Kompton - effect

1. If - coherent (classical) dispersion takes place (А_exit - work of an output electron from substance). The direction of movement of photons changes owing to influence of photons with electrons the internal level, strong connected with a nuclear. Energy and length of a wave remain constant. It does not cause biological action.

2. If the photon is absorbed, electron comes off atom: the substance is ionized (substance turns to a positive ion), the photoeffect occurs.

3. If , then where The part of energy of a photon is spent for fulfillment of work for an output of electron from the substance, other part is spent for kinetic energy free electron, the third part is radiated in the form of secondary radiation (), which dissipates in every possible directions.

Secondary radiation with length of a wave more, than length of a wave of excitation and with smaller energy is formed. This phenomenon is not coherent dispersion or Kompton-effect. Secondary radiation dissipates in every possible directions.

The photoeffect is characteristic for photons with rather low energy and occurs mainly on electronах internal level of atoms. Photons with the energy changing in enough wide limits cause Kompton - effect at interaction of photons with electrons the external levels poorly connected with a kernel. The Kompton-effect occurs in substance in parallel (and it is independent) to a photoeffect.

In medicine use x-ray radiation with energy of photons from 60 up to 200 Кelectronvolt.

Х- rays is weakened at interaction with substance. Buger’s law determines this weakening. Buger’s law for x-rays radiation looks like

- Stream of radiation, the past through substance

- Stream of the radiation, falling on substance

- linear factor of easing,

Linear factor of easing of x-ray radiation depends upon natures of substance.

Where - factor of true absorption,

- factor of dispersion of primary radiation

Radiation with the same length of a wave absorbs the more strongly, than it is more density and more nuclear number Z. The bone absorbs Х-beams more strongly, than soft tissues of the person. If a non-uniform body to place on a way of a bunch of the x-ray radiation, the fluorescing screen to place before it the shadow is formed on the screen because of non-uniform absorption. This shadow allows to judge an internal structure of a body. The bones, consisting in basic from , almost in 150 times absorb more strongly, than soft tissues (consisting basically from water ).

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