Open AccessPreclinical Single Photon Emission Computed Tomography of Alpha Particle-Emitting Radium-223
Author(s) -
Diane S. Abou,
Andrew Rittenbach,
Ryan E. Tomlinson,
Paige Finley,
B.M.W. Tsui,
Brian W. Simons,
Abhinav K. Jha,
David Ulmert,
Ryan C. Riddle,
Daniel L.J. Thorek
Publication year - 2020
Publication title -
cancer biotherapy and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.716
H-Index - 59
eISSN - 1557-8852
pISSN - 1084-9785
DOI - 10.1089/cbr.2019.3308
Subject(s) - nuclear medicine , single photon emission computed tomography , imaging phantom , correction for attenuation , collimator , emission computed tomography , relative biological effectiveness , physics , biomedical engineering , medicine , positron emission tomography , radiation , optics
Objective: Dose optimization and pharmacokinetic evaluation of α-particle emitting radium-223 dichloride ( 223 RaCl 2 ) by planar γ-camera or single photon emission computed tomography (SPECT) imaging are hampered by the low photon abundance and injected activities. In this study, we demonstrate SPECT of 223 Ra using phantoms and small animal in vivo models. Methods: Line phantoms and mice bearing 223 Ra were imaged using a dedicated small animal SPECT by detecting the low-energy photon emissions from 223 Ra. Localization of the therapeutic agent was verified by whole-body and whole-limb autoradiography and its radiobiological effect confirmed by immunofluorescence. Results: A state-of-the-art commercial small animal SPECT system equipped with a highly sensitive collimator enables collection of sufficient counts for three-dimensional reconstruction at reasonable administered activities and acquisition times. Line sources of 223 Ra in both air and in a water scattering phantom gave a line spread function with a full-width-at-half-maximum of 1.45 mm. Early and late-phase imaging of the pharmacokinetics of the radiopharmaceutical were captured. Uptake at sites of active bone remodeling was correlated with DNA damage from the α particle emissions. Conclusions: This work demonstrates the capability to noninvasively define the distribution of 223 RaCl 2 , a recently approved α-particle-emitting radionuclide. This approach allows quantitative assessment of 223 Ra distribution and may assist radiation-dose optimization strategies to improve therapeutic response and ultimately to enable personalized treatment planning.