Full-field digital mammography with grid-less acquisition and software-based scatter correction: investigation of dose saving and image quality

Fieselmann, Andreas; Fischer, Daniel; Hilal, Ghani; Dennerlein, Frank; Mertelmeier, Thomas; Uhlenbrock, Detlev

doi:10.1117/12.2007490

Cited by 16 publications

(17 citation statements)

References 17 publications

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“…Similar results can be found in Gennaro et al's study, where the grid performance was directly evaluated in a full-field digital mammography system. 11 However, these results differ substantially from the conclusion of Fieselmann et al, 18 which is based on a phantom study in which SDNR was measured according to the fourth edition of the European Guidelines protocol, 19 with and without a grid. Fieselmann et al showed that by removing the grid and applying a software-based scatter correction technique, the dose could be saved for any breast thickness without degrading the SDNR.…”

Section: Introductioncontrasting

confidence: 56%

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On image quality metrics and the usefulness of grids in digital mammography

et al. 2015

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Abstract. Antiscatter grids are used in digital mammography to reduce the scattered radiation from the breast and improve image contrast. They are, however, imperfect and lead to partial absorption of primary radiation, as well as failing to absorb all scattered radiation. Nevertheless, the general consensus has been that antiscatter grids improve image quality for the majority of breast types and sizes. There is, however, inconsistency in the literature, and recent results show that a substantial image quality improvement can be achieved even for thick breasts if the grid is disposed of. The purpose of this study was to investigate if differences in the considered imaging task and experimental setup could explain the different outcomes. We estimated the dose reduction that can be achieved if the grid were to be removed as a function of breast thickness with varying geometries and experimental conditions. Image quality was quantified by the signal-difference-to-noise ratio (SDNR) measured using an aluminum (Al) filter on blocks of poly(methyl methacrylate) (PMMA), and images were acquired with and without grid at a constant exposure. We also used a theoretical model validated with Monte Carlo simulations. Both theoretically and experimentally, the main finding was that when a large 4 × 8 cm 2 Al filter was used, the SDNR values for the gridless images were overestimated up to 25% compared to the values for the small 1 × 1 cm 2 filter, and gridless imaging was superior for any PMMA thickness. For the small Al filter, gridless imaging was only superior for PMMAs thinner than 4 cm. This discrepancy can be explained by a different sensitivity to and sampling of the angular scatter spread function, depending on the size of the contrast object. The experimental differences were eliminated either by using a smaller region of interest close to the edge of the large filter or by applying a technique of scatter correction by subtracting the estimated scatter image. These results explain the different conclusions reported in the literature and show the importance of the selection of measurement methods. Since the interesting structures in mammography are below the 1-cm scale, we advocate the use of smaller contrast objects for assessment of antiscatter grid performance.

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Section: Introductioncontrasting

confidence: 56%

“…The phantom study was performed on a full-field digital mammography system (Philips MammoDiagnost DR), with the same grid properties as the system used by Fieselmann et al 18 The system uses a-Se as the detector material. The pixel matrix is 2816 × 3584 with an 85 μm pitch, giving an image size of 24 cm × 30 cm.…”

Section: Phantom Studymentioning

confidence: 99%

On image quality metrics and the usefulness of grids in digital mammography

et al. 2015

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“…1). 3,4 To fully account for the effect of object heterogeneity and spatially varying thickness, the symmetric kernel method has recently been extended to asymmetric kernels using the fast adaptive scatter kernel superposition (fASKS) method, which allows for efficient implementation of nonstationary asymmetric kernels in Fourier space and estimates scatter from individual projections. The relationship between the estimated scatter and primary is as follows: 5…”

Section: A Description Of Correction Algorithmmentioning

confidence: 99%

Asymmetric scatter kernels for software-based scatter correction of gridless mammography

et al. 2015

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Scattered radiation remains one of the primary challenges for digital mammography, resulting in decreased image contrast and visualization of key features. While anti-scatter grids are commonly used to reduce scattered radiation in digital mammography, they are an incomplete solution that can add radiation dose, cost, and complexity. Instead, a software-based scatter correction method utilizing asymmetric scatter kernels is developed and evaluated in this work, which improves upon conventional symmetric kernels by adapting to local variations in object thickness and attenuation that result from the heterogeneous nature of breast tissue. This fast adaptive scatter kernel superposition (fASKS) method was applied to mammography by generating scatter kernels specific to the object size, x-ray energy, and system geometry of the projection data. The method was first validated with Monte Carlo simulation of a statistically-defined digital breast phantom, which was followed by initial validation on phantom studies conducted on a clinical mammography system. Results from the Monte Carlo simulation demonstrate excellent agreement between the estimated and true scatter signal, resulting in accurate scatter correction and recovery of 87% of the image contrast originally lost to scatter. Additionally, the asymmetric kernel provided more accurate scatter correction than the conventional symmetric kernel, especially at the edge of the breast. Results from the phantom studies on a clinical system further validate the ability of the asymmetric kernel correction method to accurately subtract the scatter signal and improve image quality. In conclusion, software-based scatter correction for mammography is a promising alternative to hardware-based approaches such as anti-scatter grids. Description of PurposeScattered radiation remains one of the primary challenges for digital mammography. Despite the lower energies used in mammography, the small air-gap distance leads to relatively high scatter-to-primary ratios (SPR) of ~0.2-0.7 for 2-6 cm thick breasts, respectively, that add undesirable low-frequency signal and increased noise to the projection, resulting in decreased detectability and contrast-to-noise ratio (CNR) of key features such as masses or microcalcifications. 1 Hardware-based solutions such as a Bucky anti-scatter grid can reduce scattered radiation, but are imperfect solutions due to the loss of primary radiation (~30%) and resulting radiation dose increase to compensate for the loss. Secondary considerations include the remaining transmitted scatter (~20%), mechanical complexity of a moving grid to avoid grid lines, and additional cost. 2 Alternatively, software-based scatter estimation and correction methods can be used in gridless systems to subtract the scatter signal from the measured projection to recover image contrast, improve image quality, and potentially reduce radiation dose since primary photons are no longer lost to the grid. However, conventional software-based methods typically apply symmetric kernels th...

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“…The first image was acquired with the antiscatter grid in place; the second one was acquired without antiscatter grid but with softwarebased scatter correction and reduced x-ray dose. The exams were part of an ethics committee-approved study, 25 and 74 anonymized image pairs are available. This data set is denoted as "data set 4" in Table 1.…”

Section: Same Woman Two Ffdm Acquisitionsmentioning

confidence: 99%

Volumetric breast density measurement for personalized screening: accuracy, reproducibility, consistency, and agreement with visual assessment

Fieselmann

Förnvik

et al. 2019

J. Med. Imag.

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Volumetric breast density measurement for personalized screening: accuracy, reproducibility, consistency, and agreement with visual assessment,"Abstract. Assessment of breast density at the point of mammographic examination could lead to optimized breast cancer screening pathways. The onsite breast density information may offer guidance of when to recommend supplemental imaging for women in a screening program. A software application (Insight BD, Siemens Healthcare GmbH) for fast onsite quantification of volumetric breast density is evaluated. The accuracy of the method is assessed using breast tissue equivalent phantom experiments resulting in a mean absolute error of 3.84%. Reproducibility of measurement results is analyzed using 8427 exams in total, comparing for each exam (if available) the densities determined from left and right views, from cranio-caudal and medio-lateral oblique views, from full-field digital mammograms (FFDM) and digital breast tomosynthesis (DBT) data and from two subsequent exams of the same breast. Pearson correlation coefficients of 0.937, 0.926, 0.950, and 0.995 are obtained. Consistency of the results is demonstrated by evaluating the dependency of the breast density on women's age. Furthermore, the agreement between breast density categories computed by the software with those determined visually by 32 radiologists is shown by an overall percentage agreement of 69.5% for FFDM and by 64.6% for DBT data. These results demonstrate that the software delivers accurate, reproducible, and consistent measurements that agree well with the visual assessment of breast density by radiologists. © 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.

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Full-field digital mammography with grid-less acquisition and software-based scatter correction: investigation of dose saving and image quality

Cited by 16 publications

References 17 publications

On image quality metrics and the usefulness of grids in digital mammography

On image quality metrics and the usefulness of grids in digital mammography

Asymmetric scatter kernels for software-based scatter correction of gridless mammography

Volumetric breast density measurement for personalized screening: accuracy, reproducibility, consistency, and agreement with visual assessment

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