Physics basics of Radiology Flashcards

1
Q

What are radiographs?

A
  • Images created by x-rays which have been projected through an object and then interacted with a receptor
  • Different shades of grey on image correspond to different types of tissue and thickness of tissue involved
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2
Q

Why are radiographs useful?

A
  • Can see structures within body, particularly mineralised tissues
  • Many dental related conditions affect the mineral content of tissues
  • Can show normal anatomy and pathology
  • Aid diagnosis, treatment planning and monitoring
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3
Q

Common intraoral dental radiographs

A
  • Periapical
  • Bitewing
  • Occlusal
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4
Q

Common extraoral dental radiographs

A
  • Panoramic
  • Lateral cephalograms
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5
Q

What is electromagnetic radiation?

A
  • X-rays are form of electromagnetic radiation
  • Flow of energy created by simultaneously varying electrical and magnetic fields
  • Schematically represented as a sine wave
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6
Q

Name some electromagnetic radiation properties

A
  • No mass
  • No charge
  • Always travel at speed of light = 3x10^8ms^-1= 671million mph
  • Can travel in a vacuum
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7
Q

What is the electromagnetic spectrum?

A
  • Consists of all different types of electromagnetic radiation
  • Each type has different properties dependent on its energy/wavelength/frequency
  • Divided into 7 main groups
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8
Q

What are the 7 main groups of EM radiation?

A
  • Gamma ray
  • X-ray
  • Ultraviolet
  • Visible
  • Infrared
  • Microwave
  • Radio
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9
Q

What radiation has the shortest wavelength?

A
  • Gamma ray
  • Shortest wavelength
  • Highest frequency
  • Highest energy
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10
Q

What radiation has longest wavelength?

A
  • Radio
  • Longest wavelength
  • Lowest frequency
  • Lowest energy
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11
Q

How do you measure frequency from a sine wave?

A
  • Need to know however long it took to travel e.g. 4 seconds
  • 1 cycle over 4s = 0.25cycles per second = 0.25Hz
  • 4 cycles over 4s = 1 cycle per second = 1Hz
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12
Q

Definition of frequency

A

Frequency = how many times the waves shape repeats per unit time

  • Measured in hertz, Hz
  • 1Hz= 1 cycle per second
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13
Q

Definition of wavelength

A

Wavelength = distance over which the waves shape repeats

  • Measured in metres, m
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14
Q

Define speed and how it relates to EM radiation

A

Speed = Frequency x Wavelength

  • BUT speed of all EM radiation is constant = 3x10^8ms^-1
  • So if frequency increase then wavelength must decrease and vice versa
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15
Q

What is energy directly proportional to?

A
  • Frequency
  • High frequency = high energy
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16
Q

What is Photon energy?

A
  • EM radiation involves movement of energy as ‘packets of energy’ known as photons’
  • Energy measured in electron volts, eV
  • 1eV = energy (in joules) gained by 1 electron moving across potential difference of 1 volt