Uses & Dangers of Radiation (Edexcel GCSE Physics)

Iodine-131 is often used as a radioactive tracer which is injected into the patient's bloodstream.

State two precautions taken when using a radioactive isotope as a medical tracer.

Camera lenses contains several pieces of glass. In some older cameras, one of the pieces of glass includes a radioactive isotope, thorium-232. 

Thorium-232 undergoes alpha decay and produces an isotope of radium, Ra.  

Complete the equation for this decay. 

The radioactive glass also emits beta particles from a different isotope. Figure 1 shows the position of the radioactive glass in the camera. 

Figure 1

Amateur astronomers sometimes remove an old camera lens to use as a lens in a homemade telescope.

(i) Suggest why it is safe to use radioactive glass in the camera as shown in Figure 1. 

[1]

(ii) Suggest why an astronomer should not use a lens with radioactive glass close to their eye.  

[2]

There are two sources of alpha radiation in some houses:

• Radon gas in the air

• Solid americium in a smoke alarm

Explain why the alpha particles from radon are a greater risk to health than the alpha particles from americium.

Figure 1 shows how the activity of a sample of radon-220 changes with time which is measured in seconds. 

Figure 1

Label the axes on the graph.

Use Figure 1 to find a value for the half-life of radon-220.

Explain why the risk to health from Radon gas is low.

Define the term half-life.

A doctor uses gamma radiation to produce an image of a person's brain as shown in Figure 1. The doctor injects a solution of technetium-99m, a radioactive isotope, into the patient. A detector outside the patient received gamma radiation to form the image.

Figure 1 

Technetium-99m emits gamma rays and has a short half-life.

Explain why isotopes that emit alpha particles or beta particles are not suitable for this use.

Technetium-99m has a half-life of 6 hours. A sample of technetium-99m has an activity of 380 MBq.

Calculate the activity of the technetium-99m sample after 24 hours.

    activity = ..............................................MBq

Explain why technetium-99m has a suitable half-life for use as a radioactive tracer.

Figure 1 gives information about six radioactive isotopes.

Figure 1

Two isotopes of uranium are given in the table. 

State how the nuclei of these two isotopes differ.

A doctor needs to monitor the blood flow through a patient’s kidney. 

To do this, they inject a radioactive tracer into the patient, and then monitor the level of radiation in the kidney using a GM detector and counter outside of the patient’s body.

State and explain which of the isotopes in Figure 1 would be most suitable as a medical tracer inside the human body.

State which of the radioisotopes from Figure 1 would be most suitable for monitoring the thickness of aluminium foil.

Explain the reasons for your choice.

Watering a plant with a solution containing a radioactive isotope can help scientists to understand the growth processes occurring within it.

Using information from Figure 1, explain why phosphorus-32 would be suitable as a tracer in a growing plant. 

Radioactive materials can cause irradiation and contamination. 

Explain the differences between the terms irradiation and contamination.

Discuss the following points in your answer:

• Define both irradiation and contamination

• State the source of irradiation and contamination

• Describe how to prevent irradiation and contamination

• Determine the causes of both irradiation and contamination

Describe how medical instruments are sterilised.