Radiation Dose Reduction by Using 100-kV Tube Voltage in Cardiac 64-slice Computed Tomography: A Comparative Study

Eur J Radiol. 2009; 12(7):1016

Feuchtner GM, Jodocy D, Klauser A, Haberfellner B, Aglan I, Spoeck A, Hiehs S, Soegner P, Jaschke W

OBJECTIVES: To evaluate a 100-kilovoltage (kV) tube voltage protocol regarding radiation dose and image quality, in comparison with the standard 120kV setting in cardiac computed tomography angiography (CCTA).

METHODS: 103 patients undergoing retrospective ECG-gated helical 64-slice CCTA were enrolled (100kV group: 51 patients; 120kV group: 52 patients). Inclusion criteria were: (1) BMI <28kg/m(2); (2) weight <85kg; (3) coronary calcium score <300 Agatston Units (AU). Quantitative image quality parameters were calculated [image noise, contrast-to-noise ratio (CNR), intracoronary CT-attenuation (HU)]. Each coronary artery segment (AHA/ACC-16-segments-classification) was evaluated for image quality on a 4-point scale.

RESULTS: There was no statistical difference in age, gender, BMI and eff. tube current (mAs), and the use of ECG-tube current modulation (50.9% vs. 50% of patients) between both groups. 84.2% of patients in the 100kV group had zero calcium score or less than100AU, the remaining had between 100 and 300AU. The effective radiation dose was significantly lower in the 100kV group with mean 7.1mSv+/-2.4 (range, 3.4-11.1) compared to the 120kV group with 13.4mSv+/-5.2 (range, 6.3-22.7) (p<0.001) (dose reduction, 47%). In the 100kV group, the use of ECG-dependent tube current modulation reduced the radiation exposure (by 44.8%) to 5.3mSv+/-1.1 (range, 3.4-8.5mSv) (p<0.001), the dose without was 9.6mSv+/-1.1 (range, 6.3-11.1). Image noise in the coronary arteries was not different between both groups with 29.8 and 30.5SD (HU), respectively. CNR in the 100kV group was with 20.9+/-6.8 for the coronary arteries and with 19.9+/-5.9 for the aorta similar to the 120kV group. Intraluminal CT-attenuation (HU) of the coronary arteries were higher in the 100kV group (p25kg/m(2)).

CONCLUSIONS: The 100kV protocol significantly reduces the radiation dose in CCTA in patients with a low BMI <25kg/m(2) and a low calcium load while maintaining high image quality and the advantages of helical scan algorithm.

PMID: 19671491

One Response

  1. Paul Schoenhagen, MD  on October 17th, 2009

    100 kV protocols are available for clinical use on most scanner systems. This is a direct comparison to 120 kv scanning and retrospective gated protocols.
    See also:
    Impact of a reduced tube voltage on CT angiography and radiation dose: results of the PROTECTION I study.
    Bischoff B, Hein F, Meyer T, Hadamitzky M, Martinoff S, Schömig A, Hausleiter J.
    JACC Cardiovasc Imaging.. 2009; 2(8):940-6
    PMID: 19679281


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