Test Bank For Essentials of Radiographic Physics and Imaging
3rd Edition By James Johnston; Terri L. Fauber
Which of the following is designed to withstand tremendous heat and maintain a
vacuum? - ANSWER: Glass (or metal) envelope.
By angling a rotating anode target we hope to achieve which of the following? -
ANSWER: A sharper image and large area for heating.
The most common target angle for conventional x-ray tubes is - ANSWER: 12 degrees
What part of the induction motor is outside the glass envelope? - ANSWER: Stator.
What is the radiographer responsible for? - ANSWER: safe operation and proper
maintenance
What is the housing consist of? - ANSWER: -lead lined structure
-prevents against leakage
-only part we can touch
-oil bath
-cooling only (no lubrication)
-cooling fans
-electrical insulation
-large cables
-absorbs stray photons
What is the general purpose x-ray tube is an electronic _______ tube - ANSWER:
vacuum
What does the x-ray tube consist of? - ANSWER: -anode
-cathode
-induction motor
-encased in a glass or metal enclosure
What is the main purpose of the enclosure? - ANSWER: to maintain a vacuum within
the tube to prevent electrical arching
Glass tube variety - ANSWER: generally made of borosilicate glass because it is heat
resistant
used in: CT & Fluoro
disadvantage: can still get arching & break glass
-causes vaporized tungston to group together
, Metal envelope variety - ANSWER: provides a constant electric potential between
the electron stream from the cathode and the enclosure, thereby avoiding the
arching problem and extending tube life
used in: x-ray
Anode - ANSWER: positive end of the x-ray tube
What does the anode serve as? - ANSWER: an electrical and thermal conductor
What is the source of radiation? - ANSWER: the focal spot in the anode
Stationary anode - ANSWER: -old
-only used for mammo & dentistry
-a tungsten button embedded in a copper rod
-disadvantage: the rapidly building heat can damage tube
-hits same spot over & over causing pitting
-electrons stay in pit instead of going to target
Rotating anode - ANSWER: -a rotating tungsten-coated molybdenum dis mounted on
a copper shaft with a molybdenum core
-advantage: spread heat produced during the x-ray production over a larger surface
area
-dissipates heat
In a rotating anode where does the electron stream hit? - ANSWER: the focal tract
-larger surface area
Anode Materials: Copper - ANSWER: used as part of the shaft because it has
excellent thermal and electrical conductive properties
Anode Materials: Molybdenum - ANSWER: used as the disc base and core because it
has low thermal conductivity and it is a light but strong alloy
Tungsten - ANSWER: used because it has a very high melting point and a high atomic
number (74), improving the efficiency of the x-ray
Rhenium - ANSWER: may be added to the tungsten to increase thermal capacity and
tensile strength
How is the anode rotated? - ANSWER: by an induction motor
What are the two major parts of the anode motor? - ANSWER: -stator (outside)
-rotor (inside)
3rd Edition By James Johnston; Terri L. Fauber
Which of the following is designed to withstand tremendous heat and maintain a
vacuum? - ANSWER: Glass (or metal) envelope.
By angling a rotating anode target we hope to achieve which of the following? -
ANSWER: A sharper image and large area for heating.
The most common target angle for conventional x-ray tubes is - ANSWER: 12 degrees
What part of the induction motor is outside the glass envelope? - ANSWER: Stator.
What is the radiographer responsible for? - ANSWER: safe operation and proper
maintenance
What is the housing consist of? - ANSWER: -lead lined structure
-prevents against leakage
-only part we can touch
-oil bath
-cooling only (no lubrication)
-cooling fans
-electrical insulation
-large cables
-absorbs stray photons
What is the general purpose x-ray tube is an electronic _______ tube - ANSWER:
vacuum
What does the x-ray tube consist of? - ANSWER: -anode
-cathode
-induction motor
-encased in a glass or metal enclosure
What is the main purpose of the enclosure? - ANSWER: to maintain a vacuum within
the tube to prevent electrical arching
Glass tube variety - ANSWER: generally made of borosilicate glass because it is heat
resistant
used in: CT & Fluoro
disadvantage: can still get arching & break glass
-causes vaporized tungston to group together
, Metal envelope variety - ANSWER: provides a constant electric potential between
the electron stream from the cathode and the enclosure, thereby avoiding the
arching problem and extending tube life
used in: x-ray
Anode - ANSWER: positive end of the x-ray tube
What does the anode serve as? - ANSWER: an electrical and thermal conductor
What is the source of radiation? - ANSWER: the focal spot in the anode
Stationary anode - ANSWER: -old
-only used for mammo & dentistry
-a tungsten button embedded in a copper rod
-disadvantage: the rapidly building heat can damage tube
-hits same spot over & over causing pitting
-electrons stay in pit instead of going to target
Rotating anode - ANSWER: -a rotating tungsten-coated molybdenum dis mounted on
a copper shaft with a molybdenum core
-advantage: spread heat produced during the x-ray production over a larger surface
area
-dissipates heat
In a rotating anode where does the electron stream hit? - ANSWER: the focal tract
-larger surface area
Anode Materials: Copper - ANSWER: used as part of the shaft because it has
excellent thermal and electrical conductive properties
Anode Materials: Molybdenum - ANSWER: used as the disc base and core because it
has low thermal conductivity and it is a light but strong alloy
Tungsten - ANSWER: used because it has a very high melting point and a high atomic
number (74), improving the efficiency of the x-ray
Rhenium - ANSWER: may be added to the tungsten to increase thermal capacity and
tensile strength
How is the anode rotated? - ANSWER: by an induction motor
What are the two major parts of the anode motor? - ANSWER: -stator (outside)
-rotor (inside)
