Which technical factor is primarily responsible for controlling the energy of the x-ray beam?

• A. milliamperge (mA)
• B. kilovoltage peak (kVp)
• C. exposure time (s)
• D. filament current

Answer: (B)

The energy of the x-ray beam is controlled mainly by the kilovoltage peak. The electrons are accelerated across the tube potential, gaining energy proportional to the applied voltage, and when they collide with the anode, photons can have energies up to that maximum. Increasing kVp raises the maximum photon energy and shifts the spectrum toward higher energies, boosting the beam’s penetrating power. Filtration and target material can shape the spectrum, but the primary factor setting the photon energies is the kVp.

The other factors influence how many photons are produced rather than how energetic they are: milliamperage and exposure time determine beam quantity (intensity and total dose), while filament current affects the number of electrons available for emission, again impacting quantity rather than energy.