X-radiation is produced when:

X-radiation is produced primarily when high-speed electrons generated at the cathode of an X-ray tube collide with the anode in a vacuum. During this process, the kinetic energy of the electrons is converted into X-rays upon contact with the metal target (anode).

This conversion occurs due to the rapid deceleration of the electrons as they hit the target material, leading to the emission of X-rays. The choice emphasizing the role of high-speed electrons from the cathode striking the anode captures the essential mechanism of X-ray production accurately. Understanding this process is fundamental for anyone working with industrial radiography, as it highlights the importance of both the electron source and the target material in generating the radiation used for imaging and inspection.