with scintillation cameras in place and the lid removed. Each camera is individually shielded with lead. As shown, two plates are in the highest magnification position and two plates are in the second-highest magnification position . Cables running from the PMTs to the electronics are visible.
(a) The shielding aperture and base with three pinhole plates in place. Cameras abut each of the four ports and a lid locks onto the top of the assembly. (b) A top view of the shielding assembly design. Example pinhole plates are shown on the left side of the figure and a representation of a gamma camera is shown at each port. Distances given are in inches.
(a) Aperture 1 made out of Kulite with five on-axis pinholes on the face of the plate. (b) Aperture 5 made out of tungsten-copper alloy with nine on-axis pinholes in a gold foil in the center of the plate. (c) Aperture 7 made out of tungsten-copper alloy with four angled pinholes in a rotated diamond pattern in press-fit tungsten-copper rods.
(a) Measured projection of a point signal through aperture 1. (b) Measured projection of a point signal through aperture 5. (c) Measured projection of a point signal through aperture 7.
Hot-rod phantom used in the reconstruction study. The phantom consists of clusters of columns ranging in diameter from , decreasing in steps. Each column in a given cluster is separated by two times the diameter of that cluster’s columns.
(a) Slice of an OSEM reconstruction of the hot-rod phantom performed using original matrix. (b) The same reconstructed slice as is shown in (a) but interpolated in postprocessing to match the dimensions of a reconstruction performed using an interpolated system matrix. (c) The same reconstructed slice but from a reconstruction performed using the interpolated system matrix.
(a) Slice of an OSEM reconstruction of the hot-rod phantom performed using an interpolated system matrix with aperture 2. (b) The same reconstructed slice as is shown in (a) but following postprocessing with a Butterworth filter. (c) The same slice as is shown in (a) but from a reconstruction performed using apertures 2 and 4 and postprocessed with a Butterworth filter.
Pinhole plates built for . The table includes magnification, number of pinholes, pinhole diameter, opening angle, pinhole pattern, sensitivity, (normalized to the most sensitive aperture), and material where Ku stands for Kulite and W-Cu stands for tungsten-copper. The apertures have been numbered for reference later in the manuscript.
Magnifications typically used in and their corresponding slots and location on the pinhole plate. Other magnifications are possible but not typically used because of construction considerations.
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