title: An APD-based iterative reconstruction method for simultaneous technetium-99m/iodine-123 SPECT imaging.
abstract: Dual-isotope SPECT (DI-SPECT) studies offer significant advantages over sequential scans, foremost among them faster acquisition and perfect image registration. However, reconstructed images may be affected by substantial cross-talk contamination rendering them inadequate for diagnosis. This effect is especially strong for isotopes with close photopeak energies, such as (99m)Tc (140keV) and (123)I (159keV). In this paper we present an iterative DI-SPECT reconstruction method which includes accurate, analytically computed scatter corrections provided by the APD (analytical photon distribution) algorithm. This algorithm calculates first and second order Compton scatter (based on the Klein-Nishina formula) and first order Rayleigh scatter. Both self-scatter and cross-talk between the two isotopes are evaluated using patient specific attenuation maps and an initial activity distribution estimate. To validate our method we performed experiments using the Data Spectrum, Inc. thorax phantom and a SPECT/CT camera system. Reconstructed images demonstrate significant improvement in data quantitation. Their quantitative accuracy increases up to a factor of two, even for activity ratios which strongly enhance cross-talk effects and seriously degrade projections.
authors.affiliation: Department of Radiology, University of British Columbia, 828 West 10th Avenue, Room 367, Vancouver, B.C., V5Z1L8 Canada. shcher2@interchange.ubc.ca
authors.forename: S
authors.initials: S
authors.lastname: Shcherbinin
authors.forename: A
authors.initials: A
authors.lastname: Celler
authors.forename: M
authors.initials: M
authors.lastname: Trummer
authors.forename: T
authors.initials: T
authors.lastname: Humphries
mesh_terms: D000465:Algorithms; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D007457:Iodine Radioisotopes; D008954:Models, Biological; D019047:Phantoms, Imaging; D012542:Scattering, Radiation; D013667:Technetium; D013909:Thorax / Q000000981:diagnostic imaging; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D007457:Iodine Radioisotopes; D013667:Technetium