Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: PA and lateral views of the chest demonstrate the lungs are well expanded and clear . The cardiomediastinal silhouette is unremarkable . The hilar and pleural surfaces are normal with no evidence of pleural effusion . There is no pneumothorax . The retrosternal clear space is normal with no evidence of mass lesion . No osseous abnormality is present . Surgical clips are present in the lower neck , as before .
    OUTPUT:
    
No acute cardiopulmonary process . No evidence of substernal mass .