1. 
   milliampere second
   a unit of electric charge equal to one millicoulomb NOTE - The mAs is commonly used as a unit to measure the product of average X-ray tube current and exposure time, particularly in radiography.
   Found op http://www.electropedia.org/iev/iev.nsf/display?openform&ievref=881-04-10
   
   
2. 
   milliampere-second
   (mAs) a unit of radiographic exposure equal to the product of the milliamperage and the exposure time in seconds.
   Found op http://www.encyclo.co.uk/local/21001
   
   

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