7. X-ray Emission Flashcards
Refers to the number of x-rays or intensity of the beam usually expressed in mR or mR per mAs
Quantity
Factors that Affect X-ray Quantity
o mAs
o kVp
o Distance
o Filtration
is just a measure of the total number of electrons that travel from cathode to anode
mAs
mAs =
mC (milli columb)
1 C =
6.25 x 10^18 electrons
Refers to the penetrating qualities of the x-ray beam and is expressed by kVp or HVL
Quality
Factors that Affect X-ray Quality
o kVp
o Filtration
The Thickness of an absorber needed to reduce the intensity of the x-ray beam into half of its
original value
Half-Value Layer (HVL)
product of current and time
mAs (milliamperage per second)
factor to adjust if you want to increase or decrease the energy of x-ray or it’s penetrability
kVp (kilovoltage peak)
Space between the source of x-ray and IR (film)
Distance
As distance of the patient from the source ______, the intensity/quantity of the x-rays that reach the
target ______; according to inverse square law.
increases,
decreases
Removal of flawed x-rays
Filtration
filtration occurs in x-ray tube glass
inherent filtration
can manually place between the protective housing between the x-ray tube window and
the collimator, usually made up of aluminum; can come with various shape and it also depends with your purpose
added filtration
relationship between x-ray quantity and mAs
Directly Proportional
electrons that travels from cathode to anode
Projectile electrons
relationship between quantity and kVp
Directly Proportional
also affects the number of electrons that will reach anode and eventually the patient and IR.
kVp
relationship between X-ray quantity and distance
Inversely Proportional
relationship between X-ray quantity and distance (aka)
Inverse Square Law
square law relationship
Directly Proportional
Added filtration _____ the intensity/quantity of x-rays
decrease
Added filtration _____ the quality of x-rays
increase
Standard unit for HVL is
millimeter of aluminum
quantity of x-rays
decrease as SID increases
Inverse square law
X-rays are
divergent
refers to x-ray quantity (the number of x-ray photons in the beam)
X-ray intensity
Relationship between kVp and X-ray quantity aka
Direct Square Law
is adjusted to compensate reduction from
distance changes and to maintain the exposure.
mAs
is the most appropriate in defining quality of x-rays
HVL
Average photon energy is increased with
filtration
