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Question 1
This question is about the hazards of radioactive substances. |
a) | Describe the structure of the three main types of ionising radiation.
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b) | Describe the main health hazards associated with exposure to ionising radiation.
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c) | Explain the precautions that must be taken when handling radioactive materials.
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Question 2
A radioactive isotope, technetium-99m, is commonly used as a tracer in medical imaging. It has a half life of 6 hours. |
a) | Describe how radioactive tracers are used in medical imaging.
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b) | A patient is given a dose of technetium-99m with an initial activity of 296 MBq. Calculate the activity of the tracer after 18 hours?
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c) | Describe how radioactive substances are used in radiotherapy for cancer treatment.
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Question 3
This question is about the use of radiation in smoke alarms. A smoke alarm is a device that detects smoke, usually indicating a fire. It alerts people by creating a loud noise, giving them time to evacuate safely. |
a) | State which form of radiation is used in smoke detectors.
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b) | Describe how radioactive substances are used in smoke detectors.
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c) | Describe the potential safety concerns related to the use of alpha radiation in smoke detectors.
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d) | Describe the precautions and safety measures taken to minimise the risks associated with using alpha-emitting sources in smoke detectors.
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Question 4
A factory uses beta radiation to monitor the thickness of aluminium sheets. The table below shows the relationship between the counts detected by a Geiger-Muller tube and the thickness of the aluminium sheets. |
a) | Plot a graph of thickness against counts per minute.
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b) | Describe the relationship between the counts detected and the thickness of the aluminium sheets.
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c) | Explain how beta radiation is used to measure the thickness of materials in this application.
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d) | Using your graph, estimate the thickness of an aluminium sheet if the Geiger-Muller tube detects 180 counts per minute.
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Question 5
A gamma-emitting radioactive tracer is placed inside a pipeline to detect leaks. The table below shows the radiation levels at various points along the pipeline. |
a) | Explain how radioactive tracers are used to detect leaks in pipelines.
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b) | Use data from the table to identify the location of a leak in the pipeline. Explain how you came to your answer.
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c) | Describe the advantages and safety precautions of using radioactive tracers for leak detection in pipelines.
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Question 6
A student is conducting an experiment to measure the background radiation in their classroom. They use a Geiger-Muller tube to take measurements of the counts per minute (cpm) at various locations in the room. The data collected is shown in the table below. |
a) | Explain what is meant by background radiation and give one source of background radiation.
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b) | Calculate the average background radiation count in the classroom based on the data provided.
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c) | A student places an alpha source near a Geiger-Muller tube and records a count of 185 in 30 s. Calculate the corrected count rate (in counts per minute).
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Question 7
A factory uses radiation to monitor the thickness of plastic sheets. The table below shows how the recorded count per minute varies with thickness for 3 different sources of radiation. |
a) | Describe the suitability of alpha, beta, and gamma radiation for thickness monitoring of plastic sheets. You should use data from the table in your answer.
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b) | The data in the table has not been corrected for background radiation. Describe how the workers at the factory could correct their recorded value to account for background radiation.
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c) | The factory records the background radiation to be 1 count per second. The factory wants to maintain a plastic sheet thickness of 1.5 mm. Calculate the corrected count for beta radiation to ensure the desired thickness is maintained.
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Question 8
Radioactive tracers are a useful tool in the treatment of thyroid problems. Iodine-123 is an example of a radioactive tracer used in these procedures. |
a) | Which of the following is a suitable half-life for a radioactive tracer? A A few days B A few hours C less than a second D several weeks
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b) | Radium-223 can be put inside the body to treat cancers. Radium has a half-life of 11.4 days and emits alpha radiation. Explain why radium-223 is suitable for use inside the body to treat cancers.
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Question 9
a) | Sources that emit alpha can be harmful because.. A it has a very long half-life B it has a high count rate C it is highly ionising D it is very penetrating
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b) | A radioactive tracer has an initial activity of 150 MBq. The half life of the radioactive tracer is 4 hours. Calculate the activity of the same after 16 hours. A 75 MBq B 300 MBq C 9 MBq D 19 MBq
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c) | Which of the following would be most suitable for monitoring the thickness of metal sheets. A alpha B beta C gamma
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Question 10
This question is about radioactive tracers used in medical procedures. Technetium-99m has a half life of 6 hours. |
a) | Explain what is meant by a half-life of 6 hours.
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b) | The radiographer wants the activity of the tracer to be less than 1 MBq after one day. Calculate the maximum initial activity of the tracer if it is to have an activity of less than 1 MBq after one day.
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c) | Technetium-99m is a gamma emitter. Explain why alpha emitters are not used as tracers for medical imaging.
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