2. Radiation Physics Flashcards
What does the control panel in an X-ray machine do?
Adjusts exposure time, kVp, and mA.
What does the extension arm of an X-ray machine do?
Connects the tube head to the machine, allowing positioning.
What does the tube head of an X-ray machine contain?
Contains the X-ray tube, glass envelope, insulating oil, filters, and collimator.
What is the function of the Position Indicating Device (PID) in an X-ray machine?
Directs the beam toward the target area.
What is the cathode in an X-ray tube?
The negative electrode containing the tungsten filament and focusing cup.
What is the anode in an X-ray tube?
The positive electrode with a tungsten target where electrons collide to produce X-rays.
Why is tungsten used in the X-ray tube?
High atomic number, high melting point, good thermal conductivity, and low vapor pressure.
What is thermionic emission?
Electrons are emitted from the heated tungsten filament.
What is the purpose of accelerating electrons in an X-ray tube?
High voltage accelerates electrons toward the anode to produce X-rays.
What happens when electrons strike the tungsten target?
They stop abruptly, converting kinetic energy into heat (99%) and X-rays (<1%).
What is the focal spot?
The point on the anode where electrons strike and produce X-rays.
What does a small focal spot lead to?
Higher image resolution but more heat.
How is heat managed in X-ray production?
Using rotating anodes and the line focus principle to spread out heat and improve image quality.
What is the line focus principle?
Angles the target to create a smaller effective focal spot while maintaining heat dissipation.
What is the step-down transformer used for?
Reduces voltage to heat the filament (low voltage circuit).
