Ju Yun Hye, Lee Geewon, Lee Ji Won, Hong Seung Baek, Suh Young Ju, Jeong Yeon Joo
1 Biomedical Engineering, 65448 Yonsei University , Wonju, Republic of Korea.
2 Department of Radiology, 220312 Pusan National University Hospital , Busan, Republic of Korea.
Acta Radiol. 2018 May;59(5):553-559. doi: 10.1177/0284185117726099. Epub 2017 Aug 8.
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 < 0.001). Overall image quality was best in group 1, but diagnostic acceptability of overall image qualities in groups 1-3 was not significantly different (all 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.
背景 降低辐射剂量不可避免地会增加图像噪声，因此，在低剂量计算机断层扫描（CT）中保持图像质量和病灶检测性能非常重要。目的 评估基于模型的迭代重建（MBIR）的超低剂量CT的图像质量和病灶可见性，并确定适合肺部筛查CT的方案。材料与方法 共有120名重度吸烟者接受了肺部筛查CT，并被随机且平均分为五组：第1组 = 120 kVp，25 mAs，采用滤波反投影（FBP）重建；第2组 = 120 kVp，10 mAs，采用MBIR；第3组 = 100 kVp，15 mAs，采用MBIR；第4组 = 100 kVp，10 mAs，采用MBIR；第5组 = 100 kVp，5 mAs，采用MBIR。两名放射科医生使用Kruskal-Wallis检验和卡方检验评估了各组在辐射剂量、图像噪声、图像质量和病灶可见性方面的差异。结果 第2 - 5组的有效剂量比第1组低61 - 87%。第1组和第5组的图像噪声明显高于其他组（P < 0.001）。总体图像质量在第1组最佳，但第1 - 3组总体图像质量的诊断可接受性无显著差异（所有P值 > 0.05）。第1 - 4组的病灶可见性相似，但第5组明显较差。结论 采用100 kVp和15 mAs的MBIR进行肺部筛查CT，与低剂量CT相比，可使辐射剂量降低约60%，同时保持图像质量和病灶可见性。
