Chapter 2- The X-Ray Beam
The anode includes the:
-Stator -Rotor -Target
To produce x-rays, electrons must be A. suddenly decelerated and accelerated B. suddenly decelerated and liberated from the cathode filament C. accelerated and liberated from the cathode filament D. All of above
D. All of above
As kVp increases A. beam penetrability increases and beam wavelength decreases B. beam penetrability increases and beam frequency increases C. beam wavelength decreases and beam frequency increases D. All of these occur
D. All of these occur
What is founded in the Tube housing? A. Metal or glass envelope B. Negatively charged electrode C. Positively charged electrode D. All the parts that were mentioned where included
D. All the parts that were mentioned where included
Cathode
Drawing of the cathode
Anode Heel Effect
Due to the geometry of the angled anode target, the radiation intensity is greater on the cathode side.
The anode of an x-ray tube is a positively charged electrode composed of molybdenum, copper, tungsten, and graphite. A. Molybdenum B. Copper C. Tungsten D. Graphite E. All of the above
E. All of the above
The negative electrode 1.____ is heated, and electrons are emitted 2._____
1. Cathode 2. Thermionic emission
Extending X-ray Tube Life
1. if applicable, warm up tube 2. avoid excessive heat generation 3. do not hold down rotor button without making exposure 4. use lower mA and longer exposure time 5. don't move tube while energized 6. recognize unusual noises and report
Single phase
1.00 Factor
Three phase
1.35 Factor
High frequency
1.40 Factor
X-rays are more1._____on the cathode side of the tube; their intensity2. ______ toward the anode side.
1.Intense 2. decreases
What is added to the primary beam to alter its intensity
1.Wedge filter 2.Trough filter
The maximum speed the rotating anode will typically achieve is _____rpm
10,000
How many filaments are there?
2, a small and large
How many focusing cups
2, small focal spot and a large focal spot size.
Milliamperage × time = mAs
200 mA × 0.25 s = 50 mAs
Which of the following is classified as inherent filtration? 1. The collimator mirror 2. The tube envelope 3. The oil surrounding the tube
3. The oil surrounding the tube
Doubling mA results in 1. doubling the tube current. 2. doubling the quantity of x-ray photons. 3. doubling the thermionic emission. 4. All the above
4. All the above
The target angle of rotating targets typically ranges from
5° to 20
Because tungsten has a high atomic number (74) and a______ melting point, it efficiently produces x-rays. A. High B. Low C. Medium
A. High
_____envelopes are more commonly used in today's x-ray tubes. A. Metal B. Tungsten C. Iron D. Nickel
A. Metal
Inside the x-ray tube envelope you will find A. Vacuum B. Sweeper C. Idk dont care
A. Vacuum
The quantity of electrons in the tube current and quantity of x-rays produced are___to the mA A. directly proportional B. Inversely proportional C. Nothing
A. directly proportional
mA is______ to quantity of x-rays produced A. directly proportional B. Inversly proportional
A. directly proportional
Decreasing the exposure time results in___ A. fewer x-ray photons B. More x-ray photons
A. fewer x-ray photons
´Changing the mA or time will change the quantity of x-rays produced. A. quantity B. quality
A. quantity
The smaller the anode angle, the____ the effective focal spot size A. smaller B. larger
A. smaller vis versa
Exposure time determines the____ A. the length of time x-rays are produced. B. the length of time x-rays are NOT produced.
A. the length of time x-rays are produced.
Added Beam Filtration
Aluminum (Al)-added filtration is shown at the port, or window, of the x-ray tube and the collimator mirror.
Beam Filtration
Aluminum filtration added to x-ray beam to absorb low-energy photons
The electrons are attracted to the____, move rapidly toward the positive electrode, and are stopped or decelerated. Anode or Cathode?
Anode
Space charge effect
As more and more electrons build up in the area of the filament, their negative charges begin to oppose the emission of additional electrons.
A dual-focus tube has two A. Anode Filaments B. Cathode Filaments C. No clue
B. Cathode Filaments
As compared to glass, which of the following is an advantage to having a metal envelope x-ray tube? A. Increase in off- focus radiation B. Decrease in off focus radiation C. Who cares
B. Decrease in off focus radiation
There is a direct relationship between the tungsten metal's atomic number and melting point. A. Inverse relationship B. direct relationship C. No relationship
B. direct relationship
The larger the anode angle, the___ the effective focal spot. A. Smaller B. Larger
B. larger
Changing the mA results in a____in the quantity (amplitude) of x-rays produced. A. Direct Change B. Proportional change C. Inverse Change
B.Proportional change
Filament current is approximately A. 5-9 A B. 7-8 A C. 3-5 A
C. 3-5 A
´The intensity of the x-rays____ toward the anode. A. Increase B. Stays the same C. Decreases
C. decreases
Exposure time and x-ray quantity are___proportional. A. Inversely B. Nothing C. directly
C. directly
(HU) = mA × time × kVp × generator factor.
Formula for Heat Units
_____mA or lower tube currents with longer exp. Times help to minimize wear on the filament. Lower or Higher?
Lower
´The production of x-rays requires a_____ moving stream of electrons that are suddenly decelerated or stopped. Slow or rapidly
Rapidly
The part of the x-ray tube that is connected to the target and causes it to turn is the___
Rotor
What is the name of the device in a rotating anode x-ray tube that turns the rotor?
Stator
Image of x-ray tube housing
Structure of a typical x-ray tube, including the major operational parts.
X-rays are more intense on the cathode side of the x-ray tube True or False
True
The cathode filament is made of
Tungsten
anode heel effect
Uneven distribution of radiation intensity in the x-ray beam.
Milliamperage
Unit to measure tube current or number of electrons flowing per unit time
The amount the voltage varies during an x-ray exposure is known as
Voltage Ripple
What does the filament look like?
a coil of wire
The positive side of the x-ray tube is the
anode
Actual focal spot
area on anode target exposed to tube current electrons
Why is the most important part of the x-ray machine?
because the tube is where the x-rays are produced.
The __ is the portion of the x-ray tube that contains the filament
cathode
The ____ is the portion of the x-ray tube that contains the filament
cathode
Characteristic interaction
could be defined as the production of an x-ray photon by a collision between the incident electron and a K-shell electron of the tungsten atom.
Bremsstrahlung interaction
could be defined as the production of an x-ray photon by the electrostatic attraction between the incident electron and the nucleus of the tungsten atom.
The_____ is the source of electrons during x-ray production
filament
Compensating Filtration
filters that are used to compensate for differences in subject radiopacity or to even out widely differing tissue densities
compensating filtration Wedge
filters that are used to compensate for differences in subject radiopacity or to even out widely differing tissue densities
Effective focal spot
focal spot size as measured directly under anode target
The device that nearly surrounds the filament is the
focusing cup
The device that nearly surrounds the filament is the___
focusing cup
total filtration
inherent filtration + added filtration
The focusing cup has a(n) _____ charge.
negative
The target is the part of the anode that is struck by_____ the opportunity for the production of x-rays.
the focused stream of electrons coming from the cathode. The target stops the electrons and creates
Thicker part of filter lined up with___ part allowing more even exposure to the image receptor.
thinner
Line Focus Principle
used to reduce the effective area of the focal spot
´Double the mA will double the number of____ produced.
x-ray photons
Objectives (1 of 2)
´Describe construction of an x-ray tube. ´State the function of each component of an x-ray tube. ´Describe how x-rays are produced. ´Explain the role of the primary exposure factors in determining the quality and quantity of x-rays. Explain the line focus principle.
Objectives (2 of 2)
´State how the anode heel effect can be used in radiography. ´Differentiate among the types of filtrations and explain their purpose. ´Calculate heat units. ´Recognize how changing generator output, kVp, mA, and filtration affect the x-ray emission spectrum. ´List the guidelines followed to extend the life of an x-ray tube.