Benign and self-limited disease
Generally does not require repeat imaging, and can be managed conservatively on an outpatient basis
Most cases are benign, but a minority of cases require additional testing and intervention.
Have lower threshold for additional testing and admission.
Pneumomediastinum
Acute coronary syndromes 
Hemothorax
STEMI
Chylothorax
Non-STEMI
Pneumopericardium
Unstable angina