USING RADIATION

Question 1

Give examples uses of radioactivity.

Answer 1

• Household fire alarms (smoke)
• Irradiating food
• Sterilisation of equipment
• Tracing and gauging thickness of materials
• Diagnosis and treatment of cancer

Question 2

How do smoke alarms work?

Answer 2

• A radioactive substance is in the alarm which emits alpha radiation
• The emitted alpha particle ionises the air in the detector and causes a current to flow between the plates
• When smoke interferes with the radiation, the air is no longer ionised and so no current can flow
• This reduction in current flow triggers the alarm

Question 3

State two uses of nuclear radiation in the field of medicine.

Answer 3

1. Examining of internal organs
2. Radiotherapy in the treatment of cancer

Question 4

What is the role of beta radiation in tracers?

Answer 4

• The tracer is inserted in your body, and targets a specific part of the body
• The radioactive substance in the tracer releases beta radiation which can be detected by external machines

Question 5

How is beta radiation used to determine thickness?

Answer 5

• A beta source is placed above the material and a detector is placed below it
• If there is an increase in radiation detected by the detector, too much radiation is passing through the material, and so it is too thin
• If there is a decrease in radiation is detected, then the material blocks too much radiation, and so it is too thick

Question 6

Why is ionising radiation dangerous?

Answer 6

• It can damage tissue and kill cells
• It can cause cell mutations

Question 7

What is a consequence of cell mutation?

Answer 7

Cancer

Question 8

What precautions should people take when using ionising radiation?

Answer 8

• Avoid handling the source directly (use tongs)
• Wear radiation protective clothing
• Keep the radiation in lead containers to reduce the amount of radiation that can escape
• Keep the exposure time to a minimum

Question 9

Does a long half life or a short half life make a source more dangerous?

Answer 9

If it has a long half life then it would remain highly radioactive for longer therefore making it more dangerous

Question 10

What precautions are taken to reduce harm for doctors and patients using ionising radiation?

Answer 10

• Only a small dose is given to the patient so they are not exposed to too much
• The radiation used has a shirt half life so it won’t remain highly radioactive for long. This reduces the risk to the doctors using it as well as the patient.
• Doctors and patients (when applicable) wear protective clothing.

Question 11

What is radioactive contamination?

Answer 11

The presence of unwanted radioactive nuclei on other materials

Question 12

What is irradiation?

Answer 12

• The process of exposing a material to nuclear radiation
• The material does not become radioactive

Question 13

How is a radioactive tracer used in medicine?

Answer 13

• The tracer is placed inside the body (it can be in a drink, eaten or injected)
• The tracer releases gamma radiation which is detected by a detector which moves around the body
• This can then be used to produce a picture of the patients body

Question 14

How does a PET scanner work?

Answer 14

• PET (positron emission tomography) uses a tracer, which is injected into the patients body
• The scanner detects the gamma rays which are released by the trace
• Multiple images are taken and this is used to from a 3D image of the patients body

Question 15

Isotopes are used in PET scanners. What is important about where they are produced and why?

Answer 15

They must be produced near the hospital because the isotopes used have a short half life so must be used soon after production