Sci‐Thur AM: YIS – 07: Optimizing dual‐energy x‐ray parameters using a single filter for both high and low‐energy images to enhance soft‐tissue imaging

Abstract

Objective:To optimize dual‐energy parameters of ExacTrac stereoscopic x‐ray imaging system for lung SBRT patientsMethods:Simulated spectra and a lung phantom were used to optimize filter material, thickness, kVps, and weighting factors to obtain bone subtracted dual‐energy images. Spektr simulations were used to identify material in the atomic number (Z) range [3–83] based on a metric defined to separate spectrums of high and low energies. Both energies used the same filter due to time constraints of image acquisition in lung SBRT imaging. A lung phantom containing bone, soft tissue, and a tumor mimicking material was imaged with filter thicknesses range [0–1] mm and kVp range [60–140]. A cost function based on contrast‐to‐noise‐ratio of bone, soft tissue, and tumor, as well as image noise content, was defined to optimize filter thickness and kVp. Using the optimized parameters, dual‐energy images of anthropomorphic Rando phantom were acquired and evaluated for bone subtraction. Imaging dose was measured with dual‐energy technique using tin filtering.Results:Tin was the material of choice providing the best energy separation, non‐toxicity, and non‐reactiveness. The best soft‐tissue‐only image in the lung phantom was obtained using 0.3 mm tin and [140, 80] kVp pair. Dual‐energy images of the Rando phantom had noticeable bone elimination when compared to no filtration. Dose was lower with tin filtering compared to no filtration.Conclusions:Dual‐energy soft‐tissue imaging is feasible using ExacTrac stereoscopic imaging system utilizing a single tin filter for both high and low energies and optimized acquisition parameters.