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Radiation Biologyand Safety

T. Ibraheem Mheidat

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Introduction to Radiation Biology:

For Radiation Biology, our main interest is in the biological effects of ionizing radiation produced by artificial sources or radioactive decay processes.

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Many of you will be working with radiation sources and/or radioactive materials as a profession. It is essential that you understand not only the biological effects of radiation, but also the physical interactions of radiation with matter (which by in part give rise to the biological effects).

Some radiations are more hazardous to one’s health than others, hence the reasoning for this understanding.

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The Hazards from Ionizing Radiation Depend On the Following:

1.The type of radiation.

2.The mode of decay of the radionuclide.

3.The half-life of the radionuclide.

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Radiation Energetic:

Two Classes of High Energy Radiation:

1.Particulate Radiation.

2.Electromagnetic Radiation.

Properties of Particulate Radiation:3.Mass: Particles are composed of

matter. Particles have mass.

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2.Kinetic Energy:

Classical Treatment: E = 1/2mv2

Einstein: Mass-Energy Equivalence, E = mc2 (c = 3x108 m/s)

Mass is a form of energy and mass and energy are interconvertible.

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3.Charged Particles: Charges on particles have associated electric and magnetic fields (wave-like properties).

4.Nomenclature: Electron: e- = b-Positron: e+ = b+Proton: 1H+ = p+Neutron: 1n = nDeuteron: 2H+ = d+Alpha: 4He2+ = a2+

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Properties of Electromagnetic Radiation (EMR): EMR is Often Called “Pure Energy” or “Light” :1.Mass: EMR has no mass.

2.EMR: is composed of oscillating electric & magnetic fields.

3.Charge: EMR has no charge.

4.Energy: EMR has energy. However, it is not considered to be classical kinetic energy.

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3.EMR exhibits both wave-like and particle-like properties.

Wave Properties: EMR was first depicted in the form of a wave by Maxwell in 1864.

Maxwell stated we can describe light, or EMR by the “wave equation”, c = λv, where c = the speed of light, λ = the wavelength, and v = the frequency of the oscillation (v is proportional to 1/ λ and λ is proportional to 1/v. In other words, the shorter the wavelength, the higher the frequency.