X-ray/Photon Production Flashcards
potential energy
energy at rest
What contains potential energy?
a focused electron cloud
kinetic energy
energy in motion
What contains kinetic energy?
an incident electron moving towards the anode
What happens when electrons hit the atoms of the target?
they transfer their kinetic energy to the atoms
What percentage of the kinetic energy of the incoming electrons crashing into the target is converted to HEAT?
99.8%
What percentage of the kinetic energy of the incoming electrons crashing into the target is converted to useful X-RAYS?
less than 1%
What is the distance between the filament and the x-ray tube target?
1 cm
kVp (kilovolt peak)
the measure of the maximum electrical potential across an x-ray tube
What else can kVp also be called?
Potential difference (PD)
Electromotive Force (EMF)
or Voltage (V)
electromotive force
another term for kVp
Most radiographs are produced with ____ to _____ kVp techniques
50 to 120
1 kVp = _______ Volts
1,000
higher kVp causes more electrons to be attracted to the anode target which does what?
increases the quantity of x-rays in the beam
the higher the kVp, the greater the _________ ________ of __________ in the space charge
kinetic energy; electrons
saturation current occurs:
when all possible electrons are attracted over to the anode target
kVp influences…
quantity of x-ray beam
beam intensity
quantity of the beam
quality of beam:
how much kinetic energy the electrons will possess while traveling to the target
quantity of beam:
amount of electrons travelling to the target
more efficient x-ray photon production occurs because of:
a higher kVp
Does tube current have an effect on the efficiency of photon production?
NO
keV
kilo-electron Volt
What does eV describe?
the kinetic energy of the electrons in the x-ray tube and the photons produced at the anode target
velocity
how fast an object is traveling
How fast do electrons travel from cathode to anode?
approx. half the speed of light
Photons travel at the speed of light or they do not exist.
true
tube voltage is expressed in what?
kVp
tube current is expressed in what?
mA
tube current
rate of electron flow crossing from cathode to anode
tube current is determined by the number of electrons emitted by the filament during ____________ __________.
thermionic emission
electrons are ___________ as they interact with anode target
slowed down
What is produced as a result of deceleration of electrons?
x-ray photon
What type of x-ray photon is produced by electron deceleration?
Bremsstrahlung
What happens during electron ionization?
incident electron ionizes an atom of the target material
ionization
the addition or removal of an electron
What is produced as a result of electron ionization?
x-ray photon
What type x-ray photon is produced during electron ionization?
Characteristic x-ray
How can the technologist decrease the intensity of the x-ray beam while maintaining the same beam energy?
decrease milliamperage (mA)
What 3 factors are required for x-ray production?
source of electrons
means of rapidly accelerating electrons
means of rapidly decelerating electrons
During an attempted x-ray exposure, the x-ray tube fails to create any x-ray photons. Which of the following conditions is most likely to explain this failure?
A. inadequate mA setting
B. excessive kVp setting
C. breakage of the cathode filament
D. improper warm-up sequence
C. breakage of the cathode filament
An exposure of an obese patient results in inadequate exposure. What should be modified to increase the energy and penetrability of the x-ray beam?
kVp
An exposure taken with an 80 kVp would have an x-ray energy spectrum with a maximum photon energy of:
80 keV
What factor is primarily responsible for controlling the energy of the x-ray beam?
kVp
What condition is required to induce thermionic emission within the cathode filament?
high current
Which component of the x-ray tube serves as the source of free electrons?
cathode filament
