Radiation

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Types of Radiation

Radiation is classified into:

Ionizing radiation

Non-ionizing radiation

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Ionizing Versus Non-ionizing Radiation

Ionizing Radiation

Higher energy electromagnetic waves (gamma) or heavy particles (beta and alpha).

High enough energy to pull electron from orbit.

Non-ionizing Radiation

Lower energy electromagnetic waves.

Not enough energy to pull electron from orbit, but can excite the electron.

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Ionizing Radiation

Definition:

“ It is a type of radiation that is able to disrupt atoms and molecules on which they pass through, giving rise to ions and free radicals”.

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Another Definition

Ionizing radiation

A radiation is said to be ionizing when it has enough energy to eject one or more electrons from the atoms or molecules in the irradiated medium. This is the case of a and b radiations, as well as of electromagnetic radiations such as gamma radiations, X-rays and some ultra-violet rays. Visible or infrared light are not, nor are microwaves or radio waves.

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Primary Types of Ionizing Radiation

Alpha particles

Beta particles

Gamma rays (or photons)

X-Rays (or photons)

Neutrons

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Alpha Particles: 2 neutrons and 2 protons

They travel short distances, have large mass

Only a hazard when inhaled Types and Characteristics of Ionizing Radiation Alpha Particles

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Alpha Particles (or Alpha Radiation): Helium nucleus (2 neutrons and 2 protons); +2 charge; heavy (4 AMU). Typical Energy = 4-8 MeV; Limited range (<10cm in air; 60µm in tissue); High LET (QF=20) causing heavy damage (4K-9K ion pairs/µm in tissue). Easily shielded (e.g., paper, skin) so an internal radiation hazard. Eventually lose too much energy to ionize; become He.

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Beta Particles

Beta Particles: Electrons or positrons having small mass and variable energy. Electrons form when a neutron transforms into a proton and an electron or: