How is radiation used safely, and what are its dangers to living things?
Uses of radioactive sources in medicine and industry, the dangers of ionising radiation, irradiation versus contamination, and safety precautions.
A CCEA GCSE Physics answer on the uses of radioactive sources in medicine and industry, how the choice of source depends on its radiation and half-life, the dangers of ionising radiation, and the difference between irradiation and contamination.
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What this dot point is asking
CCEA wants you to describe uses of radioactive sources in medicine and industry, explain how the type of radiation and half-life are chosen for a job, describe the dangers of ionising radiation, distinguish irradiation from contamination, and list safety precautions.
The answer
Uses of radiation
The choice of source depends on the type of radiation (its penetration) and the half-life (long enough to do the job, short enough to limit lasting hazard).
The dangers of ionising radiation
Irradiation and contamination
Safety precautions
To reduce exposure, workers increase distance (use tongs or remote handling), reduce time of exposure, and use shielding (lead, concrete or lead-lined stores), as well as wearing gloves and protective clothing and monitoring their dose.
Worked example: choosing a source
Examples in context
Example 1. A PET or kidney scan. A short-half-life gamma tracer is injected and tracked by detectors, showing how well an organ works while keeping the patient's exposure low because the source decays quickly.
Example 2. Food irradiation. Gamma rays kill bacteria on food to extend its shelf life. The food is irradiated, not contaminated, so it does not become radioactive and is safe to eat.
Try this
Q1. State one medical use of radiation. [1 mark]
- Cue. Tracers, radiotherapy or sterilising equipment.
Q2. State the difference between irradiation and contamination. [2 marks]
- Cue. Irradiation: exposure from an outside source. Contamination: radioactive material on or in the body.
Q3. State two ways a worker can reduce their radiation dose. [2 marks]
- Cue. Increase distance (use tongs); reduce time; use shielding.
Exam-style practice questions
Practice questions written in the style of CCEA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
CCEA style4 marksA radioactive tracer is used to find a leak in an underground water pipe. Explain why a gamma-emitting source with a short half-life is chosen.Show worked answer →
Gamma radiation is penetrating, so it can pass through the soil and pipe to be detected at the surface above the leak.
A short half-life means the source decays quickly, so it does not stay radioactive in the ground for a long time, reducing the lasting hazard.
Markers reward: gamma chosen because it is penetrating and can be detected at the surface; and a short half-life so it does not remain a hazard for long.
CCEA style4 marksExplain the difference between irradiation and contamination, and state two precautions a worker should take when handling a radioactive source.Show worked answer →
Irradiation is being exposed to radiation from a source outside the body; it stops when the source is removed or shielded.
Contamination is getting radioactive material on or inside the body; it continues to irradiate from within until removed.
Two precautions: handle sources with tongs (keep distance) and limit the time of exposure; wear gloves and protective clothing, and store sources in lead-lined containers.
Markers reward correct definitions of irradiation and contamination and two valid precautions.
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Sources & how we know this
- CCEA GCSE Physics specification — CCEA (2017)