Rules below are according to the of PECARN<unk>  CT Study
GCS ≤14
Altered Mental Status
Palpable Skull Fracture
Then obtain a Non-Con Brain CT (4.4% risk of cTBI)
Non-frontal scalp hematoma
LOC ≥ 5 seconds
Severe injury mechanism
pedestrian or bicyclist without helmet struck by motorized vehicle
fall >1m or 3ft<unk>  struck by high-impact object
Abnormal activity per parents
pedestrian or bicyclist without helmet struck by motorized vehicle
fall >1m or 3ft<unk>  struck by high-impact object
Then consider a Non-Con Brain CT or Observation (0.9% risk of cTBI)
GCS ≤14
Altered Mental Status
Signs of a basilar skull fracture
Then obtain a Non-Con Brain CT (4.3% risk of cTBI)
History of vomiting^
LOC
Severe injury mechanism
Pedestrian or bicyclist without helmet struck by motorized vehicle
Fall >2m or 5ft<unk>  struck by high-impact object
Severe<unk> ache
Pedestrian or bicyclist without helmet struck by motorized vehicle
Fall >2m or 5ft<unk>  struck by high-impact object
Then consider a Non-Con Brain CT or Observation (0.9% risk of cTBI)
^Consider observation in place of imaging in children with isolated vomiting (no other indication) as the sole risk factor (0.2% risk of cTBI)
Head trauma 
Traumatic brain injury
Blast injury
Intracranial hemorrhage
Traumatic asphyxia
Moderate-to-severe traumatic brain injury
Trauma 
Elevated intracranial pressure