Region of Interest Imaging for a General Trajectory with the Rebinned BPF Algorithm

The back-projection-filtration （BPF） algorithm has been applied to image reconstruction for cone-beam configurations with general source trajectories. The BPF algorithm can reconstruct 3-D region- of-interest （ROI） images from data containing truncations. However, like many other existing algorithms for cone-beam configurations, the BPF algorithm involves a back-projection with a spatially varying weighting factor, which can result in the non-uniform noise levels in reconstructed images and increased computation time. In this work, we propose a BPF algorithm to eliminate the spatially varying weighting factor by using a rebinned geometry for a general scanning trajectory. This proposed BPF algorithm has an improved noise property, while retaining the advantages of the original BPF algorithm such as minimum data requirement.

Research of Large Field of View Scan Mode for Industrial CT

For industrial computed tomography systems, generation II scan mode has a large field of view but time consuming and generation III has a small field of view but fast. In order to realize the rapid ICT test of large objects, a scan mode based on generation III called large field of view scan was discussed and its reconstruction algorithm based on FBP was deduced. The validity of the algorithm was verified by the results of computer simulation and experiments. Analysis showed that the effective scan field of view could be improved by more than 90% compared with that of generation III.

Purposeless repeated acquisition time-lapse seismic data processing

In China, most oil fields are continental sedimentation with strong heterogeneity, which on one side makes the reservoir prospecting and development more difficult, but on the other side provides more space for searching residual oil in matured fields. Time-lapse seismic reservoir monitoring technique is one of most important techniques to define residual oil distribution. According to the demand for and development of time-lapse seismic reservoir monitoring in China, purposeless repeated acquisition time-lapse seismic data processing was studied. The four key steps in purposeless repeated acquisition time-lapse seismic data processing, including amplitude-preserved processing with relative consistency, rebinning, match filtering and difference calculation, were analyzed by combining theory and real seismic data processing. Meanwhile, quality control during real time-lapse seismic processing was emphasized.

Improvement of Efficiency and Flexibility in Multi-slice Helical CT

One of the main aspects in computed tomography (CT) development is to make CT rapidly scan a large longitudinal volume with high z-axis resolution. The combination of helical scanning with multi-slice CT is a promising approach. Image reconstruction in multi-slice CT becomes, therefore, the major challenge. Known algorithms need to derive the complementary data or work only for certain range of pitches. A reconstruction algorithm was presented that works with the direct data as well as arbitrary pitches. Filter interpolation based on the proposed method was implemented easy. The results of computer simulations under kinds of conditions for four-slice CT were presented. The proposed method can obtain higher efficiency than the conventional method.