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Evaluation of the Image Quality in PET/CT Scan Associated with Low-Dose FDG Protocols and CT Image Parameters |
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PP: 211-216 |
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doi:10.18576/jrna/110303
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Author(s) |
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Mahmoud Gaber,
Khaled. M. El-Shahat,
Yasser Y. Ebaid,
Yasser M. Abdel Koway,
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Abstract |
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| Purpose: To evaluate image quality and radiation-dose trade-offs in low-dose 18F-FDG PET/CT and to convert a clinical quality-assurance dataset into a submission-ready quantitative framework with transparent reviewer safeguards. Methods: Fifty oncologic PET/CT examinations were analyzed from a structured workbook containing FDG activity, CT acquisition parameters, CTDIvol, DLP, effective dose, PET signal-to-noise ratio (SNR), PET contrast-to-noise ratio (CNR), CT noise, CT CNR, reader confidence, and clinical follow-up recommendation. Standard CT and low-dose CT protocols were compared using Welch tests and correlation analysis. A primary diagnostic ROC analysis was prespecified but considered non-estimable because all examinations were recorded as diagnostically useful. Therefore, an exploratory, explicitly confounded triage ROC was constructed using follow-up-required status. A NEMA IEC phantom and reconstruction-parameter extension was developed for future prospective validation. Results: Low-dose CT reduced CTDIvol from 8.5 to 2.1 mGy and DLP from 425 to 105 mGy.cm. Mean effective dose decreased from 9.54 +/- 1.45 to 3.74 +/- 0.10 mSv. Low-dose CT increased CT noise and reduced PET SNR/CNR, although all cases retained diagnostic utility. Primary ROC was not estimable; the surrogate triage ROC was perfectly separated but fully confounded by protocol assignment. Conclusion: The dataset supports protocol-level dose reduction but not independent diagnostic-accuracy claims. A reviewer-safe submission should frame ROC and SUV analyses as planned/phantom-supported extensions unless true ROI SUV data are acquired. |
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