Vol 25, No 4 (2020)
Published online: 2020-07-01

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Synthesized effective atomic numbers for commercially available dual-energy CT

Daisuke Kawahara1, Shuichi Ozawa12, Kazushi Yokomachi3, Chikako Fujioka3, Tomoki Kimura1, Kazuo Awai4, Yasushi Nagata12
DOI: 10.1016/j.rpor.2020.02.007
Rep Pract Oncol Radiother 2020;25(4):692-697.

Abstract

Purpose

The objective of this study was to assess synthesized effective atomic number (Zeff) values with a new developed tissue characteristic phantom and contrast material of varying iodine concentrations using single-source fast kilovoltage switching dual-energy CT (DECT) scanner.

Methods

A newly developed multi energy tissue characterisation CT phantom and an acrylic phantom with various iodine concentrations of were scanned using single-source fast kilovoltage switching DECT (GE-DECT) scanner. The difference between the measured and theoretical values of Zeff were evaluated. Additionally, the difference and coefficient of variation (CV) values of the theoretical and measured values were compared with values obtained with the Canon-DECT scanner that was analysed in our previous study.

Results

The average Zeff difference in the Multi-energy phantom was within 4.5%. The average difference of the theoretical and measured Zeff values for the acrylic phantom with variation of iodine concentration was within 3.3%. Compared to the results for the single-source Canon-DECT scanner used in our previous study, the average difference and CV of the theoretical and measured Zeff values obtained with the GE-DECT scanner were markedly smaller.

Conclusions

The accuracy of the synthesized Zeff values with GE-DECT had a good agreement with the theoretical Zeff values for the Multi-Energy phantom. The GE-DECT could reduce the noise and the accuracy of the Zeff values than that with Canon-DECT for the varying iodine concentrations of contrast medium.

Advances in knowledge

The accuracy and precision of the Zeff values of the contrast medium with the GE-DECT could be sufficient with human equivalent materials.

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Reports of Practical Oncology and Radiotherapy