基于条状挡板的kV级锥形束CT散射校正

目的 校正锥形束CT投影中的散射信号,以提高图像质量。 方法 使用条状挡板测量Varian机载kV级锥形束CT投影图像中的散射信号,并将其从再次扫描的投影中扣除,以获得原始射线的投影图像。使用空域自适应的BayesShrink小波对投影图像进行去噪处理,并导入Varian On Board Imager工作站进行重建;比较处理前后的图像质量。 结果 校正后图像的低对比度分辨力提高,噪声降低,CT值的准确性和均匀性得到改善。 结论 条状挡板能准确获取投影图像中的散射信号;扣除散射信号后使用小波阈值法去噪,可有效提高图像质量。

Scatter correction of kV cone-beam CT based on the strips block

Objective To correct the scatter signal in the projections,in order to improve image quality of kV cone-beam CT (CBCT). Methods A block composed of lead strips was used to measure the scatter signal of the projections of on-board CBCT (Varian). The scatter signal was removed in the subsequent scans to obtain the primary signal of the projections. Then the projections, free of scatter, were denoised by adaptive BayesShrink wavelet before the reconstruction in the Varian On Board Imager workstation. Finally, image quality before and after the correction were evaluated and compared. Results After the processing, the low-contrast resolution of the image was improved, the noise was lower, and the accuracy of CT number and the uniformity were also promoted. Conclusion The scatter signal can be measured exactly with the strips block. Wavelet threshold denoising method can effectively improve the image quality after the scatter signal removed.