Despite its importance, organizations have not stressed CXR interpretation. Only 29% of medical schools have a required clerkship in diagnostic radiology.22
The Liaison Committee on Medical Education (LCME) states that “Educational opportunities must be available in … diagnostic imaging.”1
Thus, specific CXR interpretation training is not mandated for undergraduate medical education.
While the American Board of Internal Medicine has a requirement for competency in electrocardiogram interpretation, there is no similar requirement for CXR interpretation.2
Surprisingly, it is also not a required procedure for board certification in cardiology, pulmonary medicine, or critical care medicine.2
The Accreditation Council for Graduate Medical Education (ACGME) is responsible for accreditation for most residency programs in the United States. The ACGME IM Residency Review Committee's program requirements state that “All residents should develop competency in interpretation of chest roentgenograms.”3
The program requirements for pulmonary medicine, cardiovascular medicine, and diagnostic radiology have similar statements.4–6
There is no mention of how competency should be achieved or assessed. The ACGME critical care medicine program requirements make no mention of CXR interpretation.7
At many institutions, house officers are expected to interpret CXR and make clinical decisions before a formal reading by a radiologist. This is particularly important for radiographic emergencies such as pneumothorax, pneumomediastinum, pneumoperitoneum, and misplacement of central venous catheters, pulmonary artery catheters, intra-aortic balloon pumps, chest tubes, gastric tubes, and endotracheal tubes.23
Our study included three emergencies—pneumothorax (misdiagnosed by 91%), misplaced central venous catheter (misdiagnosed by 74%), and pneumoperitoneum (misdiagnosed by 54%). In addition, a significant percentage of participants absolutely certain of their diagnoses on these emergencies were wrong. This is especially worrisome because house staff absolutely certain of their CXR interpretation may not ask a senior colleague for a second opinion.
Subjects also had difficulty interpreting the normal CXR. This occurred even though they were instructed that 1 or more of the CXR in the survey might be normal. Other researchers have noted difficulty in interpreting a study as normal.15,16,18,24
Potentially, interpreting a normal CXR as abnormal could lead to inappropriate decisions.
While the overall score was low, we identified several factors significantly correlated with successful interpretation. Overall certainty was correlated with overall score. Radiology residents performed significantly better than IM residents. Internal medicine interns and residents interested in a pulmonary career performed significantly better than their peers. Although we do not have data to confirm this, it is possible that residents interested in a pulmonary career may have done more self-study. Alternatively, they may have enrolled in more rotations where they were exposed to CXR teaching. Also, their attendance may have been better at CXR teaching conferences. Finally, overall score increased with level of training. This was found even though the amount of CXR instruction was not the same for each individual participant. For example, while all of the IM interns had had the opportunity to attend 6 formal CXR lectures, only 50% of the interns had had a MICU month at the time of the CXR survey.
One prior study identified certainty on a particular CXR as being associated with successful interpretation of that CXR.25
There is also evidence that when a clinician is certain about an interpretation he is less likely to be wrong.26
However, as our study demonstrates, verification may be required even when a house officer is 100% confident.
As identified by Pfeifer, 2 possible solutions exist to the problems in CXR interpretation identified by this and prior studies.27
The first approach would be to have all CXR immediately interpreted by a qualified radiologist. This could be accomplished by increasing the number of on-site radiologists or by tele-radiology. The second approach would be to improve interpretation skills of clinicians at the point of care. Theoretically, there is great value in integrating the radiographic interpretation with other findings from the history, physical exam, and laboratory findings. For example, a radiologist may interpret a CXR with bilateral infiltrates as pulmonary edema, A clinician may integrate the patient's history (cough and sputum production), physical exam (hyperthermia), and laboratory findings (increased white blood cell count) and diagnose multilobar pneumonia.
There are several possible approaches to improving CXR interpretation skills. Computer-aided diagnosis of CXR can improve interpretation.23,28,29
One study showed that using a picture archiving and communication system (PACS) rather than standard films improves interpretation.30
However, our study was done in an institution with PACS and important diagnoses were still missed. A program of formal training significantly improves CXR readings31,32
and computer-based training may be more effective than traditional methods.32
Quality improvement initiatives improve error rates.33,34
In a prospective study by Espinosa, a program stressing an interdisciplinary approach and review of all misinterpreted films led to significantly fewer errors.34
Other potential methods to improve CXR interpretation would be web-based modules or encouraging IM house staff to enroll in formal radiology electives. Perhaps the simplest method to improve CXR interpretations would be ensuring that MS and house staff read all CXR of patients under their care and review the results with a physician with proven competence in CXR interpretation. The utility of these methods warrant further investigation.
There are several strengths to our study compared with prior studies in this area. First, the study was one of the largest studies of CXR interpretation in terms of number of participants. Second, subjects from multiple fields of medicine and multiple training levels were compared. Third, this is only the second study to directly confirm that confidence on a particular CXR reading is associated with successful interpretation. Fourth, we have shown that interest in a pulmonary career is associated with successful interpretation. Fifth, we have identified particular CXR emergencies where interpretation skills are lacking. Finally, we have shown that even subjects who are 100% sure of their interpretations are wrong a high percentage of the time.
There are several limitations to our study. First, a small and somewhat arbitrary sample of CXRs was chosen for the survey. While these were representative of common conditions, results may have been different with other CXR. Second, we did not provide house staff with clinical context for the CXR. Schreiber demonstrated in 1963 that clinical history improves CXR interpretation.35
A systematic review of 16 articles also demonstrated that test interpretation improves if clinical information is provided.36
We chose not to provide clinical information because this was a study of how well trainees interpret important, common, unambiguous radiographic findings. Adding clinical information would make the results less clear as responses could reflect understanding of the clinical scenario more than ability to recognize radiographic abnormalities. Additionally, the current training system in the United States requires frequent hand-offs of clinical information that is variably transmitted to the persons required to check CXR. Third, the gold standard in our study can also be questioned. Studies have shown that even experienced radiologists may have differing interpretations of a CXR.19,37–39
In our study, the blinded experts were in 100% agreement on our series of CXR. This was probably because the CXR were classic examples of common conditions. Fourth, the CXR in the study were depicted on paper. Although the quality of the reproductions was high, subjects were used to interpreting CXR on digital monitors and this may have affected the results. Finally, this study took place at 1 teaching institution. Possibly other institutions, with different teaching methods, may have different results.
In conclusion, we have identified deficiencies in CXR interpretation with potential implications for MS education, house staff education, and patient care. If house officers are expected to make clinical decisions based on CXR readings, more effective training is needed, particularly in radiographic emergencies. Further research is needed to determine the best methods of achieving and assessing competency in CXR interpretation.