Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: AP upright and lateral views of the chest were provided . Linear densities at the left lung base are most compatible with plate - like atelectasis . Patient is known to have left - sided rib fractures which likely account for some degree of splinting on the left . These fractures are better assessed on the prior CT . The right lung is clear . No convincing signs of pneumonia . The heart and mediastinal contours appear normal .
    OUTPUT:
    
Plate - like left lower lung atelectasis without definite signs of pneumonia . Known left rib fractures are better assessed on prior outside hospital CT scan .