Tomographic phase and attenuation extraction for a sample composed of unknown materials using x-ray propagation-based phase-contrast imaging

Abstract

Propagation-based phase-contrast x-ray imaging (PB-PCXI) generates image contrast by utilizing sample-imposed phase-shifts. This has proven useful when imaging weakly attenuating samples, as conventional attenuation-based imaging does not always provide adequate contrast. We present a PB-PCXI algorithm capable of extracting the x-ray attenuation β and refraction δ , components of the complex refractive index of distinct materials within an unknown sample. The method involves curve fitting an error-function-based model to a phase-retrieved interface in a PB-PCXI tomographic reconstruction, which is obtained when Paganin-type phase retrieval is applied with incorrect values of δ and β. The fit parameters can then be used to calculate true δ and β values for composite materials. This approach requires no a priori sample information, making it broadly applicable. Our PB-PCXI reconstruction is single-distance, requiring only one exposure per tomographic angle, which is important for radiosensitive samples. We apply this approach to a breast-tissue sample, recovering the refraction component δ , with 0.6–2.4% accuracy compared with theoretical values.

Phase-contrast neutron imaging compared with wave propagation and McStas simulations

“…The benefit of the latter is that no gratings are necessary to measure the phase shift. For this reason, propagation-based imaging is very powerful and widely used in X-ray imaging (Snigirev et al, 1995;Alloo et al, 2022;Bidola et al, 2017). It has also been exploited in neutron imaging, where it has been used to detect cracks in aluminium (Fiori et al, 2006) and investigate pores in bone (Østergaard et al, 2023a,b).…”

Human lung virtual histology by multi-scale x-ray phase-contrast computed tomography

“…To this end, it is by now well appreciated that propagation-based x-ray phase-contrast tomography (XPCT) offers a unique potential to extend histology and pathohistology. It promises a scalable, isotropic resolution without destructive slicing of the specimen and quantitative density-based contrast (Khimchenko et al 2016 Recent work has significantly improved the classic phase retrieval approaches (Paganin and Nugent 1998, Cloetens et al 1999, Alloo et al 2022, for example by nonlinear generalizations and Tikhonov regularization (Lohse et al 2020, Huhn et al 2022. Furthermore, scans with highly coherent synchrotron radiation both in the parallel beam settings with high resolution scintillator-based detector systems, and in magnifying cone-beam settings now routinely reach the micron and sub-micron resolution range, respectively, down to voxel sizes around 100 nm, which can even be implemented in the same instrument (Frohn et al 2020), and at least partly in high throughput (by continuous scans and detector readout).…”

Polychromatic neutron phase-contrast imaging of weakly absorbing samples enabled by phase retrieval

“…The benefit of the latter is that no gratings or other specialized elements are needed to measure the phase shift. Therefore, propagation-based phase-contrast imaging has evolved into a very powerful tool in X-ray imaging (Alloo et al, 2022;Bidola et al, 2017;Wieland et al, 2021;Yu et al, 2021) but has only been investigated for neutrons in a very few cases (Allman et al, 2000;Jacobson et al, 2004;Lehmann et al, 2005;McMahon et al, 2003).…”