Keywords:
Cardiovascular system, CT-Angiography, Contrast agent-intravenous, Dosimetry, Dosimetric comparison
Authors:
A. Kosmala, T. Gassenmaier, S. Veldhoen, A. Kunz, T. A. Bley, B. Petritsch; Würzburg/DE
Methods and Materials
Prospectively a total of 120 patients matched for sex,
age,
and body-mass-index were identified for this study and divided in three groups of 40 patients each.
CTDIvol,
DLP,
subjective image quality as assessed by two readers (five-point scale: 1 = excellent; 2 = good; 3 = moderate; 4 = poor; 5 = non-diagnostic),
measured CT attenuation (HU) in three central and peripheral levels,
background noise (BN) and calculated signal-to-noise-ratio (SNR) were compared.
CT protocol settings of each patient group were chosen according to the manufacturer’s recommendations:
- Group 1: For conventional 64-slice SSCT the parameters were: 120 kV tube voltage,
150 mAs,
2x32x0.6 mm collimation with z-flying focal spot,
0.33 seconds gantry rotation time,
and 300 mm/s table speed at a pitch factor of 1.4.
- Group 2: For single-energy DSCT the following parameters were used: 100 kV tube voltage,
150 mAS,
192x0.6 mm collimation,
0.25 seconds gantry rotation time,
and 400 mm/s table speed at a pitch factor of 1.55.
- Group 3: For DECT acquisition the parameters were: 90 kV tube voltage (A tube) / 150 kV tube voltage (B tube),
300 mAs (A tube) / 150 mAs (B tube),
192x0.6 mm collimation,
0.25 seconds gantry rotation time,
and 200 mm/s table speed at a pitch factor of 0.55.
The dual-energy FOV was limited to 35.5 cm because of the smaller x-y axis coverage of the B detector.