British Journal of Radiology 74 (2001),230-233 © 2001 The British Institute of Radiology
The role of preliminary interpretation of chest radiographs by radiographers in the management of acute medical problems within a cardiothoracic centre
E P Sonnex, DCR (R/T),
A D Tasker, MRCP, FRCR and
R A Coulden, FRCP, FRCR
Clinical Radiology Department, Papworth Hospital, Papworth Everard, Cambridge CB3 8RE, UK
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Abstract
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Radiographic staff in a regional cardiothoracic centre were asked to assess all pre- and post-operative chest radiographs over a 6-month period. Radiographs showing new, acute changes were noted and a red dot placed on the film. Medical staff were notified of radiographs with red dots, and these were subsequently reported by radiologists. Using reports by radiologists as the gold standard, an audit was performed of the radiographers' accuracy in identifying new abnormalities. The absence of a necessary red dot as well as inappropriate use were noted. To enhance the accuracy of radiograph interpretation, a series of lectures on the chest radiograph and a protocol for red dot use were developed by senior radiologists. During this 6-month period 8614 chest radiographs were taken; red dots were applied to 464 (5%). These red dots were considered incorrect in 100 radiographs. Radiographers misinterpreted or missed potentially important changes in 38 of the remaining 8150 radiographs without red dots (sensitivity and specificity of 90% and 99%, respectively). Radiographers appeared to err on the side of caution when confronted with an abnormal chest radiograph, especially when previous radiographs and reports were unavailable. This resulted is a relatively high false positive rate. Future audits will show whether this rate can be reduced by continued training. Subtle interpretation is crucial to distinguish between an abnormal chest radiograph needing urgent medical attention and an abnormal chest radiograph with normal post-operative changes. The opinion of the experienced and trained radiographer is immediate and may be invaluable to the diagnostic care of the patient.
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Introduction
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Initial radiographer interpretation and "red dotting" of radiographs is not new in the UK. Many Accident and Emergency (A&E) departments use the system very successfully [1, 2], with the radiographer applying red dots on radiographs to highlight abnormalities for the attention of casualty officers. Many casualty staff are inexperienced and interpretation by staff in A&E departments shows frequent errors when compared with the subsequent radiologist's report [3–10]. Snow [3] compared radiographic interpretation by medical staff with the subsequent radiologist's report and found complete agreement in only 54% of cases. Of the remaining 46%, 25% were considered to have potentially important discrepancies in interpretation. In another audit of chest radiography in an A&E department, 29% of radiographs were found to have been misinterpreted by casualty officers [7].
In many A&E departments, the radiographer's opinion is the most experienced radiographic opinion available and may identify significant abnormalities missed by the casualty officer [1].
The radiographer is often considered simply as a technician, providing high quality radiographs suitable for later interpretation by the clinician. This underestimates the value of their experience and the potential of this experience in initial interpretation. With suitable experience and after tuition [11–14], selected radiographers can feel confident in assessing radiographs for pathological changes. By alerting clinicians to abnormalities requiring urgent attention, the radiographer may enhance the effectiveness of junior clinical staff and help to reduce delays in appropriate patient care.
The purpose of this study was to assess whether experienced radiographers working in a cardiothoracic surgical unit are capable of identifying significant changes on both pre- and post-operative chest radiographs. Determining the accuracy of spotting abnormalities is an important first step in the process of deciding whether radiographers have a useful role to play in more formal reporting of chest radiographs.
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Patients and methods
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The Radiology Department of Papworth Hospital NHS Trust comprises 17 radiographers, 4 consultant radiologists and 2 junior radiology staff. An audit was performed of all pre- and post-operative chest radiographs taken in the surgical unit between October 1998 and March 1999 inclusive. During this period, all radiographers were requested to carefully assess the chest radiographs they had produced and place a red dot on those radiographs that they considered to show acute changes requiring immediate medical attention. A red dot protocol was developed and all radiographers attended a programme of lectures on chest radiograph interpretation, with particular emphasis on the post-operative chest following cardiothoracic surgery. This course of lectures has been regularly repeated to maintain skills and to train new staff. In addition to this programme, there were regular feedback sessions on selected red dot radiographs.
The protocol adopted for radiographers to identify new and significant changes on chest radiographs that required urgent medical attention, i.e. those requiring a red dot, is given in Table 1
. Radiological findings that, although abnormal, were considered inappropriate for a red dot included normal post-operative changes (e.g. blunting of costophrenic angles, left lower lobe collapse and lower lobe atelectasis), previously known or reported pathology and anticipated change related to a specific operation (e.g. pneumonectomy, oesophagectomy). Attending medical staff were informed when a radiograph was assessed as abnormal by the radiographer.
Red dot radiographs were noted in a register, together with the relevant patient details and the reason why the radiograph was considered worthy of a red dot. In keeping with routine clinical practice, all chest radiographs were subsequently reported by a radiologist. At the time of reporting, radiologists were asked to comment on whether the radiographs should or should not have received a red dot and whether radiographs that had received one were red dotted for appropriate reasons.
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Results
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During the 6-month study period, 8614 plain chest radiographs were performed, including both mobile and departmental radiographs on pre- and post-operative cardiothoracic patients. 464 (5%) chest radiographs were red dotted. 100 (22%) of these were reported by the radiologist as being incorrectly red dotted. The commonest reason for an incorrect red dot was the radiograph showing "no significant change" (90%), with the remaining 10 radiographs being reported as unremarkable for that patient.
8150 radiographs did not receive a red dot and reporting radiologists considered that 38 (<0.5%) of these should have been red dotted. These radiographs showed the following abnormalities: new or significant pneumothorax/pericardium/mediastinum (13–0.2%); new pleural effusion (7–0.08%); pulmonary oedema (6–0.07%); incorrect line position (5–0.06%); and new or significant collapse/consolidation (5–0.06%).
Using the radiologist's report of the chest radiograph as the gold standard, the sensitivity and specificity of the radiographers' red dot allocation was 90% and 99%, respectively, with a negative predictive value of 99.5% and a positive predictive value of 78.4% (Table 2).
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Table 2. Assessment of application of red dot system by radiographers, with radiologists' reports as the gold standard
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Bayesian analysis combines the pre- and post-test likelihood of disease [15]. The pre-test likelihood of a significant abnormality being present was approximately 5%. Using Bayes Theorem of Conditional Probability, which is a function of the pre-test likelihood, the sensitivity and the specificity, the post-test likelihood was 79% (Table 3). In short, radiographers correctly identify four out of five radiographs with a significant abnormality in a population with an abnormality rate of 1 in 20.
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Discussion
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The initial interpretation by radiographers was generally reliable. In over 8000 chest radiographs performed during this 6-month period, radiographers "missed" potentially important changes in just 38 examinations, i.e. <0.5% of the total number of chest radiographs. The most commonly missed abnormality was a small, apical pneumothorax or a new post-operative effusion. In none of these cases was a chest drain inserted.
Radiographers working in a specialized cardiothoracic unit are constantly seeing a large numbers of pre- and post-operative chest radiographs. As a result, they may acquire interpretative skills that often go unrecognized. Accurate interpretation, however, requires more than working with plain radiographs; training is also important. Loughran [13] showed that a suitable training programme can make a significant impact on the ability of radiographers to interpret fracture radiographs in the A&E department. Following pertinent training, the sensitivity for identifying fractures rose from 81% to 95.9%, with a concomitant improvement in specificity. Similar improvements were seen with increasing years of experience [16].
22% of red dotted radiographs, 1% of the total number of chest radiographs obtained, were considered inappropriately marked. This was partly due to training, whereby radiographers were urged to err on the side of caution and to award a red dot to any radiograph where there was doubt about new changes, and partly due to interpreting radiographs without having previous chest radiographs available for comparison. The latter can be difficult outside of working hours but isessential if accuracy is to be improved. Formal reporting is enhanced by having previous radiographs and clinical information [16] available, and this red dot process should be treated the same way.It is important to remember that a large proportionof patients examined in the cardiothoracic unit have abnormal chest radiographs, particularly in the post-operative period. The radiographers in this study were required to identify radiographs with "significant" abnormalities or "significant change", not simply those with an abnormality.
There are numerous anecdotes where the immediacy of a chest radiograph report has brought major benefit to patient outcome. A clear relationship between the speed of reporting and reduced patient length of stay or complication rate, however, has not been shown. At our institution all plain radiographs are reported by a radiologist, but only 70% of these reports are available within 24 h and only 90% within 3 days. These figures could be improved with additional resources but in practice can never match the instant report of the radiographer carrying out the examination. In addition, if additional resources are made available, it is debatable whether they should be used for reporting of plain radiographs. Long waiting lists for CT, MRI, ultrasound etc. may offer better use of a scarce resource.
A red dot system may be useful in departments where not all plain radiographs are reported owing to a heavy workload and inadequate resources. Although limited to distinguishing between normal and significantly abnormal results, it would enable radiologists to prioritize their workload once alerted to the presence of an abnormality. Unless radiographers formally report radiographs, this system would only supplement the report rather than replace it, as the red dot system gives no diagnostic information. Similar pre-screening has been adopted in other fields, e.g. by cytotechnicians in cervical cancer screening, double reading by a radiographer/radiologist pair in mammography [12] and radiographer-based ultrasound services [13]. A red dot should not be considered an alternative to a radiologist's report, but with an audited and well organized system in place we believe this can be an accurate first assessment.
As in other settings where red dot reporting has been introduced, there was a mixed reception from clinical staff. Initially many felt it was inappropriate to have the radiographer draw their attention to a chest radiograph abnormality, and in some instances this led to the radiographer's advice being ignored. Exposure of junior staff to a seemingly effective red dot system over 6 months has totally reversed this attitude. All clinical staff now fully endorse the programme, the only drawback being a tendency for staff to review only those radiographs with a radiographer's red dot.
This study raises the important question of formal reporting of radiological examinations. Renwick et al [17] showed that the performance of unselected radiographers was unsatisfactory compared with that of consultant and trainee radiologists. Later studies by Robinson and colleagues [2, 18] suggested that carefully selected radiographers, given appropriate training, can report A&E department radiographs with a sensitivity and specificity similar to that achieved by radiologists. Chest radiographs are perhaps the most complex of all plain radiographs and give discordant results more frequently than other radiographs [19–21]. Our experience suggests this could be improved by training. The importance of this development, given the shortage of radiological manpower, cannot be underestimated and further evaluation of the role of the radiographer in formal plain radiograph reporting is needed.
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Acknowledgments
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We would like to thank all of the radiology staff of Papworth Hospital for their participation in this ongoing study.
Received for publication February 3, 2000.
Accepted for publication November 27, 2000.
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Abstract
Introduction
