mAs
Also written as: mAs — milliampere-seconds
Milliampere-seconds; the product of tube current and exposure time, controlling the quantity of X-ray photons produced.
Full Definition
Milliampere-seconds (mAs) is the fundamental exposure parameter that determines the total quantity of X-ray photons produced during an imaging examination. It represents the product of tube current (measured in milliamperes) and exposure time (measured in seconds). Higher mAs values produce more X-ray photons, resulting in improved image quality due to reduced quantum noise, but also increase patient radiation dose. In oncologic imaging, mAs selection must balance image quality requirements with radiation dose optimization. Automatic exposure control (AEC) systems often adjust mAs based on patient anatomy to maintain consistent image quality while minimizing radiation exposure.
Usage
Usage note: Written as 'mAs' with capital A and lowercase m and s.
In Context
- "Reduce the mAs from 200 to 150 to decrease patient dose while maintaining diagnostic quality." — Protocol optimization
- "The AEC system automatically adjusted mAs based on patient thickness." — Technical factors report