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

Xu, Jingzhu; Ham, Kyungmin; Dey, Joyoni

doi:10.1117/1.jmi.7.2.023503

Cited by 5 publications

(1 citation statement)

References 41 publications

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“…This works well if there are many projection angles. One method exploits complementary angles in full-scan CT, and uses a different grating position for each (Zhu et al 2010), while another employs a modulated phase grating (Xu et al 2020). A promising way of enabling CT imaging is described by von Teuffenbach et al (2017), where a statistical iterative reconstruction algorithm reconstructs projection images recorded with a sliding window, or a moving source (Miao et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Analyzer-free hard x-ray interferometry

Bertilson,

von Hofsten,

Maltz

et al. 2024

Phys. Med. Biol.

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Objective. To enable practical interferometry-based phase contrast CT using standard incoherent x-ray sources, we propose an imaging system where the analyzer grating is replaced by a high-resolution detector. Since there is no need to perform multiple exposures (with the analyzer grating at different positions) at each scan angle, this scheme is compatible with continuous-rotation CT apparatus, and has the potential to reduce patient radiation dose and patient motion artifacts. Approach. Grating-based x-ray interferometry is a well-studied technique for imaging soft tissues and highly scattering objects embedded in such tissues. In addition to the traditional x-ray absorption-based image, this technique allows reconstruction of the object phase and small-angle scattering information. When using conventional incoherent, polychromatic, hard x-ray tubes as sources, three gratings are usually employed. To sufficiently resolve the pattern generated in these interferometers with contemporary x-ray detectors, an analyzer grating is used, and consequently multiple images need to be acquired for each view angle. This adds complexity to the imaging system, slows image acquisition and thus increases sensitivity to patient motion, and is not dose efficient. By simulating image formation based on wave propagation, and proposing a novel phase retrieval algorithm based on a virtual grating, we assess the potential of a analyzer-grating-free system to overcome these limitations. Main results. We demonstrate that the removal of the analyzer-grating can produce equal image contrast-to-noise ratio at reduced dose (by a factor of 5), without prolonging scan duration. Significance. By demonstrating that an analyzer-free CT system, in conjuction with an efficient phase retrieval algorithm, can overcome the prohibitive dose and workflow penalties associated grating-stepping, an alternative path towards realizing clinical inteferometric CT appears possible.

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Section: Introductionmentioning

confidence: 99%

Analyzer-free hard x-ray interferometry

Bertilson,

von Hofsten,

Maltz

et al. 2024

Phys. Med. Biol.

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Neutron interferometry using a single modulated phase grating

Hidrovo

Dey

Meyer

et al. 2023

Review of Scientific Instruments

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Neutron grating interferometry provides information on phase and small-angle scatter in addition to attenuation. Previously, phase grating moiré interferometers (PGMI) with two or three phase gratings have been developed. These phase-grating systems use the moiré far-field technique to avoid the need for high-aspect absorption gratings used in Talbot–Lau interferometers (TLI) that reduce the neutron flux reaching the detector. We first demonstrate, through theory and simulations, a novel phase grating interferometer system for cold neutrons that requires a single modulated phase grating (MPG) for phase-contrast imaging, as opposed to the two or three phase gratings in previously employed PGMI systems. The theory shows the dual modulation of MPG with a large period and a smaller carrier pitch P, resulting in large fringes at the detector. The theory was compared to the full Sommerfeld–Rayleigh diffraction integral simulator. Then, we proceeded to compare the MPG system to experiments in the literature that use a two-phase-grating-based PGMI with best-case visibility of around 39%. The simulations of the MPG system show improved visibility in comparison to that of the two-phase-grating-based PGMI. An MPG with a modulation period of 300 µm, the pitch of 2 µm, and grating heights with a phase modulation of ([Formula: see text], illuminated by a monochromatic beam produces visibility of 94.2% with a comparable source-to-detector distance (SDD) as the two-phase-grating-based PGMI. Phase sensitivity, another important performance metric of the grating interferometer, was compared to values available in the literature, viz. the conventional TLI with the phase sensitivity of 4.5 × 103 for an SDD of 3.5 m and a beam wavelength of 0.44 nm. For a range of modulation periods, the MPG system provides comparable or greater theoretical maximum phase sensitivity of 4.1 × 103 to 10.0 × 103 for SDDs of up to 3.5 m. This proposed MPG system appears capable of providing high-performance PGMI that obviates the need for the alignment of two phase gratings.

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Hybrid modulated-phase-grating for phase contrast x-ray for a varying fringe period clinical interferometry system

Park

Dey

2022

Medical Imaging 2022: Physics of Medical Imaging

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

Cited by 5 publications

References 41 publications

Analyzer-free hard x-ray interferometry

Analyzer-free hard x-ray interferometry

Neutron interferometry using a single modulated phase grating

Hybrid modulated-phase-grating for phase contrast x-ray for a varying fringe period clinical interferometry system

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