Daniel Jeffrey Boulter MD, Presenter: Nothing to Disclose

Walter Huda PhD, Abstract Co-Author: Research support, Siemens AG

Matthew Stephenson, Abstract Co-Author: Nothing to Disclose

Michael Kirk Kizziah MD, Abstract Co-Author: Nothing to Disclose

Andrew D. Hardie MD, Abstract Co-Author: Nothing to Disclose

To compare radiation dose, image quality and diagnostic performance for acute intra-abdominal infection of standard single source computed tomography (CT) and high pitch dual source CT of the abdomen and pelvis.

A total of 29 patients had undergone abdominal and pelvic CT examinations with oral and intravenous contrast on both a single source CT scanner (SSCT) with standard pitch and a dual source CT (DSCT) with high pitch (3.4). We assessed the radiation dose from CTDIvol (mGy) and image noise from the measured standard deviation in region of interest measures within the liver. Image sharpness and artifacts were assessed on a four point scale ranging from excellent (4) to unsatisfactory (1). Diagnostic quality was assessed on a four point scale from fully diagnostic (4) to non-diagnostic (1) for determining the presence or absence of an acute intra-abdominal infection. Three blinded independent observers rated the images in random order. Image quality and dose indices were plotted as a function of patient AP dimension, which ranged from 18 cm to 28 cm.

There was a significant difference between the CTDIvol doses between SSCT (15.7 ± 3.8 mGy) and DSCT (8.6 ± 1.0 mGy) (p<0.01). On average, there was a 45% reduction in radiation dose for DSCT. The doses on SSCT increased with increasing AP dimension from 12.2 mGy (smallest) to 18.2 mGy (largest) but were independent of patient size on DSCT (mean 8.6 ± 0.8 mGy). Image noise was greater on DSCT (12.6 ± 2.3 HU) than SSCT (10.6 ± 1.6 HU) (p<0.01), although this difference was minimal in the smallest AP dimension (8.8 vs. 9.4 HU) and greater in the largest (13.8 vs. 17.2 HU). The readers judged DSCT image sharpness (3.8 ± 0.2) to be similar to SSCT (3.9 ± 0.2). However, readers judged more artifacts on DSCT (3.3 ± 0.2) than SSCT (3.7 ± 0.3), which was independent of AP diameter. Overall diagnostic quality of the scans was similar between SSCT (3.9 ± 0.1 SSCT) and DSCT (3.8 ± 0.2).

Use of a high pitch dual source CT scanner for performing abdominal and pelvic CT examinations reduces patient doses by nearly half with only minor reductions in image quality, which are unlikely to reduce diagnostic performance.

Use of a high pitch dual source CT significantly reduces patient doses from abdominal and pelvic CT while maintaining diagnostic performance, which is in keeping with the ALARA principle.

Boulter, D, Huda, W, Stephenson, M, Kizziah, M, Hardie, A, Dose and Image Quality for High Pitch Dual Source CT versus Standard Single Source CT Scanners in Abdominal and Pelvic Imaging.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9006131.html