LECTURE I Flashcards
what are things an x-ray operator must know?
- Proper operation of each individual x-ray machine (everyone is different)
- Positioning patient
- Controlling image quality – kVp, mA, grid, etc.
- Minimizing radiation as much as possible
- Radiation distribution in room
- Positioning personnel
- Shielding devices and monitoring devices
- Laws and policies
what are the metrics used in operating an x-ray?
kilo, 10^3
milli, 10^-3
smallest particle of matter that has all the properties of the element
Atom
of protons
Atomic Number (Z)
of protons and neutrons
Atomic Mass (A)
amount of energy that electrons have in each shell
Binding Energy (BE)
bound electrons have a positive or negative total energy?
negative
T/F, x-rays are part of the electromagnetic spectrum?
T
what is the SI unit of frequency?
Hertz (Hz)
what is the equation of velocity?
wavelength x frequency
localized electromagnetic energy that is absorbed or emitted in discrete bundles
photons
T/F, ionizing radiation is never transferred to any material with which it interacts?
F, always
term used to define:
when atoms gain or lose electrons (in outer shell)
ionization
what are the two types of electricity?
static
current
static electricity is charge at rest measured in?
coulombs
current electricity is moving charge measured in?
amperes
what direction do electric currents flow?
always flow from neg to pos
what are the two types of electric current?
AC/DC
what is the direction of flow of DC and AC?
flow of electrons in one direction
flow of electrons in alternating and opposite directions, like a negative and positive wave
for AC, what is one pulse? 1 cycle?
from - to +
2 pulses
the x-ray machine has what 3 basic components?
generator
x-ray tube
control panel
this supplies the power to the X-ray tube from the wall plug to the X-ray tube
generator
what are the step completed by the generator?
3 steps
transformation
rectification
capacitation
for the generator to be effective for the x-rays, the energy needs must be higher to accelerate electrons and this is done by what step by the generator?
transformation
since we know the energy needs cannot be an AC because of the pulsating vibes, what step of the generator fixes this?
rectification
why is pulsating bad for for the x-ray?
not safe
poor images
hard on the x-ray tube
what part of the generator process allows for the energy waves to be smooth?
capacitation
what does step one, transformation by the generator, do?
turns low voltage AC to high voltage AC
a changing magnetic field makes?
a transient electric field and vice versa
this is a coil of wire that current runs through to create a weak magnetic field, left to right run action…
solenoid
if there is another coil wrapped around the same iron core we induce an EMF in that coil as well and this called?
mutual inductance
what does rectification do?
turns AC to DC
what does capacitation do?
filters or smooths out the ripple voltage to make the radiation more effective
this is a variation in the voltage across the X-ray tube expressed as a percentage of its maximum value( the higher the percentage, the less smooth it will be)
this is what step of the generator process?
the term that best describes the option we should have for a clearer image?
ripple factor
capacitation
high frequency
so, now what part component of the x-ray makes the rays and name the steps?
X-ray tube
boiling off electrons
electrons shot at anode target
production of photons
completion of circuit
name this step of the X-ray tube:
electrons boil off at the headed tungsten filament cathode coil
boiling off electrons
this term is used to describe a structure of the cathode that surrounds the coil and has tungsten filament
focusing cup
why does the tungsten filament heat up in the boiling off electron step of the X-ray tube?
high resistance
this is the term used in the 1st step of the X-ray tube that describes electrons that are circulating around the coil boil off due to heat?
thermionic emission
term used for the cloud that stops further electron emission via electrostatic repulsion?
space charge effect
space charge effect at low anode kVp?
less than 40, the cloud limits current flow in the X-ray tube
space charge effect at high anode kVp?
greater than 40, aka the saturation phase and so electrons are pulled away from the filament and tube current is maximized
this is the step of the x-ray tube that goes from neg. cathode to pos anode target with high kVps
electrons shot at anode target
this is the part of the copper anode where the electrons reach, specifically the tungsten target completing the circuit?
focal spot
this is the step of the X-ray tube where high KE electrons interact w/ tungsten target to produce photons at x-ray wavelengths?
production of photons
what are the two types of anodes?
which one is more common?
which one spins at high speeds, dissipates and increases SA?
stationary and rotating anode
stationary anode
rotating anode
the heel effect is in what step of the X-ray tube? and what is it?
what should we take note of?
3rd step, production of photons
creation of a nonuniform x-ray beam duet to some radiation absorption by the heel
thicker body parts like heel faces the cathode and the toes face the anode
what is the 4th step of the X-ray tube? define it…
completion of the circuit
the x-rays leave through window/filter and electrons are conducted away
what are the two types of filtration?
inherent filtration
added filtration
this type of filtration is the filtering that is inherent in the X-ray tube head not added and result in the x-rays passing through glass, insulting oil, and window
inherent filtration
this type of filtration is added to the window in the path of exiting x-rays
added filtration
what can be added to filtration to be effective?
aluminum and compensating filters (compensate for density variation) like:
wedge filter
trough wedge filter
step wedge filter
what are the three basic anode interactions?
infrared radiation
Bremsstrahlung radiation
Characteristic radiation
name this basic anode radiation?
99% of anode interactions yield useless infrared (heat)
infrared radiation
name this basic anode radiation?
0.9% of anode interactions that yields the x-rays
aka braking radiation
bremsstrahlung radiation
name this basic anode radiation?
0.1% of anode interactions that also yields useful x-rays
characteristic radiation
electrons don’t collide with tungsten anode atoms because they are diverted due to opposing nuclear forces and this is called?
so deflections occur and what does this equal?
braking effect
a photon of radiation
for the polyenergetic Bremsstrahlung curve, what is significant of 33 KeV? 100 KeV? why is ht spike important?
max # of x-rays
no x-rays
spike in the graph is due to x-rays being produced by characteristic radiation
how is X-ray radiation released?
by positively charged tungsten atoms as a way of returning it to its normal energy state
the inner orbital electrons knocked off make what percent of the x-ray beam? what is the innermost shell of the tungsten atom?
10-28% of the x-ray beam
K shell 70 keV
L shell 11 keV
M shell 2 keV
