by
Les Folio, DO, MPH
Col, USAF, MC, SFS
Introduction:
The Chest X-Ray (CXR) or chest radiograph remains the most commonly ordered imaging study in medicine yet paradoxically is the most complex. The CXR is the hardest modality for which to learn, recall and master effective and accurate interpretation. The chest radiograph is difficult to interpret, especially in critical care where there are multiple findings. The chest radiograph includes everything in the thorax and provides a high yield, given the low cost and single source. The CXR is also the most commonly utilized imaging study in combat operations.
The following Guide is organized by categories of findings that can be seen on the CXR. This material is presented in a novel format using directory structures to allow students and residents to dig as deep as they like on a topic at hand. The chunked information is designed to link from a larger project called "ChestWeb," an expert system to help guide image interpretation. This content follows the organization of how material is presented to medical students at the Uniformed Services University's (USU's) F. Edward Hebert School of Medicine. The Department of Radiology and Radiological Sciences has taught the CXR in this manner to provide our students with the ability to read the CXR on their own in a variety of austere environments. Although it supplements the online ChestWeb project, this content is self-contained and can be used independently of the ChestWeb. Our students have requested the information in a format that does not depend on Internet access and this content is being distributed independently in stand-alone form to meet that request.
Radiology is taught in all four years of medical school at USU. Our second year medical students have several didactic sessions on the CXR to including an oral exam of normal anatomy and the search pattern of the frontal and lateral CXR. The material in the relevant sections of this Guide should help prepare the student for this exam and serve as a ready reference while the student is on clinical rotations.
For over 16 years, the faculty of the Department of Radiological Sciences has conducted an elective course in the fourth year titled: Radiologic Interpretation: RDR4100/RDR4110. A major educational goal of this elective is to impart to the students a systematic methodology of evaluating abnormalities shown on plain film posterior-anterior (PA)/lateral (LAT) CXRs, the most common type of medical X-Ray performed, and interpreting those findings in light of the clinical setting. The department has always viewed its undergraduate educational efforts as an integral part of its more global research interests in how to most effectively and efficiently teach principles of radiographic image interpretation.
This work presents a structured lexicon for use by USU medical students to reproducibly describe radiographic abnormalities detected on plain film CXRs. The lexicon is designed to provide the students with clinically significant differentiation of abnormalities detected. The content is chunked in a directory structure that relates specific combinations of distinct radiographic findings to classes/groupings of pathological etiologies of those findings. Recognizing the individual findings and identifying their combination or lack of combination with other individual findings allows students to create effective differential diagnoses that can then be further evaluated using other imaging procedures and/or non-radiographic clinical information. Included in this work are hundreds of images including x-rays, Computerized Tomography (CT) images, graphics, analogous models, animations and video to help teach otherwise complex processes and radiographic principles. This material is by no means comprehensive and is designed as a teaching tool. It should not be used for medical diagnosis.
The same directory structure method is taught in the National Capital Area radiology residency program in the introduction of chest imaging. It may be helpful to residents in reviewing the general differentials and discussing possibilities with faculty and referring physicians. This method may also be helpful for General Medical Officers (GMOs) in deployed or remote locations without other available references.
Acknowledgements:
This product was created by the Education & Technology (ETI) Support Office at Uniformed Services University. The ETI team methodically organized the lecture materials and other content into sections that would illuminate the complex art of the CXR and then developed the pages and the directory structure. The ETI Support Office is operated by Concurrent Technologies Corporation.
Educational support/ funding:
The ChestWeb project was supported in part by the Henry M. Jackson Foundation (HMJF) and a Corporate Research and Development Award (CRADA) with Expert-24, USU and HMJF. In addition, several intramural grants such as the Dean's Endowment fund helped develop this teaching tool.