chapter 8 & 9 ( x ray production and emission ) Flashcards
A change in_____
has no effect on the position of the discrete x-ray emission spectrum.
a.kVp
b.mAS
c.filtration
d.waveform
(All of the above)
A compensating filter is used with a body part of_____
thickness to create______
optical density in the image.
non-uniform, uniform
Added filtration results in_____
a.reduced X-ray quantity
b. an increase in the quality of the beam c.increased HvL
d. reduced patient dose
(All of the above)
A filtered diagnostic X-Ray beam at 80 kVp contains
mostly bremsstrahlung, with some characteristic X-Rays
A minimum HVL is required for diagnostic X-Ray beams because
a lower HVL would result in an increased absorbed dose to the patient with no improved image quality
An exposure taken at 100 kVp would have a maximum energy of
keV.
100
An exposure taken at 100 kVp would have an average energy of about
keV.
33
An exposure taken at 100 kVp would have an effective characteristic X-Ray energy of
keV.
70
An increase in kVp would_____
the______
of the emission spectrum
increase, amplitude and peak location (shift right)
Approximately_______
of the kinetic energy of the projectile electrons is converted to X-Rays at the target.
1%
An X-Ray beam can be made to have higher average energy if which of the following occurs?
Filtration is added
As filtration is_____
beam quality is_______
and quantity is______
increased, increased, decreased
As the number of pulses in the generator voltage waveform
the _______amplitude of the X-Ray spectrum________
and the peak shifts to the_____
increases, increases, right
Changes in______
result in directly proportional changes in only the amplitude of the emission spectrum
mAs
Characteristic X-Rays_____
are electromagnetic radiation
Characteristic X-Rays are produced when
a vacancy in the electron orbit is filled
Characteristic x-rays energies are directly affected by:
Target material (Z)
Electron interactions at the inner shell of the target atoms produce______
radiation.
characteristic
Factors that can change the X-Ray spectrum are all of the following except
focal spot
How does an increase in filtration affect the emission spectrum?
reduced amplitude and a shift to the right
If filtration is removed from the X-Ray beam, then the HVL
decreases
If the distance from the source of X-Rays is increased by a factor of two, how is the X-Ray intensity at the image affected?
It is reduced by a factor of four
If the kVp is increased, then the HVL
increases
If the mAs is increased, then the HVL
stays the same
If the technique changed from 80 kVp to 65 kVp, you would expect the peak of the bremsstrahlung spectrum to
shift to the left and decrease in amplitude
If the tube is brought closer to the patient and the technique is not changed, then the HVL
stays the same
If X-Ray quantity is increased, what happens to the digital image?
It becomes better or clearer
Increasing the_____
in digital imaging, ______
the image contrast
mAs, does not increase
Inherent filtration______
slightly increases over the tube’s lifetime
In order for a characteristic X-Ray to be produced, the energy must be______
the binding energy of the inner shell electron.
greater than
lonization occurs due to
coulombic repulsion
Penetrability of an X-Ray beam describes X-Ray
quality
The 2nd HVL for a monoenergetic beam is______
the 1st HVL.
equal to
The 2nd HVL for polyenergetic beam is______
the 1st HVL.
greater than
The bremsstrahlung process produces X-Rays when
electrons are slowed in the anode
The efficiency of X-Ray production slightly increases as_____
increases.
kVp
The HVL is____
the thickness of a material to reduce the beam intensity to half the initial intensity
The main purpose of added filtration is to reduce____
patient dose
The number of useful X-Rays in the beam defines X-Ray
quantity
The useful characteristic X-Rays in diagnostic radiology are from tungsten targets are_____
X-Rays.
K-shell
The X-Ray emission______
is a plot of______
spectrum, number of X-Rays vs energy
The X-Ray quality is____
not related to mAs
The X-Ray quality______
when distance_____
does not change, is changed
The X-Ray quality______
when kVp____
decreases,decreases
The X-Ray quantity is___
directly related to mAs
The X-Ray quantity is
directly related to kVp^2
The X-Ray quantity is
inversely related to distance^2
What happens to X-Ray penetrability as beam quantity increases?
Nothing, quantity is not effected by penetrability.
When comparing the emission spectra of molybdenum with tungsten, both at 80 kVp and 20 mAs:
molybdenum characteristic X-Rays will have lower energies than tungsten
Where are the lowest energy X-Rays that are produced most likely to be absorbed?
in the tube target
Which clinical X-Ray exam is likely to have Characteristic X-Rays in the useful beam?
Chest x rays
Which interaction involves production of Bremsstrahlung X-Rays?
Radiative
Which interaction involves production of Characteristic X-Rays?
ionization
Which interaction involves production of infrared photons?
Excitation
Which of the following, if it is the only thing changed, will increase noise on the digital image?
a. Increased source to image distance
b. Reduction of kVp
c. I ncrease in filtration
2 d. Reduction of mAs
(e. All of the above)
Which of the following is a compensating filter?
a. trough
b. wedge X
c.bow tie
d.boomerang
(e. All of the above)
Which of the following transition results in the highest energy characteristic X-Ray?
O to K
X-Ray intensity can be changed by changing
a.
distance X
F Flag question
b. filtration
C.
kVp
d. mAs
(e.
All of the above)
X-Ray quality is measured in
half-value layers (HVL)
X-Ray quantity is_____
filtration.
exponentially related to
X-Ray quantity is measured in
Roentgens (R)
