Hybrid Deterministic-Stochastic Modeling of X-Ray Beam Bowtie Filter Scatter on a CT System
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.
X. Liu and J. Hsieh, "Hybrid Deterministic-Stochastic Modeling of X-Ray Beam Bowtie Filter Scatter on a CT System," Journal of X-Ray Science and Technology, vol. 23, no. 5, pp. 593-600, IOS Press, Jan 2015.
The definitive version is available at https://doi.org/10.3233/XST-150511
Nuclear Engineering and Radiation Science
Keywords and Phrases
Atoms; Bandpass filters; Intelligent systems; Light scattering; Monte Carlo methods; Neutron emission; Photons; Scattering; Stochastic models; Stochastic systems; X rays; Analytical formulas; Anti-scatter grids; Bowtie filters; Deterministic methods; Hybrid deterministic; Primary X-ray beams; Scattered photons; Stochastic simulations; Computerized tomography; Artifact; Computer assisted tomography; Computer simulation; Human; Image processing; Imaging phantom; Markov chain; Procedures; Artifacts; Computer Simulation; Humans; Image Processing; Computer-Assisted; Phantoms; Imaging; Stochastic Processes; Tomography; X-Ray Computed; Monte Carlo simulation; Scatter
International Standard Serial Number (ISSN)
Article - Journal
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01 Sep 2015