The Effect of Dose Reduction on Overall Image Quality in Clinical Chest Tomosynthesis

Maral Mirzai; Carin Meltzer; Jenny Vikgren; Rauni Rossi Norrlund; Bengt Gottfridsson; Åse Johnsson; Magnus Båth; Angelica Svalkvist

doi:10.1016/j.acra.2020.05.041

The Effect of Dose Reduction on Overall Image Quality in Clinical Chest Tomosynthesis

Acad Radiol. 2021 Oct;28(10):e289-e296. doi: 10.1016/j.acra.2020.05.041. Epub 2020 Jul 22.

Authors

Maral Mirzai¹, Carin Meltzer², Jenny Vikgren³, Rauni Rossi Norrlund³, Bengt Gottfridsson⁴, Åse Johnsson³, Magnus Båth⁵, Angelica Svalkvist⁵

Affiliations

¹ Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-41345 Gothenburg, Sweden; Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-41345 Gothenburg, Sweden. Electronic address: maral.mirzai.beni@vgregion.se.
² Department of Radiology and Nuclear Medicine at Oslo University Hospital, Ullevål, Norway; Department of Radiology, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.
³ Department of Radiology, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden; Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
⁴ Department of Radiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
⁵ Department of Radiation Physics, Institute of Clinical Sciences, The Sahlgrenska Academy at University of Gothenburg, SE-41345 Gothenburg, Sweden; Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, SE-41345 Gothenburg, Sweden.

PMID: 32709583
DOI: 10.1016/j.acra.2020.05.041

Abstract

Rationale and objectives: To evaluate the effect of reduction in effective dose on the reproduction of anatomical structures in chest tomosynthesis (CTS).

Materials and methods: Twenty-four CTS examinations acquired at exposure settings resulting in an effective dose of 0.12 mSv for an average sized patient were included in the study. The examinations underwent simulated dose reduction to dose levels corresponding to 32%, 50%, and 70% of the original dose using a previously described and validated method. The image quality was evaluated by five thoracic radiologists who rated the fulfillment of specified image quality criteria in a visual grading study. The ratings for each image quality criterion in the dose-reduced images were compared to the corresponding ratings for the full-dose examinations using visual grading characteristics (VGC) analysis. The area under the resulting VGC curve (AUC_VGC) provides a measure of the difference between the ratings, where an AUC_VGC of 0.5 indicates no difference.

Results: The dose reductions resulted in inferior reproduction of structures compared to the original dose level (AUC_VGC <0.5). Structures in the central region of the lung obtained the lowest AUC_VGC for each dose level whereas the reproduction of structures in the parenchyma was least affected by the dose reduction.

Conclusion: Although previous studies have shown that dose reduction in CTS is possible without affecting the performance of certain clinical tasks, the reproduction of normal anatomical structures is significantly degraded even at small reductions. It is therefore important to consider the clinical purpose of the CTS examinations before deciding on a permanent dose reduction.

Keywords: Computer-assisted; Diagnostic imaging; Image processing; Radiation exposure; Thoracic radiography.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Humans
Radiation Dosage
Radiation Protection
Radiography, Thoracic* / standards