Consider a portable chest x-ray with excessive exposure. How can the technologist decrease the intensity of the x-ray beam while maintaining the same beam energy?

• A. increase milliamperage (mA)
• B. increase kilovoltage peak (kVp)
• C. decrease kilovoltage peak (kVp)
• D. decrease milliamperage (mA)

Answer: (D)

Beam energy (quality) is set by kilovoltage peak, while the beam’s intensity (how many photons) depends on the tube current and exposure time. To reduce the dose without changing the energy of the beam, you keep kilovoltage the same and lower the tube current. Dropping milliamperage reduces the number of electrons striking the target, so fewer x-ray photons are produced, which lowers intensity while preserving the energy spectrum. Increasing milliamperage would raise intensity, and changing kilovoltage would alter the beam energy, which isn’t desired. Decreasing kilovoltage would also reduce the beam energy, not keep it the same.