Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest demonstrate top normal cardiac size . The mediastinal and hilar contours are within normal limits . The lungs are clear . There is no pneumothorax , vascular congestion , or pleural effusion . Correlation with subsequent CTA demonstrating subsegmental atelectasis in the left lower lobe which is not well seen on current exam .
    OUTPUT:
    
No definite acute cardiopulmonary process .