Manual adjustment of tube current
based on patient weight or dimensions
can aid in establishing an appropriate
balance between image noise and radiation
exposure (10,12). However, these
adjustments do not guarantee constant
image quality throughout the entire examination.
For example, in CT scanning
of chest, the choice of a fixed tube current
does not account for differences in
beam attenuation between the shoulder
region and midchest region or between anteroposterior
and lateral cross-sectional dimensions.
ATCM techniques allow maintenance
of constant image quality at a
required radiation exposure level because
ATCM rapidly responds to large variations
in beam attenuation. ATCM is based on