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KMID : 1149020180200020017
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Journal of Korean Society of Computed Tomographic Technology
2018 Volume.20 No. 2 p.17 ~ p.22
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A study on image quality and radiation dose reduction effect through Virtual Non Contrast method for paranasal sinus CT
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Kim Hyun-Young
Lee Jong-Min
Nam Tae-Hyun
Gwon Sun-Ahn
Dae Chang-Min
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Abstract
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Purpose: Virtual non contrast (VNC) is a technically reconstructed “water no iodine” image which is recalculated of material decomposition with energy selective photon counting detector. In this study, we analyzed VNC image of para-nasal sinus CT as a replacement of non-contrast (NC) image without image distortion and quality degradation.
Material and methods: Total of 30 patients, who underwent PNS CT with dual layer detector CT, was enrolled for this study, retrospectively. For quantitative image quality analysis, circular ROIs were located at the same location of VNC and NC images. Paired t-test was used for comparison of CT number, noise, and SNR. For qualitative image quality analysis, both VNC and NC images were evaluated by using a 5-point scale method. Dose Length Product (DLP) was used for comparison of exposure dose between PNS CT protocol and PNS (VNC) CT protocol.
Result: There was no significant difference in quantitative image analysis between VNC and NC. Paired t-test(SPSS) values of CT number, Noise, and SNR between VNC and NC were as follows; CT number (0.63±0.23), Noise (-0.15±0.86), SNR (0.06±0.32). In qualitative image analysis, both VNC and NC images marked score of 4(very good) and 5(excellent) more than 90% (VNC 94.7%, NC 98.7%). In comparison of DLP, PNS CT protocol averagely exposed 43% higher dose than PNS (VNC) CT protocol.
Conclusion: For PNS CT, VNC protocol is highly recommended a substitute technique of NC scan protocol in order to reduce radiation exposure dose without image quality degradation.
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KEYWORD
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PNS CT, VNC, Dose reduction, Dual Layer Detector CT
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