Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP portable semi upright view of the chest . There is irregular opacity at the left lung base which could represent atelectasis or aspiration , difficult to exclude contusion given history of fall . There is also mild platelike right basal atelectasis . There is no large effusion or pneumothorax on this semi upright portable radiograph . Heart size can not be assessed . Mediastinal contour appears well - defined . Reported rib fractures are poorly visualized .
    OUTPUT:
    
Left basal opacity concerning for atelectasis versus aspiration , difficult to exclude contusion .