Department of Veterans Affairs, RR&D Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, Seattle, WA, United States; Department of Mechanical Engineering, University of Washington, Seattle, WA, United States.
Department of Veterans Affairs, RR&D Center of Excellence for Limb Loss Prevention and Prosthetic Engineering, VA Puget Sound Health Care System, Seattle, WA, United States.
Med Eng Phys. 2014 Mar;36(3):391-6. doi: 10.1016/j.medengphy.2013.08.013. Epub 2013 Sep 24.
Radiostereometric analysis has demonstrated its capacity to track precise motion of the bones within a subject during motion. Existing devices for imaging the body in two planes are often custom built systems; we present here the design and marker-based validation of a system that has been optimized to image the foot during gait.
Mechanical modifications were made to paired BV Pulsera C-arms (Philips Medical Systems) to allow unfettered gait through the imaging area. Image quality improvements were obtained with high speed cameras and the correction of image distorting artifacts. To assess the system's accuracy, we placed beads at known locations throughout the imaging field, and used post processing software to calculate their apparent locations.
Distortion correction reduced overall RMS error from 6.56 mm to 0.17 mm. When tracking beads in static images a translational accuracy of 0.094 ± 0.081 mm and rotational accuracy of 0.083 ± 0.068° was determined. In dynamic trials simulating speeds seen during walking, accuracy was 0.126 ± 0.122 mm.
The accuracies and precisions found are within the reported ranges from other such systems. With the completion of marker-based validation, we look to model-based validation of the foot during gait.
放射立体测量分析已经证明了其在运动过程中追踪受检者体内骨骼精确运动的能力。现有的用于在两个平面上成像身体的设备通常是定制的系统；我们在此介绍一种经过优化，可在步态期间对足部进行成像的系统的设计和基于标记的验证。
对配对的 BV Pulsera C 臂（飞利浦医疗系统）进行机械修改，以允许不受阻碍地在成像区域内行走。通过高速摄像机和纠正图像失真伪影来提高图像质量。为了评估系统的准确性，我们在成像区域内的已知位置放置了珠子，并使用后处理软件计算它们的表观位置。
失真校正将总体 RMS 误差从 6.56 毫米降低到 0.17 毫米。在跟踪静态图像中的珠子时，确定了 0.094 ± 0.081 毫米的平移精度和 0.083 ± 0.068°的旋转精度。在模拟步行时所见速度的动态试验中，精度为 0.126 ± 0.122 毫米。
所发现的精度和精密度在其他类似系统的报告范围内。随着基于标记的验证的完成，我们期待在步态期间对足部进行基于模型的验证。
