A 24 year old man falls on the ground when he is struck in the right temple by a baseball. While being driven to the hospital, he lapses into coma. He is unresponsive with the dilated right pupil when he reaches the emergency department. The most important step in initial management is -
Craniotomy
CT scan of the head
X-ray of the skull and cervical spine
Doppler ultrasound examination of the neck