Improving radiation dose efficiency of X-ray differential phase contrast imaging using an energy-resolving grating interferometer and a novel rank constraint.

Yongshuai Ge,Ke Li,Guang-Hong Chen,Ran Zhang

doi:10.1364/oe.24.012955

Abstract

In this paper, a novel method was developed to improve the radiation dose efficiency, viz., contrast to noise ratio normalized by dose (CNRD), of the grating-based X-ray differential phase contrast (DPC) imaging system that is integrated with an energy-resolving photon counting detector. The method exploits the low-dimensionality of the spatial-spectral DPC image matrix acquired from different energy windows. A low rank approximation of the spatial-spectral image matrix was developed to reduce image noise while retaining the DPC signal accuracy for every energy window. Numerical simulations and experimental phantom studies have been performed to validate the proposed method by showing noise reduction and CNRD improvement for each energy window.

Highlights

In recent years, grating interferometer based x-ray differential phase contrast (DPC) imaging systems [1,2,3] have been extensively investigated with the hope of finding their niche in medical applications [4,5,6,7,8,9]
X-ray photons with energies deviated from the designed value do carry phase information about the image object, due to the reduction of fringe visibility at these energies, they greatly add noise to the measured DPC signals and significantly degrade the radiation dose efficiency of the DPC imaging systems provided that an energy integration detector (EID) is used
Numerical simulation results are presented to demonstrate the rank-one nature of the noiseless DPC signal and to validate the proposed low rank approximation method to reduce noise and improve dose efficiency

Summary

Introduction

In recent years, grating interferometer based x-ray differential phase contrast (DPC) imaging systems [1,2,3] have been extensively investigated with the hope of finding their niche in medical applications [4,5,6,7,8,9]. X-ray photons with energies deviated from the designed value do carry phase information about the image object, due to the reduction of fringe visibility at these energies, they greatly add noise to the measured DPC signals and significantly degrade the radiation dose efficiency of the DPC imaging systems provided that an energy integration detector (EID) is used In this regard, an energy-resolving photon counting detector (PCD) does have potential benefits, as it enables a Talbot-Lau interferometer to be implemented as an energyresolving grating interferometer so that one can selectively use x-ray photons to achieve the highest fringe visibility in DPC imaging

Methods

Results

Conclusion