The damage to the body mainly depends on the intensity of the rays, as well as the range of radiation, (such as circumferential radiation, directional radiation, scattered rays, etc.), if the high-power ray machine a few minutes on the body can be harmed, mainly on the body's cells to cause damage, such as killing platelets, white blood cells, and so on. Ray industry is a special industry, the general unit should be equipped with ray dose alarms, as well as lead undershirts, lead shorts and other protective facilities. There is no absolute all-safe distance, depending on the intensity of the rays. However, if there is a certain thickness of lead door or lead room isolation, it should be safe. Detection room in the construction of the environmental protection department to do assessment.