mA and time together determine the total quantity of radiation produced, and this quantity is directly proportional to what?

mA and time together determine the total quantity of radiation produced, and this quantity is directly proportional to what?

• A. mA and time
• B. kVp and SID
• C. mA and kVp
• D. SID and mAs

Answer: (A)

The amount of radiation produced is determined by mA and exposure time because they control how many electrons are emitted and for how long they are accelerated across the tube. The tube current (mA) sets how many electrons flow each second, and the exposure time determines how many seconds that current is active. Multiply them to get mAs (mA·s), which directly corresponds to the total number of x-ray photons produced. Since photon quantity (not energy) is what we’re talking about here, mAs is the key factor. KVp affects the energy (quality) of the photons, not how many are produced, so it doesn’t set the quantity. SID (distance) and geometry influence how much of that produced radiation actually reaches a point on the image receptor, but they don’t determine the total production in the tube.

The amount of radiation produced is determined by mA and exposure time because they control how many electrons are emitted and for how long they are accelerated across the tube. The tube current (mA) sets how many electrons flow each second, and the exposure time determines how many seconds that current is active. Multiply them to get mAs (mA·s), which directly corresponds to the total number of x-ray photons produced. Since photon quantity (not energy) is what we’re talking about here, mAs is the key factor.

KVp affects the energy (quality) of the photons, not how many are produced, so it doesn’t set the quantity. SID (distance) and geometry influence how much of that produced radiation actually reaches a point on the image receptor, but they don’t determine the total production in the tube.