FINAL TQ PART II Flashcards
what are the three basic x-ray components?
generator
X-ray tube
control panel
what are the two types of electricity?
static
current
name this type of electricity and unit?
electric charge at rest
static
unit: coulombs
name this type of electricity and unit?
moving electric charges
current
unit: amperes
what law is the electric current based on?
ohm’s law
V=IR
what are the two electric currents?
direct and alternating current
name this defn?
flow of electrons in one direction only
direct current, flows in one direction only
name this defn?
electron flow in alternating opposite directions
alternating current, found in wall plugs
why are pulsating X-ray tubes not permitted?
not safe
poor images
hard on tube
this X-ray component supplies electric power to the X-ray tube
x-ray generator
is this a step-up or step-down transformer?
filament heating, what is the voltage?
what does electron acceleration require?
step down
10 V
40-150 kVp
the x-ray generator produces what kind of current? how?
smooth, high voltage direct current out of low voltage AC current
transform
rectify
smooth
changing magnetic field produces? electric field?
transient electric field
transient magnetic field
what is this principle?
current flow thru one coil can cause mutual inductance in a 2nd coil wrapped around the same iron core or rod
basis of transformer form induced EMFs
T/F, the step down voltage in the 2nd coil will be less than the primary circuit?
T
for transformers, current flow in one direction means what for voltage?
positive
for transformers, flow in the opposite direction means what for the voltage?
negative
law one for transformers?
law two?
Np/Ns=Vp/Vs
VpIp=VsIs
N=turns
V=voltage
I=current
T/F, a transformer can not create energy?
T
the purpose of the rectification is too?
smooth the waves out
what are the principle disadvantages of full wave rectification?
tube pulsates and anode receives dif amounts of energy
intensity of x-ray beam
quality of beam varies over each half cycle
what does increased pt dose via soft radiation mean?
its bad for patient
for best image, what type of rectification do we need?
filtered rectified, full wave
name this part of the x-ray machine?
store charge quickly and release charge quickly
capacitor
what types of rectified waves do pods use?
half wave
name this defn?
this is the variation in the voltage across the X-ray tube expressed as a percentage of its maximum value
ripple factor
half wave, unfiltered is what percent?
half wave, filtered?
full wave, unfiltered?
full wave, filtered?
what do hospitals use?
100%
20%
100%
9% (looks best)
hospitals
how does the X-ray tube work?
evacuated glass envelope and CRT
cathode to anode
window
added filtration
beam limiting device
what is important in x-ray generation?
the e’s conducted away/complete circuit have what units?
high KE e’s interact with target atoms to produce photons in x-ray wavelength
mA
what is the x-ray beam comprised of?
polyenergetic photons made of different energies directed at the window and filter
faster moving electrons produce what kind of wavelengths?
higher, shorter wavelengths
so this concept is found on the cathodes and the idea is that electrons boil off of cil and form negatively charged electron clouds?
what is this idea called
thermionic emission
T/F, cathodes have high resistance to heat?
T
filament circuit has what kind of current?
tube current?
amp
mA
in the filament circuit what is the voltage, current, power?
high resistance in filament causes temp to rise to how much?
10 V
4 amps
40 watts
> 2200 deg C., requires step down coils, thermionic emission of the electrons
electrons emitted from the filament form negative cloud called a?
space charge
for the space charge effect, less than what kVp is insufficient for the electrons to be pulled away from the filament keeping the charge in effect?
<40 kVp
target bombarded by the electrons is called?
the area/shape of the beam projected onto the patient and image receptor? what does angling do?
focal spot
effective focal spot
effective focal spot is smaller than the actual focal spot
what are the two types of anodes?
rotating
stationary
so in the anode design, name this principle?
anode angled to decrease focal spot size
smaller focal spot=?
shallow angles=?
line-focus principle
sharper images
sharper images
x-rays produced within the anode are attenuated as they pass out of the anode?
anode heel effect, more pronounced with steep anode angles with higher intensity on the cathode
the purpose of filtration does what to the waves?
filters out long wavelengths and lower energy radiation hardening the beam
required minimum total filtration for tube potential 50 to 70? under 50? above 70?
*what is true total after mirror added with tube potential between 50-70?
- 5
- 5
- 5
* 2.5
inherent filtration can consist of?
glass envelope
insulating oil
window
name the compensating filters?
wedge
trough
step-wedge filter
name this type of radiation?
electrons do not collide with tungsten anode atoms or their components
each deflection results in a braking effect yields a photon of radiation
bremsstrahlung radiation
the KE lost by electrons thru the braking effect is converted to _____?
photons of equivalent energy
spikes on the curve are called?
also this happens when electrons bombarding the target are able to knock out inner orbital electrons
characteristic radiation
binding shell energies for the following tungsten shells?
K shell
L shell
M shell
70 keV
11 keV
2 keV
the work required to remove the electron from an atom?
binding energy
name this type of radiation?
positive charged tungsten anode atom returns to its normal energy state by emitting radiation in the x-ray wavelength
characteristic radiation
