Laurence S. Wilson

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We present an automated, knowledge-based method for segmenting chest computed tomography (CT) datasets. Anatomical knowledge including expected volume, shape, relative position, and X-ray attenuation of organs provides feature constraints that guide the segmentation process. Knowledge is represented at a high level using an explicit anatomical model. The(More)
Spectral tissue strain (STS) is a new technique for measuring and imaging tissue strain from a set of images using intravascular ultrasound. The technique is based on the Fourier scaling property and uses the chirp z-transform (CZT) to estimate strain within the vessel walls. Some preliminary results, both in vitro and in vivo, are described. A novel(More)
Considering data from a Doppler sample volume as a two-dimensional function of depth and time, the properties of its two-dimensional fast Fourier transform (2DFFT) are discussed. It is shown that the 2DFFT of idealized Doppler data from moving scatterers is a line whose slope is the velocity of the scatterers. Aliasing, finite bandwidth effects, and(More)
A frequency domain signal processing scheme is developed for measuring attenuation and attenuation slope in vivo, using equally spaced depth samples and linear regression techniques. The algorithm may be expressed in terms of linear, commuting operators acting on an array of log power spectra. By interchanging operators, a computationally efficient scheme(More)
The data on the relationship of sound speed to tissue condition, and the development of methods for measurement of sound speed in vivo, are outlined. The methods developed by the authors are discussed. These include methods which use the spatial shift in images of targets viewed from different directions, time-of-flight measurements along incrementally(More)
This paper introduces a new approach to content based image retrieval by texture. There are three problems to solve: high computational time, handling high dimension data, and comparing images consistent with human perception. To decrease the computational time, we present a new strategy to extract an image feature with high retrieval accuracy. We also(More)
Ultrasonic attenuation has been measured using frequency domain signal processing in clinical trials of patients with liver and spleen diseases. By comparing the variance encountered in local measurements and in measurements at a number of adjoining sites, the need for averaging over large volumes of tissue to avoid the effects of large fluctuations is(More)
Aging populations and rising health costs have created the need to care for more patients in their own homes. Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) is developing a project, Hospital Without Walls, which aims to provide continuous monitoring of patients in certain diagnostic categories. The key technology is a(More)
While telemedicine is now well established in many areas of medical practice, it is only beginning to create impact in some of the more complex medical applications such as critical care. New systems based on advanced technologies such as the Virtual Critical Care Unit and the eICU have recently successfully demonstrated the provision of critical care(More)