Improvement of Cone Beam CT Image Using Singularity Detection

Yi-Qiang YANG  Nobuyuki NAKAMORI  Yasuo YOSHIDA  

Publication
IEICE TRANSACTIONS on Information and Systems   Vol.E86-D   No.7   pp.1206-1213
Publication Date: 2003/07/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Multiresolution Analysis)
Category: 
Keyword: 
cone beam,  computed tomography (CT),  quantum mottle,  wavelet transform,  patient's dose,  noise reduction,  

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Summary: 
In medical diagnosis, cone beam CT increases the dose absorbed by a patient. However, the radiographic noise (such as quantum noise) in a CT image increases when radiation exposure is reduced. In this paper, we propose a method to improve the CT image degraded by the quantum mottle based on 2-D wavelet transform modulus sum (WTMS). The noise and regular parts of an image can be observed by tracing the evolution of its 2-D WTMS across scales. Our experimental results show that most of the quantum mottle in the 2-D projections is removed by the proposed method and the edges preserved well. We investigate the relation between the number of X-ray photons and the quality of the denoised images. The result shows the possibility that a patient's dose can be reduced about 10% with the same visual quality by our method.