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Proceedings Paper

Self-geometric calibration of circular cone beam CT based on epipolar geometry consistency
Author(s): Liang Zheng; Shouhua Luo; Lujie Chen; Shuang Luo
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Paper Abstract

For most offline calibration methods, a specific phantom scanning is often required before the following imaging tasks. It’s time-consuming and unable to be applied to the unstable systems. Some online approaches don’t have such drawbacks but their accuracy cannot fulfil requirements compared with the offline ones. This paper proposes an Epipolar geometry consistency based online geometric calibration for cone beam CT(CBCT). Four parameters: the detector skew, rotation axis, mid-plane and the source to detector distance are employed for geometrical modeling of CBCT in this paper. A cost function is built by exploiting the Epipolar geometry consistency among the projective views. By taking advantage of the simplex-simulated annealing algorithm(SIMPSA) algorithm to minimize the cost function, we can obtain the geometric parameters of our practical CBCT systems for image reconstruction. In simulation, different noise levels are added to projection images respectively and the experimental results show that the proposed method is insensitive to noise. What’s more, the accuracies of the parameters of the detector skew and rotation axis is slightly higher than that of the other two. In the practical situation, we scanned a thin bamboo stick and a Chinese parasol tree branch. Compared with the image reconstructed with the geometric parameters calculated by the conventional offline calibration approach, the ones reconstructed with the proposed method show no apparent difference and geometric artifacts, which shows that the accuracy of our method is comparable to that of the offline calibration ones.

Paper Details

Date Published: 1 March 2019
PDF: 15 pages
Proc. SPIE 10948, Medical Imaging 2019: Physics of Medical Imaging, 109482J (1 March 2019); doi: 10.1117/12.2511127
Show Author Affiliations
Liang Zheng, Southeast Univ. (China)
Shouhua Luo, Southeast Univ. (China)
Lujie Chen, Southeast Univ. (China)
Shuang Luo, NVIDIA Semiconductor Technology (Shanghai) Co., Ltd. (China)

Published in SPIE Proceedings Vol. 10948:
Medical Imaging 2019: Physics of Medical Imaging
Taly Gilat Schmidt; Guang-Hong Chen; Hilde Bosmans, Editor(s)

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