Objective The aim of this study was to validate the efficacy of computed tomography (CT) iterative reconstruction (CT-IR) for low-dose CT attenuation correction in terms of the estimation of attenuation coefficient and quality of PET images. Materials and methods We used normal and obesity-simulating body phantoms. PET images were reconstructed using two attenuation correction maps obtained using filtered back projection (CT-FBP) and CT-IR. The CT numbers, attenuation coefficients, contrast-to-noise ratio (CNR 10 mm), and coefficient of variation were evaluated. Fifty-two consecutive patients who underwent 18 F-FDG PET/CT with low-dose CT scans were selected for the clinical study. Clinical PET images were reconstructed using CT-FBP and CT-IR, and the effects of CT-IR were examined according to the maximum standardized uptake value (SUV max), contrast-to-noise ratio in the tumor (CNR tumor), and signal-to-noise ratio in the liver (SNR liver). Results The CT number on the CT-IR was significantly lower than that of CT-FBP in the obesity-simulating body phantom. The decrease in attenuation coefficients obtained using CT-IR was smaller than that obtained using CT-FBP. The CNR 10 mm and coefficient of variation obtained using CT-IR were superior to those obtained using CT-FBP. The SUV max was not significantly different between the CT-FBP and CT-IR. Although the difference in the SNR liver between the CT-FBP and CT-IR was not significant, the CNR tumor of the CT-IR was significantly higher than that obtained using CT-FBP in obese patients. Conclusion We demonstrated that CT-IR improved the estimation of the attenuation coefficient and provided significant improvement in the CNR of the clinical PET images.
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