title: A prospective randomized clinical trial comparing two film-screen systems for chest radiography.
abstract: OBJECTIVE
  To compare conventional and asymmetric film-screen chest radiography systems in a prospective, randomized trial.
  
  
  METHODS
  Posteroanterior and lateral films were obtained with each system for one healthy volunteer and 49 consenting patients referred from pulmonary clinics and wards (for a total of 27 male and 23 female subjects ranging in age from 16 to 82 [mean 58] years). The radiographs, obtained and presented in random order, were reviewed and rated independently by two experienced radiologists and one resident in radiology; all observers were blinded to patient identification and film type. The Wilcoxon signed rank sum nonparametric test for paired samples was used to test for significant differences between the two film-screen systems. A second evaluation involving direct (blinded) comparison of the two types of films was then performed for each of the 25 patients in whom abnormality was noted during the first evaluation.
  
  
  RESULTS
  For the posteroanterior radiographs, the asymmetric film-screen system was significantly better for assessing the trachea and mainstem bronchi, the descending thoracic-aortic edge, the left paraspinal line, the thoracic vertebral body interspace and the azygo-esophageal line (p < 0.05), whereas the conventional system had superior conspicuity in the lateral subpleural zones (p < 0.05). For the lateral radiographs, the asymmetric system was superior for assessing retrosternal lung markings (p < 0.05) but inferior for assessing fissures (p < 0.05).
  
  
  CONCLUSIONS
  In general, the asymmetric system was superior for assessing mediastinal features and inferior for assessing the lateral subpleural zones in the posteroanterior radiographs. The asymmetric system was superior for assessing retrosternal lung markings and inferior for assessing fissures in the lateral radiographs. The results for the posteroanterior radiographs were consistent with the results of nonblinded studies reported elsewhere.
authors.affiliation: Department of Diagnostic Radiology, Victoria Hospital, London, Ontario.
authors.forename: M S
authors.initials: MS
authors.lastname: Lefcoe
authors.forename: I A
authors.initials: IA
authors.lastname: Cunningham
authors.forename: L C
authors.initials: LC
authors.lastname: Vanderburgh
authors.forename: R K
authors.initials: RK
authors.lastname: Sparrow
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging; D001401:Azygos Vein / Q000000981:diagnostic imaging; D001995:Bronchography; D004947:Esophagus / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D008168:Lung / Q000000981:diagnostic imaging; D008297:Male; D008482:Mediastinum / Q000000981:diagnostic imaging; D008875:Middle Aged; D010994:Pleura / Q000000981:diagnostic imaging; D011446:Prospective Studies; D011856:Radiographic Image Enhancement; D013902:Radiography, Thoracic / Q000295:instrumentation; D016037:Single-Blind Method; D013131:Spine / Q000000981:diagnostic imaging; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging; D014132:Trachea / Q000000981:diagnostic imaging; D014962:X-Ray Film; D014963:X-Ray Intensifying Screens