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Improvement of Cone Beam CT Image Using Singularity Detection
Yi-Qiang YANG Nobuyuki NAKAMORI Yasuo YOSHIDA
IEICE TRANSACTIONS on Information and Systems
Publication Date: 2003/07/01
Print ISSN: 0916-8532
Type of Manuscript: Special Section PAPER (Special Issue on Multiresolution Analysis)
cone beam, computed tomography (CT), quantum mottle, wavelet transform, patient's dose, noise reduction,
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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.