  We test the feasibility of calculating proton stopping power (SP) from a set
of virtual monochromatic (VM) CT images, created with Monte Carlo-generated CT
scans, using a dual-energy CT-to-SP procedure. The Monte Carlo CT simulations,
with 70 and 150 kVp spectra, were modeled on the x-ray tube parameters of the
SOMATOM Force dual-source DECT scanner and the Gammex RMI 467 tissue
calibration phantom. Reconstructed SP images were created with two VM x-ray
images, and the monochromatic energy pairs were chosen to minimize the SP
residual errors using the root-mean-squared-error (RMSE). The contrast of
phantom inserts has also been examined, in addition to relative errors of the
average reconstructed insert values (which are calculated using the known
electron densities and chemical compositions of each material, provided by the
manufacturer). Results were also compared to a similar dual-energy-based SP
conversion procedure for comparison. Modest reductions in errors and noise were
seen in almost all inserts in both low- and high-density configurations of the
phantom, with a visible reduction in beam-hardening streaking artifacts. Our
Monte Carlo simulated DECT scans confirm the feasibility of previously proposed
methods of DECT-based $ S(\rho_e, Z) $-determination. By utilizing VM images
and only optimizing the RMSE over specific inserts, the residual error across
the most vital bodily tissues may be reduced when extremely low- or
high-density tissues are known to be present.
