SUBJECTIVE QUALITY ASSESSMENT OF COMPUTED RADIOGRAPHY HAND IMAGES

To evaluate the sensitivity of a non-receiver-operating characteristic (ROC) study in assessing small differences of perceived image quality of hand images acquired by computed radiography (CR) and conventional screen-film systems, hand images were acquired on 12 patients with bo th conventional screen-film and CR. Each CR image was then processed w ith three different edge-enhancement algorithms. One conventional film and four CR images were then viewed side by side by five radiologists . Observers rated perceived image quality of each radiograph using a 1 0-category discrete scale. The study was repeated after 6 weeks using a different block randomization scheme. Despite the small sample size, significant differences (P < .05) in assigned image quality were dete cted among CR images acquired at low, medium, and high resolutions. Im age processing routines did not fully compensate for differences in qu ality between conventional film and CR-acquired images. The quality ra ting of the reference conventional image was found to be dependent on the quality of images with which it was compared. Small, highly sensit ive study designs can be used to identify radiologists' perceived diff erences in image quality. ''Reference'' or ''gold standard'' quality a re important in such studies. Edge-enhancement schemes cannot fully co mpensate for perceived image quality degradations because of reduced i mage resolution. Copyright (C) 1996 by W.B. Saunders Company