Queen's University - Utility Bar

QSpace at Queen's University >
Theses, Dissertations & Graduate Projects >
Queen's Theses & Dissertations >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1974/5280

Title: Improvement of Speckle-Tracked Freehand 3-D Ultrasound Through the Use of Sensor Fusion
Authors: Lang, Andrew

Files in This Item:

File Description SizeFormat
Lang_Andrew_R_200910_MASc.pdf3.36 MBAdobe PDFView/Open
Keywords: ultrasound
speckle tracking
sensor fusion
Issue Date: 2009
Series/Report no.: Canadian theses
Abstract: Freehand 3-D ultrasound (US) using a 2-D US probe has the advantage over conventional 3-D probes of being able to collect arbitrary 3-D volumes at a lower cost. Traditionally, generating a volume requires external tracking to record the US probe position. An alternative means of tracking the US probe position is through speckle tracking. Ultrasound imaging has the advantage that the speckle inherent in all images contains relative position information due to the decorrelation of speckle over distance. However, tracking the position of US images using speckle information alone suffers from drifts caused by tissue inconsistencies and overall lack of accuracy. This thesis presents two novel methods of improving the accuracy of speckle-tracked 3-D US through the use of sensor fusion. The first method fuses the speckle-tracked US positions with those measured by an electromagnetic (EM) tracker. Measurements are combined using an unscented Kalman filter (UKF). The fusion is able to reduce drift errors as well as to eliminate high-frequency jitter noise from the EM tracker positions. Such fusion produces a smooth and accurate 3-D reconstruction superior to those using the EM tracker alone. The second method involves the registration of speckle-tracked 3-D US volumes to preoperative CT volumes. We regard registration combined with speckle tracking as a form of sensor fusion. In this case, speckle tracking is used in the registration to generate an initial position for each US image. To improve the accuracy of the US-to-CT registration, the US volume is registered to the CT volume by creating individual US "sub-volumes", each consisting of a small section of the entire US volume. The registration proceeds from the beginning of the US volume to the end, registering every sub-volume. The work is validated through spine phantoms created from clinical patient CT data as well as an animal study using a lamb cadaver. Using this technique, we are able to successfully register a speckle-tracked US volume to a CT volume with excellent accuracy. As a by-product of accurate registration, any drift from the speckle tracking is eliminated and the freehand 3-D US volume is improved.
Description: Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2009-10-19 00:10:25.717
URI: http://hdl.handle.net/1974/5280
Appears in Collections:Electrical and Computer Engineering Graduate Theses
Queen's Theses & Dissertations

Items in QSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

 

  DSpace Software Copyright © 2002-2008  The DSpace Foundation - TOP