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TH‐A‐103‐07: A Pan‐Sharpening Approach to Multiresolution Image Fusion for Hybrid Counting/integrating CT
Author(s) -
Rigie D,
Riviere P La
Publication year - 2013
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4815724
Subject(s) - panchromatic film , multispectral image , sharpening , detector , image resolution , ground truth , photon counting , artificial intelligence , computer vision , optics , computer science , physics
Purpose: We investigate the application of a pan‐sharpening algorithm to a hybrid CT dataset containing low‐resolution, photon‐counting data and high‐resolution, integrating data to generate images that inherit both the resolution properties of the integrating detector and the spectral information of the photon‐counting detector.Methods and Materials: Our 2D simulation studies include a realistic x‐ray tube spectrum, a photon‐counting detector with 5 energy bins, and an energy‐integrating detector. We used several material‐specific, ellipse‐based phantoms to generate datasets with both detectors, reconstructing panchromatic 512x512 images from the integrating data and multispectral 128×128×5 images from the photon‐counting data. We also separately reconstructed 512×512×5 images from the photon‐counting data, which we regarded as the ground truth. We used a pan‐sharpening algorithm from the remote‐sensing field, which contains 5 tunable parameters that control the balance between resolution recovery and spectral distortion. The optimization‐based algorithm seeks a high‐resolution image that has the spatial detail of the panchromatic image and the spectral characteristics of the multispectral images. The parameters were selected to minimize the mean‐squared error between the pan‐sharpened images and the ground truth. Results: The pan‐sharpened images appear to have recovered nearly all of the detail of the panchromatic image without severe spectral distortion. There is some visible distortion near edges of high‐contrast objects, such as bone. Using pan‐sharpened and ground‐truth images from two of the energy bins of the photon counting detector, we looked at the angular separation of calcium and iodine which agreed to within 0.2 degrees (6%). Conclusions: Our preliminary studies suggest a possible solution to the count‐rate limitations of photon‐counting detectors. Using a high‐resolution image, acquired by a conventional detector as a prior, one may be able to acquire low‐resolution photon‐counting data and then recover spectral images that possess both good spatial resolution and the desired spectral information. This work was supported by Toshiba Medical Systems.