Flat panel detector-based cone beam CT imaging: Preliminary system evaluation

The purpose of this study was to perform a preliminary evaluation of a newly constructed s flat panel detector (FPD)-based system for cone beam CT imaging applications. A prototype flat-panel detector-based cone beam CT imaging system has been designed and constructed by modifying a GE HiSpeed Advantage CT scanner. The prototype consisted of a modified GE CT HiSpeed Advantage CT gantry, an x-ray tube, an 19.5 x 24.4 cm Varian Paxscan 2520 real time flat-panel detector mounted on the gantry, a CT table and an on-gantry PC to control image acquisition. Another PC workstation serving as an operating console controlled the CT gantry and CT table, and sent trigger pulses to dedicated electronic interface modules to control radiographic exposure and to initiate data acquisition. Captured image data sets were first stored in an on-gantry computer and then downloaded from the on-gantry PC to the operating console for high-speed 3D image reconstruction. During data acquisition, the x-ray tube 1 and the FPD can be rotated on the gantry over Nx360 degrees due to integrated slip ring technology. With a single scan, this device was able to acquire up to :288 two-dimensional projections (960 x 768 x 16 bits) for direct 3D reconstruction within 9.6 seconds. This system was used for a series of preliminary phantom studies. Using the continuous scan mode of the scanner, 298 projections were acquired for all volume scans. Direct 3D reconstructions were obtained to evaluate the system for cone beam CT for lung imaging applications. The preliminary results indicate that the newly built flat panel detector-based cone beam CT scanner worked as expected.