Irradiating power
The irradiating power of an examination is defined as the dose resulting from the injection of one million Becquerels (MBq). If one express the dose in micro-sievert (┬ÁSv) (millionths of a sievert), the irradiating character is measured in microsievert / MBq. This radiating power varies in large proportions from one type of scan to another. Bone scans are almost not radiating (5.8 microsievert / MBq), when heart scans are much more radiating (231 microsievert / MBq).
IN2P3/ Source ICRP : publication 80).