L1 Flashcards
1
Q
Radiography, fluoroscopy,
mammography, computed tomography all use very
similar ________
A
X-ray Tubes
2
Q
In all cases, the _________ has the same basic function and the same basic components.
A
X-ray Tube
3
Q
in an X-ray tube serves as the source of electrons needed for X-ray production.
A
Cathode
4
Q
It consists of a filament (usually tungsten) and a focusing cup.
A
Cathode
5
Q
When heated by an electric current, the filament undergoes thermionic emission, releasing electrons.
A
Cathode
6
Q
In cathode, The_________ directs these electrons into a narrow beam toward the anode, where they collide and generate X-rays through bremsstrahlung and characteristic radiation processes.
A
focusing cup
7
Q
Produces thermionic cloud (electron cloud)
A
Functions of cathode
8
Q
Conducts high voltage between cathode and anode
A
Functions of Cathode
9
Q
Focuses the electron stream as it speeds towards the anode
A
Functions of Cathode
10
Q
A coil of wire that is the source of projectile electrons needed for X-ray production. It is made up of thoriated tungsten.
A
Filament
11
Q
The filament in an X-ray tube is made of tungsten (W) because of its high melting point (3,410°C) and durability.
A
TUNGSTEN (W)
12
Q
resists thermal damage and provides consistent electron emission over time.
A
TUNGSTEN
13
Q
Some filaments may also contain_________, which enhances electron emission efficiency and extends filament life. It does not vaporize easily
A
thorium-doped tungsten
14
Q
_______ thorium is added to enhance the efficiency of thermionic emission and prolong the tube life.
A
1% to 2%
15
Q
1% to 2% _________ is added to enhance the efficiency of thermionic emission and prolong the tube life.
A
Thorium (Th)
16
Q
• High current passes through the tungsten filament in the cathode.
• The filament heats up, causing atoms to gain kinetic energy.
A
Step 1 : Heating the Filament
17
Q
• Atoms collide violently, knocking electrons free from the filament.
• These free electrons form an electron cloud around the cathode.
A
Step 2: Electron Release
18
Q
• A high voltage (kVp) is applied between the cathode (-) and anode (+).
• Electrons are rapidly pushed toward the anode, gaining speed.
A
Step 3: Electron Acceleration
19
Q
• Electrons collide with the tungsten target at the anode.
• Their sudden deceleration produces X-ray photons.
• Higher mA (milliamperes) More electrons More X-rays.
A
Step 4: X-ray Production
20
Q
THERMIONIC EMISSION PROCESS IN THE X-RAY TUBE
A
Step 1: Heating the Filament
Step 2: Electron Release
Step 3: Electron Acceleration
Step 4: X-ray Production
21
Q
______ has two filaments of different sizes within the cathode, allowing selection between small and large focal spots on the anode.
A
DUAL-FOCUSED X-RAY TUBE
22
Q
This design provides flexibility for different imaging needs.
A
DUAL FOCUS TUBE
23
Q
Produces different electron beam sizes.
A
Two Filaments (Small & Large)
24
Q
Directs the electrons toward the anode.
A
Focusing Cup
25
Receives electrons and produces X-rays.
Anode Target
26
Accelerates electrons toward the target.
High Voltage (kVp)
27
(from the smaller filament)
- Produces sharper images with higher spatial resolution.
- Used for detailed imaging like extremities.
Small Focal Spot
28
The small filament (≈______, ______ in diameter) produces a _______ focal spot, used for small mA selection, resulting in sharper images with better spatial resolution but localized heating.
1 cm long, 2 mm, 0.1–0.5 mm
29
(from the larger filament)
- Handles higher mA settings, producing more X-rays.
- Used for imaging larger body parts where heat management is critical.
Large Focal Spot
30
The large filament (________) produces a _______ focal spot, used for large mA selection, distributing heat over a larger area but yielding less sharp images than the small filament.
1.5–2× longer, 0.4–1.2 mm
31
Focuses the electrons into the target.
Focusing Cup
32
Surrounds the filament on its back and sides,
leaving the front open and facing the target.
Focusing Cup
33
Focusing Cup is made of _______,_______,_______— materials with a high melting point and poor thermionic emission properties.
nickel, stainless steel, or molybdenum
34
_________ receives a strong negative charge from the secondary circuit, which helps concentrate the electrons into a cloud as they are boiled off the filament (thermionic emission).
Focusing Cup
35
It functions using _________ — since like charges repel, the negative charge of the focusing cup is stronger than the individual electrons’ negative charges, forcing them into a narrow, controlled beam directed toward the anode target.
Electrostatic Repulsion (Focusing Cup)
36
serves as the target for electrons emitted by the cathode.
Anode
37
It consists of a tungsten target embedded in a copper or molybdenum base.
Anode
38
When high- speed electrons strike the target, their sudden deceleration produces X-rays through ____________ and ____________
bremsstrahlung & characteristic radiation. (anode)
39
________ also helps dissipate heat, as over ________ of the energy is converted into heat rather than X-rays.
Anode, 99%
40
It can be stationary or rotating, with _________ improving heat dissipation and allowing higher tube currents for better image quality.
rotating anodes
41
Serves as the target for electron interactions that generate X-rays.
X-ray Production
42
Conducts high voltage from the cathode back into the circuitry.
Electrical Conduction
43
Acts as a thermal conductor to manage the significant heat generated during X-ray production.
Heat Dissipation
44
The anode assembly includes components such as the ______, _______ and ________, which work together to enhance efficiency, particularly in rotating anode tubes.
rotor, stator, and anode stem
45
ANODE CONFIGURATIONS
1. Stationary Anode
2. Rotating Anode
46
The target remains fixed during exposure.
Stationary Anode
47
Common in dental and small portable X-ray machines.
Stationary Anode
48
Disadvantage: Limited heat dissipation, leading to potential overheating.
Stationary Anode
49
The anode target spins during exposure to distribute heat over a larger surface area.
Rotating Anode
50
Used in general radiography and fluoroscopy to handle higher exposure techniques.
Rotating Anode
51
Advantage: Greater heat dissipation allows for higher tube
current and longer exposure times.
Rotating Anode
52
is the portion in an X-ray tube anode, where high voltage electron stream strokes to produce X-rays.
Target
53
Target typically made of _____ with ______, ensuring durability and high X-ray production efficiency.
tungsten with rhenium
54
In a stationary anode, the target is a focal spot embedded in ________ .
Copper
55
In a rotating anode, the target is a focal track mounted on a ______________, improving heat dissipation.
molybdenum disc
56
The beveled design of the target influences the line focus principle and contributes to the___________
anode heel effect.
57
_________ is the primary choice due to its high melting point (3410°C), good thermal conductivity, and high atomic number (Z=____), which enhances X-ray production efficiency.
Tungsten, 74
58
_________ is added to increase tensile strength and prevent cracking at high temperatures.
Rhenium (5-10%)
59
_________ is used as the target material in mammography to produce lower-energy characteristic X-rays suitable for imaging soft tissues.
Molybdenum (Z=42)
60
Serves as the area where electrons from the cathode
strike, producing X-rays.
Tungsten target (focal spot)
61
Supports the tungsten target, conducts heat away to prevent overheating, and acts as an electrical conductor to return high voltage to the circuit.
Copper rod
62
typically found in low-power X-ray machines like dental or portable units.
Stationary anode
63
spreads heat over a larger surface area, allowing higher exposures and prolonged tube life, making it ideal for high-power diagnostic imaging.
Rotating Anode
64
Parts of the Rotating Anode:
1. Molybdenum disc
2. Molybdenum stem
3. induction motor
65
The motor consists of two main parts:
1. Rotor
2. Stator
66
Supports the tungsten target. and has a high melting point (2,620°C) and can store twice the heat of tungsten.
Molybdenum disc
67
also lightweight, reducing wear on bearings and making
rotation easier.
Molybdenum disc
68
Connects the anode disc to the rotor. It has low heat conductivity, preventing heat from reaching and damaging the rotor.
Molybdenum stem
69
which rotates the anode at the required speed that ranges from 3,600 to 10,000 rpm to help dissipate heat.
Induction motor
70
(inside the tube envelope): Made of iron bars
embedded in a copper shaft, it spins the anode.
Rotor
71
(outside the tube envelope): Made of electromagnets arranged in pairs, it generates a rotating magnetic field that induces movement in the rotor.
Stator
72
serves as a protective housing that maintains a vacuum
inside the tube.
Glass Envelope
73
This vacuum prevents electron collisions with air molecules, allowing efficient electron travel from the cathode to the anode.
Glass Envelope
74
The envelope is made of heat-resistant
______________ to withstand high
temperatures and minimize X-ray absorption
borosilicate glass
75
It also provides electrical insulation and houses a thin exit window, allowing X-rays to pass through with minimal attenuation.
Glass Envelope
76
serves as a protective casing that surrounds the glass
envelope.
Tube Housing
77
Tube housing is made of ______ and _____ with ______ to shield against stray radiation and reduce radiation leakage.
metal and lined with lead
78
also contains oil or a cooling system to dissipate
heat generated during X-ray production
Tube housing
79
it provides mechanical support and electrical insulation, ensuring the safe operation of the X-ray tube.
Tube housing
80
Functions of the Tube Housing:
1. Radiation shielding
2. Heat dissipation
3. Mechanical protection
4. Electrical insulation
81
Made of lead-lined metal, it prevents unnecessary radiation leakage, protecting both the patient and radiologic personnel.
Radiation shielding
82
Contains cooling oil and sometimes a fan or heat exchanger to prevent overheating during high-energy exposures.
Heat Dissipation
83
Provides structural support and protection to the fragile glass or metal X-ray tube inside.
Mechanical Protection
84
Prevents electrical hazards by isolating high-voltage components.
Electrical Insulation
85
Where X-rays are produced.
Glass or Metal X-ray Tube
86
Maintains optimal operating temperature.
Cooling Oil & Heat Exchange System
87
Reduces radiation leakage to regulatory limits.
Lead Shielding
88
Generates and directs the X-ray beam.
Anode & Cathode Assembly
89
involves placing metal sheets in the X-ray beam to remove low- energy (soft) X-ray photons.
Filtration
90
These ________ do not contribute to image quality but increase patient dose and scatter.
Photons
91
__________, these low-energy photons are absorbed by superficial tissues, raising the entrance surface dose (ESD) without enhancing image formation.
Without filtration
92
Types of Filtration:
1. Inherent Filtration
2. Added Filtration
93
Comes from the X-ray tube itself (e.g., window, housing, anode) and typically contributes around 0.5-1.0 mm Aluminum (Al) Half-Value Layer (HVL)
Inherent Filtration
94
Inherent Filtration typically contributes around ______
0.5 - 1.0 mm (AI) Half-value Layer (HVL) aluminum
95
Extra metal sheets (e.g., aluminum, copper) are placed in the beam path to further refine the X-ray spectrum.
Added Filtration
96
is the sum of inherent and added filtration
Total Filtration
97
U.S. regulations require a minimum of _________ for X-ray tubes operating above ______ kVp.
2.5 mm Al HVL, 70 kVp
98
A higher HVL means a more penetrating (harder) X-ray beam.
Indicates Beam Quality
99
Proper HVL ensures adequate imaging while minimizing unnecessary radiation exposure.
Affects Patient Dose
100
Minimum HVL values are required for safety, such as 2.5 mm aluminum (Al) for X-ray tubes above 70 kVp.
Regulatory Compliance
101
More filtration increases _______ by removing low-energy (soft) X-rays.
HVL
102
Higher kVp increases _________ , raising HVL.
Beam penetration
103
Different materials ____________ have varying abilities to attenuate X-rays.
(Aluminum, Copper, Lead)
104
- Used to calibrate X-ray machines for optimal imaging.
- Helps balance image quality and radiation safety.
- Essential for determining beam hardening effects in filtration.
HVL in practice
105
is a critical concept in radiation protection and image optimization, ensuring efficient and safe diagnostic imaging
HVL
106
- Reduces ESD and effective dose to the patient.
- Enhances image contrast by optimizing beam
penetration.
- Hardens the beam, increasing its average energy
and penetration by removing lower-energy
photons.
Effect of Filtration
107
Common in general X-ray imaging.
Aluminum and copper
108
Used in mammography for low-energy beams.
Molybdenum and rhodium
109
is a device in X-ray machines used to shape and limit the size of the X-ray beam.
Collimator
110
It improves image quality by reducing scatter radiation and unnecessary exposure to surrounding tissues.
Collimator
111
Components of a Collimator Assembly:
1. Lead Shutters
2. Light Source & Mirror
3. Aluminum Filter
4. Radiographic Scale
112
Adjustable plates inside the collimator that shape the beam.
Lead Shutters
113
Helps in positioning by projecting the X-ray field onto the patient’s body.
Lights Source & Mirror
114
Further refines the beam by removing low-energy photons.
Aluminum Filter
115
Marks for accurate beam adjustment.
Radiographic Scale
116
Limits radiation exposure to only the area of interest.
Functions of a Collimator
117
Reduces scatter radiation, enhancing contrast and
image clarity.
Functions of a Collimator
118
Minimizes patient dose by preventing unnecessary
exposure
Functions of a Collimator
