Abstract

Info

Author(s):: YIN Pengfei1; FENG Hansheng2; LI Shi2; YANG Yang2; 1.School?f?lectrical?ngineering?nd?utomation,?nhui?niversity, Hefei 230601, China 2. Institute?f?lasma?hysics,?hinese? Academy?f?ciences, Hefei 230031, China

Keywords:: Keywords: cone beam computed tomography geometric calibration nonlinear optimization

Abstract:: Abstract: Due to the posture?rror?f calibration phantom, traditional geometric calibration algorithm has a poor accuracy in the parameter calibration of cone beam computed tomography (CBCT) imaging system. In order to solve the above-mentioned problem, a CBCT geometric calibration algorithm based on analytic geometry and nonlinear optimization is proposed. A tracking method based on frame interpolation is firstly designed to extract the coordinates of feature points, thereby achieving the correspondence between the calibration phantom and the feature points in the projected image. Then the relevant parameters are calculated based on the spatial relationship between the projected image and the designed calibration phantom. Finally, the nonlinear estimation of the detected feature points is carried out to further improve the accuracy of geometric parameter calculation. The simulation results verified that the proposed algorithm can accurately calculate the geometric parameters of CBCT imaging system, and maintain a high calculation accuracy even when the posture error is occurred during phantom calibration. Based on the proposed nonlinear estimation model, the proposed method overcomes the limitation of the existing algorithm in which calibration phantom needs to be located at the isocenter and improves the accuracy of parameter calibration in CBCT imaging system.