5.7 Using Radiation in Medicine

Question 1

Why is gamma radiation the only type of radiation used in medical tracers?

Answer 1

Gamma radiation penetrates tissue, so can pass out of the body and be detected. Alpha and beta can’t and cause more damage in the body compared to gamma.

Question 2

Describe how gamma radiation is used as in medical tracers (3)

Answer 2

• Certain radioactive isotopes that emit gamma radiation are used as tracers in the body.
• They can be injected or ingested (drunk or eaten) to see how parts of the body, e.g. organs, are working.
• They spread through the body and their progress is followed on the outside using a radiation detector.

Question 3

Why does gamma radiation, that is used in medical tracers, need a relatively short half-life?

Answer 3

So that the source becomes relatively safe quite quickly, but long enough that it still emits enough radiation by the time it reaches the correct place.

Question 4

Describe how radiation kills the cancer cells without damaging too many normal cells

Answer 4

The radiation is directed carefully and at a specific dosage (depending on the size and type of size, and size and age of patient)

Question 5

What are the two things that radiation can be used for when treating cancer?

Answer 5

• To remove tumours completely
• To control and stop them spreading further

Question 6

Why might the patient feel ill when using radiation to treat their tumour/s?

Answer 6

A fair bit of damage is often done to normal cells

Question 7

Describe how radiation is used to treat cancer externally (using gamma rays)

Answer 7

• The gamma rays are focused on the tumour using a wide beam.
• The patient stays still and the beam is rotated round them with the tumour at the centre.
• This minimises the exposure of normal cells to radiation so the damage to healthy tissue is limited.
• The treatment is given in doses with time between for the healthy cells to be repaired or replaced.

Question 8

Describe how radiation is used to treat cancer internally

Answer 8

• Implants containing beta-emitters are placed next to or inside the tumour. The beta particles damage the cells in the tumour, but have a short enough range that the damage to healthy tissue is limited.
• An implant with a long half-life should be removed to stop the radiation killing healthy cells once the cancerous cells have been killed. If the half-life is short enough, the implant can be left in.
• Alpha-emitters can be injected into a tumour. Alpha particles are strongly ionising, so they do lots of damage to the cancer cells. But as they have a short range, damage to normal tissue is limited.

Question 9

What are three common symptoms of radiation symptoms?

Answer 9

• Hair loss
• Vomiting
• Tiredness

Question 10

Exposure to low levels of radiation over long periods can lead to cancer. Why is this?

Answer 10

Lower doses of ionising radiation damage living cells but causing mutations in the DNA. This can cause the cell to divide uncontrollably - which is cancer.

Question 11

What are the side effects of radiotherapy? (2)

Answer 11

• The patient feels sick
• The radiation also kills healthy cells

Question 12

If the tracer is swallowed, how does it travel through the body?

Answer 12

The tracer may be absorbed through the persons intestine and then travel via the bloodstream