Oral Imaging Center, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium.
J Appl Clin Med Phys. 2011 Nov 15;12(4):3478. doi: 10.1120/jacmp.v12i4.3478.
Cone-beam CT (CBCT) has shown to be a useful imaging modality for various dentomaxillofacial applications. However, optimization and quality control of dental CBCT devices is hampered due to the lack of an appropriate tool for image quality assessment. To investigate the application of different image quality parameters for CBCT, a prototype polymethyl methacrylate (PMMA) cylindrical phantom with inserts for image quality analysis was developed. Applicability and reproducibility of the phantom were assessed using seven CBCT devices with different scanning protocols. Image quality parameters evaluated were: CT number correlation, contrast resolution, image homogeneity and uniformity, point spread function, and metal artifacts. Deviations of repeated measurements were between 0.0% and 3.3%. Correlation coefficients of CBCT voxel values with CT numbers ranged between 0.68 and 1.00. Contrast-to-noise ratio (CNR) values were much lower for hydroxyapatite (0 < CNR < 7.7) than for air and aluminum (5.0 < CNR < 32.8). Noise values ranged between 35 and 419. The uniformity index was between 3.3% and 11.9%. Full width at half maximum (FWHM) measurements varied between 0.43 mm and 1.07 mm. The increase of mean voxel values surrounding metal objects ranged between 6.7% and 43.0%. Results from preliminary analyses of the prototype quality control phantom showed its potential for routine quality assurance on CBCT. Large differences in image quality performance were seen between CBCT devices. Based on the initial evaluations, the phantom can be optimized and validated.
锥形束 CT（CBCT）已被证明是一种用于各种口腔颌面应用的有用成像方式。然而，由于缺乏用于图像质量评估的适当工具，牙科 CBCT 设备的优化和质量控制受到阻碍。为了研究不同图像质量参数在 CBCT 中的应用，开发了一种带有用于图像质量分析插件的原型聚甲基丙烯酸甲酯（PMMA）圆柱形体模。使用具有不同扫描协议的七种 CBCT 设备评估了体模的适用性和可重复性。评估的图像质量参数包括：CT 值相关性、对比度分辨率、图像均匀性和一致性、点扩散函数和金属伪影。重复测量的偏差在 0.0%到 3.3%之间。CBCT 体素值与 CT 值的相关系数在 0.68 到 1.00 之间。羟磷灰石的对比噪声比（CNR）值要低得多（0 < CNR < 7.7），而空气和铝的 CNR 值要高得多（5.0 < CNR < 32.8）。噪声值在 35 到 419 之间。均匀性指数在 3.3%到 11.9%之间。半最大值全宽（FWHM）测量值在 0.43 毫米到 1.07 毫米之间。金属物体周围平均体素值的增加幅度在 6.7%到 43.0%之间。原型质量控制体模初步分析结果表明，它具有在 CBCT 上进行常规质量保证的潜力。不同的 CBCT 设备之间的图像质量性能存在很大差异。基于初始评估，体模可以进行优化和验证。
