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KMID : 1149020170190010035
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Journal of Korean Society of Computed Tomographic Technology
2017 Volume.19 No. 1 p.35 ~ p.43
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Comparison of bolus tracking and split injection in dynamic abdominal computed tomography : Effect on the patient exposure dose and image quality
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Lee Jae-Hyun
Chung Yong-Hwan
Nam Tae-Hyun
Gwon Sun-Ahn
Min Kwan-Hong
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Abstract
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Purpose : To compare a multi-phase test using bolus tracking and a single-phase test employing the split injection technique in dynamic abdominal computed tomography (CT), to study the influence on exposure dosage and image quality.
Materials and Methods : Among patients who underwent dynamic abdominal CT from October to December 2015, patients examined with either bolus tracking (technique A) or split injection (technique B) were included in this study. A CT system and an analysis workstation were used. Technique A involved one contrast medium (CM) injection. Scanning was conducted twice in the arterial phase and portal venous phase. CM injection in technique B comprised two phases: phase 1 and 2. However, scanning was performed once at 90s manually. The exposure dose was compared between the two tests using the DLP value. The images were quantitatively evaluated by measuring the CT number at the location of the aorta, portal vein, and liver parenchyma. Two radiologists qualitatively analyzed the images obtained using techniques A and B on 5-point scale method.
Result : The average DLP value was 1123.8 mGy*cm in technique A and 536.5 mGy*cm in technique B. The aorta CT number of technique A and B were achieving the 100% of standard value. The portal vein CT number of technique A and B were achieving 96% of the standard value. The liver parenchyma CT number of technique A and B were fulfilling 100% of the standard value. Qualitative evaluation revealed an average of 4.5 for technique A and 4.3 for technique B in the arterial phase; 4.2 and 4.5, respectively, in the portal phase image; and 4.3 and 4.2, respectively, in the interpretation category.
Conclusion : Compared to technique A, which is used currently in dynamic abdominal imaging, technique B that injects contrast medium at regular intervals can reduce the exposure dose by 47% without downgrading Image quality.
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KEYWORD
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CT, Abdomen, DLP, Contrast Medium, Split injection, Bolus Tracking
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