With all other factors held constant, which of the following mA settings will result in the greatest number of x-rays produced?

The mA setting in radiography refers to the milliamperage, which directly influences the quantity of x-rays produced during an exposure. Essentially, the higher the mA setting, the greater the number of electrons that flow through the x-ray tube, leading to the production of more x-rays.

When examining the options, a mA setting of 400 will generate a larger quantity of x-ray photons compared to lower settings, such as 100 mA, 200 mA, or 300 mA. This increase in production is due to the fact that the mA setting determines the tube current, and therefore, a higher mA results in a higher tube current. Consequently, a setting of 400 mA allows for more energetic interactions within the x-ray tube's anode, leading to more x-ray photons being emitted.

Thus, when considering the greatest number of x-rays produced, selecting 400 mA is the most definitive choice, as it maximizes x-ray output by leveraging the relationship between current and x-ray production.