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Radioactivity and PET Scans (Different Types of Radiation (Alpha (Consists…
Radioactivity and PET Scans
Different Types of Radiation
Alpha
Consists of positively charged particles, made up of two protons and two neutrons and has a charge of +2e
Beta
Consists of fast moving electrons or positrons. Positive has a charge of +e negative has a charge of -e
Gamma
High energy photons with wavelengths that are less than 10^-13m they travel at the speed of light and have no charge
This is the source of radiation used in
PET Scans
Mainly because they have no charge, have a small wavelength to pass through cells easily and travel quickly to be able to show results on a Gamma Camera
All ionising - meaning they "ionise atoms" and remove electrons from atoms making them positive
The Effect of Electric and magnetic fields
Alpha
Overall charge is positive of alpha particles so it is attracted to the negative electrode.
Have a large mass and charge so produce cause the most ionisation, can only travel a few cm and can be stopped by a thin sheet of paper - not suitable for PET scans as they wouldn't be able to penetrate the skin and reach the Gamma Camera
Beta
Beta + is attracted to the negative electrode
Beta - is attracted to the negative part electrode
Gamma
has no charge so is not effected by magnetic fields or positive or negative charges and travels in a predictable straight line
Having no charge also means that gamma rays are the least ionising and can travel very long distances.
This makes gamma rays the most suitable for PET scans as they can travel from the patient out into the gamma camera which can be positioned a few metres away compared to alpha radiation that can only travel a few cm in air