title: Hybrid deterministic-stochastic modeling of x-ray beam bowtie filter scatter on a CT system.
abstract: Knowledge of scatter generated by bowtie filter (i.e. x-ray beam compensator) is crucial for providing artifact free images on the CT scanners. Our approach is to use a hybrid deterministic-stochastic simulation to estimate the scatter level generated by a bowtie filter made of a material with low atomic number. First, major components of CT systems, such as source, flat filter, bowtie filter, body phantom, are built into a 3D model. The scattered photon fluence and the primary transmitted photon fluence are simulated by MCNP - a Monte Carlo simulation toolkit. The rejection of scattered photon by the post patient collimator (anti-scatter grid) is simulated with an analytical formula. The biased sinogram is created by superimposing scatter signal generated by the simulation onto the primary x-ray beam signal. Finally, images with artifacts are reconstructed with the biased signal. The effect of anti-scatter grid height on scatter rejection are also discussed and demonstrated.
authors.affiliation: Missouri University of Science and Technology, Nuclear Engineering, Rolla, MO, USA.
authors.forename: Xin
authors.initials: X
authors.lastname: Liu
authors.affiliation: GE Healthcare, Waukesha, WI, USA.
authors.forename: Jiang
authors.initials: J
authors.lastname: Hsieh
mesh_terms: D016477:Artifacts; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D013269:Stochastic Processes; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Bowtie filter; Monte Carlo simulation; deterministic method; scatter