Ultrasonic bone characterisation: towards in vivo proximal-femur imaging
File(s)
Author(s)
Chung-Jukko, Aaron
Type
Thesis
Abstract
Osteoporosis is a bone disease that causes fragility, affecting a third of women over 50 years of age. The current gold standard for osteoporosis testing dual-energy X-ray absorptiometry (DEXA) involves ionising radiation and is often inaccurate. This can lead to missed treatments and potentially life-threatening hip fractures, which is a fracture of the proximal femur. Since the 1990s, ultrasound has been suggested as a promising, inexpensive and portable alternative to DEXA, but existing ultrasonic methods have not met the clinical requirements of in vivo proximal-femur imaging.
In this thesis, I show that this high-contrast, extended-range imaging problem can be solved by addressing four subproblems. First, the background properties surrounding the bone can be approximated from the literature values or bent-ray tomography (BRT). Second, the bone surface can be located through beamforming. Third, the overall problem is reduced to a subproblem bounded by virtual transducers placed on the bone surface. Finally, the bone material and geometrical properties are solved, with the subsolution being fracture-site dependent.
For the proximal femoral diaphysis, I propose a guided-wave-based approach without assumptions about the waveguide. For the femoral neck, I introduce virtual initialised ray tomography (VIRT), applying BRT from the virtual transducers. VIRT shows promising results, comparable to or better than those of BRT on the bone surface. This approach could revolutionise the field of bone ultrasound, unlocking life-saving treatment for millions worldwide. Furthermore, VIRT may replace BRT in other fields due to its superior resolution, robustness, and speed.
In this thesis, I show that this high-contrast, extended-range imaging problem can be solved by addressing four subproblems. First, the background properties surrounding the bone can be approximated from the literature values or bent-ray tomography (BRT). Second, the bone surface can be located through beamforming. Third, the overall problem is reduced to a subproblem bounded by virtual transducers placed on the bone surface. Finally, the bone material and geometrical properties are solved, with the subsolution being fracture-site dependent.
For the proximal femoral diaphysis, I propose a guided-wave-based approach without assumptions about the waveguide. For the femoral neck, I introduce virtual initialised ray tomography (VIRT), applying BRT from the virtual transducers. VIRT shows promising results, comparable to or better than those of BRT on the bone surface. This approach could revolutionise the field of bone ultrasound, unlocking life-saving treatment for millions worldwide. Furthermore, VIRT may replace BRT in other fields due to its superior resolution, robustness, and speed.
Version
Open Access
Date Issued
2024-08-20
Date Awarded
01/10/2025
License URL
Advisor
Huthwaite, Peter
Publisher Department
Department of Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)