publications by G. Allan Johnson.
search www.ncbi.nlm.nih.gov.
Papers Published
- HG Chotas, RL Van Metter, GA Johnson, CE Ravin, Small object contrast in AMBER and conventional chest radiography.,
Radiology, UNITED STATES, vol. 180 no. 3
(September, 1991),
pp. 853-9 .
(last updated on 2005/08/03)Abstract:
The ability of a commercially available scanning equalization system for chest radiography to render small object contrast in the lung-, mediastinum-, and subdiaphragm-equivalent regions of an acrylic chest phantom was quantitatively evaluated. Images from nine chest phantoms that represented a wide range of patient sizes and dynamic ranges of x-ray transmittance were analyzed. Subject contrast was measured with a photostimulable phosphor detector, and images were acquired in both equalized and nonequalized (conventional) imaging modes. Available subject contrast in the lung-equivalent region was 8%-15% lower in the equalized images compared with the nonequalized images in all phantoms (patient types); contrast in the mediastinum-, retro-cardiac-, and subdiaphragm-equivalent regions was 11%-63% higher in the equalized images, with the degree of improvement increasing as patient size and dynamic range increased. Images of each phantom were also acquired with the screen-film systems currently in use at the authors' institution, permitting an assessment of the relative performance (in terms of radiographic contrast) of these imagers with and without use of equalization.Keywords:
Diaphragm • Humans • Lung • Mediastinum • Models, Structural • Radiography, Thoracic* • Technology, Radiologic • methods • radiography