Which formula is appropriate to calculate heat units for a single-phase x-ray machine?

The formula for calculating heat units for a single-phase x-ray machine is based on the factors that contribute to the heat generated during the x-ray exposure. The correct formula includes the milliampere (mA), exposure time, and kilovolt peak (kVp).

When x-rays are produced, the mA determines the quantity of x-rays generated per unit time, while the exposure time indicates how long the x-ray tube operates. The kVp represents the quality of the x-ray beam, which affects the energy of the x-ray photons produced.

Therefore, the combination of mA, exposure time, and kVp is essential in calculating the total heat units because it gives a comprehensive understanding of the energy delivered by the x-ray tube during an exposure session. This information is crucial for ensuring that the tube is not subjected to excessive heat, which could lead to damage or reduced lifespan.

The other options do not account for all necessary factors; for instance, just multiplying mA by exposure time does not consider the quality of the beam, while the product of mAs and kVp might not apply to scenarios requiring the direct impact of exposure time. Thus, the inclusion of all three variables — mA, exposure time, and kVp —