Computational simulations and assessment of two approaches for x-ray phase contrast imaging

Abstract

X-ray phase-contrast imaging is a high-resolution imaging that permits an increase of the perceptibility of the details in three-dimensional objects, such as human tissues compared to conventional absorption imaging. There are different approaches for implementing phase-contrast imaging and their introduction into clinical practice requires advanced computational tools. A long-term goal of our research is the development of computational models of breast phase-contrast imaging. The aim of this study is to develop a software module for implementing grating-based phase-contrast imaging. For this purpose, an existing in-house software application for x-ray imaging with a function to model and simulate propagation-based phase-contrast x-ray images has been extended to include a model of grating-based imaging. To test the new functionality, four computational phantoms reflecting features, which can be screened in the real breast tissue and which differ in their complexity, were designed. Planar x-ray images in absorption, propagation-based and grating-based modes were generated and compared. Results showed improved visual appearance of the simulated objects in images obtained by simulating grating-based imaging setup. The developed subroutine is planned to be experimentally validated at synchrotron facility. The new software functionality will be exploited in studies related to new x-ray imaging techniques for breast screening and diagnosing.

Virtual grating approach for Monte Carlo simulations of edge illumination-based x-ray phase contrast imaging

“…In general, modelling the effect of the gratings is a crucial aspect of the simulation. Different approaches exist, which can be roughly divided in three categories: (1) modelling the grating as a plane (2D) [18,26,27,44,23,14,15,25,24,32,20],…”

“…(2) modelling the grating as a volume with bars extending along the direction of the optical axis (3D) [21,22,40,41], or (3) simulation frameworks where the effect of the grating is accounted for implicitly, without introducing the gratings as components in the simulation [16,33,31]. Two-dimensional (flat) grating models are common in, but not restricted to, wave-optics simulations and involve either an idealised binary representation of the grating [18,26,27,44] or application of a complex transmission function (projection approximation) [23,14,15,25,24,32,20]. However, assuming the gratings are infinitesimally thin is not always a valid approximation.…”

“…XPCI simulators are often either based on wave optics calculations [13,14,15,16], Monte Carlo (MC) code [17,18,19,20,21,22], or a combination thereof [23,24,25,26,27,28]. In addition, ray tracing-based [29,30,31,32] and empirical methods [33] have been reported. Some of these studies have explicitly included simulations for EI [15,18,19,30,21,22].…”