Akihiko Nishide, Presenter: Employee, General Electric Company

Yasuhiro Imai MS, Abstract Co-Author: Employee, General Electric Company

Yotaro Ishihara MS, Abstract Co-Author: Employee, General Electric Company

Paul Licato MS, Abstract Co-Author: Employee, General Electric Company

Sachio Kuribayashi MD, Abstract Co-Author: Research grant, General Electric Company

Masahiro Jinzaki MD, Abstract Co-Author: Nothing to Disclose

We developed several new phantoms for evaluating Dual Energy CT image quality. The purpose of this study is to simulate physiological motion with fast kV switching, to evaluate beam-hardening effects, and assess pseudo enhancement of simulated cysts and tumors using a phantom model.

“Moving phantom” that simulated the motion of a large artery undergoing repeated inflation and deflation cycles ranging in frequency from 0.16 to 1.6 Hz was evaluated using back-to-back dual energy scans vs. a fast view-to-view kV switching technique. Comparison in overall image quality and motion immunity was evaluated. Its phantom body is silicon rubber with inflation and deflation motion, and simulated vessel is attached. Simulated vessel is 1cm diameter tube made of acrylic. This tube has 5% iodine contrast dilutions (Iopamiron) and 23% calcium equivalent rods (Kyoto Kagaku tough bone BE-T, BE-H, BE N). To evaluate the benefits of synthetic monochromatic images for address pseudo enhancement of cysts, a specialized phantom was constructed to simulate a cyst and tumor inside of a kidney. “Kidney phantom” was a 7cm diameter acrylic cylinder and can be filled with dilute iodinated contrast solution. In addition, it has five 1cm and 1.5cm 5 acrylic tubes inside, each of which can be filled with water, oil or contrast solution. To simulate the X-ray spectrum at the center of body, pair of “Kidney phantoms” are positioned in the 30cm body ring (Phantom Laboratory CTP539). The contrast-enhanced kidney is affected by beam hardening resulting in the pseudo enhancement of the cyst or tumor region. The effects of this pseudo enhancement were evaluated using conventional images.  

“Moving phantom” showed the different misregistration artifacts present for back-to-back dual kV scan, but were virtually eliminated for the fast kV view-to-view switching technique. “Kidney phantom” reproduced the beam-hardening phenomenon of CT number rising within the cyst or tumor regions.  

We developed several phantoms that were useful in the evaluation of image quality and performance for CT dual energy acquisition and weighted subtraction techniques.

Before using Dual Energy scanning in the clinical setting these phantoms are valuable for evaluating acquisition and reconstruction algorithms.

Nishide, A, Imai, Y, Ishihara, Y, Licato, P, Kuribayashi, S, Jinzaki, M, Development of Dual Energy Evaluation Phantoms.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6020153.html