Physics: X-Ray Production 1 (Huda)

Front 1

What is the function of an x-ray generator

Back 1

-A n x-ray generator provides power to the x-ray tube.

Front 2

What do x-ray generators control

3

Back 2

x-ray energy
exposure duration
total exposure

Front 3

What are the 3 main components of an x-ray generator

Back 3

high voltage transformer
filament transformer
rectifier circuits

Front 4

Where are the electronic circuits for voltage and current meter located

Back 4

this is part of the x-ray generator

Front 5

Does the generator have electronic circuits for manual and automatic exposure

Back 5

yes

Front 6

What type of voltage is used in the US

Back 6

120V alternatic current (AC)

Front 7

What is the frequency of ossilation of a AC in the united states

Back 7

60hz

Front 8

What is the voltage required for x-ray tube generators

Back 8

440V

Front 9

What 2 things must be accomplished by the X-generator

Back 9

A generator increases the voltage and rectifies the waveform from AC to direct
current (DC). It must be increased to 440V

Front 10

What type of current is required for a x-ray generator to work

Back 10

Direct current

Front 11

What 3 controls are operated when using an X-ray generator

Back 11

X-ray tube voltage (Kilovolts)
current (mA)
exposure time

Front 12

What does the x-ray voltage control

Back 12

the x-ray energy

Front 13

What does the current afffect

Back 13

the radiation quanity

Front 14

Where is the voltage applied

Back 14

across the x-ray tube and current flows through the x-ray tube

Front 15

What is the power used by the X-ray generator

Back 15

Th e power dissipated equals the product of tube voltage (V) in kilovolts and of current in milliamperes (I), or V x I, and is measured in kilowatts (kW).

Front 16

What is the typical transformer rating

Back 16

Typical transformer ratings in x-ray departments are 100 kV and 800 mA, which
correspond to a power of 80 kW.

Front 17

How high can the voltage that a generator produces become

Back 17

100,000V

Front 18

What is the function of a transformer

Back 18

A transformer changes the size of the input voltage and is used to produce high and
low voltages.

Front 19

What is the function of a step-up transformer

Back 19

increase the voltage

Front 20

What is the function of a step-down transformer

Back 20

decrease the voltage

Front 21

Give an example of electromagnetic induction

Back 21

I f two wire coils are wrapped around a common iron core, current in the primary
coil produces a current in the secondary coil by electromagnetic induction.

Front 22

What is the voltage in a circuit proportional to

Back 22

I f two wire coils are wrapped around a common iron core, current in the primary
coil produces a current in the secondary coil by electromagnetic induction.

Front 23

What law of physics is taken advantage of to manipulate the current

Back 23

Th e product of the voltage (V) and current (I) is equal to the power and must be
equal in the two circuits (conservation of energy) if there are no additional losses.
-Fo r an ideal transformer, the power in the primary and secondary circuits will be equal, so that Vp x Ip = Vs x Is.

Front 24

What is the principle behind step up and step down transformers

Back 24

Th e step-up transformers used in x-ray generators have a secondary coil with many
more turns (500:1) to produce a high voltage across the tube.
-Generators also have a step-down transformer with fewer turns in the secondary
coil for the x-ray tube filament circuit, which only requires about 10 V.

Front 25

What is an autotransformer

Back 25

A n autotransformer permits adjustment of the output voltage, using movable con-tacts to change the number of windings in the circuit.

Front 26

What is a transformer

Back 26

electromagnetic devices that allow a voltage of AC to be changed

Front 27

Can a transformer decrease or increase the voltage

Back 27

yes

Front 28

What are the 2 types of transformers used in an x-ray generator

Back 28

step up
step down

Front 29

What are transformers comprised of

Back 29

two sets of windings that are electrically isolated from eachother

Front 30

What is the function of each of these windings

Back 30

One set of windings is connected to a power supply and is known as the primaries. The other set of windings is connected to a load (in this case the X-ray tube) and is referred to as the secondary windings.

Front 31

What does a transformer look like

Back 31

Front 32

Back 32

Front 33

Back 33

Front 34

Why is this done

Back 34

Front 35

How does the electric current flow in with AC power

Back 35

Th e electric current from an AC power supply flows alternately in both directions,
resulting in a voltage waveform shaped like a sine wave.

Front 36

What is rectification

Back 36

Rectification changes the AC voltage into DC voltage across the x-ray tube.

Front 37

How is rectification achieved

Back 37

Rectification is achieved using diodes, which only permit current to flow in one di-rection.

Front 38

What do diodes do

Back 38

only permit current to flow in one direction

Front 39

Does rectification ensure that electrons travel from cathode to anode only

Back 39

yes

Front 40

Do transformers require AC current to work

Back 40

yes

Front 41

So what must be done after the voltage is created by the transformer

Back 41

it must be made so it is constant and not rising and falling

Front 42

What does rectified voltage look like

Back 42

Front 43

What is half wave rectification

Back 43

one direction of current is eliminated

Front 44

What does half wave rectification look like

Back 44

Front 45

What does a full wave rectifier look like

Back 45

Front 46

What does a single phase generator wave form look like

Back 46

Front 47

What does the 3, 6 and 12 pulse 3 phase generator waves look like

Back 47

Front 48

Are high frequency generators smaller and more efficient than three phase generators

Back 48

yes

Front 49

What are the best generators

Back 49

high frequency generators

Front 50

What is a voltage waveform

Back 50

a plot of voltage over time

Front 51

What is ripple

Back 51

A constant high voltage is desired across the x-ray tube for x-ray production, but in
practice, there is some variation in the voltage, which is called ripple.

Front 52

What type of ripple is preferred

Back 52

A low ripple is desirable because a more constant voltage is produced.

Front 53

What is the voltage for the different types of phase generators

Back 53

these are all voltage waveforms

Front 54

What keV is required to produce diagnostic x-ray

Back 54

Diagnostic x-rays are produced when electrons with energies of 20 to 150 kilo
electron volts (keV) are stopped in matter, producing electromagnetic radiation in
the form of x-rays.

Front 55

What determines the keV of an electron

Back 55

the applied voltage

Front 56

What is the kinetic energy of electrons converted into

Back 56

heat and x-rays when the electron strikes the anode

Front 57

What happens to the electron as it strikes the anode

Back 57

Electrons only penetrate tens of micrometers (μm) into the anode before losing
their energy by ionization and excitation of electrons in the anode material.

Front 58

What interaction occurs after the electron hits the t

Back 58

Energetic electrons loose their energy in matter by excitation, in which electrons are
energized to higher energy states; ionization, in which an outer-shell electron is re-moved; and radiation, in which the energy loss is converted directly to a photon.

Front 59

Electron hitting the anode

Back 59

Front 60

What happens to the electron after it is released by the cathode

Back 60

After the electrons are emitted from the cathode, they come under the influence of an electrical force pulling them toward the anode. This force accelerates them, causing an increase in velocity and kinetic energy.

Front 61

What happens to the kinetic energy as the electron travels from the cathode to the anode

Back 61

This increase in kinetic energy continues as the electrons travel from the cathode to the anode.

Front 62

What happens the the potential energy as the electron travels from the cathode to the anode

Back 62

As the electron moves from cathode to anode, however, its electrical potential energy decreases as it is converted into kinetic energy all along the way.

Front 63

What is the ratio of kinetic to potential energy as the electon reaches the anode

Back 63

Just as the electron arrives at the surface of the anode its potential energy is lost, and all its energy is kinetic

Front 64

What determines the energy of the electron as it hits the anode

Back 64

its velocity

Front 65

What happens to the electron as it hits the anode

Back 65

When the electrons strike the surface of the anode, they are slowed very quickly and lose their kinetic energy; the kinetic energy is converted into either x-radiation or heat

Front 66

What type of radiation is produced as the electron hits the anode

Back 66

Two types of interactions produce radiation. An interaction with electron shells produces characteristic x-ray photons; interactions with the atomic nucleus produce Bremsstrahlung x-ray photons.

Front 67

What interactions occur as the electron hits the anode

Back 67

Front 68

Do the energetic electrons interact with the electrons of the atom (on the anode)

Back 68

yes, An interaction with electron shells produces characteristic x-ray photons

Front 69

Does characteristic X-ray production result in ionization of the target atom

Back 69

yes

Front 70

What causes the anode to heat

Back 70

Energy lost in the form of excitation and ionization appears as heat in the anode.

Front 71

What are the 2 types of radiation produced

Back 71

Bremsstrahlung radiation
Characteristic radiation

Front 72

What is an example of efficiency of an X-ray

Back 72

Th e efficiency of x-ray production is approximately kV x Z x 10 − 6 and is ap-proximately 1% for materials with high atomic numbers (Z) at 100 kVp.

Front 73

What is a graph of x-ray tube output showing the number of photons at each x-ray energy

Back 73

spectrum