We examined the optimum conditions for pediatric brain CT scans. CT controls the X-ray transit dose using tube current alteration called automatic exposure control (AEC) to adjust the standard deviation (SD) value for each scanning region, and it also reduces exposure. If the SD value is inappropriate, children may be exposed to increased radiation. Therefore we acquired images of 500 children from the server, and examined the most suitable SD value for each age using the data of their SD value and age. X-ray transit control with AEC was influenced by scan position and the age of a child. We enabled accurate scanning and decreased radiation exposure by adjusting AEC to the age and the cephalic volume of each child. As a result, reduction of the X-ray exposure by up to 31.2% per slice in tube current alteration was possible using a suitable SD value for each age. On the other hand, it was possible to reduce X-ray exposure by up to 67.9% per slice with the scan technique that used age and corrected cephalic volume without adjusting AEC. Using the tube current alteration protocol for each age with the data of the SD value or cephalic volume in CT, we can more easily conduct scans of children under optimal conditions.