Takashi Takahata RT, Presenter: Nothing to Disclose

Tomokatsu Tsukamoto RT, Abstract Co-Author: Nothing to Disclose

Keisuke Nishihara MD, Abstract Co-Author: Nothing to Disclose

Kazunari Mesaki MD, Abstract Co-Author: Nothing to Disclose

Hiroki Mori MD, Abstract Co-Author: Nothing to Disclose

Katsuhide Ito MD, Abstract Co-Author: Nothing to Disclose

Yue Dong, Abstract Co-Author: Nothing to Disclose

To investigate the influence of different object size on CT number measurement consistency and beam-hardening effect on the polychromatic (POLY) scan mode (SECT: conventional single-energy CT) and monochromatic (MONO) scan mode (ssDECT: single-source dual-energy CT with fast kVp switching) by phantom experiment.

A polypropylene phantom (200mm) with a polypropylene tube (diameter of 18mm and length of 100mm, different iodine concentration 10, 20, 30 and 50 mgI/ml in tube, 50mm length of tube sets outside of phantom as Group A – minimum beam hardening effect and another 50mm length of tube sets inside of phantom as Group B) in center underwent CT (Discovery CT750 HD) scans with MONO scan mode by using one scan to reconstruct 40-140keV MONO image (1keV step) and POLY scan mode by using multi scan at 80kVp, 100kVp, 120kVp and 140kVp. We define that ⊿CT as the difference of the CT number between the group A and Group B and ⊿CT% as the percentage of ⊿CT to the CT number for Group A. We compared ⊿CT and ⊿CT% among SECT at 80 to 140 kVp and ssDECT at 50, 60, 70 and 80 keV under the 4 different contrast medium concentrations.

Under the SECT scan mode, Average⊿CT% of 4 different concentrations was 6.7, 9.8, 12.5 and 15.0 % at 80, 100, 120 and 140 kVp, respectively; under the ssDECT scan mode, ⊿CT% was 0.4, -0.1, -0.7 and -1.6 % at 50, 60, 70 and 80 keV, respectively. ⊿CT% were largely reduced at MONO Image (50 to 80 keV) compared to POLY images (80 to 140 kVp).

Monochromatic imaging at 50 to 80 keV by ssDECT makes CT number measurement more consistent and robust and much less susceptible to the beam-hardening effect caused by different phantom diameters compared to SECT.

Monochromatic imaging by DECT allows robust CT value measurement and minimal and unsusceptible beam-hardening effect even in patients with various body physiques, different from conventional CT.

Takahata, T, Tsukamoto, T, Nishihara, K, Mesaki, K, Mori, H, Ito, K, Dong, Y, Study of Beam-hardening Effect on the Polychromatic Images and Monochromatic Images - Influence of Different Object Size with Phantom Experiment.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14009996.html