| Summary: | 博士 === 國立臺灣大學 === 醫學工程學研究所 === 106 === Soft tissue artefacts (STA) have been recognized as a major source of error as applying stereophotogrammetry for human movement analysis. It not only affects the measurement of cycling motion but also limits interpretation of the results from the stereophotogrammetry-based measurement system. Currently, study of STA absent detailed, substantial results which provide guidelines for properly interpret results of cycling. 2D-3D subject-specific model-based registration method combined with biplane fluoroscopy is considered as a non-invasive accurate measurement method. However, the technique design for alternating exposures used in clinical system is not been proposed yet. Therefore, the study aims to develop 2D-3D registration methods for alternating biplane fluoroscopy and used to quantify soft tissue artefacts in the lower limb and their effects on mechanical analysis of the knee during pedalling.
A tri-alternating images registration method is proposed combined with three kinematic models (constant speed, rigid and quasi-rigid) which help to predict bone pose of the adjacent frame under sole biplane fluoroscopy or combined with assistant measurement system conditions. The methods were verified by a cadaver study. Compare to single plane and pseudo biplane registration results, fast correction algorithm based on constant speed model already decreased 89% of out-of-plane errors and the target registration error eventually less than 0.7 mm. Performance of three models were comparable to the synchronized biplane registration. The rigid kinematic model was adopted for subsequence in vivo STA quantification during pedalling.
Compare to the shank markers, the thigh markers showed greater STA and were affected more by pedal resistance. The STA varied with angles of the adjacent joints, largely linearly for shank markers while non-linearly for thigh markers. Markers near a joint experienced greater ranges of STA than mid-segment markers, but tended to have smaller variation. To estimate bone pose, STA produce greater rigid translations and rotations than the nonrigid component. Range of norigid component may not able to represent accuracy of the marker cluster used to estimate bone pose. On mechanical analysis, calculated joint angles were not affected by different resistant condition. Hybrid two marker clusters to estimate bone orientation and position separately help to reduce error of calculated joint angles and moments.
The method developed in the study help to apply clinical sytem for measuring accurate bone kinematics. Results of STA during pedalling help other cycling study and the experiment data will be useful for the further studies.
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