X-ray Tube Components

Question 1

what are the three main components of x-ray imaging systems that influences the flow of electrons?

Answer 1

1. operating console
2. generator
3. x-ray tube

Question 2

what does manipulating the intensity do?

Answer 2

amount of x-radiation used during imaging

Question 3

what does manipulating the quality of x-radiation do?

Answer 3

affecting the penetrability/energy of the x-radiation

Question 4

what does the generator provide?

Answer 4

provide a consistent power (voltage) needed to create x-ray photons

Question 5

what does a near constant potential provide?

Answer 5

minimal energy fluctuation

Question 6

high voltage generators = ____ image quality + _____ patient dose

Answer 6

increases image quality
decreases patient doses

Question 7

what are components of an x-ray tube?

Answer 7

anode, cathode – encased in a protective housing

Question 8

what 3 things does the protective housing provide?

Answer 8

1. prevents electric shock
2. reduction from leaking radiation
3. protection of the internal components

Question 9

what is the purpose of metal/glass envelopes?

Answer 9

• to maintain the vacuum inside the tube and
• structural support

Question 10

why is the vacuum necessary?

Answer 10

• it allows for more efficient x-ray production by maintaining tube current
  & to extend the tube’s life

Question 11

what are the three pros of metal envelopes over a glass one?

Answer 11

1. prevents arcing
2. enables higher tube currents
3. improves heat dissipation

Question 12

what is arcing? what causes it?

Answer 12

arcing = tube failure
caused by deposits from tungsten vaporization

Question 13

what is the purpose of a window in the metal envelope?

Answer 13

allows for maximum emission of useful x-ray photons with the least amount of absorption

Question 14

which end is the window located on?

Answer 14

anode (near target)

Question 15

what is the purpose of a cathode?

Answer 15

to produce electrons

Question 16

what is the difference between the cathode and anode?

Answer 16

cathode = negative side
anode = positive side

Question 17

what are the two primary parts of the cathode?

Answer 17

1. filament
2. focusing cup

Question 18

what does the filament do?

Answer 18

it is a coil that has electrons accumulating at
once there is enough electrons, it is released and the electrons will then be accelerated towards the metal target

Question 19

what does the coil size of the filament correlate to?

Answer 19

focal spot size (fss)

Question 20

what does the different sizes of filaments affect?

Answer 20

spatial resolution + heat

Question 21

what is the purpose of the focusing cup?

Answer 21

electrostatically confines the electrons so they can be directed towards the target

Question 22

what does the anode do?

Answer 22

produces x-rays + provides mechanical support for the target

Question 23

what are the three components of the anode?

Answer 23

1. bearing assembly
2. rotor
3. target

Question 24

what is the bearing assembly covered BY? covered IN?

Answer 24

covered by the rotor
covered in oil

Question 25

what is the purpose of the bearing assembly?

Answer 25

allows for smooth rotation of the anode disk and to allow for heat to be conducted away from the X-ray tube

Question 26

where do you find the stator?

Answer 26

tube-like structure surrounding the rotor outside of the envelope

Question 27

what is the purpose of the stator?

Answer 27

makes the TARGET rotate by electromagnetic induction

Question 28

what is the purpose of the rotor?

Answer 28

to prevent transmission of heat from the disk to the bearings

Question 29

what is the purpose of the target?

Answer 29

to produce x-rays when the electrons from the cathode strikes it

Question 30

where are the focal spot(s) located on the target?

Answer 30

on the angled portion of the target

Question 31

why are there angles on the target?

Answer 31

reduces the damaging effects of heat on the focal spot while allowing for spatial resolution

Question 32

steeper angles = _____ (smaller/larger) SA = ______ (increased/decreased) heat concentration = irradiation of ____ (narrower/wider) sections of anatomy = ______ (increased/decreased) spatial resolution

Answer 32

STEEPER angles = LARGER SA = DECREASED heat concentration = irradiation of WIDER sections of anatomy = DECREASED spatial resolution

Question 33

4 key differences between CT xray tubes + general radiography.

Answer 33

1. larger focal spot sizes
2. not too big angle (~12 degrees)
3. larger and thicker targets
4. faster target rotation speeds

Question 34

what are some cons of the all-metal target disks?

Answer 34

heavy, fixed, poor heat dissipation + short tube life

Question 35

what is a common design for a ct target in helical/spiral ct scanner?

Answer 35

brazed graphite

Question 36

what are some pros to the brazed graphite?

Answer 36

able to withstand more heat and longer tube life

Question 37

full metal disc and brazed graphite discs are some basic ct target designs, what is the other that was listed?

Answer 37

chemical vapor deposition graphite

Question 38

what are the pros to a chemical vapour deposition graphite disc?

Answer 38

able to be large but lightweight, high heat storage ability and cools fast

Question 39

what are the key differences between GR and CT x-ray tubes?

Answer 39

ct targets rotate faster + use materials designed to manage heat

Question 39

what are the key differences between GR and CT x-ray tubes?

Answer 39

ct targets rotate faster + use materials designed to manage heat