X-ray Tube and Components
The use of an x-ray tube with a large anode angle results in: 1. Increased focal spot size 2. Increased heat capacity 3. Increased heel effect
1 and 2 only
During a radiography procedure, dose to patient tissues outside of the primary exposure field is a result of: 1. Scatter radiation 2. Off-focus radiation 3. Leakage radiation
1, 2 and 3
The use of an x-ray tube with a small anode angle results in: 1. Decreased focal spot size 2. Decreased heat capacity 3. Increased heel effect
1, 2, and 3
Which characteristics of tungsten metal make it an ideal material for the construction of a radiographic anode? 1. Atomic number 2. Thermal conductivity 3. Melting point
1, 2, and 3
Which of the following factors have an influence on the heat capacity of an x-ray tube? 1. Anode rotation speed 2. Focal spot size 3. Exposure time
1, 2, and 3
The space charge effect limits the functional milliamperage (mA) of the x-ray tube to approximately:
1,000 mA
How many heat units are created from a single x-ray exposure using a single-phase x-ray machine using an exposure technique of 70 kVp and 25 mAs?
1,750 HU 70 x 25 x 1 = 1,750
What is the wave-form factor (w) for a three-phase six pulse x-ray generator?
1.35
When using a 14 x 17 inch exposure field, the intensity of the CR measures 100 mGy. What is the approximate intensity of the beam within the cathode side of the x-ray field?
120 mGy
How many heat units are created from a 20-second fluoroscopy study using a high-frequency x-ray machine set at 110 kVp and 5 mA?
15,950 HU 110 x 5 x 20 x 1.45 = 15,950
A radiographer has the choice of multiple radiographic systems, each using a different actual focal spot size. Which system should be used if maximum heat dissipation is required?
2.4 cm
Which of the following anode angles with the same size actual focal spot can tolerate the highest technical setting without overheating?
22 degrees
The typical angulation of the anode is between:
6 -20 degrees
Which of the following anode angles with the same size actual focal spot can create a radiographic image demonstrating the highest spatial resolution?
6 degrees
Which of the following collimation settings will demonstrate the most uniform beam intensity within the exposure field?
6 x6 inches
A radiographer has the choice of multiple radiographic systems, each using a different anode angle. Which system should be used if maximum spatial resolution is desired?
7 degrees
An acute abdomen series is completed with three exposures acquired at 80 kVp and 30 mAs using a three-phase six-pulse machine. What is the total number of accumulated heat units for this series?
9,720 HU 80 x 30 x 1.35 x 3 = 9,720
Approximately what percentage of the electron energy is converted to heat at the anode during x-ray production?
99%
The anode heel effect is defined as:
A variation in beam quantity across the x-ray field
The technical limitations of a stationary anode x-ray system may be inadequate for which of the following procedures?
Abdominal imaging on a bariatric patient
Which of the following situations will require the use of the large filament within a dual focus x-ray tube?
Abdominal imaging on a bariatric patient
The source of x-ray emission within an x-ray tube is called the:
Actual focal spot
Off-focus radiation is the product of electron interactions occurring within which component(s) of the x-ray tube? 1. Cathode assembly 2. Vacuum envelop 3. Anode disk
All 3
Which of the following imaging modalities use an x-ray tube? 1. Mammography 2. Fluoroscopy 3. Computed tomography
All 3
The bearings of the induction motor assembly are designed to:
Allow for low-friction rotation of the anode
What component of the x-ray tube is the source of x-rays?
Anode
The line-focus principle describes the geometric relationship between which of the following factors within an x-ray tube?
Anode angle and the effective focal spot size
Thermionic emissions occurs within the x-ray tube at the:
Cathode
What component of the x-ray tube is the source of free electrons?
Cathode
The modern x-ray tube is based on this type of tube:
Collidge tube
The name of the first x-ray tube:
Crookes tube
Which of the following exposure modifications will increase the anode heel effect?
Decreased SID
The loss of visually distinct brightness levels from off-focus radiation within the primary beam is described as:
Decreased contrast
Failure of the focusing cup within the x-ray tube will result in:
Decreased spatial resolution
The loss of structural sharpness from off-focus radiation within the primary beam is described as:
Decreased spatial resolution
Utilizing an x-ray tube with a large anode angle compared to a tube with a small angle and same size actual focal spot results in:
Decreased spatial resolution and increased anode heat capacity
As anode angle decreases, heat dissipation:
Decreases
Stationary anodes are most appropriate for which of the following x-ray systems?
Dental imaging
The area of the x-ray beam projected towards the patient is described as the:
Effective focal spot
The technologist can reduce the chance of excessive heat production and x-ray tube damage by modifying the:
Filament size
The term "space charge" within the x-ray tube refers to:
Free electrons
What component of the x-ray tube is responsible for creating a vacuum around the photon-producing components?
Glass envelope
Electron interactions within the x-ray tube anode primarily create:
Heat
The term "tube loading" refers to which of the following?
Heat energy created in the x-ray tube
What is required for the induction of thermionic emission within the x-ray tube?
High current
Which of the following changes will increase the heat capacity of an x-ray tube?
Increased anode rotation speed
What is the principal advantage of using an x-ray tube equipped with a rotating anode?
Increased heat capacity
What is the principal advantage of using the large filament within a dual focus x-ray tube?
Increased heat capacity
What is the principal advantage of using the small filament within a dual focus x-ray tube?
Increased spatial resolution
Utilizing an x-ray tube with a small anode angle compared to a tube with a large angle and same size actual focal spot results in:
Increased spatial resolution and decreased anode heat capacity
What does off-focus radiation do to patient dose?
Increases
As a result of the anode heel effect, the anode side of the x-ray field demonstrates:
Lower intensity
Directing the anode side of the x-ray field towards the toes during an AP projection of the foot results in:
More uniform receptor exposure
In order to adequately compress the electron stream with the x-ray tube, the focusing cup must be:
Negatively charged
What characteristic of off-focus radiation results in a loss of structural sharpness in a radiographic image?
Off-focus radiation is out of alignment with the primary beam
Directing the anode side of the x-ray field towards the lower chest during an AP projection of chest will result in:
Over-exposure of the upper chest
Patient exposure to off-focus radiation can be reduced by using which of the following techniques?
Patient shielding
The anode heel effect is caused by:
X-ray absorption within the anode
Which of the following formulas express the total heat units created during a series of x-ray exposures?
kVp x mA x s x W
