title: Performance evaluation of a very high resolution small animal PET imager using silicon scatter detectors.
abstract: A very high resolution positron emission tomography (PET) scanner for small animal imaging based on the idea of inserting a ring of high-granularity solid-state detectors into a conventional PET scanner is under investigation. A particularly interesting configuration of this concept, which takes the form of a degenerate Compton camera, is shown capable of providing sub-millimeter resolution with good sensitivity. We present a Compton PET system and estimate its performance using a proof-of-concept prototype. A prototype single-slice imaging instrument was constructed with two silicon detectors 1 mm thick, each having 512 1.4 mm x 1.4 mm pads arranged in a 32 x 16 array. The silicon detectors were located edgewise on opposite sides and flanked by two non-position sensitive BGO detectors. The scanner performance was measured for its sensitivity, energy, timing, spatial resolution and resolution uniformity. Using the experimental scanner, energy resolution for the silicon detectors is 1%. However, system energy resolution is dominated by the 23% FWHM BGO resolution. Timing resolution for silicon is 82.1 ns FWHM due to time-walk in trigger devices. Using the scattered photons, time resolution between the BGO detectors is 19.4 ns FWHM. Image resolution of 980 microm FWHM at the center of the field-of-view (FOV) is obtained from a 1D profile of a 0.254 mm diameter (18)F line source image reconstructed using the conventional 2D filtered back-projection (FBP). The 0.4 mm gap between two line sources is resolved in the image reconstructed with both FBP and the maximum likelihood expectation maximization (ML-EM) algorithm. The experimental instrument demonstrates sub-millimeter resolution. A prototype having sensitivity high enough for initial small animal images can be used for in vivo studies of small animal models of metabolism, molecular mechanism and the development of new radiotracers.
authors.affiliation: Division of Nuclear Medicine, University of Michigan, Ann Arbor, MI, USA. sangjune@umich.edu
authors.forename: Sang-June
authors.initials: SJ
authors.lastname: Park
authors.forename: W Leslie
authors.initials: WL
authors.lastname: Rogers
authors.forename: Sam
authors.initials: S
authors.lastname: Huh
authors.forename: Harris
authors.initials: H
authors.lastname: Kagan
authors.forename: Klaus
authors.initials: K
authors.lastname: Honscheid
authors.forename: Don
authors.initials: D
authors.lastname: Burdette
authors.forename: Enrico
authors.initials: E
authors.lastname: Chesi
authors.forename: Carlos
authors.initials: C
authors.lastname: Lacasta
authors.forename: Gabriela
authors.initials: G
authors.lastname: Llosa
authors.forename: Marko
authors.initials: M
authors.lastname: Mikuz
authors.forename: Andrej
authors.initials: A
authors.lastname: Studen
authors.forename: Peter
authors.initials: P
authors.lastname: Weilhammer
authors.forename: Neal H
authors.initials: NH
authors.lastname: Clinthorne
mesh_terms: D000818:Animals; D004867:Equipment Design; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D012825:Silicon / Q000737:chemistry*
chemical_list: D012825:Silicon