Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral chest radiograph is compared to prior radiograph dated ___ . The appearance of the thorax is not significantly changed . No focal opacity convincing for pneumonia is identified . Cardiomediastinal and hilar contours remain within normal limits . Patchy opacities within the left upper lobe and lingula are thought to reflect radiation changes . There is no pleural effusion or pneumothorax . Visualized osseous structures are without an acute abnormality .
    OUTPUT:
    
No evidence of pneumonia .