The quality (penetrating power) of X-rays is primarily dependent upon the

• A. Kilovoltage peak
• B. Milliamperage
• C. Exposure time
• D. Target (anode)

Answer: (A)

The main factor that determines the penetrating power of an X-ray beam is the energy of its photons, which is set by the kilovoltage peak. Higher kVp raises the average photon energy, so more photons can penetrate dense tissues, increasing beam quality. The other factors mainly affect how many photons are produced (quantity) rather than how energetic they are: milliamperage and exposure time control tube current and duration, increasing overall exposure but not the energy of each photon; the anode material influences the spectrum in a secondary way, but it doesn’t determine penetrating power as directly as the kilovoltage peak.