Radiotherapy Flashcards
Why is it hard to know what dose of gamma rays to give someone?
Because you need the dose high enough to kill the cancerous cells but as low as possible to minimise the harm to the patient .
What do alpha particles pass through and what are they absorbed by?
Pass through air.
Absorbed by paper.
What do gamma rays pass through and what are they REDUCED by?
Pass through few mms Al.
What do beta particles pass through and what are they absorbed by?
Passes through paper.
Absorbed by 5mm Al.
What happens when radiation is absorbed??
Living cells are damaged.
Atoms in the molecules become ionised and these ions can cause cancer.
When does ionisation happen?
When electrons are knocked out of atoms and molecules.
Neutral atoms become charged.
What are gamma rays used for ??
It’s used to kill cancer cells.
It must be directed carefully to minimise the damage to normal cells.
However some damage is unavoidable and can make the patient ill.
What do we say if a substance that is capable of always emitting radiation under any condition ?
It is radioactive.
What are the three types of radiation and what are they given off by?
Alpha
Beta
Gamma
Rocks, food, building materials, air and cosmic rays around us= called background radiation
What is an Alpha particle?
Helium nucleus and it’s charge is +2
Description: 2neutrons and 2protons are emitted from the nucleus.
RAM 4
It’s the least penetrating(goes through stuff)
What is an alpha particle absorbed by?
1 or two piece of paper.
What is a beta particle?
It’s a high energy electron. It has a charge of -1
Description: a neutron in the nucleus decays into a proton and high energy electron is emitted.
RAM 1
What is a beta particle absorbed by?
A few mm of aluminium.
What is gamma radiation?
It is a high energy electron magnetic radiation.
It doesn’t have a charge.
Description: nucleus changes shape into a more stable shape. Gamma radiation emitted as a result.
Most penetrating(doesn’t go through stuff as easily)
What is gamma radiation absorbed by?
It’s never fully absorbed but it gets weaker with a few cm of lead.
