Fluoroscopy ARRT Exam Study
guide| Questions with Solutions
- what mag modes are available? - -if you have a 16" II, you can have
12,9,6, and 4.5 "
- Compton effect - -hits the outer electron, incomplete transfer of energy,
electron released and a low energy xray is deflected
- photoelectric absorption - -x-ray totally absorbed by inner shell electron,
x-ray overcomes binding energy and knock out the electron and an outer
shell electron takes it place. When the outer electron moves to its new place,
a characteristic x-ray is formed
- what is the product of photoelectric absorption? - -electron flying ,
characteristic x-ray, and positive ion
- coherent scatter - -aka Thompson scatter, Rayleigh scatter or classical
scatter. x-ray is absorbed by entire atom and is sent off in another direction
with no energy loss
- does coherent scatter result in patient dose? - -No, this reaction only
causes excitation of the atoms shells, but there is not energy transfer nor
does the x-ray lose energy ( isotropic)
- what is the chance of coherent scatter occurring? - -5%
- attenuation - -the drop of intensity of the beam due to absorption and
scatter
- photoelectric interaction is dependent on - -Z^ 3 and 1/E^3
- as photon energy increases there is more - -penetration and a decrease in
tissue interactions
- Compton is dependent on - -energy level ( the higher it is, the greater
probability of occurrence), electrons/ gram
- attenuation equation - -I= Io e^ (-ux)
initial energy x e^( attenuation factor x tissue thickness)= resulting energy
initial energy- resulting energy= absorbed energy
- u ( tissue attenuation coeffient) is dependent on - -keV and material
,- what is the source of free electrons? - -cathode
- what is the cathode made of? - -98% tungsten, 1-2% thorium
- in what direction are electrons accelerated? - -cathode to anode
- how do we focus electron? - -we use a focusing cup made of nickel that
has a greater negative charge. This negative charge repels and squishes the
electrons that are made from thermionic emission
- how does deceleration occur in electrons? - -the closer to the nucleus the
electron is, the more attraction there is and as a result it slows down faster.
More energy is transferred to the xray and it has a higher energy as well. If
the electron is far, it wont slow down as much, it will lose less energy and will
result in a low energy electron.
- what is the cathode filament made of? - -Tungsten
- bremsstrahlung interaction - -99% heat, 1% x-ray
aka braking radiation, cathode electrons hit anode electrons. Electron that
are closer to the nucleus slow down more and lose more energy but create
higher energy electrons. Electrons that are farther away slow down less, lose
less energy and create low energy x-rays. They retain enough energy to
keep having more interactions
(electrons are more likely to hit the outer rim of the anode)
- characteristic interactions - -made 2 ways
1)cathode electrons hit anode electrons
2) PE effect from x-ray to electron interactions
- which interactions occur in the tube? - -bremsstralung
- what interactions occur in the body? - -PE, Compton, Coherent scatter
- what happens when we increase KeV? - -the chance of Compton effect
increases, and the ratio between CS and PE also increases
- equations for frequency and wavelength - -c= speed of light= 3x10^8 m/s
Hertz= cycles/s
frequency = speed of light/ wavelength
v = c/ upside down Y
- equation for energy - -E= hv
h= 6.62 x 10^-34 Js = 4.15 x 10^-15 eVs
1 eV= 1.6 x 10^-19 Js
, - quality - -overall energy of the beam
increase mAs= identical quantity
increase kVp= increase quality
increase filtration= increase quality
- quantity - -the amount of x-rays, this is directly proportional to mAs
- primary radiation - -x-ray beam after it leaves the x-ray tube and before it
reaches the object
- remnant radiation - -radiation resulting after the x-ray beam exits the
object
- inverse square law - -I1/I2 = D2^2/D1^2
- fundamental properties of x-rays - -1) EMR travel in waves at the speed of
light in a certain direction in a straight light
2)can interact with matter
wave particle duality
- tissue weighting factors - -relative sensitivity , Wt
-can be used to convert partial radiation to whole body dose
- radiosensitive factors - -oxygenation of cell and cell cycle
- Bergonie-Tribondeau law - -cells that are rapidly dividing , undifferentiated
and have a long mitotic cycle are more sensitive to radiation
- LET - -linear energy transfer
alpha, protons = high LET
xrays and electrons= low LET
- Wr - -radiation weighting factor ; difference in biological damage from
different types of ionizing radiation
It is the same thing as RBE and Q
- non-threshold - -all dose levels are potentially harmful ( stochastic)
- threshold - -there is a radiation level when no effect can be observed
- linear graph - -response is directly related to dose
- non-linear graph - -responses are not proportional to dose curve ( could
look like an s-curve)
guide| Questions with Solutions
- what mag modes are available? - -if you have a 16" II, you can have
12,9,6, and 4.5 "
- Compton effect - -hits the outer electron, incomplete transfer of energy,
electron released and a low energy xray is deflected
- photoelectric absorption - -x-ray totally absorbed by inner shell electron,
x-ray overcomes binding energy and knock out the electron and an outer
shell electron takes it place. When the outer electron moves to its new place,
a characteristic x-ray is formed
- what is the product of photoelectric absorption? - -electron flying ,
characteristic x-ray, and positive ion
- coherent scatter - -aka Thompson scatter, Rayleigh scatter or classical
scatter. x-ray is absorbed by entire atom and is sent off in another direction
with no energy loss
- does coherent scatter result in patient dose? - -No, this reaction only
causes excitation of the atoms shells, but there is not energy transfer nor
does the x-ray lose energy ( isotropic)
- what is the chance of coherent scatter occurring? - -5%
- attenuation - -the drop of intensity of the beam due to absorption and
scatter
- photoelectric interaction is dependent on - -Z^ 3 and 1/E^3
- as photon energy increases there is more - -penetration and a decrease in
tissue interactions
- Compton is dependent on - -energy level ( the higher it is, the greater
probability of occurrence), electrons/ gram
- attenuation equation - -I= Io e^ (-ux)
initial energy x e^( attenuation factor x tissue thickness)= resulting energy
initial energy- resulting energy= absorbed energy
- u ( tissue attenuation coeffient) is dependent on - -keV and material
,- what is the source of free electrons? - -cathode
- what is the cathode made of? - -98% tungsten, 1-2% thorium
- in what direction are electrons accelerated? - -cathode to anode
- how do we focus electron? - -we use a focusing cup made of nickel that
has a greater negative charge. This negative charge repels and squishes the
electrons that are made from thermionic emission
- how does deceleration occur in electrons? - -the closer to the nucleus the
electron is, the more attraction there is and as a result it slows down faster.
More energy is transferred to the xray and it has a higher energy as well. If
the electron is far, it wont slow down as much, it will lose less energy and will
result in a low energy electron.
- what is the cathode filament made of? - -Tungsten
- bremsstrahlung interaction - -99% heat, 1% x-ray
aka braking radiation, cathode electrons hit anode electrons. Electron that
are closer to the nucleus slow down more and lose more energy but create
higher energy electrons. Electrons that are farther away slow down less, lose
less energy and create low energy x-rays. They retain enough energy to
keep having more interactions
(electrons are more likely to hit the outer rim of the anode)
- characteristic interactions - -made 2 ways
1)cathode electrons hit anode electrons
2) PE effect from x-ray to electron interactions
- which interactions occur in the tube? - -bremsstralung
- what interactions occur in the body? - -PE, Compton, Coherent scatter
- what happens when we increase KeV? - -the chance of Compton effect
increases, and the ratio between CS and PE also increases
- equations for frequency and wavelength - -c= speed of light= 3x10^8 m/s
Hertz= cycles/s
frequency = speed of light/ wavelength
v = c/ upside down Y
- equation for energy - -E= hv
h= 6.62 x 10^-34 Js = 4.15 x 10^-15 eVs
1 eV= 1.6 x 10^-19 Js
, - quality - -overall energy of the beam
increase mAs= identical quantity
increase kVp= increase quality
increase filtration= increase quality
- quantity - -the amount of x-rays, this is directly proportional to mAs
- primary radiation - -x-ray beam after it leaves the x-ray tube and before it
reaches the object
- remnant radiation - -radiation resulting after the x-ray beam exits the
object
- inverse square law - -I1/I2 = D2^2/D1^2
- fundamental properties of x-rays - -1) EMR travel in waves at the speed of
light in a certain direction in a straight light
2)can interact with matter
wave particle duality
- tissue weighting factors - -relative sensitivity , Wt
-can be used to convert partial radiation to whole body dose
- radiosensitive factors - -oxygenation of cell and cell cycle
- Bergonie-Tribondeau law - -cells that are rapidly dividing , undifferentiated
and have a long mitotic cycle are more sensitive to radiation
- LET - -linear energy transfer
alpha, protons = high LET
xrays and electrons= low LET
- Wr - -radiation weighting factor ; difference in biological damage from
different types of ionizing radiation
It is the same thing as RBE and Q
- non-threshold - -all dose levels are potentially harmful ( stochastic)
- threshold - -there is a radiation level when no effect can be observed
- linear graph - -response is directly related to dose
- non-linear graph - -responses are not proportional to dose curve ( could
look like an s-curve)
