基于标定量具的快速锥束CT几何校准方法
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摘要
锥束CT的几何参数不准确会导致重建图像出现伪影,影响分析与判断。为快速可靠地获取锥束CT的几何参数,提出了一种基于标定量具的锥束CT几何参数校准方法。标定量具的基本结构为有机玻璃管内置金属细丝,外嵌金属球;通过获得量具一定幅数的单圆轨迹扫描投影,并将得到的投影图像进行叠加,根据叠加图像的对称特性,进行对称轴拟合,所得对称轴即为旋转轴投影,通过金属球轨迹与旋转轴交点的比例关系求得射束中心的坐标;最后,利用量具平移一定距离后的投影,结合量具外轮廓直径和投影的几何关系,计算出源到旋转中心及探测器的距离。实验结果表明,该方法可以获得可靠的锥束CT几何参数,具有校准速度快、鲁棒性强的特点。
Inaccurate geometric parameters of the cone beam CT will bring artifacts in the reconstructed image, which affect analysis and judgment results. To obtain the geometric parameters of cone-beam CT quickly and reliably, a calibration method of cone-beam CT geometric parameters based on the calibration measuring tool is proposed. The basic structure of the calibration measuring tool is the plexiglass tube embedded in a metal filament and an externally embedded metal ball. A certain number of projection images are obtained by scanning a single circular trajectory with measuring tool, and the obtained projection images are superimposed. The symmetry axis is fitted according to the symmetry characteristic of the superimposed image. The coordinates of the beam center are obtained by the proportional relationship between the intersection of the metal ball trajectory and the rotation axis. Finally, the measuring tool is translated by a certain distance. This distance from the source to the center of rotation and the detector are calculated according to the corresponding geometric relationship between the diameter of measuring tool and its projection. Experimental results show that the proposed method can obtain reliable cone-beam CT geometric parameters, which has the characteristics of fast calibration speed and strong robustness.
Inaccurate geometric parameters of the cone beam CT will bring artifacts in the reconstructed image, which affect analysis and judgment results. To obtain the geometric parameters of cone-beam CT quickly and reliably, a calibration method of cone-beam CT geometric parameters based on the calibration measuring tool is proposed. The basic structure of the calibration measuring tool is the plexiglass tube embedded in a metal filament and an externally embedded metal ball. A certain number of projection images are obtained by scanning a single circular trajectory with measuring tool, and the obtained projection images are superimposed. The symmetry axis is fitted according to the symmetry characteristic of the superimposed image. The coordinates of the beam center are obtained by the proportional relationship between the intersection of the metal ball trajectory and the rotation axis. Finally, the measuring tool is translated by a certain distance. This distance from the source to the center of rotation and the detector are calculated according to the corresponding geometric relationship between the diameter of measuring tool and its projection. Experimental results show that the proposed method can obtain reliable cone-beam CT geometric parameters, which has the characteristics of fast calibration speed and strong robustness.
引文
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[18] ZHANG F, DU J P, JIANG H, et al. Iterative geometric calibration in circular cone-beam computed tomography[J]. Optik-International Journal for Light and Electron Optics, 2014, 125(11):2509- 2514.
[19] SUN Y, HOU Y, ZHAO F Y, et al. A calibration method for misaligned scanner geometry in cone-beam computed tomography[J]. NDT & E International, 2006, 39(6): 499- 513.
[20] DEWULF W, KIEKENS K, TAN Y, et al. Uncertainty determination and quantification for dimensional measurements with industrial computed tomography[J]. CIRP Annals - Manufacturing Technology, 2013, 62(1): 535- 538.
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[22] KUMAR J, ATTRIDGE A, WOOD P K C, et al. Analysis of the effect of cone-beam geometry and test object configuration on the measurement accuracy of a computed tomography scanner used for dimensional measurement[J]. Measurement Science and Technology, 2011, 22(3): 035105.
[23] 李明君,张定华,黄魁东,等. 锥束计算机断层成像系统快速定位方法[J]. 兵工学报, 2010, 31(11):1455-1460.LI M J, ZHANG D H, HUANG K D, et al. Fast localization method in cone-beam computed tomography[J]. Acta Armamentarii, 2010, 31(11): 1455-1460.
[24] 李保磊,傅健,黄巧珍,等. 一种基于正弦图的工业CT系统转台旋转中心自动确定方法[J]. 航空学报, 2009, 30(7):1341-1345.LI B L, FU J, HUANG Q ZH, et al. One automated method for determination of center of rotation based on sinogram in industrial computed tomography system[J]. Acta Aeronautica ET Astronautica Sinica, 2009, 30(7):1341-1345.
[25] 张亮,卜昆,黄魁东,等. 锥束CT系统PSF的多孔成像测量与评估方法[J].仪器仪表学报,2012,33(9):2061- 2066.ZHANG L, BU K, HUANG K D, et al. Multi-pinhole imaging measurement and assessment method for PSF of cone-beam CT system[J]. Chinese Journal of Scientific Instrument, 2012, 33(9):2061- 2066.
[26] 赵文聪,吴衍青,夏慧娟,等. 粒子云-点扩散函数在X射线闪烁体成像中的应用[J].电子测量技术, 2018, 41(18): 42- 47.ZHAO W C, WU Y Q, XIA H J, et al. Particle-in-cell point spread function and its application in X-ray scintillator imaging system[J]. Electronic Measurement Technology, 2018, 41(18):42- 47.
[2] 杨春然,郭翌,汪源源. 基于高通量特征与BoF特征的肺结节诊断信息分级[J]. 电子测量与仪器学报, 2018, 32(7):46- 51.YANG CH R, GUO Y, WANG Y Y. Information classification of pulmonary nodule based on high throughput and BoF features[J]. Journal of Electronic Measurement and Instrumentation, 2018, 32(7):46- 51.
[3] 刘震,刘钰,杨子淳. 基于Radon变换和滤波反投影算法的CT系统重建算法研究[J]. 国外电子测量技术, 2018, 37(8):113-117.LIU ZH, LIU Y, YANG Z CH. Study on reconstruction algorithm of CT system based on radon transform and filtered back projection algorithm[J]. Foreign Electronic Measurement Technology, 2018, 37(8):113-117.
[4] ZHOU D Q, CHANG X, DU Y, et al. Research on the crack detection of conductive components using pulsed eddy current thermography[J]. Instrumentation, 2017, 4(3):59- 68.
[5] YANG M, WANG X L, LIU Y P, et al. Automatic calibration method of voxel size for cone-beam 3D-CT scanning system automatic calibration method of voxel size for cone-beam 3D-CT scanning system[J]. Chinese Physics C, 2014, 38(4):75- 80.
[6] STOLFI A, CHIFFRE D L. 3D artefact for concurrent scale calibration in computed tomography[J]. CIRP Annals - Manufacturing Technology, 2016, 65(1):499- 502.
[7] SHEPP L A, HILAL S K, SCHULZ R A. The tuning fork artifact in computerized tomography[J]. Computer Graphics Image Processing, 1979(10):246- 255.
[8] TAYLOR T, LUPTON L R. Resolution, artifacts and the design of computed tomography systems[J]. Nuclear Instruments & Methods in Physics Research, 1986, 242(3): 603- 609.
[9] TAN S, CONG P, LIU X, et al. An interval subdividing based method for geometric calibration of cone-beam CT[J]. NDT & E International, 2013, 58(58):49- 55.
[10] MENG Y, GONG H, YANG X. Online geometric calibration of cone-beam computed tomography for arbitrary imaging objects[J]. IEEE Transactions on Medical Imaging, 2013, 32(2):278- 288.
[11] NOO F, CLACKDOYLE R, MENNESSIER C, et al. Analytic method based on identification of ellipse parameters for scanner calibration in cone-beam tomography[J]. Physics in Medicine & Biology, 2000, 45(11):3489- 508.
[12] 王珏,葛敏雪,蔡玉芳,等. 基于线框模型的锥束CT几何参数校正方法[J]. 仪器仪表学报, 2018,39(2):177-184.WANG J, GE M X, CAI Y F, et al. Geometric parameters calibration method for cone beam CT system based on square-line phantom[J]. Chinese Journal of Scientific Instrument, 2018, 39(2):177-184.
[13] ZHANG F, YAN B, LI L, et al. Practical geometric calibration for helical cone-beam industrial computed tomography[J]. Journal of X-ray science and technology, 2014, 22(1):19-35.
[14] YANG H, KANG K, XING Y. Geometry calibration method for a cone-beam CT system[J]. Medical Physics, 2017, 44(5):1692.
[15] YANG K, KWAN A L, MILLER D F, et al. A geometric calibration method for cone beam CT systems[J]. Medical Physics, 2006, 33(6):1695-1706.
[16] 韩玉,闫镔,李磊,等. 一种迭代的锥束CT螺旋轨迹几何参数标定算法[J]. 仪器仪表学报, 2013, 34(7):134-141.HAN Y, YAN B, LI L, et al. Iterative geometric parameter calibration algorithm for the helical trajectory in cone-beam CT[J]. Chinese Journal of Scientific Instrument, 2013, 34(7):134-141.
[17] MUDERS J, HESSER J. Stable and robust geometric self-calibration for cone-beam CT using mutual information[J]. IEEE Transactions on Nuclear Science, 2014, 61(1):202- 217.
[18] ZHANG F, DU J P, JIANG H, et al. Iterative geometric calibration in circular cone-beam computed tomography[J]. Optik-International Journal for Light and Electron Optics, 2014, 125(11):2509- 2514.
[19] SUN Y, HOU Y, ZHAO F Y, et al. A calibration method for misaligned scanner geometry in cone-beam computed tomography[J]. NDT & E International, 2006, 39(6): 499- 513.
[20] DEWULF W, KIEKENS K, TAN Y, et al. Uncertainty determination and quantification for dimensional measurements with industrial computed tomography[J]. CIRP Annals - Manufacturing Technology, 2013, 62(1): 535- 538.
[21] 黄秋红,CAO G H,赵敏,等. 静态锥束CT成像系统的几何标定方法研究[J].仪器仪表学报, 2015, 36(10): 2339- 2346.HUANG Q H, CAO G H, ZHAO M, et al. Study on the geometric calibration method for static cone-beam CT imaging system[J]. Chinese Journal of Scientific Instrument, 2015, 36(10):2339- 2346.
[22] KUMAR J, ATTRIDGE A, WOOD P K C, et al. Analysis of the effect of cone-beam geometry and test object configuration on the measurement accuracy of a computed tomography scanner used for dimensional measurement[J]. Measurement Science and Technology, 2011, 22(3): 035105.
[23] 李明君,张定华,黄魁东,等. 锥束计算机断层成像系统快速定位方法[J]. 兵工学报, 2010, 31(11):1455-1460.LI M J, ZHANG D H, HUANG K D, et al. Fast localization method in cone-beam computed tomography[J]. Acta Armamentarii, 2010, 31(11): 1455-1460.
[24] 李保磊,傅健,黄巧珍,等. 一种基于正弦图的工业CT系统转台旋转中心自动确定方法[J]. 航空学报, 2009, 30(7):1341-1345.LI B L, FU J, HUANG Q ZH, et al. One automated method for determination of center of rotation based on sinogram in industrial computed tomography system[J]. Acta Aeronautica ET Astronautica Sinica, 2009, 30(7):1341-1345.
[25] 张亮,卜昆,黄魁东,等. 锥束CT系统PSF的多孔成像测量与评估方法[J].仪器仪表学报,2012,33(9):2061- 2066.ZHANG L, BU K, HUANG K D, et al. Multi-pinhole imaging measurement and assessment method for PSF of cone-beam CT system[J]. Chinese Journal of Scientific Instrument, 2012, 33(9):2061- 2066.
[26] 赵文聪,吴衍青,夏慧娟,等. 粒子云-点扩散函数在X射线闪烁体成像中的应用[J].电子测量技术, 2018, 41(18): 42- 47.ZHAO W C, WU Y Q, XIA H J, et al. Particle-in-cell point spread function and its application in X-ray scintillator imaging system[J]. Electronic Measurement Technology, 2018, 41(18):42- 47.