Robin Decoster

Do radiographers base the diagnostic acceptability of a radiograph on anatomical structures

Background The document “European Guidelines on Quality Criteria for Diagnostic Radiographic Images” describes the visualisation of anatomical criteria to which a radiograph of diagnostic quality should comply. This research investigates the correlation between the evaluation of anatomical structures, presented in the European guidelines, and the classification of radiographs for diagnostic acceptability. Methods Sixteen radiographers classified 22 chest radiographs in terms of diagnostic acceptability using the RadLex categories, and scored the representation of five anatomical criteria on a scale from 1 to 5. All radiographs were visualised with ViewDex on a DICOM calibrated display. Observers were recruited in Belgium and Ireland. An interclass correlation coefficient was applied to evaluate internal consistency for each observer group. A Mann–Whitney U-test was applied to investigate differences in classification between countries. The relationship with the evaluation of anatomical structures was investigated with ordinal logistic regression. Results Both groups of observers performed with acceptable consistency. The Mann–Whitney U test illustrated a significant difference in classification between the two countries. The ordinal logistic regression indicated for each country a weak correlation between the RadLex and the anatomical structures. Certain factors in the radiograph, possibly others than anatomical elements, must be significantly better before the observer will attribute a higher RadLex score. Conclusion The relationship between the evaluation of anatomical criteria and the diagnostic acceptability is weak for both countries. When assigning a radiograph to a certain category of acceptability, other factors influence the decision.

Variability amongst radiographers in the categorization of clinical acceptability for digital trauma radiography

Introduction: Radiographers evaluate anatomical structures to judge clinical acceptability of a radiograph. Whether a radiograph is deemed acceptable for diagnosis or not depends on the individual decision of the radiographer. Individual decisions cause variation in the accepted image quality. To minimise these variations definitions of acceptability, such as in RadLex, were developed. On which criteria radiographers attribute a RadLex categories to radiographs is unknown. Insight into these criteria helps to further optimise definitions and reduce variability in acceptance between radiographers. Therefore, this work aims the evaluation of the correlation between the RadLex classification and the evaluation of anatomical structures, using a Visual Grading Analysis (VGA) Methods: Four radiographers evaluated the visibility of five anatomical structures of 25 lateral cervical spine radiographs on a secondary class display with a VGA. They judged clinical acceptability of each radiograph using RadLex. Relations between VGAS and RadLex category were analysed with Kendall’s Tau correlation and Nagelkerke pseudo-R². Results: The overall VGA score (VGAS) and the RadLex score correlate (rτ= 0.62, p<0.01, R2=0.72) strongly. The observers’ evaluation of contrast between bone, air (trachea) and soft tissue has low value in predicting (rτ=0.55, p<0.01, R2=0.03) the RadLex score. The reproduction of spinous processes (rτ=0.67, p<0.01, R2=0.31) and the evaluation of the exposure (rτ=0.65, p<0.01, R2=0.56) have a strong correlation with high predictive value for the RadLex score. Conclusion: RadLex scores and VGAS correlate positively, strongly and significantly. The predictive value of bony structures may support the use of these in the judgement of clinical acceptability. Considerable inter-observer variations in the VGAS within a certain RadLex category, suggest that observers use of observer specific cut-off values.

Assessment of image quality in orthopaedic radiography with digital detectors: a visual grading analysis

Background: The introduction of digital detectors in the radiology predicted a dose reduction. Due to the dynamic range, radiographs of sufficient quality can be produced with a lower detector air kerma (DAK). However, this reduction was not observed. Some authors indicate a creep towards higher DAK, explained by a better appreciation of the radiographs due to a higher contrast-to-noise ratio. Methodology: To investigate the relation between the DAK and the appreciation of image quality by radiologists, 172 anterior-posterior (AP) radiographs of the knee and 152 radiographs of the pelvis were collected in 19 radiology centres. A Visual Grading Analysis (VGA) with a five-point scale was used to judge the image quality of seven different anatomic structures. The mid-point of the scale (3) was equalized to diagnostic image quality. Six experienced radiologists scored both datasets, in a controlled environment, with ViewDex®. Every observer received instructions and a training dataset. Moreover, twenty radiographs were repeated to determine intra-observer variability. Results: The intra-observer variability was not significant (p>0.05) for both datasets. The knee AP obtained a VGAS score of 3.91, the pelvis AP obtained a VGAS score of 3.71. In both cases, the inter-observer correlation was high and significant. The correlation between the VGAS and the DAK (0.41μGy – 6.18μGy) was not significant in either of the cases; neither did other analysises based on technical parameters. Conclusion: The VGA revealed an image quality higher than diagnostic necessary. Based on the DAK, an overexposure is suspected. The relation between DAK and the appreciation has to be further investigated in detail.