Milligray
A unit of absorbed radiation equal to 0.001 gray.
(A gray is the dose of one joule of energy absorbed per kilogram of matter, or 100 rad.) Because the gray is such a large unit, many radiation measurements are made in milligrays.
In particular, exposures from by X-ray equipment are typically expressed in the milligray range.
The abbreviation for milligray is mGy