Chapter 1 & 2 (X-Ray Tube) Flashcards
(93 cards)
1
Q
The target of an x-ray tube is made of what metal?
A
Tungsten
2
Q
Why is an x-ray tube immersed in oil?
A
Insulation
3
Q
What causes most x-ray failures
A
Excessive heat
4
Q
What types of primary radiation is produced when the x-ray tube is below 70?
A
Bremsstrahlung
5
Q
What type of motor drives the rotating anode?
A
Induction
6
Q
Which part of the x-ray tube has the filament wires and focusing cup
A
Cathode
7
Q
As kilovoltage is applied, the electrons are accelerated toward which part of the x-ray tube?
A
Anode
8
Q
Which kVp and mAs combination produce the least load on an x-ray tube?
A
High kVp and low mAs
9
Q
What is required of a metal target in an x-ray tube?
A
1) Ability to conduct heat
2) High atomic number
3) High melting point
10
Q
What increases the penetrating power of the x-ray tube?
A
kilovoltage
11
Q
What is the area of the x-ray target called that is stuck by electrons?
A
Actual focal spot
12
Q
When electrons strike the target of an x-ray tube, most of their energy is converted to what?
A
Heat
13
Q
What is the negative terminal x-ray tube?
A
Cathode
14
Q
What are the x-ray tubes called that have 2 filament wires?
A
Dual focus tubes
15
Q
How many kilovolts is equal to 75,000 volts?
A
75kV
16
Q
The formula, mA x kVp x time(s) is for what?
A
Finding heat units
17
Q
The small crater in the target of a used anode of an x-ray tube are known as what?
A
Pitting
18
Q
What is used to focus the electron stream toward the target of the anode?
A
Focusing cup
19
Q
Electrons travel in an x-ray tube from _____ to _____
A
Cathode, anode
20
Q
Which of the following is filtration that is manufactured into the x-ray tube
A
Inherent Filtration
21
Q
What determines the quantity of the electrons that will be accelerated across the x-ray tube?
A
Heating of the filament
22
Q
During thermoniac emission a cloud of electrons surround the filament. What is the electron cloud called?
A
Space Charge
23
Q
If used properly, will an x-ray tube last forever?
A
No, the filament wire will break
24
Q
How fast do high speed anode rotate?
A
10,000 RPM
25
What causes the pitting of the x-ray tube target?
Moderate overloading of the tube
26
According to the line focus principle, the effective focal spot is______than the actual focal spot
Smaller
27
As an x-ray tube gets older, what happens to the temperature of the filament?
Increases
28
What would Not be found on the control panel?
Rotor button
29
As electrons are accelerated across the x-ray tube, they are referred to as what?
Tube current
30
What is the purpose of the anode in an x-ray tube
Decelerates electrons
31
What is the purpose of a window in an x-ray tube?
For the emission of x-ray
32
What effect will increase the kVp have on the production of an x-ray
Their energy will increase
33
When will a space charge be present in the x-ray tube
Whenever the rotor engaged
34
What is NOT needed to produce x-rays?
Rotating anode
35
What is the definition of off focus radiation?
Photons that are not produced at the focal spot
36
Why is an x-ray tube made of Pyrex glass?
To better withstand heat
37
When electrons strike the anode of an x-ray tube, how much of their energy is converted to x-rays?
Less than 1%
38
Which parts make up the cathode end of the x-ray tube?
Filament and focusing cup
39
In a modern, rotating anode x-ray tube, what coats the tungsten disk?
Tungsten rhenium alloy
40
During an exposure, what electrical charge is placed on the anode?
Positive
41
What is the process of "boiling off" electrons called?
Thermionic Emission
42
The filament wires in radiographic tubes are made from what metal?
Tungsten
43
Which is not related to the other?
1) Rotor
2) Target
3) Filament
4) Tungsten Disk
Filament
44
In what unit is filament current measured
Amperage
45
Which is the smallest?
1) Actual focal spot
2) Effective focal spot
3) Target
Effective Focal Spot
46
Why is the x-ray tube encased in a lead housing?
Prevent leakage radiation
47
The instantaneous production of light resulting from the interaction of some type of energy and some element or compound is__________
Fluorescence
48
Radiation that has both electrical and magnetic properties is __________
Electromagnetic radiation
49
What is energy?
The ability to do work and it can exist in different form, such as electrical energy, kinetic energy, thermal energy and electromagnetic energy.
50
Electrical energy applied to an x-ray tube is transferred into ______ and ________
Heat, X-ray
51
Represents the number of waves passing a given point per given unit of time
Frequency
52
Represents the distance between two successive crests or troughs
Wavelength
53
Is a small, discrete bundle of energy
Photon
54
The quantity of exposure is expressed as________?
Roentgens
55
What is air karma?
Is the amount of energy deposited in a unit mass of air and expressed in units of gray (Gy)
56
What is the conversion factor for rads to gray?
1 Gray is = to 100 rads
57
The x-ray beam used in diagnostic radiography can be described as being________?
Polyenergetic
58
Rotating Anode
Anode
59
Stator
Anode
60
Focusing Cup
Cathode
61
Tungsten Filament
Cathode
62
Rotor
Anode
63
What is Thermionic Emission?
Refers to the boiling off of electrons from the filament
64
The physical area of the rotating anode is known as the _______?
Focal Track
65
The majority of energy produced in the target in x=ray production is termed______________?
Bremsstrahlung Radiation and or is heat
66
The components of the x-ray tube are encased in a ___________?
Glass or Metal envelope
67
Refers to any x-rays, other than the primary beam, that escape the tube housing
Leakage Radiation
68
What is the leakage allowed when the tube is operating at maximum capacity?
No more than 100mR/hr to escape when measured at a distant of 1m from the source while the tube operates a maximum output
69
What is the composition of the rotating anode?
Tungsten
70
As kVp increases, beam penetration will ________ in quantity?
Increase
71
As kVp decreases, beam penetration will__________?
Decrease
72
The speed of the electrons traveling across the tube from the cathode to the anode side will_____ as the kVp is increased.
Increase
73
Tube current or the quantity of x-rays emitted from the x-ray tube is called_______
Milliamperage
74
Higher mA results in ______ electrons moving in the tube current from the cathode to the anode side of the tube
More
75
Milliamperage does not affect the_______
Quality of energy of the x-rays produced
76
If mA is increased the number of photons is directly______
proportional to this quantity of electrons
77
What is exposure time?
Determines the length of time over which the x-ray tube produces x-rays
78
mAs is defined as?
Milliamperage is multiplied by exposure of time, the results is known as mA's
79
Amount of electrons flowing from the cathode to the anode and the quantity of x-rays produced are _______ to mA's.
Directly proportional
80
Refers to the size of an area on the anode target that is exposed to electrons from the tube current. It depends on the size of the filament producing the electrons stream.
Actual focal spot
81
Refers to focal spot size as measured directly under the anode target.
Effective focal spot
82
Occurs because of the angle of the target. Effect describes how the x-ray beam has greater intensity on the cathode side of the tube but a lower intensity toward the anode side.
Anode heel effect
83
Describes the filtration that is added to the port of the x-ray tube
Added filtration
84
Refers to the filtration that is permanently in the path of the x-ray beam
Inherent filtration
85
In the x-ray beam is the sum of the added and inherent filtration
Total filtration
86
Can be added to the primary beam to alter its intensity. These types of filters are used to image anatomic area that are non-uniform.
Compensating filter
87
The most common type of compensating filter. The thicker part of the wedge filter is lined up with the thinner portion of the anatomic part being imaged, allowing fewer x-ray photons to reach the end of the part
Wedge filter
88
Performs a function similar to a wedge filter, however it is differently designed.
Trough filter
89
Occur when a projectile electron completely avoids the orbital electrons of a tungsten atom and travel very close to its nucleus. The very strong electrostatic force of the nucleus causes the electron to suddenly "slow down." As the electron loses energy, it suddenly changes it's direction and the energy loss then reappears as an x-ray photon.
Bremsstrahlung interactions
90
Are produced when a projectile electron interacts with an electron from the inner shell (K-shell) of a tungsten atom.
Characteristic interactions
91
Properties of X-rays are:
```
invisible
neutral charge
no mass
travel at the speed of light in a vacuum
cannot be optically focused
form a polyenergetic or heterogenous beam
can be produced in a range of energies
travel in a straight line
```
92
continuous properties of x-rays are:
can cause some substance to fluoresce
cause chemical changes to occur in radiographic and photographic film
can penetrate the human body
can be absorbed or scattered by tissue in human body
can produce secondary radiation
can cause chemical and biologic damage to living tissue
93
X-rays as energy
a form of electromagnetic radiation
behaves both like waves and particles
move in waves that have wavelength and frequency
inversely related
behave like particles and move as photons
