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Dose Reduction and Image Quality Assessment in 64-Detector Row Computed Tomography of the Coronary Arteries Using an Automatic Exposure Control System

Francone, Marco MD*; Di Castro, Elisabetta PhD; Napoli, Alessandro MD*; Bolzan, Chiara PhD; Carbone, Iacopo MD*; Bertoletti, Linda MD*; Iuliano, Luigi MD‡§; Catalano, Carlo MD*; Passariello, Roberto MD*

Journal of Computer Assisted Tomography: September-October 2008 - Volume 32 - Issue 5 - p 668-678
doi: 10.1097/RCT.0b013e31815ea873
Cardiovascular Imaging: Original Article

Objective: To evaluate dose reduction and image quality in coronary 64-slice multidetector computed tomography using an automatic exposure control system (AECs).

Methods: A total of 101 patients were divided into 4 groups. Tube current was 600 and 800 mAs in groups A and B and adapted at 600 and 800 quality-reference mAs using an AECs in groups C and D. Effective dose and organ-equivalent dose were evaluated. Image noise was quantified as standard deviation of air-space attenuation. Two observers assessed technical adequacy and image quality using a 4-point scale.

Results: Effective dose ranged from 8.6 mSv (group C) to 15 mSv (group B) with significant dose reduction for examinations performed at 600 mAs (21.7%) and 800 mAs (29.4%).

Contribution of organ-equivalent doses showed higher exposure for lungs (42%) and breast (22%). Noise was significantly higher in groups studied with AECs. Larger coronary segments resulted in higher image quality scores without differences between groups.

Conclusion: Automatic exposure control systems provides images of diagnostic quality with substantial dose reduction.

From the *Department of Radiological Sciences, †Division of Physics, ‡Unit of Vascular Medicine, Polo Pontino, and §Department of Internal Medicine, University of Rome La Sapienza, Rome, Italy.

Received for publication July 27, 2007; accepted October 15, 2007.

Reprints: Marco Francone, MD, Department of Radiological Sciences, University of Rome La Sapienza, V.le Regina Elena 324, 00161 Rome, Italy (e-mail:

© 2008 Lippincott Williams & Wilkins, Inc.