click below
click below
Normal Size Small Size show me how
RADT 334
unit 6
Question | Answer |
---|---|
What is the negative side of the x-ray tube? | Cathode |
coil of wire that emits electrons | filament |
What is the positive side of the x-ray tube? | Anode |
What is the anode most commonly made of? | Tungsten, Molybdenum, Graphite |
What is the purpose of the protective housing? | guard against excessive radiation and electric shock |
What are the primary parts of the cathode? | filament and focusing cup |
What is the most common cause of tube failure? | tungsten vaporization |
T/F glass enclosures are better than metal enclosures | false |
these enclosure tubes maintain a constant electric potential between the electrons of the tube current and the enclosure | metal |
What are filaments usually made of? | thoriated tungsten |
Why is tungsten used for filaments? | higher thermionic emission, melting point of 3410 degrees Celsius, does not easily vaporize |
Which focal spot is used for better spatial resolution? | small focal spot |
Which focal spot is used for large body parts? | large focal spot |
Which focal spot uses an mA of 300 or lower? | small focal spot |
Which focal sport uses an mA of 400 or more? | large focal spot |
How is focal spot size selected? | using the mA station selector on the operating console |
What are the two types of anodes? | stationary and rotating |
this type of anode is used for dental x-ray imaging and some portable imaging systems | stationary |
This type of tube is used for general-purpose x-ray tubes | rotating |
Rotating anodes produce ______ x-ray beams | high-intensity |
What purpose does the anode serve? | an electrical conductor, radiates heat, and contains the target |
This results in a smaller effective focal spot size that the actual focal spot size | line-focus principle |
What are two advantages of the line-focus principle? | improves spatial resolution and heat capacity |
According to the Anode Heel Effect, is the intensity more or less on the cathode side? | more |
What causes Anode Heel Effect? | The x-rays emitted toward the anode side must traverse a greater thickness of target material than those directed toward the cathode |
The _____ the anode angle, the larger the heel effect | smaller |
How can x0ray tube life be extended? | use minimum radiographic factors and the use of faster image receptors |
What is a cause of tube failure? | high temperatures can cause melting and pitting |
What is another cause of tube failure? | maintaining high temperatures for long periods of time |
What chart is used to determine how much technique is safe for tube operation? | x-ray tube rating chart |
What chart is used to determine how long you should let the tube cool before making another exposure? | cooling chart |