基于旋转准直器的锥形束CT散射矫正方法

针对锥形束CT（CBCT）图像质量受散射影响比较严重的情况，提出一种基于旋转准直器的CBCT散射矫正方法。该方法在射线源和模体之间放置一个圆形的旋转准直器，并通过准直器的旋转使透过准直器的射线不断沿轴向来回扫描，以获取整个容积图像的投影图像信息，然后利用投影图像的遮挡区域估计整幅图像的散射信息并将其从投影图像中去除，最后利用改进FDK算法重建图像。结果表明，与CBCT图像相比，散射矫正后的重建图像CBCT值的均方根误差从16.00%下降为1.18%，杯状伪影从14.005%下降为0.660%，峰值信噪比从16.959 4提高到31.450 0。CBCT图像质量得到明显提高。

Cone beam computed tomography scatter correction based on rotating collimator

Abstract: In view of the great effect of scattering on cone beam computed tomography (CBCT) image quality, a CBCT scatter correction method based on rotating collimator is proposed. A rounded rotating collimator is placed between the radiation source and the phantom. Through the rotation of collimator, the continuous scanning along the axis is achieved and the projected image information of the entire volume image is obtained. And then the scattering region which is estimated using the information of the blocked region in projected image is removed from the projected image. Finally the improved FDK algorithm is used to reconstruct images. The results show that after scatter correction, the mean square error of the CBCT values of reconstructed image decreases from 16.00% to 1.18%, that the cupping artifacts reduces from 14.005% to 0.66%, and that the peak signal-to-noise ratio increases from 16.959 4 to 31.450 0. The image obtained by the projection reconstruction of the water phantom using rotating collimator can effectively suppress the scatter and improve the quality of CBCT image.