Increasing mA affects the beam by:

• A. Increases the energy per photon.
• B. Increases the quantity of photons (beam intensity).
• C. Reduces contrast.
• D. Changes wavelength.

Answer: (B)

Increasing mA raises the number of electrons emitted from the cathode and accelerated toward the anode, so more X-ray photons are produced each second. This boosts beam quantity or intensity, leading to greater exposure on the image. The energy per photon, and thus the wavelength, are set by the tube voltage (kVp); changing mA does not alter photon energy, so wavelength stays the same. Contrast, meanwhile, is influenced mainly by the energy spectrum and tissue attenuation, factors tied to kVp rather than the number of photons. Increasing mA improves image brightness and reduces noise but does not inherently change the inherent contrast. So the effect described by increasing mA is an increase in the quantity of photons in the beam.