Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral chest radiographs were obtained . The lungs are low in volume but appear clear . There is no pleural effusion or pneumothorax . The heart is normal in size with tortuous aortic contour . Left humeral head prosthesis is incompletely assessed .
    OUTPUT:
    
No acute intrathoracic process .