There are risks to using radiation

• Radiation can enter living cells and ionise atoms and molecules within them, this can lead to tissue damage

• Lower doses tend to cause minor damage without killing the cells. This can give rise to mutant cells which divide uncontrollably. This is cancer.

• Higher doses tend to kill cells completely, causing radiation sickness if a lot of cells all get blatted at once

Gamma sources are usually used in medical tracers

• Certain radioactive isotopes can be injected into people and their progress around the body can be followed using an external detector. A computer converts the reading to a display showing where the strongest reading is coming from

• One example is the use of iodine-123, which is absorbed by the thyroid gland just like normal iodine-127, but it gives out radiation which can be detected to indicate whether the thyroid gland is taking in iodine as it should

• Isotopes which are taken into the body like this are usually GAMMA, so that the radiation passes out of the body without causing much ionisation. They should have a short half-life so the radioactivity inside the patient quickly disappears

Radiotherapy-treating cancer with radiation

• Since high doses of ionising radiation will kill all living cells, it can be used to treat cancers

• Gamma rays are directed carefully and at just the right dosage to kill the cancer cells without damaging too many normal cells. Radiation-emitting implants can also be put next to or inside tumours

• However, a fair bit of damage is inevitably done to normal cells, which makes the patient feel very ill. But if the cancer is successfully killed off in the end, then it’s worth it

You have to weigh up the risks and benefits

• Risks: prolonged exposure to radiation poses future risks and causes side effects

• Benefits: can get rid of cancer entirely

• Perceived risk can vary from person to person