X-ray Production Part 1

Question 1

What are the 2 important components of the tubehead?

Answer 1

X-ray tube

Power supply/generator

Question 2

: Exposure time, kVp and mA selectors
Exposure button (dead-man type)
Indicator light and audible signal

Answer 2

I. Control panel

Question 3

:Power supply + x-ray tube
◦Glass envelope◦Insulating oil
◦Metal housing◦Tube window
◦Aluminum filters◦Lead collimator

Answer 3

II. Tubehead

Question 4

How many power supplies are in tubehead?

Answer 4

2

Question 5

Is there insulating oil in x-ray tube?

Answer 5

No it is a vacuum

Question 6

What are the 2 components of the cathode? +or _

Answer 6

Cathode (-)

Filament and Focusing cup

Question 7

_____ (cathode)
Made of tungsten
SOurce of electrons
Heated with low voltage source and emits electrons at a rate proportional to its temp (thermionic emission)

Answer 7

Filament

Question 8

_______ (cathode)
Made of molybdenum
Negatively charged
Focuses electrons into narrow beam directed to the focal spot

Answer 8

Focusing cup

Question 9

Heated with low voltage source and emits electrons at a rate proportional to its temp is called ________

Answer 9

thermionic emission

Question 10

What are the two components of the anode?

Answer 10

Anode (+)
Tungsten target
Copper stem

Question 11

_______ (anode)
Transform the kinetic energy of the colliding electrons into x-ray photons
Highly inefficient: produces 99% heat and 1% x-rays

Answer 11

Tungsten target

Question 12

_______ (anode)

Works as a thermal conductor to remove the heat from the tungsten avoiding target melting

Answer 12

Copper stem

Question 13

Tungsten has a ______ atomic number: efficient production of x-rays

Answer 13

High

Question 14

Tungsten has a _____ melting point

Answer 14

High

Question 15

Tungsten has a ______ thermal conductivity

Answer 15

High

Question 16

Tungsten has a ______ vapor pressure: helps maintain vacuum in tube at high temps

Answer 16

Low

Question 17

Which transformer/power supply generates power for cathode/ generates electrons?

Answer 17

Low voltage power supply

Question 18

What are the conditions necessary for x-ray production?

Answer 18

1. Separation of electrons
2. Production of high-speed electrons
3. Concentration of electrons
4. Sudden stoppage of electron steam

Question 19

Low voltage supply from low voltage power supply heats filament and produces thermionic emission

Answer 19

Separation of electrons

Question 20

High potential difference is produced between the cathode and anode by applying a high voltage between them using the high voltage transformer on the anode to create the potential difference between cathode and anode

Answer 20

Production of high-speed electrons

Question 21

Electron beam is focused by the focusing cup and directed to the focal spot; focusing cup is neg charged

Answer 21

Concentration of electrons

Question 22

Upon

Answer 22

Sudden stoppage of electron steam

Question 23

Area on the target to which the focusing cup directs the electrons and from which the x-rays are produced
Size is important for image quality
Smaller= more heat

Answer 23

Focal spot

Question 24

What are the 2 ways to overcome the heat issue of a small focal spot?

Answer 24

Rotating anodes
Stationary anodes (line focus principle)

Question 25

• Allows heat at the focal spot to spread out over a large surface (dark band)
• Medical devices

Answer 25

Rotating anode

Question 26

Angling the target to achieve a smaller effective focal spot than the actual focal spot
Results in sharper radiographic image while maintaining the original surface area of the target for heat dissipation

Answer 26

Line-focus principle (stationary anode)

Question 27

The projection of the focal spot perpendicular to the target

Answer 27

Actual focal spot

Question 28

The projection of the focal spot perpendicular to the electron beam

Answer 28

Effective focal spot

Question 29

Which focal spot in the stationary anode is always smaller?

Answer 29

Effective focal spot

Question 30

____ provides a low-voltage current to heat the x-ray tube filament (cathode)

Answer 30

Step down transformer

Question 31

_____ generates a high potential difference to accelerate electrons from the cathode to the focal spot on anode

Answer 31

Step up transformer

Question 32

◦Electromagnetic device that either increases or decreases the voltage in a circuit.

Answer 32

Transformer

Question 33

What are the 3 types of transformers in x-ray tube?

Answer 33

Step down
Step up
Autotransformer

Question 34

What is the step down transformer regulated by?

Answer 34

mA switch

Question 35

Increasing the mA will have what effect on number of electrons?

Answer 35

More electrons

Question 36

_______

Used to convert 110 to 20 volts to 3-5 volts to heat the filament

Answer 36

Step-down transformer

Question 37

______

Used to convert 110 to 20 volts to 60,000-100,000 volts to move the electrons across the tube

Answer 37

Step up transformer

Question 38

What is the step up transformer regulated by?

Answer 38

kV setting

Question 39

Increasing the kV will have what effect on energy of electrons traveling from cathode to anode?

Answer 39

Increase energy

Question 40

Actual time of exposure

Answer 40

◦Timing circuit:

Question 41

delay of ½ second to heat the filament

Answer 41

◦Time delay circuit:

Question 42

◦Determines amount of time the high voltage circuit is applied across the x-ray tube (amount of time x-rays are produced)

Answer 42

Exposure timer:

Question 43

controls the acceleration of electrons from cathode to anode

Answer 43

kV (kilovoltage):

Question 44

controls heating of the filament

Answer 44

mA (milliamperage):

Question 45

___ removes low energy x-rays not used in the radiographic image

Answer 45

Aluminum disc

Question 46

_______: controls the time in which x-rays are produced

Answer 46

Exposure time