Abbie Hasson1,2, Wen Jiang3, Nadia Benabdallah2,4, Peng Lu1,4, Mark S Longtine2, Bradley J Beattie5, Lucy Summer2, Hanwen Zhang2,4,6, Richard L Wahl2,6, Diane S Abou2,4,6, Daniel L J Thorek1,2,4,6. 1. Department of Biomedical Engineering, Washington University, St. Louis, Missouri, USA. 2. Department of Radiology, Program in Quantitative Molecular Therapeutics, Washington University School of Medicine, St. Louis, Missouri, USA. 3. Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA. 4. Department of Radiology, Washington University School of Medicine, St. Louis, Missouri, USA. 5. Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, New York, USA. 6. Siteman Cancer Center, Oncologic Imaging Program, Alvin J. Siteman Cancer Center, Washington University School of Medicine, St. Louis, Missouri, USA.
Abstract
Background: The majority of radiopharmaceuticals for use in disease detection and targeted treatment undergo a single radioactive transition (decay) to reach a stable ground state. Complex emitters, which produce a series of daughter radionuclides, are emerging as novel radiopharmaceuticals. The need for validation of chemical and radiopurity with such agents using common quality control instrumentation is an area of active investigation. Here, we demonstrate novel methods to characterize 227Th and 223Ra. Materials and Methods: A radio-TLC scanner and a gamma counter, two common and widely accessible technologies, as well as a solid-state alpha particle spectral imaging camera were evaluated for their ability to characterize and distinguish 227Th and 223Ra. We verified these results through purity evaluation of a novel 227Th-labeled protein construct. Results: The gamma counter and alpha camera distinguished 227Th from 223Ra, enabling rapid and quantitative determination of radionuclidic purity. The radio-TLC showed limited ability to describe purity, although use under alpha particle-specific settings enhanced resolution. All three methods were able to distinguish a pure from impure 227Th-labeled protein. Conclusions: The presented quality control evaluation for 227Th and 223Ra on three different instruments can be applied to both research and clinical settings as new alpha particle therapies are developed.
Background: The majority of radiopharmaceuticals for use in disease detection and targeted treatment undergo a single radioactive transition (decay) to reach a stable ground state. Complex emitters, which produce a series of daughter radionuclides, are emerging as novel radiopharmaceuticals. The need for validation of chemical and radiopurity with such agents using common quality control instrumentation is an area of active investigation. Here, we demonstrate novel methods to characterize 227Th and 223Ra. Materials and Methods: A radio-TLC scanner and a gamma counter, two common and widely accessible technologies, as well as a solid-state alpha particle spectral imaging camera were evaluated for their ability to characterize and distinguish 227Th and 223Ra. We verified these results through purity evaluation of a novel 227Th-labeled protein construct. Results: The gamma counter and alpha camera distinguished 227Th from 223Ra, enabling rapid and quantitative determination of radionuclidic purity. The radio-TLC showed limited ability to describe purity, although use under alpha particle-specific settings enhanced resolution. All three methods were able to distinguish a pure from impure 227Th-labeled protein. Conclusions: The presented quality control evaluation for 227Th and 223Ra on three different instruments can be applied to both research and clinical settings as new alpha particle therapies are developed.