OtherBasic Science Investigations

Performance Evaluation of the 32-Module quadHIDAC Small-Animal PET Scanner

Klaus P. Schäfers, Andrew J. Reader, Michael Kriens, Christof Knoess, Otmar Schober and Michael Schäfers
Journal of Nuclear Medicine June 2005, 46 (6) 996-1004;

Article Figures & Data

Figures

  • FIGURE 1.
    FIGURE 1.

    (A) Construction of a detector module in 3 layers: 2 converters connected by a MWPC. An incoming photon is converted into an electron that is amplified and accelerated toward the anode wires. (B) Each converter contains interleaved lead and insulation sheets, mechanically drilled with a dense matrix of small holes. A photon interacts with the lead, resulting in an electron that avalanches in a strong electrical field and accelerates toward the MWPC.

  • FIGURE 2.
    FIGURE 2.

    Reconstruction results of a 18F-filled high-resolution phantom, constructed from a plastic cylinder, in which holes of different sizes (0.5, 1, 1.5, and 2 mm) were drilled (C). Holes are clearly visible in FBP (A) and OPL-EM (B) reconstructed images down to a size of 1 mm with sharp signals in the profile lines (D and F, horizontal and vertical profiles FBP; E and G, horizontal and vertical profiles OPL-EM).

  • FIGURE 3.
    FIGURE 3.

    Absolute sensitivity of quadHIDAC for different line source lengths. Measurements were performed using method of Bailey et al. (14).

  • FIGURE 4.
    FIGURE 4.

    Count rate performance measured with line source (A), mouse phantom (B), and rat phantom (C). Denoted by × is the rate of the total number of detected coincidences. Subtracting randoms (denoted by ○), estimated from the single rate yields the set of stars (*). True unscattered coincidence rate (denoted by +) was obtained by subtracting scattered events (▵).

  • FIGURE 5.
    FIGURE 5.

    NEC rates for mouse phantom and rat phantom.

  • FIGURE 6.
    FIGURE 6.

    (A and B) Images (OPL-EM) of 22-g mouse, acquired in 15 min, 1 h after injection of 18F-FDG show maximum intensity projection (A) and a single central slice (B). (C) Maximum intensity projection of 27-g mouse, 1 h after injection of 18F fluoride.

Tables

  • TABLE 1

    Spatial Resolution (in mm) of quadHIDAC

    Spatial resolution at center of FOVFBPOPL-EM*
    FWHMFWTMFWHMFHTM
    Radial1.0782.4111.0962.450
    Tangential1.0812.4161.0822.418
    Axial1.0382.3221.0002.237

    • ↵* Without resolution recovery.

  • TABLE 2

    Count Rate Measurements of Line Source and Mouse Phantom Experiment Normalized to Computed Coincidence Decay Rate

    ParameterTotalTruesScatterScatter fraction (%)Attenuation fraction (%)
    Line source0.02380.01490.007632—
    Mouse scatter phantom0.02030.01150.00753722
  • TABLE 3

    Comparison of quadHIDAC and microPET R4

    ParameterquadHIDACmicroPET R4
    Volumetric spatial resolution (μL)
        Center of FOV1.25.1
    Sensitivity (cps/kBq)
        Line source13.7*12.2†
        Point source15.224.5†
    Maximum NEC rate
        Mouse phantom67 kcps@209 kBq/mL168 kcps@824 kBq/mL†
        Rat phantom52 kcps@96 kBq/mL89 kcps@298 kBq/mL†

    • ↵* Calculated for 7.8-cm line source.

    • ↵† Energy threshold, 350–650 keV.

    • Data for comparison are from (6).

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