title: Joint reconstruction of activity and attenuation map using LM SPECT emission data.
abstract: Attenuation and scatter correction in single photon emission computed tomography (SPECT) imaging often requires a computed tomography (CT) scan to compute the attenuation map of the patient. This results in increased radiation dose for the patient, and also has other disadvantages such as increased costs and hardware complexity. Attenuation in SPECT is a direct consequence of Compton scattering, and therefore, if the scattered photon data can give information about the attenuation map, then the CT scan may not be required. In this paper, we investigate the possibility of joint reconstruction of the activity and attenuation map using list-mode (LM) SPECT emission data, including the scattered-photon data. We propose a path-based formalism to process scattered-photon data. Following this, we derive analytic expressions to compute the Cramér-Rao bound (CRB) of the activity and attenuation map estimates, using which, we can explore the fundamental limit of information-retrieval capacity from LM SPECT emission data. We then suggest a maximum-likelihood (ML) scheme that uses the LM emission data to jointly reconstruct the activity and attenuation map. We also propose an expectation-maximization (EM) algorithm to compute the ML solution.
authors.affiliation: College of Optical Sciences, University of Arizona, Tucson, AZ, USA.
authors.forename: Abhinav K
authors.initials: AK
authors.lastname: Jha
authors.affiliation: College of Optical Sciences, University of Arizona, Tucson, AZ, USA ; Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Clarkson
authors.affiliation: College of Optical Sciences, University of Arizona, Tucson, AZ, USA ; Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Kupinski
authors.affiliation: College of Optical Sciences, University of Arizona, Tucson, AZ, USA ; Department of Medical Imaging, University of Arizona, Tucson, AZ, USA.
authors.forename: Harrison H
authors.initials: HH
authors.lastname: Barrett
keywords: Cramér-Rao bound; Fisher information; SPECT; activity and attenuation map; joint reconstruction; list-mode data; maximum likelihood expectation maximization