Chapter 5 Key Terms

Question 1

Actual focal spot

Answer 1

the physical area of the focal track that is impacted

Question 2

Anode

Answer 2

the positive side of the x-ray tube; serves as a target surface for high-voltage electrons from the filament, conducts the high voltage from the cathode back into the x-ray generator circuity, and serves as the primary thermal conductor

Question 3

Anode assembly

Answer 3

consists of anode, stator, and rotor

Question 4

Anode cooling charts

Answer 4

permits the calculation of the time necessary for the anode to cool enough for additional exposures to be taken

Question 5

Anode heel effect

Answer 5

due to the geometry of the angled anode target, the radiation intensity is greater on the cathode side

Question 6

Cathode

Answer 6

the negative side of the x-ray tube; produces a thermionic cloud, conducts the high voltage to the gap between the cathode and the anode, and focuses the electron stream as it heads for the anode

Question 7

Cathode assembly

Answer 7

consists of the filament, focusing cup, and associated wiring

Question 8

Dual-focus

Answer 8

a two-filament arrangement within the x-ray tube

Question 9

Effective focal spot

Answer 9

the area of the focal spot that is projected out of the tube toward the object being radiographed

Question 10

Envelope

Answer 10

the entire cathode and anode assembly is housed within this glass or metal structure

Question 11

Extrafocal radiation

Answer 11

photons that were not produced at the focal spot; also called off-focus radiation

Question 12

Filament

Answer 12

a small coil of thin thoriated tungsten wire

Question 13

Focal point

Answer 13

the portion of the anode where the high-voltage electron stream will impact

Question 14

Focal spot

Answer 14

the portion of the anode where the high-voltage electron stream will impact

Question 15

Focal track

Answer 15

the portion of the anode where the high-voltage electron stream will impact. When discussing a rotating anode, this describes the circular path that will be impacted by the electron beam

Question 16

Focus

Answer 16

the portion of the anode where the high-voltage electron stream will impact

Question 17

Focusing cup

Answer 17

a shallow depression in the cathode assembly designed to house the filament

Question 18

Fractional focal spot

Answer 18

a very small focal spot; usually a fraction of a millimeter in size

Question 19

Grid-biased

Answer 19

a type of tube that quickly regulates the flow of electrons, producing x-ray photons

Question 20

Grid-controlled

Answer 20

a type of tube that quickly regulates the flow of electrons, producing x-ray photons

Question 21

Grid-pulsed

Answer 21

a type of tube that quickly regulates the flow of electrons producing x-ray photons

Question 22

Housing cooling charts

Answer 22

permits the calculation of the time necessary for the housing to cool enough for additional exposures to be made

Question 23

Leakage radiation

Answer 23

any photons that escape from the housing except at the port

Question 24

Line-focus principle

Answer 24

used to reduce the effective area of the focal spot

Question 25

Off-focus radiation (extrafocal radiation)

Answer 25

photons that were not produced at the focal spot

Question 26

Protective housing

Answer 26

the entire cathode and anode assembly is housed within this metal structure

Question 27

Radiographic tube rating charts

Answer 27

a guide regarding the most common technical factor combinations that can be used without overlooking the tube

Question 28

Rotating anodes

Answer 28

an anode assembly that turns during exposure

Question 29

Rotor

Answer 29

a hollow copper cylinder or cuff that is attached to the anode disk by a molybdenum shaft

Question 30

Saturation current

Answer 30

as kVp increases, a greater percentage of the thermionically emitted electrons are driven toward the anode

Question 31

Space charge effect

Answer 31

as more and more electrons build up in the area of the filament, their negative charges begin to oppose the emission of additional electrons

Question 32

Stationary anodes

Answer 32

an anode assembly that is immobile

Question 33

Stator

Answer 33

induction-motor electromagnets that turn the anode

Question 34

Target

Answer 34

the portion of the anode where the high-voltage electron stream will impact

Question 35

Tube rating charts

Answer 35

provides a guide regarding the most common technical factor combinations that can be used without overloading the tube

Question 36

Window

Answer 36

a structure where the primary x-ray beams exit the envelope, which allows less absorption or scatter of photons

Question 37

Wiring

Answer 37

the parts within the cathode assembly that connect the elements of the assembly together