This issue is a matter of great concern to everyone who goes to the hospital for imaging examinations, and we are all very worried about whether this examination is harmful or not. To introduce to you, there are two main types of usual radiation: first, natural radiation, including ultraviolet light, etc., can cause harm to us; second, medical radiation, mainly from the two aspects of examination and treatment. Because we know that conventional X-rays produce a certain amount of radiation, it is important to master the indications for examinations and try to avoid unnecessary or excessive examinations and treatments. But the amount of radiation within the normal treatment range should not cause harm to the human body, as long as we master the three principles of protection: 1, shielding protection; 2, distance protection; 3, time protection.