Cone beam computed tomography (CBCT) systems with rotational gantries that have standard flat panel detectors (FPD) are widely used for the 3D rendering of vascular structures using Feldkamp cone beam reconstruction algorithms. One of the inherent limitations of these systems is limited resolution (<3 lp/mm). There are systems available with higher resolution but their small FOV limits them to small animal imaging only.
In this work, we report on region-of-interest (ROI) CBCT with a high resolution CMOS detector (75 μm pixels, 600 μm HR-CsI) mounted with motorized detector changer on a commercial FPD-based C-arm angiography gantry (194 μm pixels, 600 μm HL-CsI). A cylindrical CT phantom and neuro stents were imaged with both detectors. For each detector a total of 209 images were acquired in a rotational protocol. The technique parameters chosen for the FPD by the imaging system were used for the CMOS detector. The anti-scatter grid was removed and the incident scatter was kept the same for both detectors with identical collimator settings. The FPD images were reconstructed for the 10 cm x10 cm FOV and the CMOS images were reconstructed for a 3.84 cm × 3.84 cm FOV.
Although the reconstructed images from the CMOS detector demonstrated comparable contrast to the FPD images, the reconstructed 3D images of the neuro stent clearly showed that the CMOS detector improved delineation of smaller objects such as the stent struts (~70 μm) compared to the FPD. Further development and the potential for substantial clinical impact are suggested.
In this paper we propose a dynamic 3-D gamma camera consisting of multi-pinhole collimators and flat panel detectors. Through simulation studies on various pinhole configurations we determined that from a spatial and time resolution consideration, pinhole collimators with a 60 opening angle achieved acceptable dynamic 3-D imaging results. With regard to basic system performance, we estimated that the spatial and time resolution exceeds 3.5 mm and 4 s, respectively, for a small animal injected with 99m Tc with an activity of 37 MBq. In addition, from further experiments we concluded that the proposed system would be acceptable and practical as a dynamic 3-D imager for nuclear medicine applications although position calibration concerns require further study.
In this paper we propose a dynamic 3-D gamma camera consisting of multi-pinhole collimators and flat panel detectors. Through simulation studies on various pinhole configurations we determined that from a spatial and time resolution consideration, pinhole collimators with a 60 opening angle achieved acceptable dynamic 3-D imaging results. With regard to basic system performance, we estimated that the spatial and time resolution exceeds 3.5 mm and 4 s, respectively, for a small animal injected with 99m Tc with an activity of 37 MBq. In addition, from further experiments we concluded that the proposed system would be acceptable and practical as a dynamic 3-D imager for nuclear medicine applications although position calibration concerns require further study.
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