title: 223Ra-dichloride spectrometric characterization: Searching for the presence of long-lived isotopes with radiological protection implications.
abstract: 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 of226Ra yielding227Ac, which decays to227Th and223Fr, both decaying to223Ra. Since223Ra 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. Since227Ac is involved in the production of223Ra, an impurity analysis of each batch is required after production. Due to time restrictions, the manufacturer's detection limit (<0.001%) exceeds the one required to assure that227Ac concentrations are below direct disposal levels. To improve the detection limit, long-term accurate spectroscopy is required. Alpha and gamma spectroscopy measurements were carried out at the Complutense University Nuclear Physics Laboratory. After twelve months follow up of a sample,227Ac concentration was found to be smaller than 10-9. This allows for direct waste disposal and no additional radiation protection restrictions than those required for223Ra. The presence of contamination by other radioisotopes was also ruled out by this experiment. Specifically226Ra, involved in223Ra production as the original parent and with a very long-lived (T1/2=1577years) alpha emitter, was also below the experimental detection limit.
authors.affiliation: Servicio de Radiofísica y Protección Radiológica, Hospital Universitario de Burgos, Avenida Islas Baleares N°3, E-09006 Burgos, Spain. Electronic address: javiersjim@gmail.com.
authors.forename: J
authors.initials: J
authors.lastname: Sánchez-Jiménez
authors.affiliation: Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, CEI Moncloa, Avenida Complutense, E-28040 Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: López-Montes
authors.affiliation: Servicio de Radiofísica y Protección Radiológica, Hospital Universitario de Burgos, Avenida Islas Baleares N°3, E-09006 Burgos, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Núñez-Martínez
authors.affiliation: Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, CEI Moncloa, Avenida Complutense, E-28040 Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Villa-Abaunza
authors.affiliation: Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, CEI Moncloa, Avenida Complutense, E-28040 Madrid, Spain.
authors.forename: L M
authors.initials: LM
authors.lastname: Fraile
authors.affiliation: Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, CEI Moncloa, Avenida Complutense, E-28040 Madrid, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Sánchez-Tembleque
authors.affiliation: Grupo de Física Nuclear, Departamento de Física Atómica, Molecular y Nuclear, Facultad de Ciencias Físicas, Universidad Complutense de Madrid, CEI Moncloa, Avenida Complutense, E-28040 Madrid, Spain.
authors.forename: J M
authors.initials: JM
authors.lastname: Udías
mesh_terms: D015902:Gamma Cameras; D006801:Humans; D016272:Occupational Health; D061214:Patient Safety; D011835:Radiation Protection / Q000379:methods; D011850:Radioactive Waste; D011868:Radioisotopes / Q000737:chemistry; D011874:Radiometry / Q000379:methods; D011883:Radium / Q000737:chemistry*; D013057:Spectrum Analysis; D013997:Time Factors
chemical_list: D011850:Radioactive Waste; D011868:Radioisotopes; C581106:radium Ra 223 dichloride; D011883:Radium
keywords: Alpha emitters; Radiation protection; Radium-223; Spectroscopy