Which term describes the crest value of voltage applied to the X-ray tube?

• A. Kilovolt Peak (kVp)
• B. Milliamperage (mA)
• C. Kilovolt (kV)
• D. Ohm (Ω)

Answer: (C)

The crest value of voltage across the X-ray tube is the peak voltage reached during the exposure. In radiography this is described as kilovolt peak, abbreviated kVp. The peak voltage determines the maximum accelerating potential for the electrons and thus the energy of the emitted X-rays. Kilovolt (kV) is simply the unit of voltage, not specifically the peak value used to describe the exposure setting. Milliamperage (mA) affects the number of electrons produced (quantity), not the energy per electron, and Ohm is a unit of resistance, which isn’t what defines the crest voltage. So the correct way to describe the crest voltage applied to the tube is the peak value, i.e., kilovolt peak (kVp).