Biomedical subjects

G W Seeley

Publications and source records attributed to G W Seeley.

24 records · Page 2Linked to original sources

PubMed1984

A general framework for evaluating the reliability of medical measurement systems.

Measurements of physical and social phenomena are often used in the decision-making process despite the error introduced by human and context variation. It would be advantageous to a decision maker to know the sources and magnitudes of such errors in using a measurement system or in choosing among alternative measurement systems. This paper describes an approach to determining the reliability of a measurement procedure called generalizability (G) theory. G theory uses the results of a random-effects analysis of variance to estimate the magnitude of error variability associated with each of several potential sources. These estimates can then be used to calculate a number of indices which typify the amount of precision provided by a measurement system in a particular context of usage. The major concepts of G theory are described and illustrated in the context of evaluating a radiologic total lung capacity measurement system.

Analysis of Variance↗

PubMed1983

Digital nephropyelography following intravenous renal digital subtraction angiography.

A 14-inch image intensifier designed for digital radiography has made feasible adjunctive evaluation of the renal parenchyma and collecting structures following intravenous digital subtraction angiography (DSA). Initial experiments with rabbits showed digital nephrography to be superior to film-based nephrotomography in terms of renal conspicuity and imaging flexibility. Preliminary experience with 30 patients undergoing DSA reaffirms the suitability of this method for the evaluation of renal anatomy and function. Only about half the amount of contrast material needed for conventional excretory urography is required.

Angiography↗

PubMedDate not supplied

A computerized method for the measurement of conspicuity. Comparison of film and digital nephrograms.

We have designed a computer program appropriate for comparing the conspicuity of an object of interest portrayed on film-based and photoelectronic images. To test this program, we evaluated nephrograms generated by exposing matched film tomograms and digital images of rabbit kidneys following contrast administration. We then evaluated their conspicuity--a measure of how well an object can be distinguished from its surround--by a computer program which automatically traced a concentric and equal area of surrounding background around operator-defined nephrograms. Computerized evaluation of these areas provides the formula elements (mean object and background density and variance values and the number of pixels) from which conspicuity is automatically calculated. Nephrogram conspicuity was greatest for digital subtraction images. This approach is useful for comparing film and digital techniques.

Analog-Digital Conversion↗

PubMedDate not supplied

Detection of small radiation sources: the effect of mode of count-rate presentation.

We used an observer-performance study to compare four different modes of presenting count-rate data from a radiation detector. Observers searched for small, concealed radioactive sources using a hand-held radiation-detector probe. The modes of count-rate presentation were a ratemeter, howler, multichannel scaler, and HRM III. The HRM III calculates the statistical significance of the difference between current and previous count rates and presents the result as an audio signal. We tested six observers with each mode of count-rate presentation, calculated receiver operating characteristic (ROC) curves, and used the areas under the ROC curves to compare the different modes. Observer performance was better with the multichannel scaler and HRM III than with either the ratemeter or the howler. The results suggest that observer performance with devices that use ratemeters or howlers can be enhanced by improving the mode of count-rate presentation.

Cobalt Radioisotopes↗

PubMedDate not supplied

FEASIBLE (I): The PC software package for feature evaluation and system inspection by logged experiments.

FEASIBLE is an MS-DOS software package which can be used for the evaluation of: Picture Archiving and Communication System (PACS) components; diagnostic image quality; and image manipulation and representation techniques. The FEASIBLE software allows the user to design any psychophysical study in detail in the fields mentioned above, to execute an arbitrary number of sessions and to statistically analyse the results by way of the Receiver Operating Characteristic (ROC) technique. FEASIBLE consists basically of three modules: DESIGN, which allows the user to set up an experiment; EXECUTION, which allows the user to execute the experimental sessions based on the design entered in the DESIGN module and stored in the program's database; and, STATISTICS, which allows various statistical analyses on the data collected during the psychophysical sessions (including the calculation of ROC curves and related parameters) and can provide a graphical presentation of the results. FEASIBLE has been designed to support experts and those who have little knowledge of psychophysical experiments. This paper discusses the background, structure and possibilities of the FEASIBLE package at this point (version 1.2, May 1988).

Hospital Information Systems↗

PubMedDate not supplied

Conventional vs computed radiography: evaluation of myelography.

A prospective study was performed to compare the diagnostic efficacy of conventional film-screen (FS) imaging with computed radiography (CR) in myelography. Forty examinations were done with both methods. Digital myelography was found to have diagnostic accuracy equal to that of conventional film-screen examinations.

Diagnosis, Computer-Assisted↗