Recently, there have been several physics and clinical studies on the use of lower tube potentials in CT imaging,
with the purpose of improving image quality or further reducing radiation dose. We investigated an experimental
study using a series of different sized, polymethyl methacrylate (PMMA) phantoms, demonstrating the
potential strategy for dose reduction and to distinguish component of plaque by imaging their energy responses
using CT. We investigated the relationship between different sizes of cylinderic PMMA equivalent phantoms
with diameter of 12, 16, 20, 24, and 32 cm and used contrast at various tube voltages (80, 100, 120, and 140
kVp) using a 16–detector row CT scanner. The contrast represented CT numbers as different materials for the
water, calcium chloride, and iodine. Phantom insertions also allow quantitative measures of image noise, contrast,
contrast-to-noise ratio (CNR) and figure of merit (FOM). When evaluating FOM, it was found that the
lower kVp provided the better CNR. An experimental study was performed to demonstrate reduced dose for
both dose efficient and practical feasibility for different patient sizes and diagnostic tasks by relating achievable
CNR and the volume CT dose index (CTDI vol). The use of spectra optimized to the specific application
could provide further improvements of distinguishing iodine, calcium and plaque component for patient size.
The purpose of this study was to evaluate variations in image noise and contrast using different tube potentials
in a CTDI phantom on contrast imaging.