A think-aloud study to inform the design of radiograph interpretation practice.

Models for diagnostic reasoning in radiology have been based on the observed behaviors of experienced radiologists but have not directly focused on the thought processes of novices as they improve their accuracy of image interpretation. By collecting think-aloud verbal reports, the current study was designed to investigate differences in specific thought processes between medical students (novices) as they learn and radiologists (experts), so that we can better design future instructional environments. Seven medical students and four physicians with radiology training were asked to interpret and diagnose pediatric elbow radiographs where fracture is suspected. After reporting their diagnosis of a case, they were given immediate feedback. Participants were asked to verbalize their thoughts while completing the diagnosis and while they reflected on the provided feedback. The protocol analysis of their verbalizations showed that participants used some combination of four processes to interpret the case: gestalt interpretation, purposeful search, rule application, and reasoning from a prior case. All types of processes except reasoning from a prior case were applied significantly more frequently by experts. Further, gestalt interpretation was used with higher frequency in abnormal cases while purposeful search was used more often for normal cases. Our assessment of processes could help guide the design of instructional environments with well-curated image banks and analytics to facilitate the novice's journey to expertise in image interpretation.

A primer on the statistical modelling of learning curves in health professions education.

Learning curves are a useful way of representing the rate of learning over time. Features include an index of baseline performance (y-intercept), the efficiency of learning over time (slope parameter) and the maximal theoretical performance achievable (upper asymptote). Each of these parameters can be statistically modelled on an individual and group basis with the resulting estimates being useful to both learners and educators for feedback and educational quality improvement. In this primer, we review various descriptive and modelling techniques appropriate to learning curves including smoothing, regression modelling and application of the Thurstone model. Using an example dataset we demonstrate each technique as it specifically applies to learning curves and point out limitations.

Accuracy of self-monitoring during learning of radiograph interpretation.

CONTEXT: Despite calls for the improvement of self-assessment as a basis for self-directed learning, instructional designs that include reflection in practice are uncommon. Using data from a screen-based simulation for learning radiograph interpretation, we present validity evidence for a simple self-monitoring measure and examine how it can complement skill assessment. METHODS: Medical students learning ankle radiograph interpretation were given an online learning set of 50 cases which they were asked to classify as 'abnormal' (fractured) or 'normal' and to indicate the degree to which they felt certain about their response (Definitely or Probably). They received immediate feedback on each case. All students subsequently completed two 20-case post-tests: an immediate post-test (IPT), and a delayed post-test (DPT) administered 2 weeks later. We determined the degree to which certainty (Definitely versus Probably) correlated with accuracy of interpretation and how this relationship changed between the tests. RESULTS: Of 988 students approached, 115 completed both tests. Mean ± SD accuracy scores decreased from 59 ± 17% at the IPT to 53 ± 16% at the DPT (95% confidence interval [CI] for the difference: -2% to -10%). Mean self-assessed certainty did not decrease (rates of Definitely: IPT, 17.6%; DPT, 19.5%; 95% CI for difference: +7.2% to -3.4%). Regression modelling showed that accuracy was positively associated with choosing Definitely over Probably (odds ratio [OR] 1.63, 95% CI 1.27-2.09) and indicated a statistically significant interaction between test timing and certainty (OR 0.72, 95% CI 0.52-0.99); thus, the accuracy of self-monitoring decayed over the retention interval, leaving students relatively overconfident in their abilities. CONCLUSIONS: This study shows that, in medical students learning radiograph interpretation, the development of self-monitoring skills can be measured and should not be assumed to necessarily vary in the same way as the underlying clinical skill.

Prevalence of abnormal cases in an image bank affects the learning of radiograph interpretation.

OBJECTIVES: Using a large image bank, we systematically examined how the use of different ratios of abnormal to normal cases affects trainee learning. METHODS: This was a prospective, double-blind, randomised, three-arm education trial conducted in six academic training programmes for emergency medicine and paediatric residents in post-licensure years 2-5. We developed a paediatric ankle trauma radiograph case bank. From this bank, we constructed three different 50-case training sets, which varied in their proportions of abnormal cases (30%, 50%, 70%). Levels of difficulty and diagnoses were similar across sets. We randomly assigned residents to complete one of the training sets. Users classified each case as normal or abnormal, specifying the locations of any abnormalities. They received immediate feedback. All participants completed the same 20-case post-test in which 40% of cases were abnormal. We determined participant sensitivity, specificity, likelihood ratio and signal detection parameters. RESULTS: A total of 100 residents completed the study. The groups did not differ in accuracy on the post-test (p = 0.20). However, they showed considerable variation in their sensitivity-specificity trade-off. The group that received a training set with a high proportion of abnormal cases achieved the best sensitivity (0.69, standard deviation [SD] = 0.24), whereas the groups that received training sets with medium and low proportions of abnormal cases demonstrated sensitivities of 0.63 (SD = 0.21) and 0.51 (SD = 0.24), respectively (p < 0.01). Conversely, the group with a low proportion of abnormal cases demonstrated the best specificity (0.83, SD = 0.10) compared with the groups with medium (0.70, SD = 0.15) and high (0.66, SD = 0.17) proportions of abnormal cases (p < 0.001). The group with a low proportion of abnormal cases had the highest false negative rate and missed fractures one-third more often than the groups that trained on higher proportions of abnormal cases. CONCLUSIONS: Manipulating the ratio of abnormal to normal cases in learning banks can have important educational implications.