Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: Single portable view of the chest is compared with previous exam of ___ . Low lung volumes are again noted however they appear grossly clear of confluent consolidation or pulmonary vascular congestion . Rounded lucency in the retrocardiac region is suggestive of possible hiatal hernia , similar to prior exam .
    OUTPUT:
    
Low lung volumes without definite acute cardiopulmonary process .