what has to happen in order for the x-ray tube to produce x-rays
electrical current to filament and field between cathode and anode
what determines the quality of the beam
penetrating power (kVp)
what increases the quantity/intensity of the beam
number of x-rays traveling from the tube toward film over a given period of time (mA)
what happens as the mA is increased
of electrons released from filament is increased (thermonic emission)
what has a direct relationship with time
mA
the period of time x-rays leave the tue
exposure time
what is exposure time measured in
fractions of seconds
how do you calculate mAs
mA multiplied by time
what are advantages to high mA settings (4)
shorter exposure time, decreased motion artifacts, examination of thicker areas, decrease personnel exposure
what is the most common artifact in vet medicine
motion
what is the highest mA potential
1600 mA
what does higher mA capacity mean
more power/diversity
what is murphy’s law
animal will move when x-ray is taken
what is the quality of x-rays proportional to
kinetic energy of electrons reaching target
energy related to motion
kinetic energy
maximum energy available during exposure
kilovoltage peak
what does higher kVp mean (5)
more penetration, faster electron acceleration, shorter wavelength, higher % of x-rays reach film, lower mAs (shorter exposure time)
what is kVp inversely related to
mA
a method of estimating kilovoltage in relation to area thickness
santes’ rule
how do you calculate kVp
(2 X thickness)+40
FFD
focal film distance
SID
source-image distance
what does 40in in santes’ rule represent
FFD/SID
what is thickness in centimeters measured with
caliper
what is the starting point for film trays
11cm or more
what is used for radiographs with film on tabletop
10cm or less
what is the SID/FFD kept at
40 inches
SID decrease
x-ray intensity increases
SID increases
x-ray intensity decreases
what is the inverse square law
intensity inversely proportional to SID
how do you calculate new mAs
old mAs x [(new SID)2 over (old SID)2]
what is the SID usually kept between
36-40in
varying degree of blackness
density
measurable distance between two adjacent densities
contrast
what do x-rays follow the rules of
light
low mA=
less electrons
