8. X-ray Emission Spectrum Flashcards
refers to the range of types or values of any quantity such as x-ray
Spectrum
contains only specific values
Discrete Spectrum
contains all possible values
Continuous Spectrum
have precisely fixed (discrete) energies and form a discrete emission spectrum
Characteristic x-rays
have a range of energies and form a continuous emission spectrum
Bremsstrahlung x-rays
is associated with the minimum x-ray wavelength
Maximum x-ray energy
is numerically equal to the kVp
Maximum x-ray energy
the process of adding together the total number of x-rays emitted at each spectrum to get the
total number of x-rays emitted from an x-ray tube
Integration
The farther to the ____ a spectrum is, the higher the effective energy or quality of the x-ray beam
right,
The ____ the area under the curve, the higher is the x-ray intensity or quantity
larger
A change in ______ results in a proportional change in the amplitude of the x-ray emission spectrum at all
energies.
mA or mAs
Four Principal Factors Influencing the Shape of an X-ray Emission Spectrum
-The projectile electrons accelerated from cathode to anode do not all have peak kinetic energy. Depending on
the types of rectification and high-voltage generation, many of these electrons may have very low energies
when they strike the target. Such electrons can produce only heat and low-energy x-rays.
-The target of a diagnostic x-ray tube is relatively thick. Consequently, many of the bremsstrahlung x-rays emitted
result from multiple interactions of the projectile electrons, and for each successive interaction, a projectile
electron has less energy.
-Low energy x-rays are more likely to be absorbed in the target.
-External filtration is always added to the x-ray tube assembly. This added filtration serves selectively to remove
low-energy x-rays from the beam.
A change in kVp affects both the _____ and the _____ of the x-ray emission spectrum.
amplitude,
position
When kVp is increased, the relative distribution of emitted x-ray energy shifts to the ____, to a higher average energy.
right
The maximum energy of x-ray emission always remains numerically ____ to the kVp.
equal
A change in kVp has no effect on the position of the ______ x-ray emission spectrum
discrete
In diagnostic range, a 15% increase in kVp is equivalent to _____ the mAs
doubling
Effect of Tube Current
Affects Amplitude of Spectrum
Effect of Tube Voltage
Affects Amplitude and Position
Effect of Added Filtration
Decreases Amplitude (x-ray quantity), most effective of low energy
Effect of Target Material
Affects Amplitude of spectrum and position of line spectrum
Effect of Voltage Waveform
Affects Amplitude, most effective at high energy
The result of added filtration is an _____ in the average energy of the x-ray beam with an accompanying
reduction in x-ray quantity.
increase
Added filtration more effectively absorbs low-energy x-rays than high-energy x-rays; therefore, the bremsstrahlung x-ray emission spectrum is reduced further on the _____ than on the right
left
Adding filtration is sometimes called ________ because of the relative increase in average
energy.
hardening the x-ray beam
Increasing target atomic number _____ the efficiency of x-ray production and the energy of characteristic
and bremsstrahlung x-rays.
enhances
An increase in the atomic number of the target material will shift the characteristic spectrum to the ____
right
Effect of Voltage Waveform
Five voltage waveforms
- Half-wave rectification
- Full-wave rectification
- Three-phase/ six pulse
- Three-phase/ twelve pulse
- High-frequency
Because of ______, operation with three-phase power or high frequency is equivalent to an approximate
12% increase in kVp, or almost a doubling of mAs over single phase-power
reduced ripple
Increase in Current (mAs) results to
Increase in quantity. No change in quality
Increase in Voltage (kVp) results to
Increase in quantity and quality
Increase in Added Filtration results to
Decrease in quantity.
Increase in quality
Increase in Target Atomic Number (Z) results to
Increase in quantity and quality
Increase in Voltage Ripple results to
Decrease in quantity and quality
x-axis
Photon Energy (Quality of X-rays)
y-axis
Number of Photons (Quantity of X-rays)
It has an energy from 0-1 up to the maximum value or the peaked value
Bremsstrahlung x-rays
X-rays that occur when the incoming electron will interact with nuclear field
(loss of energies)
Bremsstrahlung x-rays
X-ray intensity aka
X-ray quantity
Pertains the amount or the number of electrons
X-ray intensity
A relationship between the x-ray and wavelength is
inversely proportional
A relationship between the energy and frequency is
directly proportional
defined as a flow of electrons in the conductors, controls the
amount of intensity specially combining in time
mA (current)
refers to height and x-ray
quantity in the given x-ray emission spectrum graph
Amplitude
TYPE OF RECTIFICATION
Single- phase and Self-rectified, Single-phase and Full-wave rectified, Three- phase and 12 pulse, High-frequency, Constant potential
100% Ripple
Single- phase and Self-rectified,
Single-phase and Full-wave rectified
3-5% Ripple
Three- phase and 12 pulse,
High-frequency
0% Ripple
Constant potential
There are two types of spectrum:
Discrete,
Continuous
are DISCRETE because they depend on the electron binding energy of the struck electrons.
Characteristic x-rays
For characteristic x-rays to be produced, the energy
of the incoming electron must be _______
than the electron binding energy of the struck
electron.
equal or greater
SI unit of Photon energy is
keV
Most of the bremsstrahlung x-rays are produced at
approximately ____ keV
49
X-ray energy and X-ray wavelength is
inversely proportional
gives evidence that Bremsstrahlung x-rays are continuous
bell curve
X-ray energy and frequency is
directly proportional
Frequency and wavelength are
inversely proportional
how far to the right the spectrum is or/and how high the effective energy or quality of the x-ray beam is
Position
it has something to do with the number of
electron flowing from the cathode to the
anode
mA
is a product of the tube current and exposure
time in seconds.
mAs
- 5 keV is _____ as it is discrete (in the case of
tungsten) .
constant
The _____ the amplitude, the more x-rays photons
are produced.
higher
The further the graph is to the _____, the more
penetrable the x-rays are.
right
______ as well as _____ of the X-ray emission spectrum is affected by the four principles
SHAPE,
SIZE
X-rays when produced don’t have the same
energies
Heterogenous
Discrete emission spectrum depends on the
______ of the element
characteristic
No matter how much you increase the kVp
it will not affect the position of the ______
x-ray emission spectrum
discrete
can’t be readily and easily
manipulated
Target material
Best choice of target material is
Tungsten
there is only the positive cycle and
negative cycle is eliminated
half-wave
uses a single wave like half-wave but
the negative cycle is not eliminated rather it is
converted to positive cycle. This would mean that the amount of x-rays are doubled
full-wave
there are three waves produced simultaneously
three-phase
2 types of three-phase
six pulse,
twelve pulse
negative cycle is eliminated
six pulse
negative cycle is converted
to positive cycle; more efficient
twelve pulse
happens when the voltage drops down from
the highest point to the lowest point
Ripple
x-rays are less likely to have 0 energy; efficiency is increased as well as quality of x-rays.
Reduced ripple
There is approximately ___ ripple for the high-frequency type of rectification
1%
is the ideal graph of a direct current
Constant potential
undesirable to have as it results to the decrease in quantity and quality of X-rays
Voltage ripple
The higher the voltage ripple, the more _______ the result is
undesirable
