Assessment of the central artifact in cone beam CT imaging with an offset geometry

Guozhi Zhang; Reinhilde Jacobs; Johan Nuyts; Hilde Bosmans

doi:10.1117/12.911102

3 March 2012 Assessment of the central artifact in cone beam CT imaging with an offset geometry

Guozhi Zhang, Reinhilde Jacobs, Johan Nuyts, Hilde Bosmans

Proceedings Volume 8313, Medical Imaging 2012: Physics of Medical Imaging; 83132U (2012) https://doi.org/10.1117/12.911102
Event: SPIE Medical Imaging, 2012, San Diego, California, United States

Abstract

The 'central artefact' is commonly seen in cone beam computed tomography (CBCT) images in case of an offset scanning geometry. This study evaluates the hypothesis that such artefact is caused by the rotationally asymmetric distribution of scatter. Predictions were examined by use of a hybrid simulation model in conjunction with a simple experimental design. The model accounted for the entire imaging chain of CBCT and was parameterized according to the Scanora 3D CBCT system (Soredex-PaloDEx, Finland). Computational cylinder phantoms of different cross-sections and internal structures were simulated under various symmetric and asymmetric settings. The integrated commercial software tool was employed for image reconstruction. Results confirmed that the scatter was the sole source for the central artefact. It was also found that the artefact was particularly apparent with the algebraic iterative reconstruction. The degree of asymmetry, by either the object's structure or eccentric placement, was much more influential than the effect of the truncated imaging field of view. The findings have also been further proved with a computational anatomical phantom of an adult human head. The computer simulation approach, as adopted in this study, is efficient and has broad applications to CBCT.

Citation Download Citation

Guozhi Zhang, Reinhilde Jacobs, Johan Nuyts, and Hilde Bosmans "Assessment of the central artifact in cone beam CT imaging with an offset geometry", Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 83132U (3 March 2012); https://doi.org/10.1117/12.911102

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