Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A well - defined opacity adjacent to the left side of the mediastinum likely reflects post radiotherapy change , as seen on the prior PET - CT . Lung volumes are within normal limits . The trachea is central . The cardiomediastinal contour is normal . The heart is not enlarged . No consolidation or pneumothorax seen .
    OUTPUT:
    
Postradiation changes , no acute pulmonary process seen .