P4 - Medical Uses of Radiation Flashcards
Why do gamma rays need to be controlled very carefully?
- Gamma rays have to be directed carefully and at just the right dosage so as to kill the cancer cells without damaging too many normal cells.
What is a common symptom of radiotherapy?
- A fair bit of damage is inevitably done to normal cells, which makes the patient feel very ill, however if the cancer is successfully killed off in the end then it is worth it.
How are gamma rays used to treat cancer?
- Gamma rays are focused on the tumour using a wide beam.
- The beam is rotated round the patient with the tumour at the centre.
- This minimises the exposure of normal cells to radiation, and so reduces the chances of damaging the rest of the body.
What is a feature that radioactive tracers must have?
- They must have a short half life, around a few hours, so that the radioactivity inside the patient quickly disappears.
How are tracers placed into the body?
They can be:
- Injected
- Drunk
- Eaten
- Ingested
How is the progress of a radioactive tracer followed?
- Radioactive tracers are allowed to spread throughout the whole body and their progress can be followed on the outside using a radiation detector.
What is a practical example of a radioactive tracer in use?
- Iodine 123 is absorbed by the thyroid gland, it gives out radiation which can be detected to indicate whether or not the thyroid gland is taking in the iodine as it should
What types of radiation are allowed to be used for radioactive tracers & why?
The isotopes that are taken in by the body must be Gamma or Beta ( never alpha ).
- This is because gamma and beta radiation can penetrate tissue and so are able to pass out of the body and be detected.
Why is alpha not used?
- Alpha radiation an’t penetrate tissue, so you can’t detect the radiation on the outside of the body.
- Alpha is more dangerous inside the body and will ionise cells.
What radiation is used in sterilising medical equipment?
Gamma radiation.
How can medical instruments be sterilised?
- Medical instruments can be sterilised by exposing them to a high dose of gamma rays, which will kill all microbes.
What is advantage of using radiation instead of other means for sterilising medical equipment?
- It doesn’t involve high temperatures, so heat sensitive things like thermometers and plastic instruments can be totally sterilised without damaging them.
