Osteoporosis is a degenerative bone disease characterized by decreased bone density and a deterioration of the bone structure, significantly increasing the risk of fracture. It can affect any body region but may be detected early in the radius, up to ten years before reaching the osteoporotic peak in more critical areas like the hip or spine. Ultrasonic waves have been studied for several decades to characterize skeletal bone properties. Their sensitivity to the mechanical properties of their propagation medium makes them an especially effective method for evaluating bone properties. The axial transmission technique is particularly useful for characterizing long bones, such as the radius. Ultrasound offers advantages beyond the simple density estimation provided by conventional X-ray methods like DEXA, which is insufficient for accurately assessing fracture risk. Using low-frequency allows ultrasonic waves to penetrate deeply into the bone and reveal its geometry. Additionally, osteoporosis primarily affects the endosteal region, which is the inner part of the bone. Therefore, low-frequency ultrasonic waves used in the context of axial transmission present promising potential for early and effective osteoporosis screening. Consequently, this project aims to design a portable, transportable ultrasonic detection device for osteoporosis diagnosis. To achieve this, a semi-analytical method called SAIGA was used to create a 2D model representing a cortical bone plate covered with soft tissues. This parametric model was used to build a database employed by an inversion algorithm to determine properties corresponding to experimental dispersion curves. This method, applied in the context of axial transmission of ultrasonic guided waves, enabled the precise determination of the mechanical and geometrical properties of two cortical bone phantom plates covered with soft tissue. It was then applied to a quasi-cylindrical 2.5D model. The cortical layer properties of two bone phantoms filled with material mimicking soft tissue were determined under two scenarios : (1) cylinders placed in a free medium and (2) cylinders immersed in olive oil to simulate the presence of soft tissues around the bone. The results showed a good estimation of the cortical layer’s mechanical and geometrical properties in both scenarios, despite some minor errors related to the SAIGA model’s precision. In parallel with these studies, a multi-element ultrasonic probe was developed for the transmission of guided waves within the human body. This probe is part of a complete system that will lead to the development of an affordable, portable, and easy-to-use tool for diagnosing osteoporosis in clinical settings. The components were specifically selected to enable the transmission and reception of low-frequency guided waves in an axial transmission context. The results obtained with this device on phantom plates are promising and suggest that the probe could be used in the future with some modifications.
| Date | 5 Feb 2025 |
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| Original language | French |
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| Awarding Institution | - École de technologie supérieure
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| Supervisor | Pierre Bélanger (Supervisor) |
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Chaboty, A. (Author),
Bélanger (Supervisor),
5 Feb 2025Student thesis: Doctoral thesis › Doctorate in Engineering: Engineering