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Radiation and contrast agent doses reductions by using 80-kV tube voltage in coronary computed tomographic angiography : a comparative study . OBJECTIVE To investigate the effects of 80-kilovoltage ( kV ) tube voltage coronary computed tomographic angiography ( CCTA ) with a reduced amount of contrast agent on qualitative and quantitative image quality parameters and on radiation dose in patients with a body mass index ( BMI ) < 23.0 kg/m ( 2 ) . METHODS One hundred and twenty consecutive patients with a BMI < 23.0 kg/m ( 2 ) and a low calcium load undergoing retrospective electrocardiogram ( ECG ) -gated dual-source CCTA were randomized into two groups [ standard-tube voltage ( 120-kV ) vs. low-tube voltage ( 80-kV ) ] . The injection flow rate of contrast agent ( 350 mg I/mL ) was adjusted to body weight of each patient ( 4.5-5.5 mL/s in the 120-kV group and 2.8-3.8 mL/s in the 80-kV group ) . Radiation and contrast agent doses were evaluated . Quantitative image quality parameters and figure of merit ( FOM ) of coronary artery were evaluated . Each coronary segment was evaluated for image quality on a 4-point scale . RESULTS Compared with the 120-kV group , effective dose and amount of contrast agent in the 80-kV group were decreased by 57.8 % and 30.5 % ( effective dose:2.7 ± 0.5 vs. 6.4 ± 1.3 mSv ; amount of contrast agent:57.1 ± 3.2 vs. 82.1 ± 6.1 mL ; both p < 0.0001 ) , respectively . Image noise was 22.7 ± 2.1HU for 120-kV images and 33.2 ± 5.2 HU for 80-kV images ( p < 0.0001 ) . Signal-to-noise ratio ( SNR ) and contrast-to-noise ratio ( CNR ) in the proximal right coronary artery ( RCA ) and left main coronary artery ( LMA ) were all lower in 80-kV than 120-kV images ( SNR in the proximal RCA : 16.5 ± 1.8 vs. 19.4 ± 2.8 ; SNR in the LMA : 16.3 ± 2.0 vs.19.6 ± 2.7 ; CNR in the proximal RCA : 19.4 ± 2.3 vs.22.9 ± 3.0 ; CNR in the LMA : 18.8 ± 2.4 vs. 22.7 ± 2.9 ; all p < 0.0001 ) . FOM were all significantly higher in 80-kV than 120-kV images ( proximal RCA : 146.7 ± 45.1 vs. 93.4 ± 32.0 ; LMA : 139.1 ± 47.2 vs. 91.6 ± 31.1 ; all p < 0.0001 ) . There was no significant difference in image quality score between the two groups ( 3.3 ± 0.8 vs. 3.3 ± 0.8 , p=0.068 ) despite decreased SNR and CNR of coronary artery in the 80-kV group . CONCLUSION The 80-kV protocol significantly reduces radiation and contrast agent doses in CCTA in patients with a low BMI < 23.0 kg/m ( 2 ) and a low calcium load while maintaining image quality .
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Intervention_Physical
80-kilovoltage ( kV ) tube voltage coronary computed tomographic angiography ( CCTA )
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Intervention_Physical
retrospective electrocardiogram ( ECG ) -gated dual-source CCTA
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Intervention_Control
[
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Intervention_Other
standard-tube voltage
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Intervention_Control
( 120-kV )
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Intervention_Physical
low-tube voltage
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Intervention_Other
( 80-kV ) ]
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Outcome_Other
Radiation and contrast agent doses
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Outcome_Other
Quantitative image quality parameters and figure of merit ( FOM )
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Outcome_Other
image quality
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Outcome_Other
effective dose and amount of contrast agent
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Outcome_Other
Image noise
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Outcome_Other
Signal-to-noise ratio ( SNR )
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Outcome_Other
contrast-to-noise ratio ( CNR )
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Participant_Sample-size
One hundred and twenty
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Participant_Condition
CCTA