open access

Vol 24, No 5 (2019)
Original research articles
Published online: 2019-09-01
Submitted: 2018-12-19
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Evaluation of raw-data-based and calculated electron density for contrast media with a dual-energy CT technique

Daisuke Kawahara, Shuichi Ozawa, Kazushi Yokomachi, Toru Higaki, Takehiro Shiinoki, Yoshimi Ohno, Yuji Murakami, Kazuo Awai, Yasushi Nagata
DOI: 10.1016/j.rpor.2019.07.013
·
Rep Pract Oncol Radiother 2019;24(5):499-506.

open access

Vol 24, No 5 (2019)
Original research articles
Published online: 2019-09-01
Submitted: 2018-12-19

Abstract

Objectives

The aim of the current study is to evaluate the accuracy and the precision of raw-data-based relative electron density (REDraw) and the calibration-based RED (REDcal) at a range of low-RED to high-RED for tissue-equivalent phantom materials by comparing them with reference RED (REDref) and to present the difference of REDraw and REDcal for the contrast medium using dual-energy CT (DECT).

Methods

The REDraw images were reconstructed by raw-data-based decomposition using DECT. For evaluation of the accuracy of the REDraw, REDref was calculated for the tissue-equivalent phantom materials based on their specified density and elemental composition. The REDcal images were calculated using three models: Lung-Bone model, Lung-Ti model and Lung-Ti (SEMAR) model which used single-energy metal artifact reduction (SEMAR). The difference between REDraw and REDcal was calculated.

Results

In the titanium rod core, the deviations of REDraw and REDcal (Lung-Bone model, Lung-Ti model and Lung-Ti model with SEMAR) from REDref were 0.45%, 50.8%, 15.4% and 15.0%, respectively. The largest differences between REDraw and REDcal (Lung-Bone model, Lung-Ti model and Lung-Ti model with SEMAR) in the contrast medium phantom were 8.2%, −23.7%, and 28.7%, respectively. However, the differences between REDraw and REDcal values were within 10% at 20mg/ml. The standard deviation of the REDraw was significantly smaller than the REDcal with three models in the titanium and the materials that had low CT numbers.

Conclusion

The REDcal values could be affected by beam hardening artifacts and the REDcal was less accurate than REDraw for high-Z materials as titanium.

Advances in knowledge

The raw-data-based reconstruction method could reduce the beam hardening artifact compared with image-based reconstruction and increase the accuracy for the RED estimation in high-Z materials, such as titanium and iodinated contrast medium.

Abstract

Objectives

The aim of the current study is to evaluate the accuracy and the precision of raw-data-based relative electron density (REDraw) and the calibration-based RED (REDcal) at a range of low-RED to high-RED for tissue-equivalent phantom materials by comparing them with reference RED (REDref) and to present the difference of REDraw and REDcal for the contrast medium using dual-energy CT (DECT).

Methods

The REDraw images were reconstructed by raw-data-based decomposition using DECT. For evaluation of the accuracy of the REDraw, REDref was calculated for the tissue-equivalent phantom materials based on their specified density and elemental composition. The REDcal images were calculated using three models: Lung-Bone model, Lung-Ti model and Lung-Ti (SEMAR) model which used single-energy metal artifact reduction (SEMAR). The difference between REDraw and REDcal was calculated.

Results

In the titanium rod core, the deviations of REDraw and REDcal (Lung-Bone model, Lung-Ti model and Lung-Ti model with SEMAR) from REDref were 0.45%, 50.8%, 15.4% and 15.0%, respectively. The largest differences between REDraw and REDcal (Lung-Bone model, Lung-Ti model and Lung-Ti model with SEMAR) in the contrast medium phantom were 8.2%, −23.7%, and 28.7%, respectively. However, the differences between REDraw and REDcal values were within 10% at 20mg/ml. The standard deviation of the REDraw was significantly smaller than the REDcal with three models in the titanium and the materials that had low CT numbers.

Conclusion

The REDcal values could be affected by beam hardening artifacts and the REDcal was less accurate than REDraw for high-Z materials as titanium.

Advances in knowledge

The raw-data-based reconstruction method could reduce the beam hardening artifact compared with image-based reconstruction and increase the accuracy for the RED estimation in high-Z materials, such as titanium and iodinated contrast medium.

Get Citation

Keywords

Dual-energy CT; Relative electron density; CT number; Contrast material; Beam hardening

About this article
Title

Evaluation of raw-data-based and calculated electron density for contrast media with a dual-energy CT technique

Journal

Reports of Practical Oncology and Radiotherapy

Issue

Vol 24, No 5 (2019)

Pages

499-506

Published online

2019-09-01

DOI

10.1016/j.rpor.2019.07.013

Bibliographic record

Rep Pract Oncol Radiother 2019;24(5):499-506.

Keywords

Dual-energy CT
Relative electron density
CT number
Contrast material
Beam hardening

Authors

Daisuke Kawahara
Shuichi Ozawa
Kazushi Yokomachi
Toru Higaki
Takehiro Shiinoki
Yoshimi Ohno
Yuji Murakami
Kazuo Awai
Yasushi Nagata

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