Currently, at least one manufacturer has implemented an AEC system that varies the strength of the tube current adaptation as patient size varies (ie, b value < 1). In this system, the b value used to decrease the tube current for small patient sizes is different from the b value used to increase the tube current for large patient sizes. Our practice uses a strength of b = 0.33 (“average”) for obese patients and b = 0.5 (average) for slim patients on Sensation 16 and 64 scanners (Siemens Healthcare). On Definition DS, AS+, and FLASH systems (Siemens Healthcare), we use a strength of b = 0.4 and b = 0.5 (specific b values provided by the manufacturer). For some software versions, these are global scanner settings that are independent of the specific imaging examination. For newer software versions, these can be set for each type of exam protocol. The user-prescribed reference tube current for the reference patient size determines the noise level that is acceptable for a specific diagnostic task (eg, CT colonography or CT angiography). The tube current is then decreased or increased relative to the reference values using the system’s global adaptation strengths.