Ultra-low-dose lung screening CT with model-based iterative reconstruction: an assessment of image quality and lesion conspicuity

摘要

Background Reducing radiation dose inevitably increases image noise, and thus, it is important in low-dose computed tomography (CT) to maintain image quality and lesion detection performance. Purpose To assess image quality and lesion conspicuity of ultra-low-dose CT with model-based iterative reconstruction (MBIR) and to determine a suitable protocol for lung screening CT. Material and Methods A total of 120 heavy smokers underwent lung screening CT and were randomly and equally assigned to one of five groups: group 1?=?120?kVp, 25?mAs, with FBP reconstruction; group 2?=?120?kVp, 10?mAs, with MBIR; group 3?=?100?kVp, 15?mAs, with MBIR; group 4?=?100?kVp, 10?mAs, with MBIR; and group 5?=?100?kVp, 5?mAs, with MBIR. Two radiologists evaluated intergroup differences with respect to radiation dose, image noise, image quality, and lesion conspicuity using the Kruskal–Wallis test and the Chi-square test. Results Effective doses were 61–87% lower in groups 2–5 than in group 1. Image noises in groups 1 and 5 were significantly higher than in the other groups ( P ? P values?>?0.05). Lesion conspicuities were similar in groups 1–4, but were significantly poorer in group 5. Conclusion Lung screening CT with MBIR obtained at 100?kVp and 15?mAs enables a ～60% reduction in radiation dose versus low-dose CT, while maintaining image quality and lesion conspicuity.