Uses Of Radiation Flashcards
How do household fire (smoke) alarms work?
Alpha particles from source (americium-241) ionise molecules in the air between two metal plates. These ions are attracted to plates with an opposite charge, allowing a current to flow around a circuit. Smoke particles slow down the ions when it gets into the air gap meaning that the current flowing across the gap decreases. The alarm sounds.
How does tracing (in the body) work?
A source that emits gamma rays is ingested (swallowed/injected) by the patient. The source moves around the body, emitting gamma rays that get out of the patient and are picked up by a sensor. The computer attached to the sensor can then map the body.
How is cancer most commonly treated with radiation?
External radiotherapy:
Gamma rays, X-rays or protons are focussed on the cancerous cell from outside the body at different angles, destroying the DNA and preventing it from reproducing
List some uses of radiation (and what radiation is involved)
- killing microorganisms - on food and surgical equipment (GAMMA)
- radioactive detecting - tracers (GAMMA)
- cancer - diagnose using tracers, treatment (GAMMA)
- checking thickness - of paper (BETA)
- smoke alarms (ALPHA)
- PET scans (POSITRON)
Describe how radiation is used to detect leaks in water pipes
A gamma source is added to water pipes buried underground. Where there is a leak, water flows into the surrounding earth. A Geiger-Müller tube following the path of the pipe will detect higher levels of radiation where there is a leak
What type of half-life should an isotope that is used as a tracer have?
A short half-life so it does not become a long term problem
How is the thickness of paper checked?
A detector counts the rate at which beta particles get through the paper from a source on the opposite side. When the paper is too thin, more beta particles penetrate the paper and the detector records a higher count rate. A computer senses that the count rate has risen and reduces the force applied rollers to make the paper thicker. The opposite happens when the paper is too thick
How do PET scans work?
A positron-emitting radionuclide is put into the body - this acts as a tracer. When the positron is emitted from the material, it will annihilate with the first piece of normal matter it encounters. The result is two gamma rays which can be detected outside the body. This can be used to map someone’s insides
What is internal radiotherapy?
A beta emitter such as iodine-131 is placed inside the body, within or very close to a tumour (this does not always require surgery). Either:
- a wire made of radioactive material can be inserted then removed later after patient has had enough radiation
OR
- tiny ’seeds’ made of radioactive material implanted next to tumour and left permanently
Are used.
The patient stays in a room alone while the source is in place (as beta radiation can get out of the patient and be absorbed by someone else)
Why aren’t alpha or beta particles used for external radiotherapy?
They can’t get deep into the body
What are the pros of nuclear power stations?
- reliable
- high energy density of fuel
- no CO2 released, so no contributions to climate change
What are the cons of nuclear power stations?
- daughter nuclei produced in fission are highly radioactive, meaning the spent fuel rods must be buried underground or otherwise stored safely and under high security
- nuclear power stations are incredibly expensive due to the advanced technology needed for safe running
- the fuel, Uranium, is non-renewable
- Uranium can be used in a similar process to build nuclear weapons
- very slow shut-down time so can only be used for base load
- the public fear nuclear power due to the catastrophic effects of an accident, even though these events are very rare
