Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: An ill - defined opacity is seen which is appreciated only on the lateral view located in the posterior and lower lungs . This is seen only on the lateral view . This may be located in either of the lower lobes . Upper lungs are clear . There is no pleural abnormality . Heart size , mediastinal and hilar contours are normal . Mild atherosclerotic calcification is present in the aortic arch .
    OUTPUT:
    
Ill - defined opacity in the lower lungs appreciated on the lateral radiograph is concerning for focus of infection . This is seen only on the lateral view and anatomically may be located in either of the lower lobes . Followup radiographs is recommended in four weeks after appropriate treatment to assess for interval changes .