What unit is used to indicate the total quantity of x-rays in an exposure?

The total quantity of x-rays produced during an exposure is measured in milliampere-seconds (mAs). This unit reflects both the current (measured in milliamperes, mA) and the duration of the exposure (measured in seconds). Essentially, mAs indicates the amount of radiation produced; a higher mAs value corresponds to a greater number of x-ray photons being generated.

Kilovoltage (kVp) is not a measure of x-ray quantity, but rather it indicates the energy of the x-rays produced, influencing their penetration power. The Gray (Gy) is a unit of measurement that reflects the amount of radiation absorbed by a material but does not quantify the x-ray exposure itself. Roentgen (R) measures ionization produced in air by x-ray or gamma radiation, but it is not an indicator of the total quantity of x-rays in a specific exposure setting.

Therefore, when assessing the total quantity of x-rays in an exposure, milliampere-seconds (mAs) is the appropriate unit to use, as it directly correlates with the production of x-ray photons during the exposure time.