Large-angle x-ray scatter in Talbot–Lau interferometry for breast imaging

Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew

doi:10.1088/0031-9155/59/21/6387

Cited by 11 publications

(5 citation statements)

References 56 publications

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“…The analyzer double functions as a scatter grid. 41 However, in conventional BCT and mammography, the scatter grid not only absorbs fluence but also requires careful alignment; failing in this results in image artifacts leading to repeat scans. 42 Hence, the current trend in BCT or mammogram is to perform grid-less scatter correction algorithms that produce equivalent image quality.…”

Section: Discussion and Future Workmentioning

confidence: 99%

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

Ham

Dey

2020

J. Med. Imag.

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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 sourcedetector 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.

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Section: Discussion and Future Workmentioning

confidence: 99%

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

Ham

Dey

2020

J. Med. Imag.

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“…Lastly, large angle scatter was not accounted for. Most applications of interest are limited in size and the contribution of scatter to the detector is assumed to be minimal (Vedantham et al 2014, Vignero 2018.…”

Section: Discussionmentioning

confidence: 99%

A hybrid simulation framework for computer simulation and modelling studies of grating-based x-ray phase-contrast images

et al. 2018

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Clinical studies performed using computer simulation are inexpensive, flexible methods that can be used to study aspects of a proposed imaging technique prior to a full clinical study. Typically, lesions are simulated into (experimental) data to assess the clinical potential of new methods or algorithms. In grating-based phase-contrast imaging (GB-PCI), full wave simulations are, however, computationally expensive due to the high periodicity of the gratings and therefore not practically applicable when large data sets are required. This work describes the development of a hybrid modelling platform that combines analytical and empirical input data for a more rapid simulation of GB-PCI images with little loss of accuracy. Instead of an explicit implementation of grating details, measured summary metrics (i.e. visibility, flux, noise power spectra, presampling modulation transfer function) are applied in order to generate transmission and differential phase images with large fields of view. Realistic transmission and differential phase images were obtained with good quantitative accuracy. The different steps of the simulation framework, as well as the methods to measure the summary metrics, are discussed in detail such that the technique can be easily customized for a given system. The platform offers a fast, accurate alternative to full wave simulations when the focus switches from grating/system design and set up to the generation of GB-PCI images for an established system.

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“…The emission angles (fan and cone angles) from the source were constrained to the detector dimensions. During the simulation, each photon incident on the detector was classified as incoherent scattering if it underwent at least one Compton interaction, as coherent scattering if it underwent Rayleigh interaction alone, and as primary photons if it did not undergo any interaction (Vedantham et al, 2014). The sum of incoherent and coherent scattered photons provided the total number of scattered x-ray photons.…”

Section: Methodsmentioning

confidence: 99%

Towards standardization of x-ray beam filters in digital mammography and digital breast tomosynthesis: Monte Carlo simulations and analytical modelling

2017

Self Cite

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In digital breast tomosynthesis and digital mammography, the x-ray beam filter material and thickness vary between systems. Replacing K-edge filters with Al was investigated with the intent to reduce exposure duration and to simplify system design. Tungsten target x-ray spectra were simulated with K-edge filters (50μm Rh; 50μm Ag) and Al filters of varying thickness. Monte Carlo simulations were conducted to quantify the x-ray scatter from various filters alone, scatter-to-primary ratio (SPR) with compressed breasts, and to determine the radiation dose to the breast. These data were used to analytically compute the signal-difference-to-noise ratio (SDNR) at unit (1 mGy) mean glandular dose (MGD) for W/Rh and W/Ag spectra. At SDNR matched between K-edge and Al filtered spectra, the reductions in exposure duration and MGD were quantified for three strategies: (i) fixed Al thickness and matched tube potential in kilovolts (kV); (ii) fixed Al thickness and varying the kV to match the half-value layer (HVL) between Al and K-edge filtered spectra; and, (iii) matched kV and varying the Al thickness to match the HVL between Al and K-edge filtered spectra. Monte Carlo simulations indicate that the SPR with and without the breast were not different between Al and K-edge filters. Modelling for fixed Al thickness (700μm) and kV matched to K-edge filtered spectra, identical SDNR was achieved with 37–57% reduction in exposure duration and with 2–20% reduction in MGD, depending on breast thickness. Modelling for fixed Al thickness (700μm) and HVL matched by increasing the kV over [0,4] range, identical SDNR was achieved with 62–65% decrease in exposure duration and with 2–24% reduction in MGD, depending on breast thickness. For kV and HVL matched to K-edge filtered spectra by varying Al filter thickness over [700,880]μm range, identical SDNR was achieved with 23–56% reduction in exposure duration and 2–20% reduction in MGD, depending on breast thickness. These simulations indicate that increased fluence with Al filter of fixed or variable thickness substantially decreases exposure duration while providing for similar image quality with moderate reduction in MGD.

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Large-angle x-ray scatter in Talbot–Lau interferometry for breast imaging

Cited by 11 publications

References 56 publications

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

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

A hybrid simulation framework for computer simulation and modelling studies of grating-based x-ray phase-contrast images

Towards standardization of x-ray beam filters in digital mammography and digital breast tomosynthesis: Monte Carlo simulations and analytical modelling

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