10 Questions
Which type of focal spot refers to the area on the target surface that is struck by the electron stream?
Actual focal spot
What is the line focus principle?
The size of the effective focal spot influences resolution in the image.
What is the size of the small focal spot in most x-ray tubes used today?
0.6-mm
Why is a large actual focal spot desirable?
To dissipate the heat of large exposures
What is the practical limit on how steep the target angle can be?
12 degrees
What is the standard rotation speed of x-ray tubes during exposure?
1000 rpm
What is the purpose of high-speed rotation in x-ray tubes?
To dissipate the heat generated by high technical factors more efficiently
What is the target angle in x-ray tubes?
The angle at which the oncoming electron stream strikes the anode surface
What is the maximum target angle in x-ray tubes?
17 degrees
What happens during the short delay after the exposure button is pushed?
The filament is heated
Study Notes
X-ray Tube Focal Spot
- The focal spot refers to the area on the target surface struck by the electron stream.
Line Focus Principle
- The line focus principle involves angling the target to focus the electron beam into a smaller area, increasing x-ray intensity.
Focal Spot Size
- The small focal spot in most x-ray tubes used today is around 0.3-1.2 mm in size.
Advantages of Large Focal Spot
- A large actual focal spot is desirable to reduce the heat generated per unit area, increasing tube lifespan.
Target Angle Limitation
- The practical limit on how steep the target angle can be is around 7-10°, as excessive angling can lead to x-ray absorption.
X-ray Tube Rotation
- X-ray tubes typically rotate at a standard speed of 3,600 rpm during exposure.
Purpose of High-Speed Rotation
- High-speed rotation is used to dissipate heat generated by the electron beam, preventing tube damage.
Target Angle
- The target angle in x-ray tubes typically ranges from 7-10°.
Maximum Target Angle
- The maximum target angle in x-ray tubes is around 10°.
Delay after Exposure Button Pushed
- During the short delay after the exposure button is pushed, the x-ray tube rotates to the correct position, and high voltage is generated before the x-ray beam is produced.
Test your knowledge on the line focus principle and its role in image resolution with our quiz on the actual and effective focal spot. Learn about the difference between the two terms and how they affect the quality of medical imaging. Boost your understanding of radiography with this short and informative quiz.
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