Huishu Yuan MD, Presenter: Nothing to Disclose

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

JianYing Li, Abstract Co-Author: Employee, General Electric Company

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

Evaluate dual energy spectral CT imaging for beam hardening artifacts (BHA) correction with phantom and patient data.

Both an iodine-filled tube phantom (two 5mm diameter cylinders 3cm apart in a water bath) and 100 brain patients scanned with spectral CT imaging mode were used for the evaluation. Both conventional 140kVp polychromatic and monochromatic images were generated from a single dual energy spectral CT acquisition. CT number variations in the areas surrounding the iodine tubes in phantom study were measured. Image noise in the corona (as background) and medulla oblongata, cerebellar, pons and the inferior part of frontal lobes (as regions of interest) were measured in the patient study. The BHA index, defined as the square root of the squared noise difference between the region of interest and background, was calculated and compared between the polychromatic and monochromatic images.

In the conventional kVp phantom images, dark bands were formed between the two iodine cylinders, with the maximum CT number non-uniformity being 200HU. The monochromatic 90keV image totally eliminated the dark bands with much more uniform overall CT number distribution (maximum CT number deviation <10HU). For the patient study, compared with the polychromatic images, monochromatic images at 75keV from spectral CT reduced the BHA indices for the 4 anatomic regions by 52.8, 75.1, 64.9, 41.3%, respectively, while image noises were similar between the two types of images.

The dual energy spectral CT imaging with the ability of generating monochromatic images substantially reduces beam hardening artifacts and maintains similar image noise compared to the conventional CT imaging.

Monochromatic images obtained with dual energy spectral CT imaging can substantially reduce beam hardening artifacts caused by dense materials and provide more accurate CT images for diagnosis.

Yuan, H, Lin, X, Li, J, Shen, Y, Evaluation of Dual-Energy Spectral CT Imaging for Beam Hardening Artifacts Correction.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034284.html