Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single AP view of the chest . No prior . Linear opacity identified at the left lung base suggestive of atelectasis . Elsewhere , the lungs are grossly clear . There is no evidence of pulmonary vascular engorgement . Costophrenic angles are sharp . Cardiomediastinal silhouette is within normal limits , as are the osseous and soft tissue structures .
    OUTPUT:
    
No acute cardiopulmonary process . No evidence of frank pulmonary edema .