Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The visualized lung fields are clear of any focal opacities , pleural effusions or pneumothorax . Lung markings in the retrocardiac space are likely atelectasis within the left lower lobe . The cardiac and mediastinal silhouette is unremarkable . Visualized osseous structures are unremarkable .
    OUTPUT:
    
No acute cardiopulmonary process .