The spiral scan with a wide detector row such as the 64-detector row computed tomography (CT) system may increase radiation exposure for infants because the irradiation range is wider than the planned range. The adaptive dose shield (ADS) prevents radiation exposure greater than the planned range. We examined the usefulness of the protection effect of the ADS for the infant inner ear CT. To confirm the protection effect of the ADS, we scanned X-ray films by using the 64-detector row CT system and measured the difference of the planned range and the irradiation range. The result of that is that when the planned range was small, the protection effect for the scan ending side was inferior to the scan starting side. And also, when the gantry rotation speed and pitch factor (PF) were high values, the protection effect was inferior to a low gantry rotation speed and low PF. There was a combination of gantry rotation speed and PF at which the protection effect decreases. Due to changes of the scanning direction and PF for the infant inner ear, the crystalline lens radiation exposure dose decreased from 11.89 mGy to 4.37 mGy. In conclusion, the ADS can reduce the radiation exposure dose of an adjacent organ. Therefore, it was thought that the ADS was a useful radiation exposure reduction function for infants in the 64-detector row CT system.