A projection-based method for motion-compensated noise suppression

The diagnostic value of medical images significantly depends on the signal-to-noise ratio (SNR). Especially in fluoroscopic tomography, the SNR is limited by the radiation dose (Computer Tomography), or by the suitable acquisition techniques (Magnetic Resonance Imaging). The purpose of this paper is to introduce a projection-based method for the motion-compensated SNR enhancement applied in Radon space. It is based on a projection-based motion estimation with subsequent motion-compensated, edge-preserving filtering of the measured projections. The effect of temporal filtering as well as spatial filtering will be presented. In contrast to the recently introduced image-based approach, this method allows a very efficient computational implementation, likely to be used in real time imaging. It will be shown that a significant increase of the SNR can be achieved without introducing additional motion artifacts or blurring in the reconstructed images. The proposed technique has the potential to be used for SNR enhancement in low-dose fluoroscopy applications in CT as well as for SNR improvements in MR fluoroscopy using projection reconstruction based techniques.