Abstract

RAMIREZ GIRALDO, Juan Carlos; FLETCHER, Joel J  and  MCCOLLOUGH, Cynthia H. NOISE REDUCTION IN COMPUTED TOMOGRAPHY IMAGES USING AN ANISOTROPIC BILATERAL FILTER. Rev. ing. biomed. [online]. 2010, vol.4, n.7, pp.55-62. ISSN 1909-9762.

This work proposes the use of an anisotropic bilateral filter (ABF) to reduce the noise in computed tomography images. The FBA is implemented in the tridimensional space, allowing the adjustment of filter parameters depending on the image resolution in each axis. The utility of the FBA was demonstrated using a standard image quality phantom which was scanned using a 240 mAs reference dose, and subsequently with 50 % and 25 % of the reference dose. Additionally, two clinical cases were processed, corresponding to routine clinical, intravenous contrast-enhanced abdomen and thorax scans. The phantom study found that the FBA keeps a better tradeoff between noise, spatial resolution, and low contrast detectability, when it is compared to traditional filtered backprojection reconstructions, routinely employed by current computed tomography scanners. Hence, results in the phantom suggest it is possible to reduce radiation dose by at least 50% without affecting spatial resolution or low contrast detectability. The clinical studies revealed that the FBA can decrease image noise and still provide enough information for adequate diagnosis. Prospective clinical studies are necessary to demonstrate whether or not the observed noise reduction would allow a significant decrease in radiation dose.

Keywords : Bilateral filter; Ionizing radiation; X-rays; Radiation dose reduction; Noise reduction; Computed tomography.

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