Wei Tang MD, Presenter: Nothing to Disclose

Zukun Xiong, Abstract Co-Author: Nothing to Disclose

Yao Huang MD, Abstract Co-Author: Nothing to Disclose

Ning Guo, Abstract Co-Author: Nothing to Disclose

Ning Wu MD, Abstract Co-Author: Nothing to Disclose

To compare dual-energy spectral computed tomography (CT) imaging and conventional CT imaging in terms of accuracy of the measurement of CT numbers under beam hardening conditions with phantoms.

A circular phantom (QSP-1, Fuyo Corporation) was used. Eight 20mm-diameter tubes filled with water (condition1) or iodine contrast medium at 20mg/ml (condition2,weak beam hardening) or iodine contrast medium at 50mg/ml (condition3, severe beam hardening) were placed in peripheral holes of the phantoms. One test tube of filled with iodine contrast media solutions at various concentration levels (0,0.1,0.5,1,2,5,10,20,50mg/ml) were placed in the phantoms. At each condition and test tube of each iodine concentration, the phantom was scanned by both conventional CT and dual energy spectral CT. Conventional CT was performed at tube voltage of 80kVp, 100 kVp, 120 kVp and 140 kVp. Virtual monochromatic (VNC) images from 40 to 140 keV (interval of 10keV) were obtained by dual-energy CT spectral imaging. For each concentration of the test tube, the CT number of each iodine tube. The delta CT number were calculated according to the formulas: ΔCT=CTcondition2-CTcondition1 or ΔCT=CTcondition3-CTcondition1. The results were compared with one-way ANOVA analysis.

At condition2, the mean ΔCT of VNC images (40keV to 140keV) varies from (-3.72±3.63) to (5.50±1.83) , lower than that of conventional CT images(80kVp, -39.05±16.90; 100kVp, -33.14±15.82;120kVp, -22.80±14.08; 140kVp, -25.89±12.81) (p<0.001). At condition3, the mean ΔCT of VNC images (40keV to 140keV) varies from (-62.72±25.14) to (22.29±4.40), lower than that of conventional CT images(80kVp, -163.08±44.79; 100kVp, -129.39±37.40;120kVp, -111.86±33.24; 140kVp, -99.70±29.96) (p<0.001); the mean ΔCT of VNC images (60keV to 140keV) varies from (-17.12±6.59) to (22.29±4.40), lower than that of VNC images (40keV, -62.72±25.14;50keV. 38.04±4.65) (p<0.001). 

At both weak and severe beam hardening conditions, dual-energy CT spectral imaging provides more accurate CT numbers, at severe beam hardening condition, the CT numbers of VNC images at high keV levels are accurate than those in low keV levels.

At both weak and severe beam hardening conditions, dual-energy CT spectral imaging provides more accurate CT numbers, at severe beam hardening condition, the CT numbers of VNC images at high keV levels are accurate than those in low keV levels.

Tang, W, Xiong, Z, Huang, Y, Guo, N, Wu, N, Accuracy of the Measurement of CT Numbers of Dual-energy Spectral CT Imaging under Beam Hardening Conditions.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009942.html