scandium44

Scandium-44 (44Sc) is a radionuclide of the element scandium (atomic number 21) with mass number 44. The nucleus contains 21 protons and 23 neutrons. 44Sc is a positron-emitting isotope that decays to the stable isotope calcium-44 (44Ca) with a half-life of about 4 hours. Its decay characteristics make it of interest for medical imaging applications, particularly in positron emission tomography (PET).

Production and availability: 44Sc can be produced in cyclotrons via the 44Ca(p,n)44Sc reaction, or generated on site from a long-lived parent such as 44Ti in a 44Ti/44Sc generator. The 44Ti half-life is about 60 years, which allows the generator to supply 44Sc over extended periods. This generator-based approach enables on-site access to 44Sc for research and clinical imaging.

Applications: In radiopharmacy, 44Sc is used to label peptides and proteins for PET imaging. Chelating agents such as DOTA and NOTA enable the attachment of 44Sc to biomolecules, including somatostatin receptor–targeting peptides, forming 44Sc-labeled radiopharmaceuticals. These compounds are studied as alternatives or complements to other PET isotopes, offering compatible chemistry and timing for imaging workflows.

Chemistry: In solution, 44Sc behaves as a trivalent cation (Sc3+). Radiolabeling typically proceeds with chelators under controlled pH and temperature to form stable radiometal complexes suitable for in vivo imaging.

See also: 44Ti, 44Ti/44Sc generator, PET imaging, DOTA, NOTA.

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