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KMID : 1131320160180010025
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Journal of Korean Society of Computed Tomographic Technology
2016 Volume.18 No. 1 p.25 ~ p.30
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A Study on Image Quality Evaluation and Dose Reduction Effect according to Variation of Reference mAs in C-Spine CT
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Ryu Na-Ry
Kwon Seoung-Ohk
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Abstract
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Purpose : C-Spine CT is not required high mAs. besides, Radiation-sensitive organs, including the thyroid gland is decreased because the dose should be considered. Therefore, in order to see if there are any changes of the image quality according to reference mAs adjustment. We want to find out proper reference mAs in C-Spine CT.
Materials and methods : This study used Somatom Definition AS 128 channel(Siemens, Germany) and rando phantom to measure the noise, HU at a Siemens workstation. And we used an american association of physicists in medicine(AAPM) phantom to measure the sharpness and spatial resolution.
All images obtained by changing from 10 to 330 mAs at intervals of 20 mAs. and then images reconstructed B30 and B60. Then, setting a region of interest in the vertebral body and the spinal cord was measured by noise and HU, AAPM phantom images was transferred to the GE workstation by measuring the sharpness and spatial resolution.
CTDIvol and DLP were reference to the dose report.
Statistical significance was verified using the SPSS Statistics 21 for Window.
Results : Noises measured in the vertebral body and the spinal cord in images reconstructed with B30 and B60 did not differ when the reference mAs is lowered by 130 mAs. Only the noise but the difference was measured in the spinal cord in image reconstructed with B60. Also there were no significant differences in HU, sharpness, spatial resolution too.
on the other hand, there were significant differences in CTDIvol about 11.32 mGy and DLP about 226 mGy·cm.
Conclusion : C-Spine CT to see the bone structure relates to kVp rather than mAs. therefore, if reduce the reference mAs properly, can expect a reduction of the exposure dose while maintaining the same image quality.
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KEYWORD
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Reference mAs, Noise, HU, Sharpness, Spatial resolution
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