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Biomedical subjects

Robert K Dyer

Publications and source records attributed to Robert K Dyer.

2 recordsLinked to original sources

An advanced computer-aided geometric modeling and fabrication method for human middle ear.

This paper presents a practical and systematic method for reconstructing accurate computer and physical models of the entire human middle ear. The proposed method starts with the histological section preparation of human temporal bone. Through tracing outlines of the middle ear components on the sections, a set of discrete points is obtained and employed to construct B-spline curves that represent the exterior contours of the components using a curve-fitting technique. The surface-skinning technique is then employed to quilt the B-spline curves for smooth boundary surfaces of the middle ear components using B-spline surfaces. The solid models of the middle ear components are constructed using these surfaces and then assembled to create the entire middle ear in a computer-aided design environment. This method not only provides an effective way to visualize and measure the three-dimensional structure of the middle ear, but also provides a detailed knowledge of middle ear geometry that is required for finite element analysis or multibody dynamic analysis of the human middle ear. In addition, the geometric model constructed using the proposed method is smooth and can be fabricated in various scales using solid freeform fabrication technology. The physical model of the human middle ear is extremely effective in realizing the middle ear anatomy and enhancing discussion and collaboration among researchers and physicians.

Anatomy, Cross-Sectional↗

Three-dimensional modeling of middle ear biomechanics and its applications.

HYPOTHESIS: This study investigated whether combined technologies of finite element (FE) analysis and three-dimensional reconstruction of human temporal bones could be used to construct a computational model, useful in describing normal and pathologic middle ear sound conduction. BACKGROUND: FE models for biologic systems have been used in ear biomechanics. Three-dimensional reconstructions have also been made, but not in combination with FE modeling and laser interferometry measuring of human temporal bones. Furthermore, an FE model for the human middle ear with its ossicular attachments has not been reported on the basis of temporal bone histologic sections and morphometric reconstruction, to the authors' best knowledge. Because of the size, variability, and complexity of the middle ear, accurate morphologic data and boundary conditions are necessary for accurate FE modeling. METHODS: A fresh temporal bone was decalcified, embedded in celloidin, sectioned and stained, scanned, and digitized, and the normal middle ear was reconstructed. The histologic sections were used to construct a computer-aided design model with ligaments, muscles, and tendons as boundary conditions. The data thus obtained were converted into an FE mechanical model that was validated by comparison with displacements obtained by laser Doppler interferometry on 17 fresh human temporal bones. RESULTS: An FE model was generated, demonstrating dynamic behavior that moderately approximated the laser interferometric data from human temporal bones receiving 90-dB sound pressure level auditory frequencies at the tympanic membrane. CONCLUSION: Accurate FE modeling, incorporating both morphometric and interferometric performance data, predicted both normal and pathologic mechanical performance of the human ossicular chain.

Biomechanical Phenomena↗