Medical Uses of Radiation (AQA GCSE Physics)

Revision Note

Test yourself
Katie M

Author

Katie M

Last updated

Medical Uses of Radiation

Medical Tracers

  • A tracer is a radioactive isotope that can be used to track the movement of substances, like blood, around the body
  • Gamma emitters are usually used for this purpose
    • Gamma rays are highly penetrating and so will be able to pass through the body and be detected outside the body

  • This allows an internal image of the body to be created

Iodine-131 is an example of a radioactive tracer

  • Since gamma rays are less ionising than some other forms of radiation, the harm caused to the patient is also minimised
  • As well as choosing a gamma emitter:
    • The amount of isotope used is kept to a minimum to reduce people’s exposure to radiation
    • Isotopes are chosen that have short half-lives of around a few hours: Long enough to carry out the procedure, but not so long that they cause long term harm

Radiotherapy

  • Radiotherapy is the name given to the treatment of cancer using radiation
  • Although radiation can cause cancer, it is also highly effective at treating it
  • Radiation can kill living cells
    • Some cells, such as bacteria and cancer cells, are more susceptible to radiation than others

  • During external radiotherapy, beams of gamma rays are directed at the cancerous tumour
    • The machine rotates to target the tumour from different angles
    • This minimises the exposure of healthy tissue to the gamma rays and minimises damage to healthy cells

Radiation Therapy 1, downloadable AS & A Level Physics revision notes

During radiotherapy, the beams are moved around to minimise harm to healthy tissue whilst still being aimed at the tumour

  • During internal radiotherapy, small pellets of radioactive materials can also be inserted into a tumour exposing it directly to radiation

Sterilising Medical Equipment

  • Gamma radiation is widely used to sterilise medical equipment
  • Gamma is most suited to this because:
    • It is the most penetrating out of all the types of radiation
    • It is penetrating enough to irradiate all sides of the instruments
    • Instruments can be sterilised without removing the packaging

Worked example

A new medical tracer is required for investigating the absorption of a particular substance found in blood around the body.Tracer examples, downloadable IGCSE & GCSE Physics revision notesWhich of the different isotopes in the table would be most suitable?

ANSWER:  C

    • A suitable medical tracer must:
      • Be able to penetrate out of the body
      • Have a long enough half-life to move around the body before it decays away
      • Have a short enough half-life that it won’t remain in the body at dangerous levels for too long

    • The answer is not A because alpha radiation cannot penetrate out of the body
    • The answer is not B because the half-life is too short
    • The answer is not D because the half-life is too long

Risks of Nuclear Radiation

  • The use of radiation in medicine carries risk
  • Radiation can:
    • Kill or damage living cells
    • Cause cancer
    • Cause mutations

  • As a result, its use needs to be kept to a minimum
  • However, the benefits of using radiation in medicine can out weigh the potential risks
    • The risks posed by the radiation are smaller than the risks associated with leaving the condition untreated

  • For example, if a person has a cancerous tumour that is likely to kill them, then it is less of a risk to use radiotherapy than to leave the tumour

Examiner Tip

You may be given data and asked to evaluate the risk of nuclear radiation in a particular example. Remember to compare the potential dangers with the benefits.

Katie M, Physics

Teacher tip

Katie M

Physics

I really enjoy teaching this lesson at GCSE because I have found that students are interested in the real-life applications of physics. Many students have the misconception that all radiation is bad for you, which is not the case. We are exposed to low levels of radiation all the time. It is exposure to high levels of radiation that can be harmful. This lesson provides an opportunity for students to ask questions, and learn about weighing up the risks and benefits of radiation therapies. Medical physics is explored in more detail at A Level so it can also lead to a discussion about studying physics beyond GCSE. Students are often surprised to learn that physics plays a vital role in medicine and that there are plenty of career opportunities in this field.

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Katie M

Author: Katie M

Expertise: Physics

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.