Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Frontal and lateral chest radiographs demonstrate a normal cardiomediastinal silhouette and well - aerated lungs without focal consolidation , large pleural effusion , or pneumothorax . Mild blunting of posterior costophrenic angles could represent trace effusions . Vague opacity projecting over the left anterior fourth rib is most suggestive callus formation from prior rib fracture .
    OUTPUT:
    
No acute cardiopulmonary process .