静态锥束CT成像系统的几何标定方法研究

采用X射线源阵列的静态CT成像系统为消除机械运动伪影,提高重建图像质量以及扫描成像效率提供了有效途径。高效、准确的几何标定方法是对X射线源阵列标定的关键。提出通过对一个已知三维标定模板的一次投影成像,采用最小二乘的直接线性变换法实现X射线成像系统的内、外参数准确估计的方法,以此方法用于静态CT扫描成像系统的几何标定。实验和仿真结果表明,该标定方法无需辅助装置,避免了满足要求条件的多次投影成像的过程;不受标定模板空间姿态的限制,一个X射线源与探测器的几何标定只需一次投影成像过程,方法简单、准确、易于操作,适于平面探测器的静态锥束X射线源阵列的成像系统几何参数的准确标定。

Study on the geometric calibration method for static cone beamCT imaging system

Static CT imaging system with array X ray source provides an effective method to decrease mechanical motion artifacts, improve reconstructed image quality and scanning imaging efficiency. High efficiency and accurate geometric calibration method is the key step for array X ray source calibration. In this paper, a geometric calibration method for static CT scanning imaging system is presented, in which the least square direct linear projection transformation method is used to evaluate the internal and external parameters of the X ray imaging system with one projection imaging for a known three dimensional calibration phantom. The method was used in the geometric calibration of the static CT scanning imaging system. Experiment and simulation results show that this calibration method does not require any auxiliary device, avoids the multiple projection imaging process meeting required specific conditions. This method is not confined by the phantom space pose. The geometric parameters of an X ray source imaging system are calibrated only with one projection imaging process. The method is simple, precise and easy to operate, and is suitable for the geometric parameter precise calibration of the imaging system of the static cone beam array X ray source with plane detector.