Fortschr Röntgenstr 2019; 191(02): 122-129
DOI: 10.1055/a-0668-6031
Chest
© Georg Thieme Verlag KG Stuttgart · New York

Evaluation of Radiation Dose and Image Quality using High-Pitch 70-kV Chest CT in Immunosuppressed Patients

Article in several languages: English | deutsch
Ibrahim Yel
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Simon S. Martin
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Julian L. Wichmann
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Lukas Lenga
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Moritz H. Albrecht
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Andreas M. Bucher
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Benjamin Kaltenbach
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Christoph Polkowski
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Christian Booz
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Thomas J. Vogl
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
,
Renate Maria Hammerstingl
Department of Diagnostic and Interventional Radiology, University-Hospital Frankfurt, Germany
› Author Affiliations
Further Information

Publication History

25 January 2018

07 July 2018

Publication Date:
04 September 2018 (eFirst)

Abstract

Purpose The aim of the study was to evaluate high-pitch 70-kV CT examinations of the thorax in immunosuppressed patients regarding radiation dose and image quality in comparison with 120-kV acquisition.

Materials and Methods The image data from 40 patients (14 women and 26 men; mean age: 40.9 ± 15.4 years) who received high-pitch 70-kV CT chest examinations were retrospectively included in this study. A control group (n = 40), matched by age, gender, BMI, and clinical inclusion criteria, had undergone standard 120-kV chest CT imaging. All CT scans were performed on a third-generation dual-source CT unit. For an evaluation of the radiation dose, the CT dose index (CTDIvol), dose-length product (DLP), effective dose (ED), and size-specific dose estimates (SSDE) were analyzed in each group. The objective image quality was evaluated using signal-to-noise (SNR) and contrast-to-noise ratios (CNR). Three blinded and independent radiologists evaluated subjective image quality and diagnostic confidence using 5-point Likert scales.

Results The mean dose parameters were significantly lower for high-pitch 70-kV CT examinations (CTDIvol, 2.9 ± 0.9 mGy; DLP, 99.9 ± 31.0 mGyxcm; ED, 1.5 ± 0.6 mSv; SSDE, 3.8 ± 1.2 mGy) compared to standard 120-kV CT imaging (CTDIvol, 8.8 ± 3.7mGy; DLP, 296.6 ± 119.3 mGyxcm; ED, 4.4 ± 2.1 mSv; SSDE, 11.6 ± 4.4 mGy) (P≤ 0.001). The objective image parameters (SNR: 7.8 ± 2.1 vs. 8.4 ± 1.8; CNR: 7.7 ± 2.4 vs. 8.3 ± 2.8) (P≥ 0.065) and the cumulative subjective image quality (4.5 ± 0.4 vs. 4.7 ± 0.3) (p = 0.052) showed no significant differences between the two protocols.

Conclusion High-pitch 70-kV thoracic CT examinations in immunosuppressed patients resulted in a significantly reduced radiation exposure compared to standard 120-kV CT acquisition without a decrease in image quality.

Key Points:

  • Third-generation dual-source CT units enable high-pitch 70-kV CT examinations of the chest.

  • High-pitch 70-kV CT examinations show a significantly reduced radiation dose compared to standard 120-kV CT examinations.

  • High-pitch 70-kV CT examinations of the chest show comparable objective and subjective image quality.

  • Subjectively deteriorated image noise and sharpness of 70-kV CT did not impact diagnostic confidence.

Citation Format

  • Yel I, Martin SS, Wichmann JL et al. Evaluation of Radiation Dose and Image Quality using High-Pitch 70-kV Chest CT in Immunosuppressed Patients . Fortschr Röntgenstr 2019; 191: 122 – 129