For children as young as one or two years old, they have little awareness of hazards and limited control over their own behavior, so they often bump their heads and parents are generally not very concerned about it. But if a child’s head is bumped, adults will be more worried, and anxious parents may immediately think of going to the hospital for a CT examination of their child. The trouble is that while CT exams may be helpful in determining the child’s injury, they may have an impact on the child’s future intellectual development. According to reports, Swedish scientists writing in a journal article pointed out that receiving radiation treatment in early childhood may impair future mental development. Scientists at the Karolinska Institute in Sweden studied more than 2,000 babies who had their birthmarks removed by radiation between 1930 and 1959, based on the Swedish Army’s medical files, and found that those boys who received treatment were significantly less able to learn and analyze logically than children who had not received radiation treatment by the time they were 18 or 19 years old. In addition, only 17 of the treated children ％ went on to high school, while 32 of the untreated children ％ made it to high school.