University of Michigan Transportation Research Institute, Ann Arbor, MI, USA.
Ann Biomed Eng. 2011 Dec;39(12):2984-97. doi: 10.1007/s10439-011-0409-z. Epub 2011 Sep 24.
In this study, a statistical model of cranium geometry for 0- to 3-month-old children was developed by analyzing 11 CT scans using a combination of principal component analysis and multivariate regression analysis. Radial basis function was used to morph the geometry of a baseline child head finite element (FE) model into models with geometries representing a newborn, a 1.5-month-old, and a 3-month-old infant head. These three FE models were used in a parametric study of near-vertex impact conditions to quantify the sensitivity of different material parameters. Finally, model validation was conducted against peak head accelerations in cadaver tests under different impact conditions, and optimization techniques were used to determine the material properties. The results showed that the statistical model of cranium geometry produced realistic cranium size and shape, suture size, and skull/suture thickness, for 0- to 3-month-old children. The three pediatric head models generated by morphing had mesh quality comparable to the baseline model. The elastic modulus of skull had a greater effect on most head impact response measurements than other parameters. Head geometry was a significant factor affecting the maximal principal stress of the skull (p = 0.002) and maximal principal strain of the suture (p = 0.021) after controlling for the skull material. Compared with the newborn head, the 3-month-old head model produced 6.5% higher peak head acceleration, 64.8% higher maximal principal stress, and 66.3% higher strain in the suture. However, in the skull, the 3-month-old model produced 25.7% lower maximal principal stress and 11.5% lower strain than the newborn head. Material properties of the brain had little effects on head acceleration and strain/stress within the skull and suture. Elastic moduli of the skull, suture, dura, and scalp determined using optimization techniques were within reported literature ranges and produced impact response that closely matched those measured in previous cadaver tests. The method developed in this study made it possible to investigate the age effects from geometry changes on pediatric head impact responses. The parametric study demonstrated that it is important to consider the material properties and geometric variations together when estimating pediatric head responses and predicting head injury risks.
在这项研究中，通过对 11 例 CT 扫描进行主成分分析和多元回归分析，建立了 0-3 月龄儿童颅腔几何形态的统计模型。使用径向基函数将基线儿童头颅有限元模型的几何形状变形为代表新生儿、1.5 月龄和 3 月龄婴儿头颅的模型。在近顶点撞击条件的参数研究中，使用这三个有限元模型来量化不同材料参数的敏感性。最后，根据不同撞击条件下尸体测试中的峰值头部加速度对模型进行验证，并使用优化技术确定材料特性。结果表明，该颅腔几何形态统计模型生成的 0-3 月龄儿童颅腔尺寸和形状、缝尺寸和颅骨/缝厚度具有真实感。通过变形生成的三个儿科头颅模型具有与基线模型相当的网格质量。颅骨弹性模量对大多数头部撞击响应测量值的影响大于其他参数。在控制颅骨材料后，头部几何形状是影响颅骨最大主应力（p=0.002）和缝最大主应变（p=0.021）的重要因素。与新生儿头相比，3 月龄头模型产生的峰值头部加速度高 6.5%，缝的最大主应力高 64.8%，应变高 66.3%。然而，在颅骨中，3 月龄模型产生的最大主应力比新生儿头模型低 25.7%，应变低 11.5%。大脑的材料特性对颅骨和缝内的头部加速度和应变/应力影响不大。使用优化技术确定的颅骨、缝、硬脑膜和头皮的弹性模量在报告的文献范围内，产生的撞击响应与以前的尸体测试测量值非常吻合。本研究中开发的方法使得研究儿童头部撞击响应中几何形状变化的年龄效应成为可能。参数研究表明，在估计儿科头部响应和预测头部受伤风险时，同时考虑材料特性和几何变化非常重要。
