Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The left lung is well expanded and clear . The right lung shows a persistent right lower lobe opacity with an associated effusion , mildly progressed from the preceding radiograph . The cardiomediastinal silhouette , and hilar contours are normal . No pneumothorax is present . Old bilateral rib fractures are noted .
    OUTPUT:
    
Right lower lobe opacity , possibly atelectasis , with associated moderate sized effusion .