Geometric calibration for a dual tube/detector micro-CT system.
The authors describe a dual tube/detector micro-computed tomography (micro-CT) system that has the potential to improve temporal resolution and material contrast in small animal imaging studies. To realize this potential, it is necessary to precisely calibrate the geometry of a dual micro-CT system to allow the combination of projection data acquired with each individual tube/detector in a single reconstructed image. The authors present a geometric calibration technique that uses multiple projection images acquired with the two imaging chains while rotating a phantom containing a vertical array of regularly spaced metallic beads. The individual geometries of the imaging chains are estimated from the phantom projection images using analytical methods followed by a refinement procedure based on nonlinear optimization. The geometric parameters are used to create the cone beam projection matrices required by the reconstruction process for each imaging chain. Next, a transformation between the two projection matrices is found that allows the combination of projection data in a single reconstructed image. The authors describe this technique, test it with a series of computer simulations, and then apply it to data collected from their dual tube/detector micro-CT system. The results demonstrate that the proposed technique is accurate, robust, and produces images free of misalignment artifacts.
Center for In Vivo Microscopy, Box 3302, Duke University Medical Center, Durham, North Carolina 27710, USA.
Samuel M
SM
Johnston
G Allan
GA
Johnson
Cristian T
CT
Badea
D000465:Algorithms; D000818:Animals; D016477:Artifacts; D002138:Calibration; D004867:Equipment Design; D006801:Humans; D008670:Metals; D051379:Mice; D015233:Models, Statistical; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods; D015203:Reproducibility of Results; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*; D014965:X-Rays
D008670:Metals