Abstract
Ray-tracing based simulation methods are widely used in modeling X-ray propagation, detection and imaging. While
most of the existing simulation methods rely on analytical modeling, a novel hybrid approach comprising of statistical
modeling and analytical approaches, is proposed here.
Our hybrid simulator is a unique combination of analytical modeling for evoking the fundamentals of X-ray transport
through ray-tracing, and a look-up-table (LUT) based approach for integrating it with the Monte Carlo simulations that
model optical photon-transport within scintillator. The LUT approach for scintillation-based X-ray detection invokes
depth-dependent gain factors to account for intra-pixel absorption and light-transport, together with incident-angle
dependent effects for inter-pixel X-ray absorption (parallax effect). The model simulates the post-patient collimator for
scatter-rejection, as an X-ray shadow on scintillator, while handling its position with respect to the pixel boundary, by a
smart over-sampling strategy for high efficiency.
We have validated this simulator for computed tomography system-simulations, by using real data from GE Brivo
CT385. The level of accuracy of image noise and spatial resolution is better than 98%. We have used the simulator for
designing the post-patient collimator, and measured modulation transfer function (MTF) for different widths of the
collimator plate.
Validation and simulation study clearly demonstrates that the hybrid simulator is an accurate, reliable, efficient tool for
realistic system-level simulations. It could be deployed for research, design and development purposes to model any
scintillator-based X-ray imaging-system (2-dimensional and 3-dimensional), while being equally applicable for medical
and industrial imaging.
