Browsing by Author "McCollough, C. (Cynthia)"

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    PublicationOpen Access
    Reducción del ruido en imágenes de tomografía computarizada usando un filtro bilateral anisotrópico
    (2014-04-24) Ramírez-Giraldo, J. C. (Juan Carlos); Fletcher, J. (Joel); McCollough, C. (Cynthia)
    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.
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    PublicationOpen Access
    Tomografía computarizada por rayos X: fundamentos y actualidad
    (2014-04-23) Ramírez-Giraldo, J. C. (Juan Carlos); Arboleda-Clavijo, C. (Carolina); McCollough, C. (Cynthia)
    This paper reviews the fundamentals of x-ray computed tomography. It starts by summarizing the early days of the technique and its evolution through time, as well as the physical principles of x-ray production. Subsequently, the mathematical principles of image reconstruction are discussed with emphasis in both analytical and iterative reconstruction methods. A complete section is dedicated to review the main concepts related with the risks of ionizing radiation, and discuss some of the most recent controversies about CT radiation and how those risks affect scanning protocols. Finally, based on the most recent advances and trends in CT, the paper discuss about those areas, which, presumably, will be the research focus of CT in the near future.