Flashcards in HEALTH Nuclear Radiation Deck (29)
What effect does radiation have on living cells?
It kills them,
What can nuclear radiation be used for?
To sterilise medical equip,net by killing germs and to kill cancerous cells (using a beam of gamma rays from different directions so that surrounding tissue is not harmed).
Why can radiation be used as tracers?
They emit waves so can be detected and a picture boult up using a gamma cameraThey are specifically chosen for the organ that is being investigated.
How is alpha radiation affected in air and what is it absorbed by?
20cm in air and a sheet of paper
How is beta radiation affected in air and what is it absorbed by?
Few meters, 2-3mm of aluminium
How is gamma radiation affected in air and what is it absorbed by?
Not absorbed, 2-3cm of lead
Why a happens when radiation passes through a material?
Some of it is absorbed (depending on the radiation and material as to how much)
Describe an atom
Orbiting electrons and a nucleus containing protons and neutrons.
Which radiant particle cause most ionisation?
What effect does radiation have in non living things?
Ionisation, photographic film, scintillation.
What affe t does radiation have in photographic film?
What is scintillation?
When matierals absorb the energy and remit it as light.
What is the activity of radiation?
The number of atoms that decay (are released) in one second.
What is activity measured in?
Does activity increase or decrease over time?
What safety precautions should be taken with radioactive materials?
Use tongs, store in a lead container. Point away from body, label sources, wash hands afterwards.
What is dose equivalent?
Measure of the biological risk
What is dose equivalent measured in?
What is ionisation?
The addition or removal of an eke torn from an uncharged atom.
How does a Geiger muller tube detect radiation?
When radiation enters the tube it causes ionisation in the gas. This sends a pulse of electricity between the electrodes and these aw counted by the counter.
How does photographic film detect radiation?
It blackens it.
Different sections of a piece of photographic paper with varying thickness are used. Type is determined by what sections are blacked (gamma blackens all) and amount by how black.
What is half life?
The time taken for the activity of the source to fall by half.
How is half life measured?
Take regular measurements of the activity of the source using a Geiger muller tube and counter, background radiation is then subtracted from each reading and result plotted on a graph. Graph is then used to find half life.
What does biological effect of radiation depend on?
Type of absorbing tissue, type of radiation and total energy absorbed,
Way does dose equivalent take in account?
Type and energy if radiation.
Why is gamma chosen as a tracer?
Alpha or beta rays would be absorbed by the tissue and would not be detected outside the body.
Why is radiation with a half life of around 6 hours used?
Shorter time would be too difficult to make measurements and longer would increase the amount of radiation to the body.
What are advantages of MRI?
No ionisation, better for displaying soft tissue than a CT scan, nom after effects.