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summary The Hospital Without Walls is an ongoing ambitious project in home telecare that incorporates research into physiological monitoring, low-power radio communication, database storage of physiological data and methods of viewing clinically relevant information from large quantities of stored data. The system records vital signs from patients in their homes using a body-mounted, two-way radio system and a base station located in the home, which transmits data records to a central recording facility every day or in response to predefined emergency events. The prototype system has successfully undergone preliminary clinical trials, with a particular clinical emphasis on monitoring activity using three-axis accelerometers. Our experience with the trial suggests that there are significant differences in the technical design required for a long-term, home monitoring system and one where monitoring takes place in an environment staffed by health professionals.

With the widespread clinical use of sonography there is a need to introduce the topic into the curriculum. A new problem-based course in clinical sonography without lectures was developed to emphasise experiential learning, and engage students actively in individual and collective acts of discovery. Four different approaches were used to deliver the new course to 141 veterinary medical students over four semesters. The physical principles of sonography were taught by computer-assisted instruction and a practical class, clinical examinations were introduced during a session with a tutor, and finally each student wrote an essay on a sonographic topic of their choice. To evaluate the new course, students' responses to a questionnaire were analyzed. Students gained reasonable understanding of the physical principles of sonography and had some confidence in conducting a sonographic examination of an animal. Of most use to student learning was discussion with the teachers. Surprisingly, half the students thought the topic should also be taught by lectures. The students learned the material and acquired the sonographic skills through processes which required more independence and self-responsibility than traditional teaching methods. The teachers' interaction with students on an individual basis, as they encountered individual problems, was the most important resource in learning about sonography. The continued request for lectures suggests an insecurity in some students caught between two different paradigms of teaching and learning (experiential, problem-based learning versus lectures).

In this initial report, an imaging technique is described for automatically recognising the walls of a blood vessel during Doppler measurements, and hence automatically adjusting the position of the sample volume. The method reduces the inherently two-dimensional edge detection problem to a one-dimensional one, and iterates over several imaging frames to optimise the information. The orientation and diameter of the vessel are also measured. The technique has been clinically tested off-line and is particularly applicable to Doppler volumetric flow studies.

Home telecare uses a number of telemedicine technologies used for caring for patients in their homes rather than in the hospital system. To provide continuous monitoring of vital signs with minimal disruption of a normal lifestyle, we have developed an ultra-low power wireless and sensing system which may be installed in the home. The system is built around a two-way, 2.4 GHz radio system including miniature patient-worn units. A PC and small base station in the home collect and upload information to a monitoring centre at regular intervals, or in response to defined events. The system is designed to be installed in a home for periods of monitoring as a replacement for more expensive institutional care. The initial clinical application is a group of elderly patients who have presented following a number of idiopathic falls. In order to both detect a fall and determine its cause (which may be cardiovascular), the wearable radio system is equipped with accelerometers and equipment for measuring heart rate. A web-based distributed information system for caregivers incorporates automatic recognition of events or trends requiring intervention. The system is currently undergoing preliminary clinical trials.

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 miniature, wearable, low-power radio that can transmit vital sign and activity information to a home computer, from which data may be sent by telephone line and the Internet to appropriate medical professionals. The initial clinical scenario for this work is monitoring of elderly patients who have presented to hospitals following repeated falls. Accelerometers built into the radio sets will monitor activity and detect and characterise falls. Simultaneous measurement of heart rate will provide information about abnormalities of cardiovascular physiology at the time of a fall. The system has been tested in laboratory conditions and is being adapted for initial clinical trials.

The advent of real-time ultrasound in the 1970s, together with a growing interest in tissue characterization, led to a number of investigators using the nature of tissue motion to distinguish healthy from diseased tissue. Our group at the (then) Ultrasonics Institute demonstrated the use of phase methods for detecting very small tissue motions, using natural stimuli. The method could also be applied in the lag (autocorrelation) domain to directly measure the amount of deformation to high accuracy. This method was also applied to measuring the amount of dilatation of blood vessels using both conventional and intravascular ultrasound. A basic limitation of these techniques was the poor spatial resolution, and quasistatic methods soon replaced this method of measuring tissue deformation. However, a new way of assessing the health of tissues had been established.

Rationale and Objectives. The application of information technology to teaching radiology will profoundly change the way learning is mediated to students. In this project, the integration of veterinary medical students' knowledge of sonography was promoted by a computer-assisted instruction program and a subsequent practical class. Methods. The computer-assisted instruction program emphasized the physical principles of clinical sonography and contained simulations and user-active experiments. In the practical class, the students used an actual sonographic machine for the first time and made images of a tissue-equivalent phantom. Students' responses to questionnaires were analyzed. Results. On completing the overall project, 96% of the students said that they now understood sonographic concepts very or reasonably well, and 98% had become very or moderately interested in clinical sonography. Conclusions. The teaching and learning initiatives enhanced an integrated approach to learning, stimulated student interest and curiosity, improved understanding of sonographic principles, and contributed to an increased confidence and skill in using sonographic equipment.

Grey scale echography portrays the internal echoes originating from small impedance discontinuities formed by the structural organisation of soft tissue. These internal echoes are independent of inclination whilst their size and distribution is specific to the type of tissue examined. Thus normal and pathological tissues are portrayed with a differing appearance allowing their identification on the echograms. The principle of selecting a range of magnitudes of echoes for display on a restricted dynamic range of a display unit is described as well as methods used for compensating for the factors that effect the magnitude of echoes. Grey scale echography gives a new active role to simple scanning and a comparison of the features of simple and compound scanning is made. The simples and most reliable application of grey scale echography is the differentiation between cystic and solid structures and the criteria used in this application are discussed. The classification of soft tissue is more difficult, normal soft tissues being classified primarily by the appearance of the internal echoes, whilst the classification of localized pathological processes is based on the appearance of both the internal and the boundary echoes. The diagnosis of diffuse pathological conditions is the most difficult and is based on the change in the normal structural echo pattern.

A real time scanner which images in compound scan as well as simple scan mode offers advantages over a conventional unit which only produces simple scans in one format. A linear array scanner in which the line of sight can be steered gives a variety of formats for both simple scan and compound scan imaging. The design considerations and capabilities of a scanner with these multiple modes of operation is discussed. The initial clinical results and potential applications are presented.