Affiliations: [a] Missouri University of Science and Technology, Nuclear Engineering, Rolla, MO, USA | [b] GE Healthcare, Waukesha, WI, USA
Correspondence:
[*]
Corresponding author: Xin Liu, Missouri University of Science and Technology, Nuclear Engineering, 301 W14th Street, Rolla, MO 65401, USA. Tel.: +1 573 341 4693; Fax: +1 573 341 4720; E-mail:xinliu@mst.edu
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.
Keywords: Bowtie filter, scatter, Monte Carlo simulation, deterministic method
