Summarize the radiology report findings into an impression within 3 sentences.
    INPUT: The right chest pigtail drain projects over the mid anterior lateral hemithorax . The right pneumothorax has substantially decreased in size in the interim , now small . Right lung has partially re-expanded with residual atelectasis predominantly in the lower lobe . The lungs are otherwise clear . No pleural effusion . The heart is top - normal in size . The mediastinum is not widened . No acute osseous abnormality .
    OUTPUT:
    
Improved right pneumothorax .