X-ray interferometry without analyzer for breast CT application: a simulation study

Jingzhu Xu; Kyungmin Ham; Joyoni Dey

doi:10.1117/1.JMI.7.2.023503

X-ray interferometry without analyzer for breast CT application: a simulation study

J Med Imaging (Bellingham). 2020 Mar;7(2):023503. doi: 10.1117/1.JMI.7.2.023503. Epub 2020 Mar 26.

Authors

Jingzhu Xu¹, Kyungmin Ham², Joyoni Dey¹

Affiliations

¹ Louisiana State University, Department of Physics and Astronomy, Baton Rouge, Louisiana, United States.
² Louisiana State University, Center for Advanced Microstructures and Devices, Baton Rouge, Louisiana, United States.

Abstract

Purpose: We investigate an analyzer-less x-ray interferometer with a spatially modulated phase grating (MPG) that can deliver three modalities (attenuation image, phase image, and scatter images) in breast computed tomography (BCT). The system can provide three x-ray modalities while preserving the dose to the object and can achieve attenuation image sensitivity similar to that of a standard absorption-only BCT. The MPG system works with a source, a source-grating, a single phase grating, and a detector. No analyzer is necessary. Thus, there is an approximately 2x improvement in fluence at the detector for our system compared with the same source-detector distance Talbot-Lau x-ray interferometry (TLXI) because the TLXI has an analyzer after the object, which is not required for the MPG. Approach: We investigate the MPG BCT system in simulations and find a clinically feasible system geometry. First, the mechanism of MPG interferometry is conceptually shown via Sommerfeld-Rayleigh diffraction integral simulations. Next, we investigate source coherence requirements, fringe visibility, and phase sensitivity dependence on different system parameters and find clinically feasible system geometry. Results: The phase sensitivity of MPG interferometry is proportional to object-detector distance and inversely proportional to a period of broad fringes at the detector, which is determined by the grating spatial modulation period. In our simulations, the MPG interferometry can achieve about 27% fringe visibility with clinically realistic BCT geometry of a total source-detector distance of 950 mm and source-object distance of 500 mm. Conclusions: We simulated a promising analyzer-less x-ray interferometer, with a spatially sinusoidal MPG. Our system is expected to deliver the attenuation, phase and scatter image in a single acquisition without dose or fluence detriment, compared with conventional BCT.

Keywords: analyzer-less phase-contrast breast computed tomography; modulated phase-grating interferometry; no analyzer phase-contrast x-ray; phase-contrast breast computed tomography.

© The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.