kVp determines

• A. Maximum energy of emitted X-rays
• B. X-ray beam intensity
• C. X-ray wavelength
• D. Number of X-ray photons emitted

Answer: (C)

When the tube is accelerated to a higher voltage, the electrons gain more energy before they strike the target. The photons produced by Bremsstrahlung have energies that can reach up to that electron energy, and photon energy is inversely related to wavelength (E = hc/λ). So increasing kVp sets the maximum photon energy and, consequently, the shortest wavelength that can be produced. In other words, kVp determines the X-ray wavelength spectrum, especially the shortest wavelength, because higher energy corresponds to shorter wavelengths.

Beam intensity and the number of photons emitted are mainly influenced by the tube current and exposure time, not the voltage. The target material dictates characteristic X-ray energies, which are separate from the effect of kVp on the continuum spectrum.