I n 2015, approximately 137 million patients presented to the emergency department (ED) in the United States (43.3 visits per 100 persons) (1). Respiratory diseases were the second most common primary diagnosis in these patients, accounting for 9.8% of all visits (1). Chest radiography is the first-line examination for the evaluation of various thoracic diseases (2-8). The number of chest radiographs per ED visit increased by 81% between 1994 and 2014, suggesting an increasing dependency on chest radiographs (9). The interpretation of chest radiographs is a challenging task, requiring experience and expertise. Previous studies have reported suboptimal performance in the interpretation of chest radiographs by ED physicians compared with expert radiologists (10-13). In addition, the American College of Radiology recommends that qualified radiologists be available to interpret all radiographs obtained in the ED (14). However, there is a practical limitation with regard to the full-time availability of expert radiologists, especially for after-hours coverage. In a 2014 survey (15), 73% of the academic radiology departments in the United States did not provide overnight coverage by faculty. Thus, for after-hours ED coverage, a computer-aided detection system for clinically relevant findings on chest radiographs may help improve the quality of radiographic interpretation and overall turnaround time. Recently, deep learning (DL) algorithms with medical image analysis systems have been evaluated for retinal fundus photographs (16,17), pathologic images (18), and