6 March 2013 A comparison study of sinogram- and image-domain penalized re-weighted least-squares approaches to noise reduction for low-dose cone-beam CT
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Proceedings Volume 8668, Medical Imaging 2013: Physics of Medical Imaging; 86683E (2013) https://doi.org/10.1117/12.2007111
Event: SPIE Medical Imaging, 2013, Lake Buena Vista (Orlando Area), Florida, United States
Abstract
Reducing X-ray exposure to the patients is one of the major research efforts in the computed tomography (CT) field, and one of the common strategies to achieve it is to lower the mAs setting (by lowering the X-ray tube current and/or shortening the exposure time) in currently available CT scanners. However, the image quality from low mAs acquisition is severely degraded due to excessive quantum noise, if no adequate noise control is applied during image reconstruction. Different from filter-based algorithms, statistical reconstruction algorithms model the statistical property of the noise using a cost function and minimize the cost function for an optimal solution in statistical sense. The algorithms have shown to be feasible and effective in both sinogram and image domain. In our previous researches, we proposed penalized reweighted least-squares (PRWLS) approaches to sinogram noise reduction and image reconstruction for low-dose CT imaging, which are in this statistical category. This work is a continuation of the research along this direction and aims to compare the reconstruction quality of two different PRWLS implementations for low-dose cone-beam CT reconstruction: (1) PRWLS sinogram restoration followed by analytical Feldkamp-Davis- Kress reconstruction, (2) fully iterative PRWLS image reconstruction. Inspired by our recent study on the variance of low-mAs projection data in presence of electric noise background, a more accurate weight was adopted in the weighted least-squares term. An anisotropic quadratic form penalty was utilized in both PRWLS implementations to preserve edges during noise reduction. Experiments using the CatPhan® 600 phantom and anthropomorphic head phantom were carried to study the relevant performance of these two implementations on image reconstruction. The results revealed that the implementation (2) can outperform implementation (1) in terms of noise-resolution tradeoff measurement and analysis of the reconstructed small objects due to its matched image edge-preserved penalty in the image domain. However, those gains are offset by the cost of increased computational time. Thus, further examination of real patient data is necessary to show the clinical significance of the iterative PRWLS image reconstruction over the PRWLS sinogram restoration.
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Hao Zhang, Hao Zhang, Yan Liu, Yan Liu, Hao Han, Hao Han, Jing Wang, Jing Wang, Jianhua Ma, Jianhua Ma, Lihong Li, Lihong Li, Zhengrong Liang, Zhengrong Liang, } "A comparison study of sinogram- and image-domain penalized re-weighted least-squares approaches to noise reduction for low-dose cone-beam CT", Proc. SPIE 8668, Medical Imaging 2013: Physics of Medical Imaging, 86683E (6 March 2013); doi: 10.1117/12.2007111; https://doi.org/10.1117/12.2007111
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