High resolution CT is important for qualitative feature identification and quantitative measurements for many clinical applications. To optimize the spatial resolution, filtered backprojection (FBP) based methods use various sinogram domain frequency boosting filters to provide flexible control of frequency responses in reconstructed images. In comparison, model-based iterative reconstruction (MBIR) methods usually rely on a single regularization strength parameter to control the image resolution, and there is limited flexibility in controlling the spectral response. Alternatively, MBIR can also improve the spatial resolution by sinogram preprocessing with frequency boosting filters. Focal spot deflection technology has been introduced to high-end CT scanner to increase the effective detector sampling rate. With higher Nyquist sampling rate along detector channels, we can design frequency boosting filters with a much wider frequency range and recover higher resolution details in the reconstructed images. In this paper, we explore the potential of sinogram rebinning and frequency boosting method for high resolution MBIR from data with focal spot deflection data. The proposed method is tested with phantom and clinical data. Compared with MBIR that models native focal spot deflection geometry, our results show that MBIR from the rebinned geometry with frequency boosting filters can achieve higher resolution and better noise-resolution tradeoff. Moreover, we also demonstrate some improvement in contrast and sharpness in clinical images. The proposed method provides a way to flexibly change the noise and resolution tradeoff in MBIR images similar to adjusting the filter kernels in FBP method.

Date Published: 19 March 2014
PDF: 11 pages
Proc. SPIE 9033, Medical Imaging 2014: Physics of Medical Imaging, 903333 (19 March 2014); doi: 10.1117/12.2042914

Published in SPIE Proceedings Vol. 9033:
Medical Imaging 2014: Physics of Medical Imaging
Bruce R. Whiting; Christoph Hoeschen, Editor(s)