Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable chest radiograph demonstrates apparent widening of mediastinum this is due to patient rotation . Cardiomediastinal and hilar contours are unremarkable . Low lung volumes with vascular crowding . Lungs are clear . No pleural effusion or pneumothorax .
    OUTPUT:
    
No acute intrathoracic process .