A novel projection data domain material decomposition method for dual-energy CT and its impact on the accuracy of attenuation values

TL;DR

This paper introduces a new method for improving the accuracy of CT scans by decomposing materials in the projection data domain, reducing artifacts and errors in attenuation values.

Contribution

A novel projection data domain material decomposition method with object-specific scatter correction is proposed for dual-energy CT.

Findings

The method significantly improves attenuation value accuracy, especially at low energies (<70 keV).

It reduces beam hardening artifacts and provides more uniform quantitative error across non-water inserts.

Object-specific scatter correction prevents major artifacts and performs well in abdominal phantom imaging.

Abstract

Objective. Despite major advances in dual-energy computed tomography (CT), obtaining accurate attenuation values for quantitative applications remains a technical challenge. To address this topic, we introduce a novel projection data domain material decomposition method that is an extension of an approach we recently proposed for beam hardening correction in single energy CT. Approach. The proposed method employs object-specific scatter correction and an analytical energy response model. We compare its performance to image-based material decomposition on accuracy of attenuation values using the American College of Radiology (ACR) CT accreditation phantom, scanned with consecutive low and high energy axial scans in centered and off-centered positions. Accuracy is assessed across the five inserts, and the images are analyzed for beam hardening artifacts and noise. Additionally, we assess the usefulness of object-specific scatter correction, and we assess performance over conventional data domain material decomposition and for anthropomorphic abdomen phantom imaging. Main results. In the ACR phantom, the proposed method yielded a significant improvement in accuracy of the attenuation values, particularly at low energies (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{upgreek}
\usepackage{mathrsfs}
\setlength{\oddsidemargin}{-69pt}
\begin{document}
$ \lt\!\!70$\end{document}<70 keV), and an important reduction in beam hardening artifacts. While similarly high accuracy was achieved for water, quantitative error within the non-water inserts was lower and more uniform across the 30–140 keV range, especially in the more challenging off-centered positioning of the phantom. Noise showed expected parabolic behavior, but with minimum at lower keV, which may be clinically advantageous. Object-specific scatter correction was shown to prevent major artifacts. Advantages over conventional data-domain decomposition clearly appeared when only a standard phantom is available to calibrate the latter. Lastly, the proposed method was shown to perform well, without any changes, in the more complex scenario of abdominal phantom imaging. Significance. This work demonstrates that data-based material decomposition using an analytical energy response model with object-specific scatter correction offers a promising pathway to improve accuracy of CT attenuation values.

Figures