A multi-institutional assessment of low-dose protocols in chest computed tomography: Dose and image quality

Elena Tonkopi; Mercy Afadzi Tetteh; Catherine Gunn; Haseem Ashraf; Sigrid Lia Rusten; Perkhah Safi; Nora Suu Tinsoe; Kylie Colford; Olivia Ouellet; Salma Naimi; Safora Johansen

doi:10.1177/20584601241228220

A multi-institutional assessment of low-dose protocols in chest computed tomography: Dose and image quality

Acta Radiol Open. 2024 Jan 30;13(1):20584601241228220. doi: 10.1177/20584601241228220. eCollection 2024 Jan.

Authors

Elena Tonkopi^{1

2

3}, Mercy Afadzi Tetteh⁴, Catherine Gunn^{2

5}, Haseem Ashraf^{4

6}, Sigrid Lia Rusten⁷, Perkhah Safi⁷, Nora Suu Tinsoe⁷, Kylie Colford⁵, Olivia Ouellet⁵, Salma Naimi⁴, Safora Johansen^{7

8

9}

Affiliations

¹ Department of Diagnostic Radiology, Dalhousie University, Halifax, NS, Canada.
² Department of Radiation Oncology, Dalhousie University, Halifax, NS, Canada.
³ Department of Diagnostic Imaging, Nova Scotia Health Authority, Halifax, NS, Canada.
⁴ Department of Diagnostic Imaging, Akershus University Hospital, Loerenskog, Norway.
⁵ School of Health Sciences, Dalhousie University, Halifax, NS, Canada.
⁶ Medicine Faculty, University of Oslo, Oslo Norway.
⁷ Health Faculty, Department of Life Sciences and Health, Oslo Metropolitan University Oslo, Norway.
⁸ Department of Cancer Treatment, Oslo University Hospital, Oslo, Norway.
⁹ Health and Social Science Cluster, Singapore Institute of Technology, Singapore.

Abstract

Background: Low-dose CT (LDCT) chest protocols have widespread clinical applications for many indications; as a result, there is a need for protocol assessment prior to standardization. Dalhousie University and Oslo Metropolitan University have a formally established cooperative relationship.

Purpose: The purpose is to assess radiation dose and image quality for LDCT chest protocols in seven different hospital locations in Norway and Canada.

Material and methods: Retrospective dosimetry data, volumetric CT dose index (CTDI_vol), and dose length product (DLP) from 240 average-sized patients as well as CT protocol parameters were included in the survey. Effective dose (ED) and size-specific dose estimate (SSDE) were calculated for each examination. For a quantitative image quality analysis, noise, CT number, and signal-to-noise ratio (SNR) were determined for three regions in the chest. The contrast-to-noise ratio (CNR) was calculated for lung parenchyma in comparison to the subcutaneous fat. Differences in dose and image quality were evaluated by a single-factor ANOVA test. A two-sample t-test was performed to determine differences in means between individual scanners.

Results: The ANOVA test revealed significant differences (p < .05) in dose values for all scanners, including identical scanner models. Statistically significant differences (p < .05) were determined in mean values of the SNR distributions between the scanners in all three measured regions in the chest, as well as the CNR values.

Conclusion: The observed variations in dose and image quality measurements, even within the same hospitals and between identical scanner models, indicate a potential for protocol optimization in the involved hospitals in both countries.

Keywords: image quality; low-dose computed tomography; radiation dose.