S4.11.6 For the adult
Uses of radiation
A doctor gives a patient a small amount of radioactive material to scan the body. Which kind of radiation should it give out?
What this chapter teaches
Radiation is chosen for the job. A medical tracer gives gamma, so it can be detected outside the body, and has a short half-life, so the dose is small. Radiotherapy crosses beams at a tumour. Beta suits a thickness gauge and alpha a smoke alarm. Carbon dating measures the carbon 14 left in remains of living things, and uses its half-life of about 5 700 years.
Three questions to ask
There is no one right wording. Listen for the idea.
- Why does a tracer give gamma and have a short half-life?
- How do crossed beams protect healthy tissue?
- Why can carbon dating not date a rock?
After the chapter, the learner can
- Explain medical uses, such as tracers and cancer treatment
- Explain how carbon dating shows how old remains are
What they copy into their notebook
Tracers: gamma, short half-life. Radiotherapy: beams cross at the tumour. Beta gauges thickness, alpha works in smoke alarms. Carbon dating: carbon 14 halves every 5 700 years. Only for once-living things, to about 50 000 years.