How is milliampere-seconds (mAs) calculated from milliampere (mA) and exposure time?

The calculation of milliampere-seconds (mAs) is fundamentally linked to the two components involved: the milliampere (mA) and the exposure time. The formula for determining mAs involves multiplying the mA value, which indicates the amount of current flowing through the x-ray tube, by the exposure time, which is the duration for which the current is applied.

When mA is multiplied by the exposure time in seconds, it accurately reflects the total amount of radiation produced during that exposure. This is because mAs represents the total electrical charge (or quantity of x-rays) delivered to the imaging receptor. A higher mAs results in a greater amount of radiation, leading to an increased exposure for the resultant image.

Using exposure time in milliseconds would not yield the correct outcome since the standard measurement for exposure time in the mAs formula is in seconds. Similarly, dividing exposure time by mA or adding the two does not reflect their relationship in generating the total exposure, which is why those options do not provide the correct calculation for mAs. Thus, the correct answer involves the straightforward multiplication of mA and exposure time in seconds.