Introduction of slip-ring technology with subsequent development of single– and
multi– detector row helical computed tomographic (CT) scanners have expanded
the applications of CT, leading to a substantial increase in the number of CT
examinations being performed. Owing to concerns about the resultant increase in
associated radiation dose, many technical innovations have been introduced. One
such innovation is automatic tube current modulation. The purpose of automatic
tube current modulation is to maintain constant image quality regardless of patient
attenuation characteristics, thus allowing radiation dose to patients to be reduced.
This review discusses the principles, clinical use, and limitations of different automatic
tube current modulation techniques.