No abstract

Usage of any items from the University of Cumbria's institutional repository 'Insight' must conform to the following fair usage guidelines.Any item and its associated metadata held in the University of Cumbria's institutional repository Insight (unless stated otherwise on the metadata record) may be copied, displayed or performed, and stored in line with the JISC fair dealing guidelines (available here) for educational and not-for-profit activities provided that• the authors, title and full bibliographic details of the item are cited clearly when any part of the work is referred to verbally or in the written form• a hyperlink/URL to the original Insight record of that item is included in any citations of the work • the content is not changed in any way• all files required for usage of the item are kept together with the main item file. You may not• sell any part of an item• refer to any part of an item without citation • amend any item or contextualise it in a way that will impugn the creator's reputation• remove or alter the copyright statement on an item.The full policy can be found here. Alternatively contact the University of Cumbria Repository Editor by emailing insight@cumbria.ac.uk. Abstract. A test bank of verified chest radiographs was compiled for visual search experiments to investigate radiology performance in the detection of early lung cancer. A measure of the physical characteristics of the lesions was derived to determine the conspicuity (x) of the nodules and to investigate possible causes of failed detection. Observer performance was measured by alternate free response operating characteristic (AFROC) methodology and was supplemented with visual search recording. Correlation of AFROC scores and the x values was poor but inspection of the visual search recordings showed that most nodules were fixated. Fixations on missed lesions produced average dwell times greater than three times the minimum duration thought to be associated with detection. We conclude that the majority of errors were failures of decision rather than detection and comment on the implications of this for strategies to improve diagnostic effectiveness.

No abstract

Two specially trained radiographers at York District Hospital have been reporting appendicular plain radiograph X-ray examinations for Accident and Emergency (A&E) patients since February 1995. This study explores the potential for further expanding their reporting role. This was achieved by assessing the two radiographers' and a group of consultant radiologists' ability to report on a retrospectively selected random stratified sample of 400 A&E and General Practitioner (GP) plain radiograph X-ray examinations for all body areas. Using receiver operating characteristic (ROC) curve analyses there was no statistically significant difference at the 5% level between the area under the ROC curves for the radiographers and consultant radiologists when reporting A&E or GP plain radiographs. It may be feasible to expand the reporting role of suitably trained radiographers to include plain radiograph X-ray examinations for all A&E patients and for GP patients, with no detriment to the quality of reports.

Research concerning disease prevalence has inferred that indices of observer performance become, in part, a function of predetermined prevalence. The cause of this modified performance and decision-making is not fully understood, although the alteration of the criterion level of the observer may be a feature. Novice radiography students were randomly assigned to one of three digitised test banks of 72 wrist images. Test bank A, B and C represented a fracture prevalence of 50%, 83% and 22% respectively. Half of the observers from each group were made aware of the prevalence of their respective test bank. Observers recorded their decisions on an operator rating scale. Results showed significant differences in overall Az between the 50% and 83% prevalence sets (p=O.O4) and the 50% and 22% prevalence sets (p=O.OO5). Knowledge of the prevalence influenced both sensitivity and specificity values at the 83% prevalence level (p=O.O3 and 0.02) but not at the lower levels. For test bank A sensitivity was 87%; specificity 53%; Az 0.80, test bank B sensitivity 81%; specificity 48%; Az 0.71 and test bank C sensitivity 85%; specificity 43%; Az 0.68. Analysis of the eye movement patterns of observers under conditions of varying prevalence is in progress.