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KMID : 1131320150170020017
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Journal of Korean Society of Computed Tomographic Technology
2015 Volume.17 No. 2 p.17 ~ p.25
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A Study on Dose and Image Quality Evaluation of Mobile CT
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Yang Kyeong-Ho
Lee Ki-Baek
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Abstract
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Purpose : Mobile CT is useful because it can move to operation rooms or intensive care units. However, there is no guidelines for dose or image quality because it had been introduced in recent years In this reason, We conducted quantitative evaluation by using pediatric and adult head phantom to compare performance of mobile CT to established CT scanner. With this data, we attempt to provide information of dose and image quality to user who want perform mobile CT examination.
Materials and Methods : Mobile CT, CereTomTM NL-3000(Neurologica, Danvers, MA, USA) and 64 Slice Light Speed VCT XTe(GE health care, wisconsin, USA) are used as scanner. We used head parts of adult Rando Phantom (ART-200-5, Fluke Bimedical, WA, USA) and Atom Dosimetry Phantom (705-D, Magnus, VA, USA).We performed CT scans for adult and pediatric phantom changing mAs, kVp, rotation time then we measured CNR, SNR and CTDIvol. Scans are performed with mobile CT and VCT, respectively. We compared CNR and SNR of each scanner when we use similar CTDIvol.
Results : Using mobile CT, increase of CTDIvol is 3.6 per 1 mA when kVp is set to 100 and rotation time is 2 seconds. In same parameter, if kVp is changed to 120, increase of CTDIvol is 5.9 per 1 mA when rotation time increases 2 seconds to 4 seconds, increase of CTDIvol per 1 mA is become twice. In similar ways, CTDIvol and DLP is become twice when double rotation time. when mAs and kVp are increased, HU is barely changed but CNR and SNR are increased. If kVp is fixed, changes of SD, CNR, SNR are being decreased as mAs increases. Comparing to images of VCT in similar CTDIvol, those of mobile CT show lower CNR and SNR when rotation time is 2 seconds. however, when we set rotation time to 4 seconds, images of mobile CT show higher CNR and SNR.
Conclusion : We think that data about changes of image quality due to various parameters can help users to lower radiation dose and optimize image quality in using mobile CT.
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KEYWORD
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Mobile CT, Light Speed VCT XTe, CNR, SNR
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