Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Portable upright radiograph of the chest demonstrates a large amount of intraperitoneal free air lifting the diaphragm off the liver surface . Within the upper abdomen , there are severely dilated loops of colon , with the transverse colon measuring up to 11 cm in diameter . The lungs are clear . The hilar and cardiomediastinal contours are normal . There is no pneumothorax or pleural effusion . Pulmonary vascularity is normal .
    OUTPUT:
    
1 . Perforated toxic megacolon secondary to C . difficile colitis . 2 . No acute cardiopulmonary process .