Section 1 of 7How radiation damages the body
1Ionising radiation enters tissue
- Ionising radiation enters tissue Radiation passes into cells and ionises the atoms and molecules it meets.
2DNA is damaged
- DNA is damaged If atoms in a DNA strand are ionised, the strand can be broken or chemically altered.
3Cell dies or mutates
- Cell dies or mutates The cell may be killed, or it may repair the DNA incorrectly and survive with a mutation.
4Cancer may develop
- Cancer may develop A mutated cell that keeps dividing can form a tumour, which is a cancer.
Section 2 of 7Effects of exposure
Low doses over time
- Low doses over time The main risk is a greater chance of cancer developing later in life.
High, short-term doses
- High, short-term doses Radiation burns of the skin similar to severe sunburn can occur.
- The number of white blood cells can fall, weakening the immune system and making infections more likely.
Measuring dose
- Measuring dose The dose of radiation received by a person is measured in sieverts (Sv).
- One sievert is a very large dose that would cause radiation sickness.
Section 3 of 7Three ways to reduce the risk
| Method | How it helps | Examples |
|---|---|---|
| Reduce time | A shorter exposure means a smaller dose | Staff spend as little time near a source as they can |
| Increase distance | Radiation spreads out and fewer particles reach a person who is further away | Handling sources with tongs; building nuclear plants in remote places; burying waste far from where people live |
| Use shielding | Barriers absorb the radiation before it reaches people | Lead aprons, lead or concrete walls, and water around spent fuel |
Section 4 of 7Shielding in medical X-rays
1
The patient is shielded over the parts of the body that do not need to be imaged.
2
The radiographer stands behind a lead barrier, or leaves the room, while the X-ray is taken.
3
Exposure is kept as short as is needed to produce a clear image.
4
Staff who work with radiation wear badges that record the dose they have received.
Section 5 of 7Safe storage and handling
Storage
- Storage Radioactive sources are kept in lead-lined containers that are clearly labelled with the hazard symbol, and locked away when not in use.
Handling
- Handling Use long tongs rather than fingers, point sources away from the body, and return them to storage as soon as the work is finished.
Waste
- Waste Nuclear waste is sealed in containers and buried deep underground, far from places where people live.
Section 6 of 7Key terms
| Term | Meaning |
|---|---|
| Ionising radiation | Radiation that can remove electrons from atoms, which can damage living cells. |
| Mutation | A change in the DNA of a cell. |
| Dose | The amount of radiation absorbed by the body, measured in sieverts (Sv). |
| Shielding | A barrier, such as lead or concrete, that absorbs radiation. |
| Tumour | A mass of cells growing out of control, as happens in cancer. |
Section 7 of 7Exam technique
1
Saying that radiation makes a person radioactive. Exposure is different from contamination.
2
Giving only one safety measure when asked for the principles; remember time, distance and shielding.
3
Writing that the sievert measures how radioactive a source is. It measures the dose received by a person.
4
Forgetting the link from ionisation to DNA damage to mutation to cancer when asked to explain a risk.
5
Suggesting that thin paper or plastic is enough to shield against all radiation; gamma rays need thick lead or concrete.