Evaluation of Cone Beam Computed Tomography Enhancement Using a Liver Specific Contrast Agent For Stereotactic Body Radiation Therapy Guidance

Abstract

This study evaluated contrast enhancement provided by Gadoxetate Disodium, a liver specific contrast agent. Image quality from cone-beam computed tomography was benchmarked against helical fan-beam computed tomography for comparison in cylindrical and ellipsoidal geometries. Concentrations were diluted to 0.0125 – 0.1 mmol/kg corresponding to expected physiological concentrations in the liver. CBCT imaging parameters tube voltage, tube current, and filtration were investigated on board a TrueBeam STx linear accelerator. All parameters were optimized according to the contrast-noise ratio, following the Rose criterion. Acceptable combinations of contrast dose, tube voltage, tube exposure-time product, and filtration gave CNR greater than three. This was found in a range of expected concentrations from 0.025 to 0.1 mmol/kg for a tube voltage of 100 kV, half-fan bowtie filtration, and exposures between 2025 and 5085 mAs. This research provides optimized pre-clinical dosing information and imaging parameters to use Gadoxetate Disodium in a clinical trial with CBCT.