Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The cardiomediastinal and hilar contours are stable with calcification of the aortic knob . There is no pneumothorax or pleural effusion . The lungs are well - expanded . A small peripheral left base opacity may represent atelectasis or scarring and was present on the most recent prior chest radiograph . Moderate degenerative changes are present throughout the thoracic spine .
    OUTPUT:
    
No acute cardiopulmonary process .