Protective Housing
Envelope
Filament
Focusing Cup
Anode
100
When x-rays are produced, they are emitted _______, that is, in all directions.
What is isotropically
100

The most common enclosure used to maintain a vacuum inside an x-ray tube in high-capacity x-ray tubes today. 

What is the metal. 

Pyrex glass can be used. Metal has a longer life and less likely to fail. 

100
Atomic number of tungsten.
What is 74
100

A device that electrostatically confines the electron beam. 

What is a focusing cup?

100

The area of the anode struck by the electrons from the cathode. 

What is the target?

200
The x-rays emitted through the window.
What is the useful beam
200
Allows the tube to have more efficient x-ray production and a longer tube life.
What is a vacuum tube
200
The process where, once a filament is sufficiently heated, outer shell electrons are boiled and ejected from the filament.
What is thermionic emission
200
The charge given to the focusing cup.
What is negative
200
Typical type of anode used in dental radiography.
What is a stationary anode
300
X-rays that penetrate through the protective housing.
What is leakage radiation
300

This early type of tube contained controlled quantities of gas in the glass envelope.

What is Crookes tube

300

The filament is approximately ___mm in diameter and __ or ___cm long. 

2; 1 or 2

300
The focusing cup directs the electron beam towards the ______.
What is anode
300
Metal material added to the tungsten anode.
What is rhenium
400
Acts as both an electrical insulator and a thermal cushion in the protective housing around the x-ray tube.
What is oil
400
the width of the x-ray tube window which allows for maximal emission of x-rays.
What is 5cm
400

The most common cause of tube failure.

What is tungsten filament burn out

400
The focusing cup is made out of this material.
What is molybdenum or nickel
400
The typical angle of the anode at an SID of 40 inches.
What is 12 degrees
500
Lines the inside of the protective housing.
What is lead
500

The amount of leakage radiation must kept below this amount. 

1 mGya/hr at 1 meter. 

500
The addition of this metal to the filament increases efficiency of thermionic emission and prolongs tube life.
What is thorium
500

The effectiveness of the focusing cup is determined by what 4 characteristics?


1) Size and shape

2) It's charge

3) Filament size and shape

4) Position of the filament within the focusing cup. 

500

Three characteristics of a good anode material. 

1) Atomic Number - High efficiency x-ray production

2) Thermal conductivity -Efficient at dissipating heat

3) High melting point - 3400 degrees Celsius

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