Biological effects of radiation on humans, organisms/

Biological effects of radiation on humans, organisms.

It all starts from the moment when the body was exposed to radiation (ionizing radiation).

Absorption of radiation energy

It all starts with a purely physical process — the absorption of radiation energy in the biosubstrate. Charged particles, neutrons and photons interact with the atoms of a biological object and transfer part or all of their energy to them.

Let’s list the mechanisms of radiation energy transfer to matter – photoelectric effect, inelastic scattering, formation of electron-positron pairs. It is these mechanisms that carry out the transfer of energy from particles and photons by the atoms of the biosubstrate.

Figure 1. Stages of radiation damage.

The effect of ionizing radiation (Radiation).

The act of ionization determines the moment and place of transmission of radiation energy to the substance. But it is very important to know in which part of the object this act of ionization will occur. The probability of each act of ionization is determined, of course, by statistical patterns.

But the general course and rate of energy transfer to a substance can always be calculated if the composition of the substance and the energy of particles or photons are known (Fig. 2).

Photons with an energy of up to 1 Mev give the maximum absorption in the most superficial layer of a living object (up to 0.5 cm), since it is in this layer that the most secondary electrons are formed.

Fig.29. Absorption curves of radiation energy in an object (water) for radiations with different photon energies.

As we move deeper into the stream of photons weakens, and therefore the number of ions decreases. Photons with an energy higher than 1 Mev will create a maximum of ionization acts in the depths of tissues, and the deeper the greater their energy.

Thus, when interacting with a biosubstrate, each type of radiation spends its energy on ionization and excitation of the atoms of the medium, causing a characteristic pattern of micro-distribution of energy depending on the type of particles (photons) and their energy.

Conclusion

Is it possible after irradiation to somehow influence this physical stage – the stage of energy absorption?

Modern science does not know such ways. After all, the process of energy absorption occurs almost instantly within 10-12 seconds.

The physical process of energy absorption inevitably ends with the formation of ionized and excited, and therefore chemically very active atoms and molecules.

 

From the book:

“Medical Radiology” by L.D. Lindenbraten

Publishing house “Medicine” Moscow 1969.

 

It is also recommended to read the article:

General laws of attenuation of a narrow beam of X-rays and gamma rays (radiation)

Is a person dangerous after radio (radiation) therapy in oncology?

 

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