[Radiation exposure doses in medical procedures].

An investigation was conducted concerning long-term changes of patients' radiation exposure doses in medical procedures such as chest X-ray and CT scans. The result of the investigation compelled consideration of methods for reducing the exposure doses. While the exposure doses have decreased in chest X-ray compared with 30 years ago, they have remained unchanged in CT scan compared with 20 years ago. The following address possible causes of unchanged doses for CT scan: Measuring doses is difficult. Technology to reduce patients' doses has yet to be used effectively. It is important to take deterministic causes into consideration. More research and attention to the issue are needed.