Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart is not enlarged . The cardiomediastinal silhouette is within normal limits . No CHF , focal infiltrate , effusion , or pneumothorax is detected . Possible minimal atelectasis at the left lung base . No focal opacity to suggest an area of aspiration pneumonitis at this time . Left convex bowing of the trachea likely relates to position of the head . Bony structures are grossly unremarkable . No free air seen beneath the diaphragm .
    OUTPUT:
    
Possible minimal atelectasis in the left lower lung . Otherwise , no acute pulmonary process identified . No findings suggestive of pneumonic infiltrate .