Final Review (history and xray tube)

Question 1

Who were xrays discovered by?

Answer 1

Wilhelm Conrad

Question 2

When were xrays discovered?

Answer 2

November 8, 1895

Question 3

What was the first xray?

Answer 3

Roentgens wife’s hand

Question 4

Who was the first fatality from xrays?

Answer 4

Clarence Dally

Question 5

Who won the first Nobel prize presented for physics in 1901?

Answer 5

Roentgen

Question 6

Who devised a fluoroscope using a fluorescing screen

Answer 6

Thomas Edison

Question 7

Who improved crookes tube?

Answer 7

William Coolidge

Question 8

what are the 3 Cardinal Rules of Radiation Protection?

Answer 8

Time, Distance, Shielding

Question 9

What was designed in order to prevent radiation injury and effects?

Answer 9

-Cardinal Rules (time, distance, shielding)
-lead protective apparel worn by all radiation workers
-Radiation dose monitored through the use of a dosimeter

Question 10

Four things that are needed for the production of xrays?

Answer 10

-Source of electrons (cathode filament)
- Target (tungsten anode)
-High voltage
-vacuum

Question 11

A form of electromagnetic radiation

Answer 11

Xrays as energy

Question 12

Behave both like waves and like particles

Answer 12

Xrays as energy

Question 13

Move in waves that have wavelength and frequency

Answer 13

Xrays as energy

Question 14

Wavelength and frequency are inversely related

Answer 14

Xrays as energy

Question 15

Xrays also behave like particles and move as photons

Answer 15

Xrays as energy

Question 16

What are some properties of xrays?

Answer 16

-xrays are invisible
-xrays are electrically neutral
-Xrays have no mass
-Xrays travel at the speed of light in a vacuum
-Xrays cannot be optically focused
-Xrays form a polyenergetic or heterogeneous beam
-Xrays can be produced in a range of energies
-Xrays travel in straight lines
- Xrays can cause some substances to fluoresce
-Xrays cause chemical changes to occur in radiographic and photographic film
-Xrays can penetrate the human body
-Xrays can be absorbed or scattered by tissues in the human body
- Xrays can produce secondary radiation
-Xrays can cause chemical and biologic damage to living tissue

Question 17

Xray prodcution

Answer 17

-The production of xrays require a rapidly moving stream of electrons that are suddenly decelerated or stopped.
-The negative
electrode (cathode) is
heated, and electrons
bare emitted
(thermionic emission)
- The electrons are
attracted to the anode,
move rapidly towards
the positive electrode
and are stopped or
decelerated.

Question 18

Protects against leakage radiation and electric shock

Answer 18

Tube housing

Question 19

-metal or glass envelope
-negatively charged electrode
-positively charged electrode

Answer 19

Xray tube housing

Question 20

What is part of the cathode?

Answer 20

Filament and focusing cup

Question 21

Cathode assembly

Answer 21

Filament (coiled tungsten wire helix)
Focusing cup
associated wiring
low voltage side of xray circuit
Source of electrons

Question 22

What types of coiled tungsten wire is there?

Answer 22

wire filament for large and small focal spot

Question 23

What charge is the cathode?

Answer 23

Negative

Question 24

What charge is the anode?

Answer 24

Positive

Question 25

What kind of material is the filament made of?

Answer 25

Thoriated tungsten

Question 26

What material is the focusing cup made of?

Answer 26

Nickel

Question 27

May also be called the focal point, focal spot or the focal track?

Answer 27

Target

Question 28

The process of boiling off electrons and produces a cloud of electrons by heating the filament

Answer 28

Thermionic emission

Question 29

Dangers of Radiation

Answer 29

-Never stand in primary beam -Collimating as small as you can -Never hold patient -Females 11-50 always shield

Question 30

Occurs when no more electrons can be boiled off of the filament

Answer 30

Space charge effect

Question 31

Is the primary thermal conductor of the tube

Answer 31

Anode

Question 32

Three components of the anode

Answer 32

Anode, stator, and rotor

Question 33

Why is tungsten used?

Answer 33

High melting point and difficult to vaporize

Question 34

What are the two types of anods

Answer 34

Rotating and stationary

Question 35

portion of the anode struck by the electrons

Answer 35

Target

Question 36

What is the anode made up of

Answer 36

Tungsten Rhenium Alloys

Question 37

What does it mean to have two filaments?

Answer 37

Dual Focus tube

Question 38

Why does the xray tube need to be warmed up?

Answer 38

To prevent cracking and maintain vacuum

Question 39

Purpose of rotating anode

Answer 39

promote greater heat dissipation

Question 40

-Decelerates and stops electrons -energy converted to heat and xrays -Brems and characteristic interactions

Answer 40

Target

Question 41

What does a rotating anode require?

Answer 41

-requires a stator and rotor to rotate -tungsten metal

Question 42

What determines the number of electrons boiled off

Answer 42

mA

Question 43

Atomic number of tungsten rhenium alloy

Answer 43

74

Question 44

Absorption of xrays produces in the tube by the anode, causes uneven distribution of xray intensity between the cathode and anode, more intensity of cathode side (fat cat)

Answer 44

Anode heel effect

Question 45

Area where electrons strike the anode

Answer 45

Focal Spot

Question 46

Leakage radiation Limit

Answer 46

100 milliroentgens per hour at 1 meter

Question 47

Physical area of the focal track being hit by the electrons

Answer 47

Actual focal spot

Question 48

What is the environment inside the xray tube once all air has been removed

Answer 48

Vacuum

Question 49

Tube failure

Answer 49

-Tube arcing (vaporized tungsten collection on envelope) -filament breakage ("boost" and hold)

Question 50

-Filament heated -causes electrons to be released from filament -similar to filament heating in an incandescent lightbulb -cathode filament is in a low temperature, pre-heat mode until xray exposure is initiated

Answer 50

Thermionic Emission

Question 51

Xray tube efficiency

Answer 51

1% xray 99%heat

Question 52

is housed in focusing cup and produces electrons to produce image

Answer 52

filament

Question 53

Three functions of the anode:

Answer 53

-Target surface for xray production -Conducts high voltage -serves as primary thermal conductor

Question 54

What changes the charge of the focusing cup from negative to positive

Answer 54

Grid Biased Tubes

Question 55

Necessary qualities of the anode

Answer 55

High atomic number high melting point high heat conduction ability

Question 56

Heat tolerant pyrex glass or metal

Answer 56

Envelope

Question 57

What do the electrons become when they hit the anode

Answer 57

photons

Question 58

What two things control the size of the effective focal spot

Answer 58

Size of the focal spot and anode target angle

Question 59

-assists with heat loading -backed with molybdenum and/or graphite -backing acts as "heat sink" -Increases xray tube thermal capacity

Answer 59

Anode layering

Question 60

-space charge effect -compresses thermionic cloud -concentrate the electron beam towards the focal spot of the anode

Answer 60

Focusing cup

Question 61

What is the anode made up of?

Answer 61

Tungsten rhenium alloy

Question 62

-made of molybdenum -connects the anode to the rotor

Answer 62

Stem

Question 63

What is the line focus principle

Answer 63

Spreads heat over a greater area of the anode and allows the effective focal spot to be smaller than the actual focal spot

Question 64

What is the purpose of the glass envelop

Answer 64

Absorbs xrays and ensures a vacuum

Question 65

Purpose of the focusing cup

Answer 65

To group the electrons for their passage to the anode

Question 66

Why do we follow the warm up procedure?

Answer 66

To prevent the tube from cracking and to maintain vacuum

Question 67

A molybdenum shaft is used to connect the anode to the rotor because

Answer 67

It is a less dense metal with a high melting point that helps anode to spin faster

Question 68

What does "pitting" mean

Answer 68

Holes on the focal track

Question 69

Portion of anode that electron stream contacts

Answer 69

Target Area

Question 70

Purpose of the fan in the tube housing is to

Answer 70

Promote heat dissipations

Question 71

Average anode rotation speeds in diagnostic ray tubes are in the ranges of:

Answer 71

3,000-10,000

Question 72

The only thing located outside of the envelope that consists of copper windings

Answer 72

Stator

Question 73

Made of a copper cylinder in the step of the xray tube and is supported by the high strength ball bearings

Answer 73

Rotor

Question 74

What does the protective housing consist of ?

Answer 74

Metallic supports xray tube controls leakage and scatter radiation prove mechanisms to cool tube

Question 75

How can we extend the life of the tube

Answer 75

-tube warm up -avoid frequent “boosting” -use low mA when possible -use low speed rotation when possible -follow rotating charts -avoid rough handling -listen to unusual sounds

Question 76

What is off focus radiation

Answer 76

Undesirable part of the beam, not hitting anode, low energy and no diagnostic value, produces "ghosting"

Question 77

What does xray stand for

Answer 77

the X in xray means unknown

Question 78

What is the divergence of the beam

Answer 78

Energy that is coming out and whats interacting with the patient

Question 79

Compare and contrast actual focal spot and effective focal spot

Answer 79

Actual focal spot is the area being hit by electrons and effective focal spot is projected area of xray beam. Effective focal spot should be smaller. **A before E**

Question 80

results in suboptimum anode rotation speed

Answer 80

stator failure

Question 81

True or False Xrays are invisible

Answer 81

true

Question 82

True or false Xrays can travel around corners

Answer 82

False

Question 83

Sequence of taking xrays

Answer 83

1. Current runs through the filament circuit 2. Filament gets hot 3. Filament glows 4. Filament boils of electrons 5. Electrons form a space cloud 6. Electrons are repelled from the focusing cup 7. Electrons are attracted by the anode 8. Electrons move over to the anode 9. Electrons slam into the anode at the target 10. Electrons lose energy 11. Light, heat and X-rays are produced 12. Focal spot is formed 13. X-rays are emitted isotropically 14. X-rays are absorbed by the glass and metal housing

Question 84

What helps the stator to rotate properly

Answer 84

Ballbearings

Question 85

-Ferromagnetic bars arranged in cylindrical pattern -inside xray tube glass envelope -copper cylinder connected to anode disk by molybdenum stem -turns when stator is energized

Answer 85

Rotor

Question 86

what type of body parts would the large filament focus on

Answer 86

large focusing body parts (more heat)

Question 87

what does the filament length and width impact

Answer 87

recorded detail or special resolution

Question 88

Typically controlled by the xray circuitry and wont go higher than what is already set

Answer 88

Saturation Current

Question 89

-Heat tolerant pyrex glass or metal -Two functions: supports anode/cathode assemblies and maintain a vacuum -modern tubes now metal

Answer 89

Envelope

Question 90

Near perfect and critical to efficient xray productions

Answer 90

vacuum

Question 91

Protective housing provides mechanisms to cool tube

Answer 91

-cooling oil surrounding tube -cooling fans -water cooling in high end tube designs

Question 92

-metallic -supports xray tube -controls leakage and scatter radiation(lead lined) -provides mechanisms to cool tube

Answer 92

Protective housing

Question 93

**Be able to label xray tube**