ASNT Industrial Radiography Radiation Safety Practice Test

What produces X-radiation in an X-ray tube?

1. High-speed electrons striking the cathode

2. High-speed electrons striking the anode

3. Low-speed photons striking the detector

4. Protons interacting with the target

The correct answer is: High-speed electrons striking the anode

In an X-ray tube, X-radiation is produced when high-speed electrons strike the anode. This process occurs when electrons are emitted from the cathode and accelerated toward the anode through a high-voltage potential difference. When these electrons collide with the anode material, their kinetic energy is converted into X-ray radiation due to two primary mechanisms: characteristic radiation and bremsstrahlung radiation. Characteristic radiation occurs when the electrons knock out inner-shell electrons from the anode atoms, causing higher-energy outer-shell electrons to drop down and fill the vacancy, releasing energy in the form of X-ray photons. Bremsstrahlung radiation, on the other hand, is produced when the high-speed electrons are deflected by the electric field of the nuclei of the anode material, losing energy in the form of X-rays. This understanding is fundamental in industrial radiography and highlights the importance of the anode's material and design in determining the efficiency and quality of the produced X-rays.