Triple Physics specification mind-map - Radiation in treatment and medicine

Created by: libbygrace
Created on: 07-05-16 18:33

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Radiation in treatment and medicine
- Medical Physics
  - CAT scans
    - Imaging device
    - Use a computer to make a 3D image of body
      - Uses images from many different X-Rays
  - Ultrasounds
    - Lubricant used
    - Detects problems in orans
    - Foetal scanning
  - Endoscopy
    - Optical fibers - thin, flexible glass rods
    - Total internal reflection
    - Through natural openings in body or through small incisions (keyhole surgery)
    - To examine
      - Oesophagus
      - Stomach
      - Colon
      - Respiratory system
      - Urinary tract
      - Reproductive system
  - Radiation
    - Ionising
      - Gamma rays
        Detect and treat cancers
      - Radioactive sources
        monitor digestive system
        
        Taken into the body and monitored
    - Non-ionising
      - Light in devices which look into the body
- Lenses
  - Converging
    - Thicker in the middle
      - Bends light inwards
  - Diverging
    - Thinner in the middle
      - Bends light outwards
  - Thicker lenses are more powerful
  - power of lens (dioptre, D) 5 1/focal length (meter, m)
  - 1/f = 1/u + 1/v
- Radiation
  - Any form of energy originating from a source
    - Both waves and particles
  - Intensity
    - Intensity of radiation will decrease with distance from a source
    - Intensity = power of incident radiation / area
      - I = P/A
      - P = I*A
      - A = P/I
- The Eye
  - Diagram of the eye
  - Light is focused on the retina by the lens and the cornea
  - Human Eye
    - Near point of about 25cm
    - No far point
      - Only restricted by shape of the eye
  - Sight problems
    - Long-sight
      - Cant see up close
    - Short-sight
      - Can't see long distance
    - Correcting sight problems
      - Glasses
        Short sight
        Diverging lens
        
        Long sight
        Converging lens
        Stops light from focusing too soon
      - Contact Lenses
      - Laser eye surgery
        Short sight
        Some thickness from central part of cornea removed
        Reduces focusing power of eye
        
        Long sight
        Curve of cornea increased by removing tissue at its' side
        Increases focusing power of eye
      - Lenses
        Converging
        Thicker in the middle
        Bends light inwards
        
        Diverging
        Thinner in the middle
        Bends light outwards
        
        Thicker lenses are more powerful
        
        power of lens (dioptre, D) 5 1/focal length (meter, m)
        
        1/f = 1/u + 1/v
- Reflection and Refraction
  - Refraction
    - when a wave passes from on medium to another causing a change in speed and direction
  - Reflection
    - Deflection of a ray of light when it hits the boundary between two different surfaces
    - Total Internal Reflection (TIR)
      - The total internal reflection of light that occurs at the boundary of two materials where the angle of incidence exceeds the critical angle
      - Optical fibers and Endoscopes
        In an optical fiber, an intense light ray enters a long section of glass at a precise angle to give TIR inside the entire length of glass
        
        2 bundles used
        One carries light to the object, one back to the eyepiece
      - Total internal reflection

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Triple Physics specification mind-map - Radiation in treatment and medicine

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