What are the requirements of radiation protection for radioactive particle puncture needle implantation?

Because of the different mechanisms of interaction between different rays and substances, the protection methods for different rays are also different.

Alpha -- alpha particles are the nuclei of the higher energy helium-4. Due to its large mass and two positive charges, the energy of α particles is quickly consumed in the absorbing material due to the Coulomb field action of the absorbing material and the elastic collision with other atoms. So alpha particles are easily protected from external irradiation, usually by a piece of paper; The harm of alpha particles mainly comes from internal irradiation. Since alpha particles consume all the energy within a very short distance (about 4 ~ 8MeV), the damage to the irradiated cells and tissues is very severe.

Beta -- Beta particles are high-speed electron beams with a negative charge (a positive charge for positrons) and a mass 1/1837 of a proton or neutron. The penetration capacity of beta rays is average, between alpha and gamma rays. Bremsstrahlung is easy to be generated when beta rays interact with substances. This phenomenon is especially easy to be found in substances with large atomic weight. Therefore, the protection of beta radioactive sources with large activity is generally first protected by light materials such as plexiglass, and then shielded by substances with large atomic weight. Both internal and external exposures should be considered for protection against beta rays.

γ-γ rays (X-rays) are essentially high-energy photon beams (electromagnetic radiation), because the photon is not charged, and its rest mass is 0, less easy to lose energy. When γ rays interact with matter, there are mainly three kinds of effects: photoelectric effect, Compton scattering and electron pair annihilation to lose energy (the proportion of different energy is different). The penetration capacity of gamma rays is strong, and it is generally necessary to shield materials with higher atomic number (such as lead, depleted uranium, tungsten) or concrete and water with larger thickness for shielding. In general, higher energy gamma rays are harder to protect against. The protection of γ-rays is mainly concerned with external irradiation. Of course, gamma rays usually occur with alpha and beta decay, so the protection from internal irradiation cannot be ignored.

n -- The neutron has a mass number of 1, the same mass as a proton, and has no charge. Elastic and inelastic collisions may occur when neutrons interact with matter. When elastic collision occurs, the neutron loses a certain energy and slows down gradually. When inelastic collision occurs, the energy is absorbed by the target nucleus and nuclear reaction occurs. Because neutrons have no charge, they have greater penetration. Neutrons are mainly absorbed by materials with low atomic numbers (their energy is consumed by elastic collisions). Paraffin, graphite and other materials are very good protection materials.