Abstract
Objectives
To compare the image quality and radiation dose of a deep learning image reconstruction (DLIR) algorithm compared with iterative reconstruction (IR) and filtered back projection (FBP) at different tube voltages and tube currents.
Materials and methods
A customized body phantom was scanned at different tube voltages (120, 100, and 80 kVp) with different tube currents (200, 100, and 60 mA). The CT datasets were reconstructed with FBP, hybrid IR (30% and 50%), and DLIR (low, medium, and high levels). The reference image was set as an image taken with FBP at 120 kVp/200 mA. The image noise, contrast-to-noise ratio (CNR), sharpness, artifacts, and overall image quality were assessed in each scan both qualitatively and quantitatively. The radiation dose was also evaluated with the volume CT dose index (CTDIvol) for each dose scan.
Results
In qualitative and quantitative analyses, compared with reference images, low-dose CT with DLIR significantly reduced the noise and artifacts and improved the overall image quality, even with decreased sharpness (p < 0.05). Despite the reduction of image sharpness, low-dose CT with DLIR could maintain the image quality comparable to routine-dose CT with FBP, especially when using the medium strength level.
Conclusion
The new DLIR algorithm reduced noise and artifacts and improved overall image quality, compared to FBP and hybrid IR. Despite reduced image sharpness in CT images of DLIR algorithms, low-dose CT with DLIR seems to have an overall greater potential for dose optimization.
Key Points
• Using deep learning image reconstruction (DLIR) algorithms, image quality was maintained even with a radiation dose reduced by approximately 70%.
• DLIR algorithms yielded lower image noise, higher contrast-to-noise ratios, and higher overall image quality than FBP and hybrid IR, both subjectively and objectively.
• DLIR algorithms can provide a better image quality, much better than FBP and even better than hybrid IR, while facilitating a reduction in radiation dose.
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Abbreviations
- ASIR:
-
Adaptive statistical iterative reconstruction
- CNR:
-
Contrast-to-noise ratio
- DCNN:
-
Deep convolutional neural network
- DLIR:
-
Deep learning image reconstruction
- FBP:
-
Filtered back projection
- HU:
-
Hounsfield unit
- IR:
-
Iiterative reconstruction
- mGy:
-
Milligrays
- ROI:
-
Regions of interest
- SSIM:
-
Structural similarity
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Acknowledgements
This work was supported by the Soonchunhyang University Research Fund. The authors thank Kyoung-A Um for their technical support.
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This work was supported by the Soonchunhyang University Research Fund.
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The scientific guarantor of this publication is Seo-Youn Choi, M.D. PhD..
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One of the authors (Yunsub Jung) is an employee of GE Healthcare. The remaining authors declare no relationships with any companies whose products or services may be related to the subject matter of the article.
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One of the authors is a statistician (Bora Lee, PhD, of medical statistics with 15 years of experience and majored in statistics) kindly provided statistical advice for this manuscript.
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This study was performed with a phantom not human patients or animal; institutional review board (IRB) approval was not required and informed consent was not needed as well.
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This study was performed with a phantom not human patients or animal; institutional review board (IRB) approval was not required and informed consent was not needed as well.
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Supplementary file1 Note.—FBP = filtered back projection, ASIR-V = adaptive statistical iterative reconstruction V, DLIR-L = low-level deep learning imaging reconstruction, DLIR-M = medium-level deep learning image reconstruction, DLIR-H = high-level deep learning imaging reconstruction, CNR = contrast-to-noise ratio, SSIM = structural similarity.(DOCX 24 KB)
*Blur metrics is the index representing image sharpness. †SSIM is the index indicating overall image quality.
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Park, H.J., Choi, SY., Lee, J.E. et al. Deep learning image reconstruction algorithm for abdominal multidetector CT at different tube voltages: assessment of image quality and radiation dose in a phantom study. Eur Radiol 32, 3974–3984 (2022). https://doi.org/10.1007/s00330-021-08459-8
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DOI: https://doi.org/10.1007/s00330-021-08459-8