体积CT系统中的平板探测器校正方法

在体积CT系统上通过样本实验研究了平板探测器的校正问题。提出了一种基于统计模型的平板探测器校正方法 ,详细讨论了坏像素的探测、校正矩阵的生成和原始投影图像的校正方法。校正过程包括实时的模糊和图像滞后校正、图像的标准化、增益修正和坏像素点的校正。通过样本实验研究对所提出的校正算法进行了验证 ,通过比较重建图像的信噪比对该算法的效果进行了评估。研究结果表明 :平板探测器的制造缺陷等固有噪声源将在重建图像中被增强 ,并表现为大量的条纹和环形伪影 ;通过校正后 ,重建图像中的上述伪影明显减少 ,图像质量明显改善 ,且系统的低对比度探测能力也得到相应提高。

Accurate and Efficient Calibration Method for a Selenium Flat-panel Detector-based Volume Tomographic Angiography Imaging System

It researched correction problem of the flat panel d et ector (FPD) by phantom testing. A calibration method based on statistical models of the FPD is proposed. The generation of calibration matrix for bad pixels det ection and a calibration method of original projection image are discussed. It i ncludes the real|time background correction, image standardization, gain correc tion, and bad pixels correction. The calibration algorithm is examined through p hantom studies and evaluated by comparing the artifacts and noise in reconstruct ed images. It is obvious that the stationary noise sources of the FPD will be en hanced in reconstructed images. These defects will result in severe streaks and ring artifacts. Improvement of image quality is obtained utilizing the calibrati on technique. It has been clearly verified that the streaks and ring artifacts i n reconstructed images are significantly reduced.