While no one can point to a single individual and say that his/her cancer was caused by medical radiation, it has been suggested in some studies that exposure to radiation levels during diagnostic CT scans may slightly increase the risk of future cancer. The evidence for this is still controversial, and needs to be interpreted against the risk of developing cancer over ones lifetime. For every 1,000 children, 200 to 400 will eventually develop cancer during their lifetime, regardless of exposure to medical radiation (risk of 20 percent to 40 percent). The theoretical increased risk of cancer during ones lifetime from a single CT scan is a small fraction of this baseline risk. Unnecessary radiation should be avoided, but for any child the risk/benefit ratio of each CT scan must be considered with regard to the child's specific clinical condition and concerns.