摘要
针对锥束CT系统旋转平移(RT)轨迹中几何参数难以直接测量的问题,在单圆轨迹标定方法的基础上,提出了一种适用于RT轨迹的几何参数标定方法。该方法利用定标体模投影轨迹的椭圆参数与系统几何参数建立关系,解析求解出系统的内部参数。在此基础上,外推得到旋转轴所有的位置参数,并求得符合理想轨迹要求的几何参数。所求参数都可以通过解析的公式得到,能有效避免迭代法陷入局部最优的问题。对存在偏差的系统进行了仿真,并利用该方法进行标定,实验结果表明,该方法能有效抑制由于几何参数误差造成的几何伪影,提高图像质量。
In cone-beam CT imaging system, it is difficult to directly measure the geometry parameters. In this paper, a ge- ometry calibration method for rotation translation trajectory is proposed. Intrinsic parameters are solved from the relationship built on geometry parameter of the system and projection trajectory of calibration object. Parameters of rotation axis are extrapo- lated from the unified intrinsic parameter, and geometry parameters of the idle trajectory are acquired too. The calibration geome- try can he analytically determined using explicit formulae, it can avoid getting into local optimum in iterative way. Simulation ex- periments are carried out on misaligned geometry, experiment results indicate that geometry artifacts due to misaligned geometry are effectively depressed by the proposed method, and the image quality is enhanced.
出处
《强激光与粒子束》
EI
CAS
CSCD
北大核心
2013年第10期2693-2698,共6页
High Power Laser and Particle Beams
基金
国家高技术发展计划项目
关键词
锥束CT
几何参数
几何伪影校正
RT扫描轨迹
cone-beam CT
geometric parameter
geometric artifact correction
rotation-translation trajectory
