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Precision of the measurement of CT numbers: comparison of dual-energy CT spectral imaging with fast kVp switching and conventional CT with phantoms

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Abstract

Purpose

To compare dual-energy computed tomography (CT) spectral imaging and conventional CT imaging in terms of precision of the measurement of CT numbers in phantoms.

Materials and methods

A circular phantom (CP) and an elliptical phantom (EP) were used. Capsules filled with iodine contrast media solutions at various concentration levels were placed in the phantoms. Conventional CT was performed at a tube voltage of 120 kVp. Simulated monochromatic images at 65 keV were obtained by dual-energy CT spectral imaging. The CT number of each iodine capsule was measured. A linear regression model was used to evaluate linearity, while analysis of covariance was used to investigate the degree of variability according to phantom shape for each imaging method.

Results

With conventional imaging, the slopes of the regression lines for CT numbers measured at the EP center and EP periphery were significantly lower than those measured for CP (P < 0.0001 for both EP center vs. CP and for EP periphery vs. CP). No significant difference in slope was found among phantom shapes in dual-energy spectral CT imaging.

Conclusion

Computed tomography numbers varied considerably depending on the phantom shape in conventional CT, whereas dual-energy CT provided consistent CT numbers regardless of the phantom shape.

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Acknowledgments

We gratefully acknowledge Kosuke Sasaki, M.S., and Koji Segawa, R.T., for their technical support and assistance in data acquisition.

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Authors and Affiliations

  1. Department of Radiology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan

    Izuru Matsuda, Masaaki Akahane, Jiro Sato, Masaki Katsura, Akira Kunimatsu & Kuni Ohtomo

  2. Department of Radiology, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo, 108-8639, Japan

    Shigeru Kiryu

  3. Department of Integrated Imaging Informatics, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan

    Naoki Yoshioka

  4. Department of Clinical Radiology, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan

    Kenji Ino

Authors
  1. Izuru Matsuda
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  2. Masaaki Akahane
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  3. Jiro Sato
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  4. Masaki Katsura
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  7. Akira Kunimatsu
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  8. Kenji Ino
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  9. Kuni Ohtomo
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Corresponding author

Correspondence to Izuru Matsuda.

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Matsuda, I., Akahane, M., Sato, J. et al. Precision of the measurement of CT numbers: comparison of dual-energy CT spectral imaging with fast kVp switching and conventional CT with phantoms. Jpn J Radiol 30, 34–39 (2012). https://doi.org/10.1007/s11604-011-0004-0

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  • DOI: https://doi.org/10.1007/s11604-011-0004-0

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