Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The lungs are clear with relatively low lung volumes . The heart size is top - normal . The mediastinal silhouette , hilar contours , and pleural surfaces are normal . Mild linear atelectasis is noted in the lower left lung . No pneumothorax , pulmonary edema , or pneumonia .
    OUTPUT:
    
No acute intrathoracic process .