Chapter 12 Notes Flashcards
prime factors
mAs, kVp, and distance
x-ray emission can be described in terms of both its
quantity (amount) and quality (penetrability)
x-ray quantity is affected by
mAs, distance, kVp, and filtration
x-ray quality is affect by
kVp and filtration
mAs is directly proportional to
number of x-ray photons created in tube
kilovoltage affects
both quantity and quality
if kVp is doubled
x-ray quantity would increase by a factor of 4
15% rule
an increase in kVp by 15% will cause and approximate doubling of exposure; to maintain exposure, mAs must be reduce to one-half its original value
third prime factor
distance from actual focal spot to IR
quantity of x-ray photons is inversely proportional to
square of the distance
quantity is measured in
roentgens (R)
quality is numerically represented by
HVL
changing the current to the filament
changes number of electrons released through thermionic emission
unit of current
ampere (A); 1 A = 1 C/sec (coulomb)
short exposure times useful in
reducing motion artifacts
mAs reciprocity
same IR exposure will result from different mA and time selections, provided that mAs totals are equal
more density =
darker image
less density =
light film image
brightness
how dark or light digital image appears on monitor
kVp should not be used to control
IR exposure
as SID increases, beam intensity _____
decreases
inverse square law
I1/I2 = D2 (squared)/D1(squared
doubling the distance reduces the beam intensity by a factor of
4
density maintenance formula
mAs1/mAs2 = D1 (squared)/D2 (squared)
