Radioactivity and radiation protection
Ionising radiation in medicine: the kinds of radiation and what stops them, half-life, the becquerel, the gray and the sievert, irradiation and contamination, and the rules of radiation protection (time, distance, shielding) applied to imaging and nuclear medicine.
- 32 cards
- 3 topics
- Free
The outline, topic by topic
Each topic is weighted the way the exam weighs it.
- Concepts
- Scenarios
- Understand
A few cards from the deck
Radioactive isotope: what is it?
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An unstable atom that changes spontaneously while emitting radiation.
Nuclear medicine uses them to track a molecule through the body.
Iodine-131 has a half-life of 8 days. What share of activity remains after 24 days?
- One eighth
- One third
- One quarter
- Half
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One eighth
24 days is three half-lives: ½ × ½ × ½ = ⅛.
Alpha radiation: what is it?
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Helium nuclei, highly ionising but stopped by a sheet of paper or the skin.
They are dangerous mainly when inhaled or swallowed, like radon.
Why is ionising radiation dangerous to cells?
- They heat cells strongly
- They make cells magnetic
- They have no effect
- They strip electrons and break molecules, DNA included
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They strip electrons and break molecules, DNA included
Poorly repaired DNA damage can lead to cancer.
Beta radiation: what is it?
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Electrons (or positrons) emitted by the nucleus, stopped by a few millimetres of plastic or aluminium.
Positrons are used in PET imaging.
Which shield protects effectively against X-rays in radiology?
- A sheet of paper
- Lead (apron, screen)
- A cotton gown
- Thin plastic
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Lead (apron, screen)
Photons are penetrating: a dense material is needed.