PubMed Health⌕ Search

Biomedical subjects

E Vogelstein

Publications and source records attributed to E Vogelstein.

5 recordsLinked to original sources
PubMed1985

Scanning equalization radiography of the chest: assessment of image quality.

An evaluation of the image quality of scanning equalization radiography (SER) of the chest was conducted with 60 volunteer patients. Posteroanterior chest radiographs by SER and conventional methods were compared by six radiologists to determine the adequacy and uniformity of the film exposure and the visualization of normal anatomic structures. The radiographs by the SER technique were deemed to be superior for visualization of most anatomic features. With SER there were no film artifacts from the scanning technique and there was only occasional blurring of some structures with a 4.7-sec scan time.

Cardiomegaly↗
PubMedDate not supplied

A scanning system for chest radiography with regional exposure control: practical implementation.

An experimental scanning apparatus for chest radiography is described which offers good scatter rejection and regional manipulation of film exposure. The apparatus is capable of studying two scanning geometries that uses either a fan of radiation swept laterally over the film in 5s or a spot of radiation scanned over two dimensions in a raster pattern in 8.8s. The manipulation of tube output during the scan is achieved by pulse width modulation with film exposure monitored by a fluorescence detector placed behind the film cassette. Measurement of the scatter rejection properties of the system show that it is superior to that of a 10:1 grid when used with 120-kVp radiation. Phantom images with both geometries demonstrate the capability of the system to improve uniformity of film exposure and soft tissue contrast throughout the mediastinal, diaphragmatic, and retrocardiac areas. The relative characteristics of the one- versus two-dimension scan geometries are given. Clinical raster images formed with the 8.8-s scan time show signs of motion unsharpness which becomes insignificant when the scan time is reduced to 4.5 s.

Radiography, Thoracic↗
PubMedDate not supplied

Exposure artifacts in raster scanned equalization radiography.

The image artifacts characteristic of a scanning chest radiographic system are reviewed. The technique employs a pulsed beam of radiation swept in an overlapping raster pattern that can result in severe ripple and scan line artifacts with improper scanning parameters. A one-dimensional treatment of the scanner geometry shows that the artifacts can be eliminated when the beam width is an integral multiple of interpulse spacing. An extension to a two-dimensional analysis indicates that with the collimator geometries employed, artifact-free images are not possible with a fixed x-ray frequency but can be achieved when a variable frequency source is used. A treatment of the sensitivity for artifact formation shows that with proper choice of scanning parameters sizable errors in beam width can be tolerated without significant artifact formation.

Humans↗
PubMedDate not supplied

Grid controlled x-ray tube switching time: implications for rapid exposure control.

The transient response properties of a conventional grid controlled x-ray source and the implications for rapid exposure control are studied. The use of a cathode cable with a length of only 1 m to connect the x-ray tube and the grid control electronics results in a switching time of 19 microseconds. The phototiming artifacts from the delayed radiation delivered during this transition time can be severe for short pulses. An analog correction technique that anticipates the magnitude of the delayed radiation is used to overcome this limitation and allows accurate phototiming over a wide range of pulse widths ranging down to 20 microseconds.

Humans↗