How does increasing milliampere-seconds (mAs) affect the exposure of the x-ray beam?

How does increasing milliampere-seconds (mAs) affect the exposure of the x-ray beam?

• A. Exposure increases
• B. Exposure remains the same
• C. Exposure decreases
• D. Exposure varies unpredictably

Answer: (A)

Increasing mAs raises the number of X-ray photons produced by the tube. mAs combines tube current (mA) and exposure time (s), so with the kilovoltage held constant, changing mAs changes the beam’s quantity. More photons exiting the tube means more reach the patient and the image receptor, producing greater exposure on the image. The relationship is essentially linear, so doubling the mAs roughly doubles the exposure, assuming distance, filtration, and kVp are unchanged. This also means higher patient dose when mAs is increased.

Increasing mAs raises the number of X-ray photons produced by the tube. mAs combines tube current (mA) and exposure time (s), so with the kilovoltage held constant, changing mAs changes the beam’s quantity. More photons exiting the tube means more reach the patient and the image receptor, producing greater exposure on the image. The relationship is essentially linear, so doubling the mAs roughly doubles the exposure, assuming distance, filtration, and kVp are unchanged. This also means higher patient dose when mAs is increased.