What are the 3 controls on the x-ray machine?

• A. kVp, mA, time
• B. kVp, mAs, distance
• C. kVp, mA, distance
• D. mA, time, distance

Answer: (A)

The main idea is: the x-ray unit is controlled by the factors that directly determine exposure—the energy of the beam, the quantity of photons produced, and how long the beam is on. Kilovoltage peak (kVp) sets the beam’s energy, which influences image contrast and penetration. Milliamperage (mA) controls the electron current and thus the number of photons generated per unit time. Exposure time determines how long the beam is active. The product of mA and time, called mAs, represents the total exposure. Distance changes beam intensity via the inverse square law, but it isn’t a primary control on the machine console. So the three controls are kVp, mA, and time.