David Volk Beard

Force display performs better than visual display in a simple 6-D docking task

A simplified docking problem is studied. The user attempts to find the potential-energy minimum in a 6-D space defined by six Hookes-law springs attached to a manipulable object. This space has no other local minima. A pilot-controlled experiment with seven subjects, twelve trials each, showed that performance with a force display is better (p<0.01) than performance with a visual display alone, and that subjects are able to find the zero-force position more than twice as fast with a force display alone than with a visual display alone. Also described is a way of graphically representing the resultants of a set of forces and torques acting on a body. Even though the experiment shows force display to be more effective, it also shows that the simple 6-D docking task can reliably be done with this visual display alone.<<ETX>>

Navigational techniques to improve the display of large two-dimensional spaces

Abstract Often the components of a problem can be arrayed on a two-dimensional information space—for example, as an abstract tree or hypertext—far too large to fit onto a computer display. With current navigational techniques it is often difficult for users to keep track of their location or to move rapidly to remote locations in the space. We implemented two similar direct-manipulation techniques, both of which use a map window—a miniature of the entire information space—with a wire-frame box to aid users in remembering their location. The first technique allows the user to rapidly roam over the information space by moving the location of the wire-frame box. The second allows for zooming as well as roaming. A controlled experiment compared the above techniques to scroll bars for determining whether a target word was in a large balanced binary tree of words. The experiment also examined the merit of the map window. Map windows significantly improved user performance, and the roam and zoom techniques were ...

Designing a radiology workstation: A focus on navigation during the interpretation task

The potential cost and logistic improvements of picture archive and communication system (PACS) over film-based medical image management awaits the development of viable radiology workstations (RWS) targeted for the primary interpretation task. While the quality of electronically displayed images has been highly investigated, only recently have design and experimental work been devoted to the other critical aspect of workstation design, mainly its computer human interaction, and, in particular, its navigation. By RWS navigation we include its underlying mental model or metaphor, and the commands and hand motions used to access patient folders and to display images. For the last 5 years, the University of North Carolina (UNC) Medical Image Display Research Group has analyzed the primary interpretation task and designed, developed, and evaluated the FilmPlane series of RWS prototypes. This work has helped us understand both RWS requirements and viable design approaches. In this paper, we present our workstation design strategy and our observations and understanding of the issues and problems with RWS navigation. To illustrate the discussion, we describe FilmPlane2, the UNC radiology workstation. We also briefly detail three rapid-evaluation techniques (including two observer experiments) for quickly gaining feedback on a design. These observations and evaluation techniques may aid other RWS designers in producing superior tools for the clinicians.

Quick and dirty GOMS: a case study of computed tomography interpretation

An adjustable motion transfer device for transmitting movement from a drive member to a driven member, and particularly for transferring rotational motion to linear motion. The device is particularly designed for transmitting motion from a power source or motor drive shaft to a pump piston and may be quickly and easily adjusted to provide substantially any desired length of linear movement or reciprocal movement for the pump piston. The device may be connected directly to the drive shaft of the motor and carries an adjustable cam drive member for connection with the pump piston for transmitting the linear motion thereto. The cam drive member may be substantially infinitely adjusted to provide substantially any desired drive or speed ratio between the drive shaft and piston.

A cost analysis of film image management and four PACS based on different network protocols

Picture Archive and Communication Systems (PACS), which allow the electronic acquisition, storage, transportation, and viewing of medical images, hold the eventual promise of reduced costs, improved imagemanagement logistics, and ultimately, improved patient care. But at what point in the future will PACS really cost less than film-based image management for a given hospital size; and how are these costs affected by the choice of the digital communication network? To address these questions, a static differential cost model has been constructed. PAC systems based on two high-speed networks (less than 150 megabytes per second Mbps) and two lowspeed networks, as well as film, were considered for five different sized hospitals (ranging from 15,000 to 125,000 procedures per year) and two time periods (1995 and 2000). PACS equipment was assumed to have a payoff of five years. The model considered all capital and supply costs and personnel costs for the PACS and for film storage and retrieval. It did not consider any possible cost savings from logistics improvement likely to result from the adoption of a PACS. Based on the assumptions outlined, high-speed-network PACS are less costly than those based on low-speed networks for all scenarios considered. Further, even though all possible PACS cost savings were not considered, high-speed network PACS appear to be less costly than film for hospitals larger than 60,000 procedures in 1995 and larger than 15,000 in 2000, while low-speed-network PACS should cost less than film for 60,000 and 30,000 procedure hospitals in 1995 and 2000 respectively.

Real-time radiologist review of remote ultrasound using low-cost video and voice

RATIONALE AND OBJECTIVES.A radiologist practicing remote ultrasound occasionally needs to review a case in real time before releasing the patient. The authors conducted a pilot study to evaluate one solution in which the radiologist views real-time images on a video monitor while conversing with the technologist via a headset telephone. METHODS.Two experienced ultrasonographers and five technologists participated in a 5-week pilot study in adjacent rooms. RESULTS.Subjective assessment indicated that the system could function well enough for use at a remote site. CONCLUSIONS.Although this technology appears effective, an ongoing training environment is recommended.

A study of radiologists viewing multiple computed tomography examinations using an eyetracking device

Understanding the scan patterns radiologists use to view medical images is critical to the design of image viewing devices. In this study, and eyetracker, a device for recording eye and head movement, was used to determine the scan patterns during the interpretation of single and multiple computed tomographic (CT) examinations presented on a four-over-four viewbox. CT examinations were used because they represent complex viewing situations. In two separate studies, radiologists viewed patient folders containing single or multiple CT chest examinations and dictated a report. Eye movement was recorded with an eyetracker and video camera. After mounting the films in order, radiologists generally started with a sequential scan through the entire examination, followed by careful viewing of two to four clusters of three to six images, followed by dictation. These results indicate that a well designed radiology workstation should provide an image index, sufficient display area to simultaneously view 10 or more images, random and sequential movement through the examination, image comparison, and image marking.

Medical image work stations: Functions and implementation

Electronic work stations are becoming a standard means of presenting medical images for diagnosis and consultation, and they will become more wide-spread as picture archiving and communication systems (PACS) come into use. These work stations must allow the user both to perceive the patterns necessary for accurate diagnosis and to “navigate” efficiently within large sets of related images, ie, quickly find and compare desired images. The work stations must operate without a feeling of “friction” and have an affordable cost. In this report we survey the tasks and system objectives, first regarding the perceptual needs and second with respect to the navigational needs. We then survey the technology available to satisfy these needs and conclude with a list of needed research and technology that can be expected or should be provided in the future.

QGOMS: a direct-manipulation tool for simple GOMS models

OOMS models can be practical if the effort required to product them is commensurate with their limited practical accuracy.” This demonstration details a direct manipulation tool for quickly building OOMS models. Advanced features allow rapid model construction and analysis.

Cost analysis of film image management and four PACS systems

Picture Archive and Communication Systems (PACS), which allow the electronic acquisition, storage, transportation, and viewing of medical images, hold the eventual promise of reduced costs, improved image-management logistics, and ultimately, improved patient care. But at what point in the future will PACS really cost less than film-based image management for a given hospital size; and how are these costs affected by the choice of the digital communication network? To address these questions, a static differential cost model has been constructed. Four PAC systems based on different speed networks as well as film, were considered for five different sized hospitals and two time periods. Based on the assumptions outlined, high-speed-network PACS (greater than 150 Mbps) are less costly than those based on low-speed networks for hospitals generating more than 15,000 procedures per year starting in 1995. Further, even though all possible PACS cost savings were not considered, high-speed network PACS appear to be less costly than film for hospitals larger than 30,000 procedures in 1995 and larger than 15,000 in 2000, while low-speed-network PACS should cost less than film for 60,000 and 30,000 procedure hospitals in 1995 and 2000respectively.