Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single upright portable chest radiograph demonstrates clear lungs bilaterally . Cardiomediastinal silhouette is within normal limits . There is no pneumothorax or pleural effusion . Imaged osseous structures demonstrates no acute abnormality . Upper abdomen is unremarkable .
    OUTPUT:
    
No acute intrathoracic abnormality .