PURPOSE: Stereoscopic x- @entity16039 image guided radiotherapy for @entity2 is often hindered by bone overlap and limited soft-tissue contrast. This study aims to evaluate the feasibility of dual-energy imaging techniques and to optimize parameters of the ExacTrac stereoscopic imaging system to enhance soft-tissue imaging for application to lung stereotactic body radiation therapy. METHODS: Simulated spectra and a physical lung phantom were used to optimize filter material, thickness, tube potentials, and weighting factors to obtain bone subtracted dual-energy images. Spektr simulations were used to identify material in the atomic number range (3-83) based on a metric defined to separate spectra of high and low-energies. Both energies used the same filter due to time constraints of imaging in the presence of respiratory motion. The lung phantom contained bone, soft tissue, and @entity5 mimicking materials, and it was imaged with a filter thickness in the range of (0-0.7) mm and a kVp range of (60-80) for low energy and (120,140) for high energy. Optimal dual-energy weighting factors were obtained when the bone to soft-tissue contrast-to-noise ratio (CNR) was minimized. Optimal filter thickness and tube potential were achieved by maximizing @entity5 -to-background CNR. Using the optimized parameters, dual-energy images of an anthropomorphic Rando phantom with a spherical @entity5 mimicking material inserted in his lung were acquired and evaluated for bone subtraction and @entity5 contrast. Imaging dose was measured using the dual-energy technique with and without beam filtration and matched to that of a clinical conventional single energy technique. RESULTS: Tin was the material of choice for beam filtering providing the best energy separation, @entity137 , and non-reactiveness. The best soft-tissue-weighted image in the lung phantom was obtained using 0.2 mm tin and (140, 60) kVp pair. Dual-energy images of the Rando phantom with the tin filter had noticeable improvement in bone elimination, @entity5 contrast, and noise content when compared to dual-energy imaging with no filtration. The surface dose was 0.52 mGy per each stereoscopic view for both clinical single energy technique and the dual-energy technique in both cases of with and without the tin filter. CONCLUSIONS: Dual-energy soft-tissue imaging is feasible without additional imaging dose using the ExacTrac stereoscopic imaging system with optimized acquisition parameters and no beam filtration. Addition of a single tin filter for both the high and low energies has noticeable improvements on dual-energy imaging with optimized parameters. Clinical implementation of a dual-energy technique on ExacTrac stereoscopic imaging could improve @entity2 visibility.

Optimizing dual-energy x- XXXX parameters for the ExacTrac clinical stereoscopic imaging system to enhance soft-tissue imaging.

@entity5 :: ('MESH:D009369', 'Disease') :: ['tumor'] @entity2 :: ('MESH:D008175', 'Disease') :: ['lung tumors', 'lung tumor'] @entity16039 :: ('255564', 'Species') :: ['ray'] @entity137 :: ('MESH:D064420', 'Disease') :: ['non-toxicity']
@entity16039 :: (255564,Species) :: ['ray']
