Fluoroscopy Validation of Noninvasive 3D Bone-Pose Tracking via External Pressure-Foils (original) (raw)
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Model-based tracking of the bones of the foot: A biplane fluoroscopy validation study
Computers in biology and medicine, 2018
Measuring foot kinematics using optical motion capture is technically challenging due to the depth of the talus, small bone size, and soft tissue artifact. We present a validation of our biplane X-ray system, demonstrating its accuracy in tracking the foot bones directly. Using an experimental linear/rotary stage we imaged pairs of tali, calcanei, and first metatarsals, with embedded beads, through 30 poses. Model- and bead-based algorithms were employed for semi-automatic tracking. Translational and rotational poses were compared to the experimental stage (a reference standard) to determine registration performance. For each bone, 10 frames per pose were analyzed. Model-based: The resulting overall translational bias of the six bones was 0.058 mm with a precision of ± 0.049 mm. The overall rotational bias of the six bones was 0.42° with a precision of ± 0.41°. Bead-based: the overall translational bias was 0.037 mm with a precision of ± 0.032 mm and for rotation was 0.29° with a pr...
Medical engineering & physics, 2018
Biplane 2D-3D model-based registration and radiostereometric analysis (RSA) approaches have been commonly used for measuring three-dimensional, in vivo joint kinematics. However, in clinical biplane systems, the x-ray images are acquired asynchronously, which introduces registration errors. The present study introduces an interpolation technique to reduce image registration error by generating synchronous fluoroscopy image estimates. A phantom study and cadaveric shoulder study were used to evaluate the level of improvement in image registration that could be obtained as a result of using our interpolation technique. Our phantom study results show that the interpolated bead tracking technique was in better agreement with the true bead positions than when asynchronous images were used alone. The overall RMS error of glenohumeral kinematics for interpolated biplane registration was reduced by 1.27 mm, 0.40 mm, and 0.47 mm in anterior-posterior, superior-inferior, and medial-lateral tr...
Journal of Applied Biomechanics, 2014
Accurate measurements of in-vivo hip kinematics may elucidate the mechanisms responsible for impaired function and chondrolabral damage in hips with femoroacetabular impingement (FAI). The objectives of this study were to quantify the accuracy and demonstrate the feasibility of using dual fluoroscopy to measure in-vivo hip kinematics during clinical exams used in the assessment of FAI. Steel beads were implanted into the pelvis and femur of two cadavers. Specimens were imaged under dual fluoroscopy during the impingement exam, FABER test, and rotational profile. Bead locations measured with model-based tracking were compared with those measured using dynamic radiostereometric analysis. Error was quantified by bias and precision, defined as the average and standard deviation of the differences between tracking methods, respectively. A normal male volunteer was also imaged during clinical exams. Bias and precision along a single axis did not exceed 0.17 and 0.21 mm, respectively. Comparing kinematics, positional error was less than 0.48 mm and rotational error was less than 0.58°. For the volunteer, kinematics were reported as joint angles and bone-bone distance. These results demonstrate that dual fluoroscopy and model-based tracking can accurately measure hip kinematics in living subjects during clinical exams of the hip.
Proceedings Of The Institution Of Mechanical Engineers, Part H: Journal Of Engineering In Medicine, 2012
The aim of this study is to evaluate the performance of a motion capture system and discuss the application potential of the proposed system in in vivo bone-segment deformation measurements. In this study, the effects of the calibration procedure, camera distance and marker size on the accuracy and precision of the motion capture system have been investigated by comparing the captured movement of the markers with reference movement. The results indicated that the system resolution is at least 20 mm in a capture volume of 400 3 300 3 300 mm 3 , which mostly covers the range of motion of the tibia during the stance phase of one gait cycle. Within this volume, the system accuracy and precision decreased following the increase of camera distance along the optical axis of the cameras. With the best configuration, the absolute error and precision for the range of 20 mm displacement were 1.2-1.8 mm and 1.5-2.5 mm, respectively. Small markers (Ø3-8 mm) yielded better accuracy and repeatability than the larger marker (Ø10.5 mm). We conclude that the proposed system is capable of recording minor displacements in a relative large volume.
3D elbow kinematics with monoplanar fluoroscopy: in silico evaluation
EURASIP Journal on Advances in …, 2010
An in-silico assessment of the performance of 3D video-fluoroscopy for the analysis of the kinematics of long bones is proposed. A reliable knowledge of in-vivo joints kinematics in physiological conditions is fundamental in the clinical field. 3D videofluoroscopy theoretically permits a mm/deg level of accuracy in joint motion analysis, but the optimization algorithm for the pose estimation is highly dependent on the geometry of the bone segment analyzed. An automated technique based on distance maps and tangency condition was applied to the elbow bones. The convergence domain was explored to quantify and optimize measurement accuracy in terms of bias and precision. By conditioning the optimization algorithm using simple image features, the estimation error had small dispersion (interquartile range within 0.5 and 0.025 mm/deg for out-of-plane and in-plane pose parameters, resp.), but with occasional bias and outliers. 3D video-fluoroscopy produced promising results for the elbow joint, but further in-vitro validation studies should be carried out.
3D Elbow Kinematics with Monoplanar Fluoroscopy
Eurasip Journal on Advances in Signal Processing, 2010
An in-silico assessment of the performance of 3D video-fluoroscopy for the analysis of the kinematics of long bones is proposed. A reliable knowledge of in-vivo joints kinematics in physiological conditions is fundamental in the clinical field. 3D videofluoroscopy theoretically permits a mm/deg level of accuracy in joint motion analysis, but the optimization algorithm for the pose estimation is highly dependent on the geometry of the bone segment analyzed. An automated technique based on distance maps and tangency condition was applied to the elbow bones. The convergence domain was explored to quantify and optimize measurement accuracy in terms of bias and precision. By conditioning the optimization algorithm using simple image features, the estimation error had small dispersion (interquartile range within 0.5 and 0.025 mm/deg for out-of-plane and in-plane pose parameters, resp.), but with occasional bias and outliers. 3D video-fluoroscopy produced promising results for the elbow joint, but further in-vitro validation studies should be carried out.
Journal of Biomechanics, 2012
While measuring knee motion in all six degrees of freedom is important for understanding and treating orthopaedic knee pathologies, traditional motion capture techniques lack the required accuracy. A variety of model-based biplane fluoroscopy techniques have been developed with sub-millimeter accuracy. However, no studies have statistically evaluated the consistency of the accuracy across motions of varying intensity or between degrees of freedom. Therefore, this study evaluated the bias and precision of a contour-based tracking technique by comparing it to a marker-based method (gold standard) during three movements with increasing intensity. Six cadaveric knees with implanted tantalum markers were used to simulate knee extension, walking and drop landings, while motion was recorded by a custom biplane fluoroscopy system. The 3D geometries of the bones were reconstructed from CT scans and anatomical coordinate systems were assigned. The position and orientation of the bone and marker models were determined for an average of 27 frames for each trial and knee joint kinematics were compared. The average bias and precision was 0.0170.651 for rotations and 0.0170.59 mm for joint translations. Rotational precision was affected by motion (p¼ 0.04) and depended on the axis of rotation (p¼0.02). However, the difference in average precision among motions or axes was small (r0.131) and not likely of consequence for kinematic measurements. No other differences were found. The contour-based technique demonstrated sub-millimeter and sub-degree accuracy, indicating it is a highly accurate tool for measuring complex three dimensional knee movements of any intensity.
3D video-based deformation measurement of the pelvis bone under dynamic cyclic loading
Biomedical Engineering Online, 2011
Background Dynamic three-dimensional (3D) deformation of the pelvic bones is a crucial factor in the successful design and longevity of complex orthopaedic oncological implants. The current solutions are often not very promising for the patient; thus it would be interesting to measure the dynamic 3D-deformation of the whole pelvic bone in order to get a more realistic dataset for a better implant design. Therefore we hypothesis if it would be possible to combine a material testing machine with a 3D video motion capturing system, used in clinical gait analysis, to measure the sub millimetre deformation of a whole pelvis specimen. Method A pelvis specimen was placed in a standing position on a material testing machine. Passive reflective markers, traceable by the 3D video motion capturing system, were fixed to the bony surface of the pelvis specimen. While applying a dynamic sinusoidal load the 3D-movement of the markers was recorded by the cameras and afterwards the 3D-deformation of the pelvis specimen was computed. The accuracy of the 3D-movement of the markers was verified with 3D-displacement curve with a step function using a manual driven 3D micro-motion-stage. Results The resulting accuracy of the measurement system depended on the number of cameras tracking a marker. The noise level for a marker seen by two cameras was during the stationary phase of the calibration procedure ± 0.036 mm, and ± 0.022 mm if tracked by 6 cameras. The detectable 3D-movement performed by the 3D-micro-motion-stage was smaller than the noise level of the 3D-video motion capturing system. Therefore the limiting factor of the setup was the noise level, which resulted in a measurement accuracy for the dynamic test setup of ± 0.036 mm. Conclusion This 3D test setup opens new possibilities in dynamic testing of wide range materials, like anatomical specimens, biomaterials, and its combinations. The resulting 3D-deformation dataset can be used for a better estimation of material characteristics of the underlying structures. This is an important factor in a reliable biomechanical modelling and simulation as well as in a successful design of complex implants.
Medical Engineering & Physics, 2013
Measurement of accurate in vivo hip joint kinematics in 6-DOF is difficult. Few studies have reported non-invasive measurements of the hip kinematics. The objective of this study was to validate a noninvasive dual fluoroscopic imaging system (DFIS) for measurement of hip kinematics. Bi-lateral hip joints of a cadaveric pelvic specimen were CT scanned to create bone models of the femur and pelvis, and subsequently tested in static and dynamic conditions inside the DFIS. The poses of the hip in space were then determined by matching the bone models with the fluoroscopic images. The pose data was compared to those obtained using a radio-stereometric analysis to determine the accuracy of the DFIS. The accuracy ± precision for measuring the hip kinematics were less than 0.93 ± 1.13 mm for translations and 0.59 ± 0.82 • for rotations in all conditions. The repeatability of the DFIS technique was less than ±0.77 mm and ±0.64 • in position and orientation for measuring hip kinematics in both static and dynamic positions. This technique could thus be a promising tool for determining 6-DOF poses of the hip during functional activities, which may help to understand biomechanical factors in hip pathologic conditions such as osteoarthritis and femoroacetabular impingement before and after surgical treatment.