The dose efficiency of dual energy imaging can be improved if the spectra are filtered to increase spectral separation.
Our preliminary simulations showed that a fixed Gd filter can be efficacious in rapid kVp-switching systems. We
conducted physical experiments on a table top x-ray system to verify the performance improvement before moving
forward to a real CT scanner. We chose a commercial
Gd2O2S screen as our filter and used an acrylic-copper step wedge
phantom. Data were collected at 70 and 125 kVp, with and without the filter. The tube current was adjusted to make the
exposure rate with and without the filter to be roughly the same. The data were decomposed into basis material images
and the variance of the decomposition was measured for each
acrylic-copper thickness pair. Simulations were done with
the same experimental settings for comparison and validation.
The experiments verified that a Gd filter can reduce the variance at fixed dose. The variance reduction is monotonically
stronger as the object becomes more attenuating. This study demonstrates the potential of fixed Gd filtration to improve
the dose efficiency and material decomposition precision for rapid kVp-switching dual energy systems.
Yuan Yao,
Adam S. Wang,
Norbert J. Pelc,
"Efficacy of fixed filtration for rapid kVp-switching dual energy x-ray systems: experimental verification", Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 83131F (3 March 2012); doi: 10.1117/12.913222; https://doi.org/10.1117/12.913222
Yuan Yao, Adam S. Wang, Norbert J. Pelc, "Efficacy of fixed filtration for rapid kVp-switching dual energy x-ray systems: experimental verification," Proc. SPIE 8313, Medical Imaging 2012: Physics of Medical Imaging, 83131F (3 March 2012);