Research of reconstruction algorithm based on projection data fuse for dual energy CT of multilayer spherical shell
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摘要: 对高密度差多层球壳结构件进行双能CT检测，需要研究同时基于高低能射线两套投影数据的图像重建方法。先分别重建再进行图像融合的方法，不能充分利用两种能量射线投影的互补信息，重建图像质量不高。针对高密度差多层球壳结构特征，通过设计限定投影扫描方式获取区域分布明确的高、低能射线投影正弦图，基于正弦图区域分割重组和交集数据等值化一致性处理实现双能投影数据融合，在此基础上完成图像重建。根据以上设计归纳出基于投影融合的多层球壳双能CT重建算法，仿真结果表明算法可行，且重建结果明显好于基于图像融合的方法。Abstract: Using dual energy CT method to detect multilayer spherical shell components with great density difference, it is necessary to study the image reconstruction method based on two sets of projection data. The Method of Reconstructed at First and then Fused Based on Images cannot make full use of dual energy X-ray projection information, by which simulation research shows it is difficult to get good reconstructed image. On this basis, the paper focuses on the Method of Fused Based on Projection Data at First and then Reconstructed. Firstly, considering the structure characteristics of the multilayer spherical shell components with great density difference, the X-ray projection sinogram with clear regional distribution can be obtained through a specially designed scanning mode. Then extract effective projection data respectively from the high and low energy X-ray projection sinogram, do the consistency processing, and integrate them to become one sinogram. Finally use the FBP algorithm to complete the image reconstruction process. The concrete realization of the algorithm based on projection data fuse for dual energy CT of multilayer spherical shell is summarized, and computer simulation shows that better reconstructed images can be obtained.
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Key words:
- dual energy CT /
- image reconstruction algorithm /
- multilayer shells /
- simulation research
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图 2 基于先重建再融合过程的双能CT图像重建仿真
Figure 2. Simulation of dual energy CT reconstruction with the flow of reconstructed at first and then fused based on images
(a)sectional model of multilayer spherical shell；(b)simulant projection sinogram of low energy X-ray；(c)high energy X-ray projection；(d)reconstructed image with FBP for low energy projection；(e)reconstructed image for high energy projection；(f)final image
图 3 限定扫描方式下的投影正弦图空间分布特征
Figure 3. Regional distribution of projection sinogram based on appointed scanning mode
图 4 投影正弦图区域分割重组及FBP重建
Figure 4. Image reconstruction based on combined projection without consistency process
(a)simulant high energy X-ray projection；(b) low energy projection； (c)projection directly pieced together by area；(d) reconstructed image with FBP
图 5 基于投影融合的双能CT图像重建算法流程
Figure 5. Flow chart of image reconstruction based on projection data fuse
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