Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral views of the chest were obtained . Subtle patchy left lower lobe opacity could represent atelectasis ; however , underlying infection is not excluded in the appropriate clinical setting . The right lung is clear . There is no pleural effusion or pneumothorax . The cardiac and mediastinal silhouettes are unremarkable .
    OUTPUT:
    
Questionable subtle focal left lower lobe opacity could be due to atelectasis or infection .