Acta Photonica Sinica, Volume. 51, Issue 4, 0412005(2022)
Geometric Parameters Calibration Method for Optically CCD-coupled CT System
Micro-computed tomography is widely used for medical diagnosis and non-destructive testing since the 1970s. In three-dimensional micro-CT imaging, the quality of the reconstructed images depends highly on the precision of the geometric parameters of the system. Image quality could be severely degraded by misaligned parameters, resulting in artifacts, blur and lower resolution in images, especially for CCD-coupled CT system (CCT system). Therefore, high-precision methods for estimating CT system parameters are necessary. Different research groups have proposed various methods to estimate geometric parameters for fan-beam CT or cone-beam CT. In terms of data acquisition methods, the main methods can be categorized as multi-angles projection and single-angle projection. However, due to the narrow field of view caused by the ultra-high resolution of the CCD-coupled detector, neither of these two methods can be applied to CCT system directly. Generally, a CCT system consists of an X-ray source, a CCD-coupled detector, and a precision rotation stage for placing samples, in which the X-ray source and detector are distributed on both sides of the sample. During scanning, the sample rotates around the rotation axis, while the X-ray source and the detector remain stationary. In an ideal CCT system, strict geometric alignment must be satisfied. It can be summarized as follows: Firstly, the X-ray focal spot, the axis of the rotation, and the center of the detector should be in a plane; secondly, the straight line which passes the focal spot and the detector center, should be perpendicular to the axis of rotation and the detector; thirdly, the axis of the rotation should be parallel to the row of the detector. Basing on precious studies, there are five geometric parameters to be calibrated totally in a CCT system. We conclude all the calibrated parameters as follows: 1)
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Jing ZOU, Yiming JIANG, Xiaodong HU, Jintao ZHAO. Geometric Parameters Calibration Method for Optically CCD-coupled CT System[J]. Acta Photonica Sinica, 2022, 51(4): 0412005
Category: Instrumentation, Measurement and Metrology
Received: Oct. 18, 2021
Accepted: Nov. 24, 2021
Published Online: May. 18, 2022
The Author Email: ZHAO Jintao (zjt2019@tju.edu.cn)