Exam 1 - X-Ray Production

what part of the x-ray machine delivers power to the x-ray tube and circuits

generator

what does the generator permit

selection of x-ray energy, quantity, and exposure time

does the generator need to be AC (bidirectional) or DC (one direction)

DC

what is the name of the process in which the generator is converted from AC to DC

rectification

rectification creates unidirectional flow in the x-ray tube between what structures

cathode to anode

what are the 3 types of generators

single-phase

three-phase

high frequency

what does half-wave rectification do

removes just the negative voltage

what does full-wave rectification do

rectifies the negative component to a positive on

is half-wave rectification or full-wave rectification more efficient? why?

full-wave

no gaps in the wave, entire waveform is used

rectification picture to explain

voltage ripple describes the variation in what

x-ray beam energy level (quality)

a single-phase, full-wave rectification will have a ___% ripple

100

a 3-phase, full-wave rectification will have a ___-___% ripple

5-15

high frequency, 500+ Hz will have a <____% ripple

1

is a higher or lower ripple desired? why?

lower

increases the quantity and quality of the x-ray beam

Voltage Ripple Picture to explain

what kind of generator has the lowest dose of x-ray absorption and shortest image time

high frequency

what button do you press to cause the anode to start rotating

Prep

once Prep is pushed, you will then push what button

exposure

pressing which button will allow the production of x-rays

exposure

t/f

there is NO radiation produced until you press the exposure button

true

when you press the exposure button, electrons move from the ____(-) to the ___(+)

cathode, anode

the filament circuit in the cathode will cause what to heat up? why is heat important to the process?

tungsten

outer electrons get released - thermionic emission

what controls the current supplied to the filament circuit

mAs

a hotter filament means there is a higher mAs, this means there are (more or less?) electrons being produces over the set period of time

more

what is the Space Charge Effect

electrons accumulate around the filament and forms a negative charge which repels and limits further emission of electrons from the surface

what 2 components make up the cathode

tungsten filament and focusing cup

when electrons are accelerated from the cathode to the anode, some of their kinetic energy is lost. Where does this energy go?

released as x-rays and heat

an increase in kVp increases the average energy of the x-ray beam and the ___ of x-rays produced

number

what % of electron interactions get converted into x-rays

1%

why is it important for the anode to rotate

dissipates heat produced through x-ray production....99% of electron interactions are converted into heat

What are the 2 forms of x-ray production

Bremsstrahlung radiation

characteristic radiation

what is the name of the process that produces the highest number of x-ray photons

Bremsstrahlung

describe the process of Bremsstrahlung radiation

electron travels close to nucleus, slows down, bends around nucleus

Bremsstrahlung radiation is referred to as ___ radiation

braking

Bremsstrahlung radiation accounts for ___% of the x-ray beam when the kVp is above 70 and ___% when kVp is lower than 70

85%, 100%

describe characteristic radiation

inner shell electron is ejected and creates a hole in the electron configuration, a cascade effect takes place and the electron from the next shell will fill the gap....this produces an x-ray photon

characteristic radiation utilizes what metal?

tungsten

what % of x-ray production does characteristic radiation account for? what energy level must be met for these interactions to occur?

15%,

69.5 kVp

discrete peaks of x-ray related to the anode material are noted with which interation?

characteristic radiation

on a graph, what interactions are represented by the smooth curves

bremsstrahlung

increasing the energy of the x-ray production will ___ the quantity

decrease

increasing kVp, increases the maximum photon energy, and increases the number of ____ produced

photons

x-ray photons are produced from interactions at what structure

anode