26. Radiology. Radiation – Definition, Emissions’ Types, Characteristics

Radiology. Radiation- definition. Emission types and characteristics

Written by Anam Hussain

Definition:

Radiation is the process in which energy travels through a medium or through space, ultimately to be absorbed by another body. This energy is emitted and travels in the form of particles of electromagnetic waves.

Types of radiation emission and characteristics:

• Alpha
• Beta
• Gamma
• Neutrons

1. Alpha:

• Positively charged particles (2 protons and 2 neutrons)
• mainly emitted in the decay of large nuclei
• Particles are large, heavy with low range and extremely low penetration
• Particles can be stopped with a piece of paper
• Ionizing capacity is very high so can be very dangerous if ingested or inhaled

2. Beta:

• Beta radiation involves positive or negatively charged particles
• Consists of either electron or positron
• Mass is smaller compared to alpha particles so travels at greater distance than alpha
• Cause direct ionization but less ionizing than alpha but more ionizing than gamma
• Velocity and penetration are greater than alpha radiation
• A metal (aluminium or plastic) shields are required for protection

3. Gamma:

• Gamma rays are electromagnetic waves with the velocity of lights and range of km
• Enormous penetration ability as almost nothing could stop them
• Heavy lead shields and antinuclear shelters are used for protection and to decrease their activity
• For evert 15cm the activity drops by a half but some residual activity remains
• Gamma rays have low energy
• Energy is not enough for direct ionization
• When this type of radiation is absorbed, energy instability is provoked and the atoms could emit particles or rays to become stable again
• Ionizing capacity is lower than that of beta particles

4. Neutron radiation:

• Is the flow of non-charged particles
• High penetration, High speed, High range
• Ionizing capacity is extremely potent compared to gamma rays
• Lead shields are not an efficient barrier against neutrons and concrete shelters with thick walls are used/required for protection instead.