Effect of screen/film combinations on diagnostic certainty: Hi-Plus/RPL versus Lanex/Ortho G in excretory urography

A method using radiologists' subjective judgments was developed to compare the quality of the diagnostic image information from two different screen/film combinations (Hi Plus/RPL versus Lanex/Ortho G). A sample of 148 comparison film pairs was obtained in the course of performing 74 urograms using the two film/screen combinations. Each film pair was evaluated by three radiologists, using a blind film-reading format, in regard to:(1) anatomic diagnostic criteria visualization; (2) radiologic diagnostic certainty; (3) presence or absence of quantum mottle; and (4) prediction of which film of a pair was the rare earth screen/film combination. There was a significant difference favoring Hi Plus/RPL in perceived quality of visualization of anatomic criteria. However, the difference was more of statistical rather than practical importance. Diagnostic certainty differed only marginally and slightly favored the Hi Plus/RPL combination. No signficant differences in perception of quantum mottle were attributable to either screen/film combination. Radiologists were able to correctly identify the screen/film combination a significant proportion of the time. Radiation exposure with the Lanex/Ortho G combination was about half that with the Hi Plus/RPL combination. In this study, this would seem to constitute the major factor in film/screen selection.