Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The heart size is normal . The mediastinal and hilar contours are unremarkable . Subsegmental atelectasis is demonstrated within the right lower lobe . Focal opacity within the lower lobe posteriorly on the lateral view , likely within the right lower lobe is present . There is an associated small right pleural effusion . No pneumothorax is seen . The pulmonary vasculature is normal .
    OUTPUT:
    
Posterior lower lobe opacity noted on the lateral view is likely within the right lower lobe and may reflect an area of infarction or infection . Small right pleural effusion is also demonstrated .