Morgan Williamson

Objective measures of quality assurance in a computed radiography-based radiology department

Parameters are needed to assess quality assurance in a radiology department where computed radiography (CR) is the principal means of image acquisition. Laser-printed computed radiographs were collected for all patients examined over a period of several days. A sample of 1200 was sorted by subject anatomy and the associated exam information was entered into an EXCEL spreadsheet. Sensitivity (S) numbers were sorted into histogram and analyzed using standard descriptive statistics. Each film was over-read by a board-certified radiologist to assess whether the image was diagnostic and to determine if there were pathologic findings. A significant proportion of images were acquired using inappropriate menu codes. The histogram of S numbers for a given menu code describes a log normal distribution. The S number depends on the technologists ability to control the technique. A significant proportion of the images were deemed non diagnostic, and many correlated to excessive S numbers. Some were a result of mispositioning. The S number is a valid retrospective measure of radiographic quality assurance. Departments using CR should strive for control on menu codes selected and S numbers produced. Such data should be available from PACS databases.

Clinical Experience with Teleradiology in the U.S. Military

The U.S. military through the Medical Diagnostic Imaging Support (MDIS) system is installing teleradiology at multiple medical treatment facilities throughout the US and abroad. The goals are to improve patient care, maximize limited resources, and realize cost savings. This presentation reviews early experience with clinical use of the MDIS teleradiology configuration. Emphasis is on lessons learned in the areas of image quality, speed of image transmission, communication between sites, and the advantages of the MDIS two-way teleradiology configuration. The data is accumulated from the combined experience of the authors at multiple different sites within the continental US, Hawaii, and Korea.

Non-destructive reversible resistive switching in Cr doped Mott insulator Ca2RuO4: Interface vs bulk effects

A non-destructive reversible resistive switching is demonstrated in single crystals of Cr-doped Mott insulator Ca2RuO4. An applied electrical bias was shown to reduce the DC resistance of the crystal by as much as 75%. The original resistance of the sample could be restored by applying an electrical bias of opposite polarity. We have studied this resistive switching as a function of the bias strength, applied magnetic field, and temperature. A combination of 2-, 3-, and 4-probe measurements provide a means to distinguish between bulk and interfacial contributions to the switching and suggests that the switching is mostly an interfacial effect. The switching was tentatively attributed to electric-field driven lattice distortions which accompany the impurity-induced Mott transition. This field effect was confirmed by temperature-dependent resistivity measurements which show that the activation energy of this material can be tuned by an applied DC electrical bias. The observed resistance switching can potent...

Development of a multimedia CD-ROM on telemedicine and teleradiology

The Department of Defense Telemedicine Test Bed produced a CD-ROM including information on telemedicine, teleradiology and military medical advanced technology projects. The CD-ROM was produced using media from the Telemedicine Test Bed World Wide Web site and academic papers and presentations. Apple Media Tools software was used to produce the interactive program and the authoring was done on a high speed Apple Macintosh Power PC computer. The process took roughly 100 hours to author 50 Mb of data into 200 frames of interactive material. Future versions of the Telemedicine CD-ROM are in progress which will include much more material to take advantage of the 650 Mb available on a compact disk. This paper graphically depicts and explains the authoring process.