Rika Fukui, Presenter: Nothing to Disclose

Isao Tanaka, Abstract Co-Author: Nothing to Disclose

Haruhiko Machida MD, Abstract Co-Author: Nothing to Disclose

Xiao Zhu Lin MD, Abstract Co-Author: Nothing to Disclose

Tubasa Iwasaki, Abstract Co-Author: Nothing to Disclose

Eiko Ueno MD, Abstract Co-Author: Nothing to Disclose

Yun Shen PhD, Abstract Co-Author: Employee, General Electric Company Researcher, General Electric Company

To assess in a phantom if reducing beam hardening by fast switching of 80 and 140 kVp in each view (fast kVp-switching) with single-source dual-energy CT (ssDECT) depends on the diameter of enhanced structures in contrast-enhanced (CE) CT.

At isocenter, we placed a cylindrical phantom (QSP-1, FUYO) containing an 18-mm-diameter cylindrical tube at its center filled with 100.0 mg/mL of iodine contrast medium and 8 cylindrical tubes of 4- to 18-mm (2-mm step) diameter filled with 10.0 mg/mL of iodine contrast medium located symmetrically in the phantom’s periphery, all 9 parallel to the z-axis. With a 64-detector ssDECT scanner (Discovery CT750 HD, GE), we scanned the phantom using 120-kVp helical and fast kVp-switching DE techniques; reconstructed 120-kVp and monochromatic 40- to 140-keV (10-keV step) axial images of 1.25-mm thickness. On 3 different slices of each image, we placed circular regions of interest of the same area to measure the standard deviation of CT attenuation at the midpoint between the center of the phantom and each tube (SDa) and at each remote site of the minimal artifact as background (SDb). We calculated artifact index (AI) as ([SDa]2 - [SDb]2)1/2 and compared AI for each diameter using Tukey-Kramer test.

The mean AI of all the different diameters was 10.5 ± 0.1 HU at 120 kVp and 16.7 ± 2.1, 10.7 ± 1.3, 7.1 ± 0.7, 4.7 ± 0.4, 3.9 ± 0.3, 3.8 ± 0.3, 3.6 ± 0.3, 3.6 ± 0.2, 3.6 ± 0.2, 3.7 ± 0.1, and 3.7 ± 0.3 HU at 40 to 140 keV (10-keV step); AI was lowest at 120 keV. With the different diameters (4 to 18 mm), AI at 120 kVp was 4.4 ± 0.3, 5.6 ± 0.3, 7.6 ± 0.1, 9.7 ± 0.2, 11.5 ± 0.2, 13.0 ± 0.3, 15.4 ± 0.1, and 16.7 ± 0.1 HU; AI at 120 keV was 3.4 ± 0.6, 4.0 ± 0.5, 2.9 ± 0.8, 2.9 ± 0.8, 4.3 ± 0.5, 3.6 ± 1.1, 4.0 ± 0.8, and 3.9 ± 0.9 HU. Between any 2 diameters, AI was significantly different (P 0.05) at 120 keV.

In CECT, beam hardening was maximally reduced at 120 keV using fast kVp-switching with ssDECT compared to conventional 120 kVp CT, especially independent of the diameter of enhanced structures.

Fast kVp-switching with single-source dual-energy CT is clinically useful for reducing beam-hardening artifact and improving diagnostic accuracy in contrast-enhanced CT.

Fukui, R, Tanaka, I, Machida, H, Lin, X, Iwasaki, T, Ueno, E, Shen, Y, Does Beam-hardening Reduction by Fast kVp-switching with Single-Source Dual-Energy CT Depend on the Diameter of Enhanced Structures in Contrast-enhanced CT? A Phantom Experiment.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12043922.html