Which statement is true about heat units calculation?

Which statement is true about heat units calculation?

• A. HU equals kVp × mA × s
• B. HU equals kVp × mA × s × W
• C. HU equals kVp × mA × s × 0.5
• D. HU equals mA × s × W

Answer: (B)

Heat units reflect the energy deposited as heat in the x-ray tube during an exposure. The heat produced is proportional to the voltage across the tube (kVp), the current (mA), and the exposure time (s). Because the actual energy delivered depends on the generator’s waveform, a waveform factor W is included to adjust for how the power is produced. The correct formula is HU = kVp × mA × s × W. If you’re using a single-phase machine with 100% ripple, W = 1, so HU becomes simply kVp × mA × s. For three-phase or high-frequency generators, W is greater than 1, yielding higher heat units for the same exposure settings. The other options omit the waveform factor, omit kVp, or add an incorrect multiplier, so they don’t correctly represent heat units.

Heat units reflect the energy deposited as heat in the x-ray tube during an exposure. The heat produced is proportional to the voltage across the tube (kVp), the current (mA), and the exposure time (s). Because the actual energy delivered depends on the generator’s waveform, a waveform factor W is included to adjust for how the power is produced. The correct formula is HU = kVp × mA × s × W. If you’re using a single-phase machine with 100% ripple, W = 1, so HU becomes simply kVp × mA × s. For three-phase or high-frequency generators, W is greater than 1, yielding higher heat units for the same exposure settings. The other options omit the waveform factor, omit kVp, or add an incorrect multiplier, so they don’t correctly represent heat units.