223Ra-dichloride spectrometric characterization: Searching for the presence of long-lived isotopes with radiological protection implications

• Published in: Physica medica 2017-03, Vol.35, p.97-101
• Main Authors: Sánchez-Jiménez, J., López-Montes, A., Núñez-Martínez, L., Villa-Abaunza, A., Fraile, L.M., Sánchez-Tembleque, V., Udías, J.M.
• Format: Article
• Language: English
• Subjects: Alpha emitters; Radiation protection; Radium-223; Spectroscopy
• ISSN: 1120-1797; 1724-191X
• DOI: 10.1016/j.ejmp.2017.02.006

•No concentration of 227Ac above 10−7 relative to 223Ra was found on Xofigo compounds.•No other long-lived radioisotope contamination was present.•Radiation protection restrictions should be limited to those of 223Ra. 223Ra-dichloride was approved with the commercial name of Xofigo in 2014 for treatment of metastatic castration-resistant prostate cancer. 223Ra is obtained by neutron irradiation of 226Ra yielding 227Ac, which decays to 227Th and 223Fr, both decaying to 223Ra. Since 223Ra is predominantly (95.3%) an alpha emitter with a 11.42days long half-life, the radiopharmaceutical, its remnants, the patient, and waste material can be managed and disposed with low radiation protection requirements. 227Ac is a long-lived (T1/2=21.77years) beta emitter that demands strong radiation protection measures. In particular waste disposal has to follow the International Atomic Energy Agency (IAEA) and European Commission (EC) regulations. Since 227Ac is involved in the production of 223Ra, an impurity analysis of each batch is required after production. Due to time restrictions, the manufacturer’s detection limit (