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DMD 5340 Oral Imaging > Physics > Flashcards

Physics Flashcards

1
Q

What is atomic number and atomic mass?

A 
AN= Proton #
AM= Protons and Neutrons
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2
Q

What is ionization?

A

Neutral atom loses electron and becomes charged and unstable.

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3
Q

What is the basics of the X-ray tube (anode, cathode, tungsten, filiment,)

A

Filament (tungsten wire) generates electrons at cathode (-), shoots at anode (+) (tungsten target).

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4
Q

What is the focusing cup?

A

Focuses electrons from filament into narrow beam directed at anode focal spot.

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5
Q

What is the anode wrapped in? Why?

A

Wrapped in copper to act as a heat sink.

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6
Q

Why is tungsten used?

A

Higher melting point, high atomic number (dense), high conductivity, low vapor pressure.

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7
Q

What is radiation?

A

Transmission of energy through space and matter.

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8
Q

What is particulate radiation?

A

Large unstable atoms breaking apart and shooting smaller particles that ionize other things.

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9
Q

What is Electromagnetic radiation (EMR)? shorter wavelength equals what kind of energy?

A

Movement of energy through space as a combination of electric and magnetic fields.
Shorter wavelength=higher energy.

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10
Q

How is EMR generated?

A

Velocity of an electrically charged particle is altered.

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11
Q

What is Bremsstrahlung radiation? 2 types?

A

Sudden stopping or slowing of electrons.

  1. Electron directly hits atom nucleus, turns into x-ray (photon)
  2. Electron flies close to nucleus, veers off course, and released x-ray photons.
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12
Q

What is characteristic radiation?

A

Electron hits and ejects inner electron of atom. Electrons move down to fill that shell and release x-ray (photons).

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13
Q

What is voltage? Measured in?

A

Force that pushed electrons. determined by potential difference between two points. Measured in kVp.

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14
Q

what is filament voltage? Want it high or low?

A

Foltage across the filament wire. Want it low to not burn it out and create electron cloud.

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15
Q

What is current? Measured in?

A

Current is # of electrons flowing. Measured in mA.

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16
Q

What is filament current? Tube current?

A 
FC= # of electrons in filament.
TC= # of e- from anode to cathode.
17
Q

what does the power supply do?

A

Generates high potential difference from cathode to anode.

18
Q

What does a step-up transformer do? Used for?

A

Increases voltage from incoming power source. Used to increase V from cathode to anode.

19
Q

Step down transformer does what? Used for?

A

Decreases voltage from power source. Used for filament.

20
Q

Energy in beam is controlled by? # of photons?

A 
E= kVp
#= kVp and mA
21
Q

What is increasing exposure doing?

A

Increases exposure time increases # of photons.

22
Q

Increase tube voltage (kvP) does what?

A

Increases photons and their energy level.

23
Q

What is inherent and added filtration?

A
  1. Inherent= materials photons encounter as they travel from focal spot to detector.
  2. Added= Aliminum discs added .
24
Q

what does the collimation do?

A

Limits x-ray exposure and reduces scatter.

25
Q

What is preferred, round or rectangular collimation?

A

Rectangular.

26
Q

Intesity of beam is measured how?

A

I1/ I2 = (D2)2/ (D1)2

27
Q

What are apsorption and scattering interactions?

A 
A= photons ionized atom, energy of photon absorbed.
S= photons interacts with atom, and gets ejected.
28
Q

What is photoelectric absorption? Important for what?

A

Photon hits electron, knocks it out, and then ceases to exist. Most important for imaging production.

29
Q

What is coherent scattering?

A

Absorbs and spits out same electron.

30
Q

What is compton scattering?

A

Photon knocks out electron, photon changes direction.

31
Q

What is beam attenuation? Penetrating value determined by what?

A

Beam loses intensity.

Determined by thickness of material. (reduces in half)

DMD 5340 Oral Imaging (10 decks)

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