When a patient visits a hospital for diagnostic imaging, such as receiving X-rays, CT, PET, isotope therapy, and other diagnostic instruments and receive a certain amount of exposure. These radiations are inherently harmful, but are not relevant if they are not used frequently.
The radiation dose for a bone density test is 1 microsievert (μSv), a chest radiograph is 100 microsieverts (μSv), a whole-body CT is 10,000 microsieverts (μSv), and a lumbar spine radiograph is 1,500 microsieverts (μSv).
Currently, the internationally recognized personal safety dose limit is 2 millisieverts per year = 2000 microsieverts per year. (1 Sieverts Sv = 1000 millisieverts mSv = 1,000,000 microsieverts μSv)
CT "shine" too much, will increase the incidence of cancer. CT examination is actually a kind of X-ray examination, CT radiation belongs to the ionizing radiation, too much ionizing radiation on the human body has the risk of causing cancer. Ionizing radiation can damage the structure of DNA in human cells. Some damaged DNA can be repaired, but too much damaged and severely damaged DNA cannot be repaired. In this way, genes change, producing cancer cells and cancer.
The annual radiation dose from the natural environment to an individual is about 2,000 microsieverts (μSv), while the radiation dose from 1 abdominal, spinal or whole-body CT is about 10,000 microsieverts (μSv), the total amount of radiation in the natural environment in 4 years; the radiation dose from head and heart CT is smaller, and there are 2,000 microsieverts (μSv) at one time. Multiple repeated CT examinations, radiation dose and the corresponding hazards can be cumulative, the incidence of cancer may increase.
Studies have shown that among the population, the most sensitive to ionizing radiation are children and young women; among human organs, the lungs are the most susceptible to damage; and among young women, the most sensitive to ionizing radiation is the breast.