17 October 2012 An iterative reconstruction method for high-pitch helical luggage CT
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Abstract
X-ray luggage CT is widely used in airports and railway stations for the purpose of detecting contrabands and dangerous goods that may be potential threaten to public safety, playing an important role in homeland security. An X-ray luggage CT is usually in a helical trajectory with a high pitch for achieving a high passing speed of the luggage. The disadvantage of high pitch is that conventional filtered back-projection (FBP) requires a very large slice thickness, leading to bad axial resolution and helical artifacts. Especially when severe data inconsistencies are present in the z-direction, like the ends of a scanning object, the partial volume effect leads to inaccuracy value and may cause a wrong identification. In this paper, an iterative reconstruction method is developed to improve the image quality and accuracy for a large-spacing multi-detector high-pitch helical luggage CT system. In this method, the slice thickness is set to be much smaller than the pitch. Each slice involves projection data collected in a rather small angular range, being an ill-conditioned limited-angle problem. Firstly a low-resolution reconstruction is employed to obtain images, which are used as prior images in the following process. Then iterative reconstruction is performed to obtain high-resolution images. This method enables a high volume coverage speed and a thin reconstruction slice for the helical luggage CT. We validate this method with data collected in a commercial X-ray luggage CT.
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Hui Xue, Hui Xue, Li Zhang, Li Zhang, Zhiqiang Chen, Zhiqiang Chen, Xin Jin, Xin Jin, } "An iterative reconstruction method for high-pitch helical luggage CT", Proc. SPIE 8506, Developments in X-Ray Tomography VIII, 85061O (17 October 2012); doi: 10.1117/12.928950; https://doi.org/10.1117/12.928950
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