Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP supine portable chest radiograph demonstrates low lung volumes . This is thought to result in apparent cardiomegaly , exaggerated by expiratory films , the heart probably normal in size . There is no pneumothorax or pleural effusion . No air under the right hemidiaphragm is seen . Ribs are without an obvious displaced rib fracture . Clavicles appear intact .
    OUTPUT:
    
No acute intrathoracic abnormality . No rib fracture . If concern for fracture , consider rib films with radiopaque marker indicating site of concern .