乳腺断层成像系统几何校正新方法

为了使乳腺断层成像(DBT)系统得到较高的重建图像质量,需要对DBT系统的几何参数进行校正.在Matlab平台上通过仿真DBT系统成像过程的方式,提出了一种DBT系统的数字几何校正模体以及相应的校正算法.仿真结果表明,平板探测器摆角和滚角的偏差范围分别是(0,0.01°)和(-0.04°,0.07°),机架旋转角度偏差的范围是(-0.05°,0.06°),X射线源焦点的x和y坐标偏差范围分别是(-0.05 mm,0.05 mm)和(-0.04 mm,0.09 mm),射线源到平板距离的偏差范围是(0,0.62 mm).在几何校正模体位置未知的情况下,该校正方法的计算精度仍可以满足DBT系统高质量图像重建的要求.

New method for geometry calibration of digital breast tomosynthesis system

In order to aquire higher quality of reconstruction images for digital breast tomosynthesis(DBT)system, the geometry parameters for the DBT system need to be calibrated. By simulating the imaging process of the DBT system on Matlab platform, a digital geometry calibration phantom and the correspoonding calibration algorithm for the DBT system were proposed. The simulated results show that the deviation range of yaw angle and roll angle for the flat panel detector is(0, 0.01°)and(-0.04°, 0.07°), respectively. The deviation range of gantry rotation angle is(-0.05°, 0.06°)and the deviation range in the coordinates of X ray source focal spot is(-0.05 mm, 0.05 mm)for x-axis and(-0.04 mm, 0.09 mm)for y-axis. In addition, the deviation range in the distance between the X ray source and detector is(0, 0.62 mm). Even though the location of geometry calibration phantom is unknown, the calculation accuracy of new calibration algorithm can also satisfy the requirement of high quality image reconstruction of DBT system.