It's just that one inspection is not too harmful, and the radiation dose is within the safe range. Don't worry too much. If we must compare the two kinds of injuries, we can only say that CT will be bigger, or for example, when eating, B-ultrasound is equivalent to choking in the nose, and CT is equivalent to choking in the trachea. Relatively speaking, choking in the trachea is a bit dangerous, but you can't stop eating because you choke.