Radiation safety

From the point of view of radiation safety, methods that do not use ionizing radiation, such as ultrasound and MRI, have undoubted advantages.

Strictly speaking, the safety of the impact of a strong magnetic field on the body used in MRI still requires clarification, given that the method has only recently come into use and much experience has not yet been accumulated. Therefore, it is considered undesirable to use MRI during pregnancy, especially in the first trimester. MRI is potentially dangerous and therefore contraindicated for patients with implanted pacemakers, metallic foreign bodies sensitive to magnetic fields.

Among the methods based on the use of ionizing radiation, the safest is radionuclide visualization, in which (especially when using short-lived isotopes) the radiation dose is tens or hundreds of times less than in X-ray and CT. The most dangerous is CT, in which the dose of ionizing radiation is significantly higher than in conventional X-ray examination, and directly depends on the number of sections performed, i.e. increasing the resolution leads to an increase in radiation exposure.

Possible harmful effects of ionizing radiation on the body include two large groups - deterministic and stochastic. Deterministic effects occur if the radiation dose is above a certain threshold value, and their severity increases with increasing dose. First of all, rapidly dividing cells, tissues with intensive metabolism are affected: epithelium, red bone marrow, reproductive and nervous systems. Deterministic effects occur soon after irradiation, are easy to study, so today effective methods for their prevention have been developed. First of all, this is the use of radiation doses significantly below the threshold for diagnostic purposes. Thus, the threshold erythemal dose of X-ray radiation is achieved by performing 10,000 radiographs, or 100 CT, which never happens in real conditions.

The difference between stochastic effects and deterministic ones is that the radiation dose determines not the severity, but the probability of developing a complication. These include carcinogenesis and genetic mutations. The danger of stochastic effects is that the dose threshold for them is unknown, so any study using ionizing radiation is associated with a risk of complications, even with a minimum radiation dose and the use of protective equipment. To reduce radiation exposure, protective shielding devices are used, the irradiation time is reduced, and the distance between the radiation source and the patient is increased. However, these measures only reduce the likelihood of developing stochastic effects, but do not eliminate it completely. Since any study with ionizing radiation can potentially lead to carcinogenesis and mutations, and the radiation doses received in different studies are summarized, it is recommended to limit the use of these types of radiation diagnostics as much as possible, whenever possible, and perform them according to strict indications. CT should be performed only in cases where other available visualization methods cannot provide the necessary information; In this case, it is necessary to strictly limit the area of interest and clearly justify the number of sections produced.

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