Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A portable radiograph of the chest was acquired . Lung volumes are slightly low , causing accentuation of the pulmonary vasculature . Aside from minimal bibasilar atelectasis , the lungs are clear . The descending thoracic aorta is mildly tortuous , as before . The cardiac and mediastinal contours are otherwise normal . There are no pleural effusions . No pneumothorax is seen . Multiple old right posterior rib fractures are again seen .
    OUTPUT:
    
No acute intrathoracic process .