Plain radiographs may be appropriate in low-risk patients
High risk patients requiring CT:
Closed head injury
Neurologic deficits
High energy trauma
Unreliable examination
Pain out of proportion to exam
Inadequate plain films
Closed head injury
Neurologic deficits
High energy trauma
Unreliable examination
Pain out of proportion to exam
Inadequate plain films
Cervical spine x-ray interpretation
Chest x-ray interpretation
Canadian cervical spine rule
X-ray interpretation 
Neck diagnoses
Tongue diagnoses
NEXUS cervical spine rule
Predicting the difficult airway