 小时。为了找到从辐照钙靶中分离 43Sc 的最佳方法，测试了先前为 44Sc 开发的三种方法。用 DOTATATE 放射性生物缀合物进行放射性标记实验，并在人血清中测试所得 43Sc-DOTATATE 的稳定性。
α粒子辐照（nat）CaCO3 靶的研究表明，最佳的α粒子能量范围在 24-27MeV 之间，产生 102MBq/μA/h 的 43Sc 放射性活度，为生产数 GBq 的 43Sc 提供了机会。进行的分离实验表明，与 44Sc 一样，由于操作简单，以及获得的 43Sc 的化学纯度高，最好的分离过程是使用 UTEVA 树脂。在高温下，用所得的 43Sc 对 DOTATATE 缀合物进行标记，产率>98%。
通过用α束辐照天然钙，可获得数十 GBq 高放射性核纯度的 43Sc，可用于临床应用。
