Chapter 6 Exam Flashcards
Involves the K-shell (first shell around the nucleus, has the strongest binding energy)
Only the interactions involving K-shell are of sufficient energy to be useful
Characteristics Interactions
If its energy is greater than the binding energy from the orbital electron, It is removed from orbit
A filament electron
when the filament electron removes the K-shell electron and the outer-shell electrons drop to fill inner-shell vacancies
This interaction is happening on the anode target
Cascade effect
Characteristic is only x-ray production that uses _______ (in the tube)
cascade
A tungsten atom has ___ electrons in ___ different shells
74, 6
K-shell electrons in tungsten have the strongest binding energy at ____ keV
69.5 keV
_______ is the majority of our x-ray photons
The majority of the x-rays in the primary beam are ______
Brems
How many characteristic x-ray photons are created at 59 keV?
0, it has to be 69.5 or higher
what does bremsstrahlung mean in German?
breaking or slowing down
Filtration, IR, and high speed imaging are part of:
radiation protection
The filtration total must total ______ of aluminum equivalent
2.5mm
Beam quantities main contributing factor is:
mAs, quantity decreases as we increase distance
If kVp is doubled, the intensity (quantity) increases by a factor of:
four
raising kVp does or doesn’t create more x-rays?
doesn’t
what is increased when kVp is raised? which allows more of the original x-rays to make it through the filters
quality
If you bump up ____ it is like turning up the stove and boiling more electrons off of the filament
mA
What is bad for quality and quantity?
distance
which has more interactions, brems or characteristics?
brems
A filament electron interacts with an outer-shell electron of tungsten but does not remove it. Which of the following is produced? 50keV photon, 70 keV photon, heat, brems photon
Heat
At what point in the interaction chain of events is a characteristic photon produced?
Outer-shell electron filling inner-shell vacancy
A filament electron enters a tungsten target atom with an energy of 70 kVp. It interacts first with an L-shell electron, then with a K-shell electron. Which of the following are produced? 1. K-characteristic x-ray photon, 2. L-characteristic x-ray photon, 3. heat. 1 & 2, 1& 3, 2 & 3, 1, 2, & 3
2 & 3 only
What is the energy of an x-ray photon produced when an O-shell electron fills a K-shell vacancy?
69.42 KeV
What is the energy of an x-ray photon produced when an L-shell electron fills a K-shell vacancy?
57.4 KeV
What is the energy of an x-ray photon produced when an M-shell electron fills an L-shell vacancy?
9.28 KeV
What is the energy of an x-ray photon produced when an O-shell electron fills and L-shell vacancy?
12.02 KeV
Which of the following is a major source of occupational exposure?
Compton interactions
Which interaction, within the diagnostic range, does not involve the removal of an orbital electron?
Classical scattering
Which interaction requires 1.02 MeV of energy?
Pair production
A photon of 10 MeV colliding with a nucleus will likely result in what type of interaction?
Photodisintegration
Which technique will produce the greatest number of photodisintegration events in an average abdomen? 120 kV and 5 mAs, 108 kV and 10 mAs, 98 kV and 20 mAs, none of the above
None of the above
Which of the following events will not occur in the diagnostic range of x-ray energies? Classical, compton, photoelectric, photodisintegration
Photodisintegration
Positive contrast media is administered to increase what type of interactions?
Photoelectric
Which of the following contributes most to image fog? Classical, photoelectric, pair production, compton
Compton
Which interaction in the diagnostic range involves the total absorption of the incident photon?
Photoelectric effect
When the kV selected is equal to or slightly greater than the inner-shell binding energy of a target tissue atom, which interaction predominates?
photoelectric
The filament electrons interact with target atoms
to produce x-rays in the following two ways:
characteristic interactions & bremsstrahlung (brems) interactions
Energy is “characteristic” or dependent on the difference in binding energy between the shells involved
Characteristic photons
The filament electron misses all the orbital electrons
and interacts with the nucleus of the target atom
The attraction causes the filament electron to slow down and change direction, and in doing so it loses kinetic energy
bremsstrahlung interactions
how can the energy of a brems photon can be found?
by subtracting the energy that the filament electron
leaves the atom with from the energy it had upon
entering
With a tungsten target, most of the photons produced are:
brems
Essential to the tube head assembly
The target window is the primary contributor
inherent filtration
In a general radiography tube head assembly, this filtration comes in the form of another 2.0 mm Al placed between the target window and the top of the collimator
added filtration
The combination of inherent and added filtration
total filration
Adjust for variations
in patient thickness
or density and create
a more uniform
exposure to the IR
Attach to the bottom
of the collimator or
placed adjacent to or
on the anatomic part
of interest
compensating filters
the total number of x-ray photons in a beam
affected by mAs, kVp, distance, and filtration
beam quantity
increase in mAs ______ quantity
increases
increase in kVp ______ quantity
increases
increase in distance _______ quantity
decreases
increase in filtration _______ quantity
decreases
The penetrating power of the x-ray beam
Beam quality
This refers to those x-ray photons that are transmitted through the body and reach the image receptor
penetration
serves to remove the lower-energy photons, making the average energy higher
filtration
measures beam quality
defined as the thickness of absorbing material necessary to reduce the energy of the beam to one-half its original intensity
found by measuring beam intensity with a radiation detector
half value layer (HVL)
what is the normal HVL of a diagnostic beam?
3-5 mm Al
Refers to the x-ray beam
as it is upon exiting the
collimator and exposing
the patient
primary beam
Refers to the x-ray beam
that remains after
interaction with the patient
and is exiting the patient to
expose the image receptor
remnant beam
illustrates characteristic x-ray production.
Called this because the photon energies are
limited to just a few exact values
discrete emission spectrum
Produced when outer-shell electrons fill inner-shell
vacancies in atoms
Named for the shell being filled; there are a number of
bars at each level (K, L, M, etc.) representing the
energy variations depending on the shells involved
characteristic photons
Brems photons
illustrates brems x-ray production
X-axis: energy
Y-axis: number of photons
A graph of brems photons creates a bell-shaped continuum
continuous emission spectrum
x-ray emission spectrum
Y-axis changes indicate:
changes in quantity
x-ray emission spectrum
X-axis changes indicate:
changes in quality
Five factors change the appearance of the
x-ray emission spectrum:
mA, kVp, tube filtration,
generator type, and target material
An increase in mA
________ the
amplitude of both the
continuous and
discrete portions of
the spectrum
increases
An increase in kVp
________ the
amplitude of both
continuous and
discrete portions of
the spectrum and
shifts the right side of
the curve to the right
along the x-axis
increases
What happens to x-ray production when you change the generator type?
High-frequency units are more efficient in producing x-rays than single-phase units
Target materials:
As the atomic
number (Z number)
of the target material
_______, so does the
average energy,
quantity of photons,
and the position of
the discrete line of
the spectrum
increases
increase in mA _____ quantity and _____ quality
increases, no effect
increase in kVp _____ quantity and _____ quality
increases, increases
increase in tube filtration _____ quantity and _____ quality
decreases, increases
increase in generator type _____ quantity and _____ quality
increases, increases
increase in target material _____ quantity and _____ quality
increases, increases
K shell binding energy for tungsten:
69.5 keV
L shell binding energy for tungsten:
12.1 keV
M shell binding energy for tungsten:
2.82 keV
N shell binding energy for tungsten:
0.6 keV
O shell binding energy for tungsten:
0.08 keV
P shell binding energy for tungsten:
0.008 keV
when characteristic x-rays are produced, the energy of the x-rays is characteristic of:
the atomic number of the target
Approximately how much of a filament electron’s kinetic energy is used to produce x-rays instead of heat?
1%
when a bremsstrahlung x-ray is produced:
a projectile electron loses energy
within diagnostic range, which type of interaction produces the majority of x-rays?
bremsstralung
in a tungsten-targeted x-ray tube operated at 90 kVp, the most abundant x-rays would be at:
30 keV
the area under the curve of the x-ray emission spectrum represents:
the quantity
the x-ray emission spectrum is a plot of:
the number of x-rays versus energy
which factor has greatest control over the quality of x-rays?
kVp
