Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: A single portable chest radiograph was obtained . An airspace opacity in the left lower lobe is new since ___ . The left heart border remains sharp . The medial left hemidiaphragm is obscured . In addition , there is a small left pleural effusion . There may be a subtle , developing opacity in the right lower lobe . There is no pneumothorax . Cardiac and mediastinal contours are normal .
    OUTPUT:
    
Left lower lobe pneumonia and parapneumonic effusion . A follow up radiograph should be obtained in ___ weeks to ensure resolution .