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40 Cards in this Set
- Front
- Back
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Image formation occurs when......
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The xray photons pass through tissue and interact with an image receptor
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_______ and ______ affect the type of interaction with the various tissues of the body
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Quality and quantity
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Characteristic that affect photon interaction;
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Atomic number
Thickness Compactness |
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Differential absorption
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A process whereby some of the xray beam is absorbed in the tissue and some passes through (transmits) the anatomic part
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Five possible interactions with matter;
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Photoelectric effect
Compton's scatter Coherent scatter Pair production Photodisintegration |
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Photoelectric effect
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Photon absorption by matter
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Compton's Scatter
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Photon changes direction
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Coherent (classical) scatter
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An interaction with low energy xrays, below the diagnostic range. The incoming photon interacts with the atom causing it to become excited. The xray doesn't lose energy but changes direction.
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Pair production
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Doesn't occur in diagnostic ranges (PET imaging)
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Photodisintegration
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Doesn't occur indiagnostic ranges (Nuclear Medicine)
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Beam attenuation
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Reduction in the energy of photons in the primary beam as they pass through matter - reduces the number of photons that reach the IR
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Three processes occur in beam attenuation;
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Absorption
Scattering Photon transmission |
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Absorption
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Photon is absorbed by matter it is passing through
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Scattering
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Incoming photons are not absorbed, but instead lose energy during interactions with atoms of the tissue and change direction - may leave the anatomic part
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Photon transmission
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Goes through without interaction
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Photoelectric effect
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Complete absorption occurs when the photon has enough energy to remove an inner shell electron from the tissue's atom
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Removing electrons is called ?
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Ionization
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The ejected electron is called a ?
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Photoelectron
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Difference in the energy between the two shells will result in ????
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Results in another photon being emitted which becomes radiation scatter and may or may not react with anything else in the area
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Compton's effect
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The photon interacts with an outer shell electron, ejecting it from it's orbit. The photon changes direction and looses energy -
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Compton's effect is responsible for
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Film fog
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Coherent scatter
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Low energy xrays, usually below diagnostic range - Interacts with an atom, causing it to become excited - Photon does not lose energy but changes direction
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Transmission
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Photon goes through anatomic part without any interaction (goes straight through)
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Lower Kv =
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more photon interactions
less transmission (penetrates less) |
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Higher Kv =
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less photon interactions
more transmission (penetrates more) |
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Some incoming x-ray photons will pass through the anatomic part without any interactions
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Transmission
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Exit radiation is also called
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Remnant radiation
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Exit radiation is compose of
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Scattered and transmitted radiation
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Type of scatter radiation that does not provide any diagnostic information about the anatomical area
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Compton's
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Type of scatter that causes "fog" on the xray
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Compton's
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Three types of xrays are important to the making of a radiograph
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Those scattered by Compton Interaction
Those absorbed photoelectrically Those transmitted through the patient without interaction |
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Attentuation
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Reduction in the energy of the primary xray beam as it passes through anatomic tissue
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Coherent scattering
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An interaction with low energy xrays, below the diagnostic range. The incoming photon interacts with the atom causing it to become excited - the xray does not lose energy but changes in direction
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Compton effect
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The loss of energy of the incoming photon when it ejects an outer-shell electron from the atom. The remaining lower-energy xray photon changes direction and may leave the anatomic part
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Compton electron/secondary electron
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The ejected electron resulting from the Compton effect interaction
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Differential absorption
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A process whereby some of the xray beam is absorbed in the tissue and some passes through (transmits) the anatomic part
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Exit radiation
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The attenuated xray beam leaves the patient and is composed of both transmitted and scattered radiation
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Fog
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Unwanted density on the radiographic image
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Photoelectric effect
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Complete absorption of the incoming xray photon when it has enough energy to remove (eject) an inner shell electron.
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Photoelectron
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The ejected electron resulting from total absorption of the photon during the photoelectric effect interaction.
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