title: Fisher Information Analysis of Depth-of-Interaction Estimation in Double-Sided Strip Detectors.
abstract: In very-high-spatial-resolution gamma-ray imaging applications, such as preclinical PET and SPECT, estimation of 3D interaction location inside the detector crystal can be used to minimize parallax error in the imaging system. In this work, we investigate the effect of bias voltage setting on depth-of-interaction (DOI) estimates for a semiconductor detector with a double-sided strip geometry. We first examine the statistical properties of the signals and develop expressions for likelihoods for given gamma-ray interaction positions. We use Fisher Information to quantify how well (in terms of variance) the measured signals can be used for DOI estimation with different bias-voltage settings. We performed measurements of detector response versus 3D position as a function of applied bias voltage by scanning with highly collimated synchrotron radiation at the Advanced Photon Source at Argonne National Laboratory. Experimental and theoretical results show that the optimum bias setting depends on whether or not the estimated event position will include the depth of interaction. We also found that for this detector geometry, the z-resolution changes with depth.
authors.affiliation: Department of Medical Imaging, Center for Gamma-Ray Imaging and College of Optical Sciences, University of Arizona, Tucson, AZ 85724 USA.
authors.forename: Esen
authors.initials: E
authors.lastname: Salçin
authors.affiliation: Department of Medical Imaging, Center for Gamma-Ray Imaging and College of Optical Sciences, University of Arizona, Tucson, AZ 85724 USA.
authors.forename: Harrison H
authors.initials: HH
authors.lastname: Barrett
authors.affiliation: Department of Medical Imaging, Center for Gamma-Ray Imaging and College of Optical Sciences, University of Arizona, Tucson, AZ 85724 USA.
authors.forename: H Bradford
authors.initials: HB
authors.lastname: Barber
authors.affiliation: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 229-8510, Japan.
authors.forename: Shin'ichiro
authors.initials: S
authors.lastname: Takeda
authors.affiliation: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 229-8510, Japan, and also with the Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Shin
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kanagawa 229-8510, Japan, and also with the Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan.
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Takahashi
authors.affiliation: Department of Medical Imaging, Center for Gamma-Ray Imaging and College of Optical Sciences, University of Arizona, Tucson, AZ 85724 USA.
authors.forename: Lars R
authors.initials: LR
authors.lastname: Furenlid
keywords: CdTe; CdZnTe; DOI; Fisher Information; double-sided strip; semiconductor detectors