How many heat units (HU) are generated from a single exposure using a single-phase x-ray machine with 70 kVp and 25 mAs?

To determine how many heat units (HU) are generated from a single exposure using a single-phase x-ray machine, you can use the formula specific to single-phase equipment. The formula for calculating heat units in this context is:

[ \text{HU} = \text{kVp} \times \text{mAs} \times \text{constant} ]

For single-phase x-ray machines, the constant used is typically 1. The specific values provided are 70 kVp and 25 mAs.

Applying the values from the question:

[ \text{HU} = 70 , \text{kVp} \times 25 , \text{mAs} \times 1 ]

Doing the multiplication:

[ \text{HU} = 70 \times 25 = 1,750 , \text{HU} ]

Therefore, the correct answer is that 1,750 HU are generated from a single exposure using a single-phase x-ray machine with the given parameters. This highlights the direct relation between kVp, mAs, and the heat generated in the x-ray tube during an exposure, which is critical for understanding the operational efficiency and thermal management in radiographic imaging systems.