Visual Interpretation of Plain Radiographs in Orthopaedics Using Eye-Tracking Technology

Abstract

Background: Despite the importance of radiographic interpretation in orthopaedics, there not a clear understanding of the specific visual strategies used while analyzing a plain film. Eyetracking technology allows for the objective study of eye movements while performing a dynamic task, such as reading X-rays. Our study looks to elucidate objective differences in image interpretation between novice and experienced orthopaedic trainees using this novel technology.

Methods: Novice and experienced orthopaedic trainees (N=23) were asked to interpret AP pelvis films, searching for unilateral acetabular fractures while eye-movements were assessed for pattern of gaze, fixation on regions of interest, and time of fixation at regions of interest. Participants were asked to label radiographs as "fractured" or "not fractured." If "fractured", the participant was asked to determine the fracture pattern. A control condition employed Ekman faces and participants judged gender and facial emotion. Data were analyzed for variation in eye movements between participants, accuracy of responses, and response time.

Results: Accuracy: There was no significant difference by level of training for accurately identifing fracture images (p=0.3255). There was a significant association between higher level of training and correctly identifying non-fractured images (p=0.0155); greater training was also associated with more success in identifying the correct Judet-Letournel classification (p=0.0029). Response Time: Greater training was associated with faster response times (p=0.0009 for fracture images and 0.0012 for non-fractured images). Fixation Duration: There was no correlation of average fixation duration with experience (p=0.9632). Regions of Interest (ROIs): More experience was associated with an average of two fewer fixated ROIs (p=0.0047). Number of Fixations: Increased experience was associated with fewer fixations overall (p=0.0007).

Conclusions: Experience has a significant impact on both accuracy and efficiency in interpreting plain films. Greater training is associated with a shift toward a more efficient and thorough assessment of plain radiographs. Eyetracking is a useful descriptive tool in the setting of plain film interpretation.

Clinical relevance: We propose further assessment of eye movements in larger populations of orthopaedic surgeons, including staff orthopaedists. Describing the differences between novice and expert interpretation may provide insight into ways to accelerate the learning process in young orthopaedists.

Keywords: eyetracking; orthopaedic resident; orthopaedic surgery; radiographs; resident education; technology.

Figure 1.

This image shows an example of a fractured AP pelvis x-ray, with subsequent task screens.

Figure 2.

This graph demonstrates participant accuracy and speed of response after visualizing fractured images.

Figure 3.

This graph demonstrates participant accuracy and speed of response after visualizing non-fractured images.

Figure 4.

This graph demonstrates the regions of interest (number of pauses on a pre-determined area of importance) of fixation for each participant by level of training.

Figure 5.

This graph demonstrates the number of fixations (total number of discrete pauses on the image) for each participant by level of training.