Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal radiographs of the chest demonstrate low lung volumes . Heart size is normal . Bibasilar atelectasis is present but the lungs are otherwise clear . The cardiomediastinal silhouette and hilar contours are normal . No pleural effusion or pneumothorax . No displaced rib fracture identified .
    OUTPUT:
    
No convincing evidence of pneumonia on this exam limited by low lung volumes .