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Title: Freehand three- dimensional ultrasound calibration
Author: Hsu, P.-W.
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2008
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In this thesis, we investigate how to achieve an accurate reliable and rapid probe calibration. Our first step is to improve the reliability of an accurate calibration technique from the literature. The Cambridge phantom, a variant of plane-based calibration, has been shown to be one of the most accurate calibration techniques. Unfortunately, calibrations performed using plane-based techniques are often unreliable. We show how it is possible to provide feedback on the reliability of the calibration. This allows the user to rectify an unreliable calibration. Having achieved an accurate and reliable calibration, we now search for a fast and easy calibration technique. We study a class of two-dimensional alignment phantoms – the Z-fiducial phantom. Probe calibration using such a phantom only requires a single image of the phantom. However, calibration speed using this phantom is impeded by the necessity of segmenting isolated points on the phantom reliably, which requires human intervention. We solve this problem by mounting a thin rubber membrane on top of the phantom. The membrane is segmented automatically and the phantom features can be easily located. This enables us to segment isolated points automatically at the full PAL frame rate of 25Hz, enabling calibration to be completed in a few seconds. In addition, to improve the existing calibration techniques, we present two novel phantoms – the cone phantom and the Cambridge stylus. They are both simple in design, easy to use and produce accurate calibrations. The cone phantom produces calibrations with accuracies matching the Cambridge phantom. The Cambridge stylus is small in size and can be carried around conveniently. These phantoms offer alternatives to the Cambridge phantom and the Z-phantom, ensuring calibration reliability and simplicity, while producing accurate calibrations.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available