Title :
Online Geometric Calibration of Cone-Beam Computed Tomography for Arbitrary Imaging Objects
Author :
Yuanzheng Meng ; Hui Gong ; Xiaoquan Yang
Author_Institution :
Britton Chance Center for Biomed. Photonics, Huazhong Univ. of Sci. & Technol, Wuhan, China
Abstract :
A novel online method based on the symmetry property of the sum of projections (SOP) is proposed to obtain the geometric parameters in cone-beam computed tomography (CBCT). This method requires no calibration phantom and can be used in circular trajectory CBCT with arbitrary cone angles. An objective function is deduced to illustrate the dependence of the symmetry of SOP on geometric parameters, which will converge to its minimum when the geometric parameters achieve their true values. Thus, by minimizing the objective function, we can obtain the geometric parameters for image reconstruction. To validate this method, numerical phantom studies with different noise levels are simulated. The results show that our method is insensitive to the noise and can determine the skew (in-plane rotation angle of the detector), the roll (rotation angle around the projection of the rotation axis on the detector), and the rotation axis with high accuracy, while the mid-plane and source-to-detector distance will be obtained with slightly lower accuracy. However, our simulation studies validate that the errors of the latter two parameters brought by our method will hardly degrade the quality of reconstructed images. The small animal studies show that our method is able to deal with arbitrary imaging objects. In addition, the results of the reconstructed images in different slices demonstrate that we have achieved comparable image quality in the reconstructions as some offline methods.
Keywords :
calibration; computerised tomography; image reconstruction; medical image processing; phantoms; arbitrary cone angles; arbitrary imaging objects; comparable image quality; cone-beam computed tomography; geometric parameters; image reconstruction; in-plane rotation angle; noise levels; numerical phantom; objective function minimization; online geometric calibration; source-to-detector distance; symmetry property; Calibration; Computed tomography; Detectors; Image reconstruction; Linear programming; Phantoms; Cone-beam computed tomography (CBCT); geometric calibration; Algorithms; Calibration; Cone-Beam Computed Tomography; Internationality; Radiographic Image Enhancement; Radiographic Image Interpretation, Computer-Assisted; Reproducibility of Results; Sensitivity and Specificity;
Journal_Title :
Medical Imaging, IEEE Transactions on
DOI :
10.1109/TMI.2012.2224360