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KMID : 1131320150170020059
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Journal of Korean Society of Computed Tomographic Technology
2015 Volume.17 No. 2 p.59 ~ p.67
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Evaluation of image quality of Ultra Algorithm in Temporal Bone CT
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Choi Jae-Woon
Lee Ki-Baek
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Abstract
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Purpose : To find out the usefulness ultra algorithm in temporal bone CT which requires high spatial resoultion by comparing ultra with conventional bone plus and edge algorithm.
Materials and Methods : Temporal bone CT imgaes of 30 patients were reconstructed by 6 type 3 different algorithms(bone plus, edge, and ultra algorithm) and 2 different reconstruction techniques (FBP and ASIR30%). ACR pahntom was scanned and acquired images were reconstructed by same way. We set the ROIS on soft tissue and bone of paitent’s CT images and analyzed the images. We also evaluated spatial resolution using LSF by measuring MTF 50% and MTF 10% of ACR phantom images.
Result : bone plus algorithm was in the conrtol group for analysis of patient data. In SD of soft tissue, there was no difference between ultra and bone plus algorithms. SD increased by 28.78% and34.63% in FBP and ASIR 30% images of edge algorithm, respectively. in case of bone, images of ultra algorithm showed increased SD by 18.88% and 19.78% in FBP and ASIR 30%, repectively, whilethose of edge algorithm showed decreased SD by 10% and 9.1% in FBP and ASIR 30%. As a result of spatial resolution and sharpness, the value of MTF 50% was 4.28, 0.62 and 5.64 in FBP images and 4.39, -3.77 and 6.17 in ASIR 30% images for bone plus, edge and ultra algorithm, respectively. The value of MTF 10% was 6.50. 5.85 and 10.01 in FBP images and 6.91, 5.74 and 21.98 in ASIR 30% images for bone plus, edge and ultra algorithm, respectively. Spatial resolution and sharpness of ultra algorithm showed thr best.
Conclusion : Ultra algorithm emphasizes high-frequency without increase of low-frequency noise and shows considered to be usefulexcellent image quality compared to conventional bone plus or edge algorithm. Therefore, ultra algorithm is considered useful in clinical temporal bone CT.
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KEYWORD
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temporal bone CT, algorithm, FBP, ASIR
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