Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral radiographs of the chest show a persistent bulla in the posterior right lower lobe best appreciated on the lateral radiograph . Persistent linear opacities in the right lung base likely represent scarring . The right costophrenic angle is clear without pleural effusion . No pneumothorax is present . The lungs are hyperinflated with coarse interstitial markings consistent with background COPD / emphysema , which is unchanged over multiple prior studies . The overall appearance of the lungs is unchanged from the preceding radiograph without new focal consolidation . The cardiac silhouette is normal in size . The mediastinal and hilar contours are within normal limits . The thoracic aorta is mildly tortuous . Healed rib fractures are unchanged .
    OUTPUT:
    
Findings consistent with COPD / emphysema with stable scarring of the right lung base and a posterior right lower lobe bulla without evidence of acute infection .