Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single semi-erect portable chest radiograph demonstrates decreased lung volumes from ___ . The lungs are clear without evidence of focal consolidation , pleural effusion , or pneumothorax . Increased opacification at the lung bases without obscuration of the diaphragm or heart borders is consistent with atelectasis in the setting of low lung volumes . The cardiac silhouette is within normal limits . The mediastinal and hilar contours are stable from the preceding study allowing for differences in technique . The thoracic aorta is mildly unfolded with calcification at the aortic knob .
    OUTPUT:
    
No radiographic evidence of pneumonia .