20 April 2005 Camera calibration for synthetic digital tomography
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Abstract
A method for calibrating camera geometry is described. This method has been used to implement synthetic tomography on a commercially available full-field digital mammography system. The method utilizes a phantom containing six point-like calibration objects whose positions are approximately known. The image of five calibration objects in a given projection allows an associated projection matrix to be determined up to one free parameter. By using the positions of the shadows of the sixth calibration object in three or more views, one can fit the remaining free parameter associated with each view and the position of the sixth calibration object relative to the first five. Uncertainty in the position or geometry of the phantom does not affect the geometric consistency, thus tomograms produced by back-projection suffer no blurring from errors in the determination of camera geometry. Uncertainties in the position or geometry of the phantom result in proportionate translations or distortions of the tomograms. For a tomogram corresponding to a plane containing an object, the positions of the backprojections of the shadows of the object are consistent to the same precision as the measurements of the shadows in each projection, i.e., the positions of the backprojections differ by about the size of the pixel spacing in the detector.
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Michael Albert, Michael Albert, Ann-Katherine Carton, Ann-Katherine Carton, Andrew D. A. Maidment, Andrew D. A. Maidment, } "Camera calibration for synthetic digital tomography", Proc. SPIE 5745, Medical Imaging 2005: Physics of Medical Imaging, (20 April 2005); doi: 10.1117/12.597316; https://doi.org/10.1117/12.597316
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