Unit 1: Target Interactions (review) Flashcards
the cathode houses the:
filaments and focusing cup
the focusing cup focuses the electrons during:
thermionic emission
thermionic emission:
the boiling off of electrons due to the heating of a small coil of thoriated tungsten wire
electrons form a:
thermionic cloud or space charge
most common type of x-ray tube failure:
tungsten filament vaporization
most x-ray tubes are:
dual focus
the chosen filament is heated until it becomes ______________ where electrons are then boiled off
incandescent
Why does increasing kVp improve the average quality of the beam
increasing kVp will increase the kinetic energy/keV of the electrons, causing a higher energy photon
Why is a tungsten target an “efficient” producer of x-ray photons?
it is able to dissipate heat due to high melting point and high Z number
We use keV to discuss what?
kinetic energy of the incoming electron
the production of a Brems photon involves interaction between an incident electron and what else?
the nucleus
define electromotive force:
another term for kVp (potential difference)
most radiographs are produced between what kVp?
50-120
tube current is expressed in:
mA
Bremsstrahlung x-rays occur when:
the incident electron is slowed down or stopped
the “skid mark” resembles the:
x-ray photon that’s created
Bremsstrahlung x-ray production is responsible for the:
polyenergetic nature of the beam
K-shells have a binding energy of:
69 keV
Which form of photon production involves the process of ionization?
characteristic
Which portion of the primary beam is the “discrete” portion?
characteristic
Characteristic x-rays result when the interaction:
ionizes the target atom through removal of inner-shell that causes a void and is then filled through the cascading effect
What percentage of the primary beam will be made of characteristic photons with a kVp setting of 65?
none (has to be 69)
a characteristic x-ray is characteristic because:
they are always 57 keV
at 100 kVp the percentage of characteristic x-rays will be:
15%
