reveal additional diagnostic information,
images with higher noise may obscure
lesions that might have been visible in
lower-noise images (7–9).
Authors of previous clinical and experimental
studies have reported that satisfactory
image quality can be obtained
with a reduction of tube current on the
basis of weight and cross-sectional dimensions
of patients undergoing CT
scanning (10–12). Results of these studies
may be explained on the basis of variable
attenuation of the incident beam traversing
a particular cross-sectional dimension
at a particular projection angle (1,2).
The resultant attenuation determines image
noise and is affected by scanning parameters,
particularly tube current. For
example, greater beam attenuation in a
particular dimension or projection will
result in greater noise and will require
higher tube current than that needed by
a beam undergoing less attenuation in
another projection.