Health Physics

Physics is helping people throughout the world back to health.

The picture on the left is a CT scan of a patient`s brain. Can you see the folds of the brain matter? This is a method of taking X-Ray pictures in a series of slices through the body. In this section of your Physics you will study the physics behind devices and ideas that help people when they are sick. In this section of my web page you can revise the health physics section by trying the questions below.

1. Harry & Fiona are trainee doctors.
   a) Describe in detail how they would use their thermometers to check if a patient is running a high temperature.
   b) What are the main differences between a clinical thermometer and an ordinary one?
   
   

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2. Ultrasound of frequency 3MHz is used to examine a patient`s heart. If the speed of ultrasound in the heart muscle is 1500m/s calculate the wavelength of the ultrasound.

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3. What is the sound level at which a lot of exposure to will result in hearing damage?

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4. Mr & Mrs Dolland have just bought new glasses. They both found it difficult to read their newspapers but found it easy to see things in the distance.
   a) What eye defect have they?
   b) Draw the eye defect and say what kind of lens is needed to correct their vision.

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5. An optician`s prescription gives the lens required for an eye as + 2.5D. What kind of lens is this & what is the focal length ?

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6. Copy and complete the following table showing how the three main types of radiation can be stopped:
   
   

   Type of Radiation	How it can be stopped.
   Alpha
   Beta
   Gamma

   
   

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7. Mary is in hospital because her parents are worried that she has no energy and is always tired. The doctors think it might be her thyroid gland that is not working well. To find out if it is working they inject her with iodine because the thyroid absorbs this element. The doctor puts in Iodine-131 which is radioactive and has a half life of 8 days. A radiation detector can then see how much radioactive iodine Mary`s tyroid has taken up.
   a) What is meant by the term half life?
   b) If the activity of the iodine-131 is 400MBq calculate the activity 32 days later.
   c) Iodine-131 emits gamma radiation. Why do you think this is important in Mary`s case ?

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8. What is meant by ionisation?

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9. What does the unit sievert measure?

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10. Sharon is a doctor and uses her stethoscope to listen to a patients chest.
    Click on the target to hear what she picked up.
    Explain how the stethoscope works and also say which bell Sharon was using to pick up the sound.

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