What is irradiation
Irradiation happens when there is a radioactive material outside your body, but the radiation could travel into your body.
What is contamination
Contamination happens when you take radioactive material into your body or if it is on your skin.
How is gamma radiation used to detect cancer
- Radioactive materials are used as tracers for detecting cancer.
- Tracers are bind onto proteins that specific human organs absorb and get injected into the patient’s body.
- Using a Gamma camera we can detect where the tracer has concentrated.
- Therefore, gamma rays are emitted from outside the body focused on that area (Gamma Knife).
Hazards of radioactive tracers
The shorter the tracer’s half life the less ionisation takes place in our body.
The smaller the amount of the tracer used the faster it will exit our body.
Apart from choosing an appropriate half-life, suggest one other action a radiographer could take to reduce the risk of the patient contracting cancer
- could take into consideration the AMOUNT of the tracer needed ti be injected
Why do doctors choose tracers that emit gamma and not alpha or beta
Gamma is the least ionising
Explain why the risk of cancer is usually higher when you are contaminated than when you are irritated
When we are contaminated the radioactive source is inside our body therefore ionisation takes place.
α - radiation cannot penetrate our skin but when ingested it is dangerous as it is the most ionising / damaging the DNA.
Compare the use of tracers and gamma knives
- Both use isotopes that emit gamma rays.
- The gamma rays travel through the body.
- With a tracer the material is inside the body, but with a gamma knife it is outside.
- The aim of a tracer is not to damage cells, but the aim of a gamma knife is to destroy them.
Why are some nuclei unstable
They have an imbalance between the number of protons to neutrons resulting in too much energyv
Define nuclear fission
The splitting of a nucleus into 2 smaller nuclei, with the release of energy and neutrons
How is fission induced in a nuclear reactor
when a Uranium-235 nucleus is hit with a neutron.
What does the splitting of a Nucleus produce
The two smaller nuclei (daughter nuclei) which are themselves unstable, and become stable by undergoing radioactive decay
Properties of nuclear waste
Very dangerous
Very long half-life
Must be buried and guarded
Define a chain reaction
Process in which neutrons released during a fission event, go on to produce further fission events.
What is a controlled fission event
Only one neutron from each fission event is able to produce another fission event.Control rods in power plants absorb surplus neutrons and energy is generated at a steady rate.
How are controlled chain reactions controlled
WITH CONTROL RODS
Control rods in power plants absorb surplus neutrons and energy is generated at a steady rate.
What is an uncontrolled fission reaction
Every neutron from each fission event goes on to produce further fission events.Energy released at an exponential rate.
What is a fissionable isotope
are those that can be made unstable.(BUT THEY THEMSELVES ARE STABLE)
Example of a fissionable element
U-235 = fissionable (∵ U-236 is unstable)
Name a fissionable material and describe what happens when it undergoes fission
U-235 is a fissionable isotope of Uranium
A neutron is absorbed by a nucleus of U-235, transforming it into U-236, which is unstable and breaks apart into two smaller daughter nuclei.
Explain why there must be a material that absorbs neutrons un a nuclear reactions
Without a material to absorb neutrons, an uncontrolled chain reaction occurs.
Energy is released at an increasing, exponential rate.
This is dangerous and will lead to an explosion.
Define nuclear fusion
The joining of two small nuclei to form a larger nucleus, releasing energy
Where does nuclear fusion occur
Occurs in stars when 2 very light nuclei (isotopes of Hydrogen) are forced together at high speeds, to form heavier Helium nucleus.
Advantages of nuclear fusion
- No radioactive waste produced.(unlike fission… very long half-life radioactive waste)
- The fuel required for fusion is readily available in water.(unlike fission… Uranium is non-renewable)
- Nuclear fusion produces a lot more energy than fission.(four times as much than fission)
