Juan Carlos Ramirez Giraldo PhD, Presenter: Employee, Siemens AG

Marilyn J. Siegel MD, Abstract Co-Author: Research Consultant, Siemens AG Speakers Bureau, Siemens AG

R Bankwitz, Abstract Co-Author: Employee, Siemens AG

Marga Leuthe, Abstract Co-Author: Employee, Siemens AG

Bernhard Schmidt PhD, Abstract Co-Author: Employee, Siemens AG

To evaluate the organ and effective doses of dual-energy CT (DECT) in pediatric-sized phantoms in comparison to low tube potential single-energy CT (SECT) with the same radiation output.

Two anthropomorphic phantoms simulating a 1 year-old and a 5 year-old that had inserted thermoluminescent dosimeters (TLDs) were scanned using a dual-source 128-slice CT system operated with conventional SECT at low tube potential and also DECT at 80/140 kVp with tin filtration. The scan range included both abdomen and pelvis. For the SECT scans, the tube potential and corresponding tube current were selected by using an automated tube potential selection tool (CARE kV), using 120 kVp and 150 mAs as reference, with optimization for CT angiography. The scanner output, as measured by the volume CT dose index (CTDIvol), was recorded and used to adjust the mAs in the DECT scans such that CTDIvol was the same as the SECT scan. Organ doses in mGy were measured and the effective dose in mSv was calculated by summing the absorbed doses (mGy) of individual organs considering ICRP103 weighting factors.

The resulting CTDIvol values were 0.67 mGy and 2.73 mGy for the 1 year-old and 5 year-old phantoms, respectively. The calculated effective doses were 1 and 1 mSv (1 year-old), and 3 and 3 mSv (5 year-old) for the 80 kVp and 80/140 kVp scans, respectively. In the 1 year-old phantom, organ doses were statistically the same with average difference of 0.11 mGy (P=0.07) between 80 kVp and 80/140 kVp. In the 5 year-old phantom, organ doses were also statistically the same with average difference of 0.35 mGy (P=0.15) between 80 kVp and 80/140 kVp.

At matched radiation scanner output, organ and effective doses of DECT scans are comparable to those from conventional SECT at a low tube potential of 80 kVp.

The ability of DECT to achieve comparable organ and effective doses relative to optimized low-tube potential CT angiography in pediatrics, is a pre-requisite for consideration of its use clinically.

Ramirez Giraldo, J, Siegel, M, Bankwitz, R, Leuthe, M, Schmidt, B, Organ and Effective Doses in Dual-energy CT of Pediatric Contrast-enhanced Examinations: Comparison to Single-energy CT Using Low Tube Potential.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13028877.html