The final decision on how much CT radiation is available must be based on the patient’s examination site and examination items, as follows: 1. Just doing a CT flat scan of the head, the radiation dose is approximately equal to 2mSv. 2. Doing a flat scan of the chest, the radiation dose is approximately 6-8mSv. 3. Choosing to do a low dose CT flat scan of the chest, the radiation dose will be reduced by at least half, which is approximately 3-4mSv. 4. Doing a CT flat scan of the abdomen, the radiation dose will be approximately 15-20mSv. 5. Therefore, to evaluate the radiation dose of a CT examination, the patient’s examination site and items must be integrated and evaluated.