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

• A. kvp, mA, time
• B. kvP, mA, distance
• C. kV, mA, screen speed
• D. kVp, mAs, exposure time

Answer: (A)

The main concept is how the x-ray beam output is controlled. The three adjustable settings on the generator that directly shape the beam are kilovoltage peak, tube current, and exposure duration. Kilovoltage peak sets the energy of the photons, influencing penetration and image contrast. The tube current (mA) determines how many electrons cross the tube each second, affecting the number of photons produced and thus image brightness. Exposure duration (time) controls how long the tube is energized; together with mA it defines the total exposure, commonly referred to as mAs (mA × seconds). This is why the best answer uses kvp, mA, and time—these are the direct controls on the x-ray machine that govern beam quantity and quality. Distance is a geometric factor that influences dose at the receptor via the inverse square law, not a direct machine control, and screen speed relates to the imaging receptor, not the generator settings.