RTBC Advanced Exposure Factors Practice Test 2026 - Free Exposure Factors Practice Questions and Study Guide

Milliampere-seconds (mAs) is calculated by multiplying the tube current in milliamperes (mA) by the exposure time in seconds. In this scenario, the tube current is 200 mA, and the exposure time is given in milliseconds. To convert 300 ms to seconds, you divide by 1000, resulting in 0.3 seconds.

The formula for mAs is:

mAs = mA × time (in seconds)

Substituting the values:

mAs = 200 mA × 0.3 seconds = 60 mAs

This calculation correctly reflects how mA and exposure time work together to determine the total radiation exposure in a given imaging process.