[Diagnostic Neuroradiology in Head Injury]

The 4th edition of the Guidelines for Treatment and Management of Head Injury by the Japan Society of Neurotraumatology newly published a three-step evaluation method for CT, indications for repeat CT, cancer risk associated with radiation exposure, and preparation of examination guidelines for reduction of radiation exposure. This manuscript describes how to proceed with diagnostic imaging of head injuries and the new items. The important points are as follows: •CT is the first-step diagnostic imaging method in the acute phase. •Initial CT assesses the presence or absence of intracranial hemorrhage requiring emergency craniotomy. •It is necessary to perform repeat CT to assess secondary injury. •For minor head injuries, the indication for CT should be determined by confirming neurological concomitant symptoms considering radiation exposure.