Zellner Michael, Tschauner Sebastian, Weyland Mathias S, Hotz Peter Eggenberger, Scheidegger Stephan, Kellenberger Christian J
University Children's Hospital Zürich, Department of Diagnostic Imaging, Zurich, Switzerland.
University Children's Hospital Zürich, Children's Research Centre, Zurich, Switzerland.
Eur J Radiol Open. 2024 Nov 24;13:100614. doi: 10.1016/j.ejro.2024.100614. eCollection 2024 Dec.
BACKGROUND/PURPOSE: To investigate a quantitative method for assessing image quality of low dose lung computed tomography (CT) and find the lowest exposure dose providing diagnostic images.
Axial volumetric lung CT acquisitions (256 slice scanner) were performed on three different sized anthropomorphic phantoms at different dose levels. The maximum steepness of sigmoid curves fitted to line density profiles was measured at lung-to-pleura interfaces. For each phantom, image sharpness was calculated as the median of 468 measurements from 39 different locations. Diagnostic image quality for the adult and paediatric phantom was rated by three radiologists using 4-point Likert scales. The image sharpness cut-off for obtaining adequate image quality was determined from qualitative ratings.
Adequate diagnostic image quality was reached at a median steepness of 713 HU/mm in the adult phantom with a corresponding CTDIvol of 0.14 mGy and an effective dose of 0.13 mSv at a dose level of 100 kVp and 10 mA. In the paediatric phantom diagnostic image quality was reached at a median steepness of 1139 HU/mm with a corresponding CTDIvol of 0.13 mGy and an effective dose of 0.08 mSv at a dose level of 100 kVp and 10 mA.
Determination of image sharpness on line density profiles can be used as quantitative measure for image quality of lung CT. Sufficient-quality lung CT can be achieved at effective radiation doses of 0.13 mSv (adult phantom) and 0.08 mSv (paediatric phantom). These findings suggest that substantial dose reduction is feasible without compromising diagnostic accuracy.
背景/目的：研究一种评估低剂量肺部计算机断层扫描（CT）图像质量的定量方法，并找出能提供诊断图像的最低曝光剂量。
在三种不同尺寸的仿真人体模型上，于不同剂量水平进行轴向容积肺部CT扫描（256层扫描仪）。在肺与胸膜界面处测量拟合线密度剖面的S形曲线的最大斜率。对于每个模型，图像清晰度通过来自39个不同位置的468次测量的中位数来计算。三名放射科医生使用4级李克特量表对成人和儿童模型的诊断图像质量进行评级。根据定性评级确定获得足够图像质量的图像清晰度临界值。
在100 kVp和10 mA的剂量水平下，成人模型中，当最大斜率中位数达到713 HU/mm时可获得足够的诊断图像质量，相应的容积CT剂量指数（CTDIvol）为0.14 mGy，有效剂量为0.13 mSv。在儿童模型中，当最大斜率中位数达到1139 HU/mm时可获得诊断图像质量，相应的CTDIvol为0.13 mGy，有效剂量为0.08 mSv。
根据线密度剖面确定图像清晰度可作为肺部CT图像质量的定量指标。在0.13 mSv（成人模型）和0.08 mSv（儿童模型）的有效辐射剂量下可实现质量足够的肺部CT扫描。这些发现表明，在不影响诊断准确性的情况下大幅降低剂量是可行的。
