Sebastian Tobias Schindera MD, Presenter: Nothing to Disclose

Marc Hagemeister MD, Abstract Co-Author: Nothing to Disclose

Michael A. Patak MD, Abstract Co-Author: Nothing to Disclose

Andrea Rosskopf MD, Abstract Co-Author: Nothing to Disclose

Peter Vock MD, Abstract Co-Author: Nothing to Disclose

Zsolt Szucs-Farkas MD, PhD, Abstract Co-Author: Nothing to Disclose

To compare abdominal-pelvic CT angiography at 100 and 80 kVp for image quality and radiation dose.

In a retrospective study, our standard 100-kVp protocol for abdominal-pelvic 64-slice CT angiography was compared with an 80-kVp protocol in two groups each consisting of 30 consecutive patients. Group A (mean weight, 77.0 kg; weight range, 50-105 kg) was acquired with 100 kVp and group B (mean weight, 80.4 kg; weight range, 48 -118 kg) with 80 kVp. Automatic tube current modulation was applied using effective mAs settings of 160 for group A and 260 for group B. Otherwise, scanning parameters and contrast material injection (60 mL of iodinated contrast material followed by 40 mL of saline flush) were kept identical for both groups. Mean aorto-iliac attenuation and image noise were quantified; signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The effective dose was estimated based on the dose-length-product using standardized conversion factor of 0.015 mSv/mGy. Three independent readers performed the qualitative assessment regarding image noise and overall image quality. Unpaired Student t-test and Mann-Whitney-U-test were performed.

The 80-kVp protocol demonstrated a significantly higher mean aorto-iliac attenuation than the 100-kVp protocol (433.8HU ± 90.5 vs 364.7HU ± 103.5, respectively; P<0.01). There was a significantly higher mean image noise for the 80-kVp protocol than for the 100-kVp protocol (18.1HU ± 5.2 vs 12.7HU ± 2.4, respectively; P<0.001). No difference was seen between the 80-kVp and the 100-kVp protocol for the SNR (28.2 ± 12.1 vs 32.5 ± 15.8, respectively; P=0.24) and CNR (25.4 ± 11.4 vs 29.0 ± 14.7, respectively; P=0.30). Mean effective dose for the 80-kVp protocol was significantly lower than that for the 100-kVp protocol (3.57mSv ± 0.32 vs 5.29mSv ± 0.81, respectively; P<0.001). Subjective image assessment yielded significantly higher image noise for the 80-kVp protocol (P<0.05) but no significant difference in overall image quality (P=0.83).

Tube voltage reduction from 100 to 80 kVp for abdominal-pelvic CT angiography resulted in significant reduction of effective dose without significant change in image quality.   

It is beneficial to use an 80-kVp protocol for abdominal-pelvic CT angiography to further reduce  patient radiation dose.

Schindera, S, Hagemeister, M, Patak, M, Rosskopf, A, Vock, P, Szucs-Farkas, Z, Abdominal-Pelvic 64-Slice CT Angiography with 100-kVp and 80-kVp: Comparison of Image Quality and Radiation Dose.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6014626.html