Optimizing breast-tomosynthesis acquisition parameters with scanning model observers

Gifford, Howard C.; Didier, Clay; Das, Mini; Glick, Stephen J.

doi:10.1117/12.771018

Cited by 17 publications

(24 citation statements)

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“…With extensive ROIs, the full set of z j values may be efficiently obtained through a functional cross correlation of f with the shift-invariant observer template w = U j U t js (16) that uses the mean shifted-lesion profile as defined by Eq. (8).…”

Section: A Scanning Cnpw Observermentioning

confidence: 99%

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Visual‐search observers for assessing tomographic x‐ray image quality

2016

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Purpose: Mathematical model observers commonly used for diagnostic image-quality assessments in x-ray imaging research are generally constrained to relatively simple detection tasks due to their need for statistical prior information. Visual-search (VS) model observers that employ morphological features in sequential search and analysis stages have less need for such information and fewer task constraints. The authors compared four VS observers against human observers and an existing scanning model observer in a pilot study that quantified how mass detection and localization in simulated digital breast tomosynthesis (DBT) can be affected by the number P of acquired projections. Methods: Digital breast phantoms with embedded spherical masses provided single-target cases for a localization receiver operating characteristic (LROC) study. DBT projection sets based on an acquisition arc of 60• were generated for values of P between 3 and 51. DBT volumes were reconstructed using filtered backprojection with a constant 3D Butterworth postfilter; extracted 2D slices were used as test images. Three imaging physicists participated as observers. A scanning channelized nonprewhitening (CNPW) observer had knowledge of the mean lesion-absent images. The VS observers computed an initial single-feature search statistic that identified candidate locations as local maxima of either a template matched-filter (MF) image or a gradient-template MF (GMF) image. Search inefficiencies that modified the statistic were also considered. Subsequent VS candidate analyses were carried out with (i) the CNPW statistical discriminant and (ii) the discriminant computed from GMF training images. These location-invariant discriminants did not utilize covariance information. All observers read 36 training images and 108 study images per P value. Performance was scored in terms of area under the LROC curve. Results: Average human-observer performance was stable for P between 7 and 35. In the absence of search inefficiencies, the VS models based on the GMF analysis provided the best correlation (Pearson ρ ≥ 0.62) with the human results. The CNPW-based VS observers deviated from the humans primarily at lower values of P. In this limited study, search inefficiencies allowed for good quantitative agreement with the humans for most of the VS observers. Conclusions: The computationally efficient training requirements for the VS observer are suitable for high-resolution imaging, indicating that the observer framework has the potential to overcome important task limitations of current model observers for x-ray applications. C 2016 American Association of Physicists in Medicine. [http://dx

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Section: A Scanning Cnpw Observermentioning

confidence: 99%

“…10 Popescu and Myers 9 evaluated test images that lacked structural inhomogeneities in the first place, tantamount to the BKE approach in Ref. 8.…”

Section: Introductionmentioning

confidence: 99%

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Visual‐search observers for assessing tomographic x‐ray image quality

2016

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“…Specifically, optimization of the x-ray source scan angle and angular sampling scheme is an area of interest in recent literature. [6][7][8][9][10][11][12][13][14][15][16][17] These studies could reduce the number of physical prototype iterations and eventually lead to task-and patient-specific optimization of tomosynthesis. But to achieve these goals, we first need accurate, task-based strategies for evaluating key DBT system parameters in simulation.…”

Section: Introductionmentioning

confidence: 99%

A virtual trial framework for quantifying the detectability of masses in breast tomosynthesis projection data

et al. 2013

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Purpose: Digital breast tomosynthesis (DBT) is a promising breast cancer screening tool that has already begun making inroads into clinical practice. However, there is ongoing debate over how to quantitatively evaluate and optimize these systems, because different definitions of image quality can lead to different optimal design strategies. Powerful and accurate tools are desired to extend our understanding of DBT system optimization and validate published design principles. Methods: The authors developed a virtual trial framework for task-specific DBT assessment that uses digital phantoms, open-source x-ray transport codes, and a projection-space, spatial-domain observer model for quantitative system evaluation. The authors considered evaluation of reconstruction algorithms as a separate problem and focused on the information content in the raw, unfiltered projection images. Specifically, the authors investigated the effects of scan angle and number of angular projections on detectability of a small (3 mm diameter) signal embedded in randomly-varying anatomical backgrounds. Detectability was measured by the area under the receiver-operating characteristic curve (AUC). Experiments were repeated for three test cases where the detectability-limiting factor was anatomical variability, quantum noise, or electronic noise. The authors also juxtaposed the virtual trial framework with other published studies to illustrate its advantages and disadvantages. Results: The large number of variables in a virtual DBT study make it difficult to directly compare different authors' results, so each result must be interpreted within the context of the specific virtual trial framework. The following results apply to 25% density phantoms with 5.15 cm compressed thickness and 500 μm 3 voxels (larger 500 μm 2 detector pixels were used to avoid voxel-edge artifacts): 1. For raw, unfiltered projection images in the anatomical-variability-limited regime, AUC appeared to remain constant or increase slightly with scan angle. 2. In the same regime, when the authors fixed the scan angle, AUC increased asymptotically with the number of projections. The threshold number of projections for asymptotic AUC performance depended on the scan angle. In the quantum-and electronic-noise dominant regimes, AUC behaviors as a function of scan angle and number of projections sometimes differed from the anatomy-limited regime. For example, with a fixed scan angle, AUC generally decreased with the number of projections in the electronic-noise dominant regime. These results are intended to demonstrate the capabilities of the virtual trial framework, not to be used as optimization rules for DBT. Conclusions:The authors have demonstrated a novel simulation framework and tools for evaluating DBT systems in an objective, task-specific manner. This framework facilitates further investigation of image quality tradeoffs in DBT.

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“…27 Various efforts are underway to compare these algorithms to one another 26,27,[39][40][41] and to determine the optimum set of acquisition parameters. 15,[42][43][44][45] There is also ongoing work to determine the best visual presentation of tomosynthesis images. Subjectively, images processed and reconstructed with deblurring algorithms can have a "high-pass filtered appearance" and may lose some of the overall grayscale range typical of conventional chest or breast imaging.…”

Section: Iva1 Reconstruction Algorithmsmentioning

confidence: 99%

Tomosynthesis imaging: At a translational crossroads

2009

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Tomosynthesis is a decades-old technique for section imaging that has seen a recent upsurge in interest due to its promise to provide three-dimensional information at lower dose and potentially lower cost than CT in certain clinical imaging situations. This renewed interest in tomosynthesis began in the late 1990s as a new generation of flat-panel detectors became available; these detectors were the one missing piece of the picture that had kept tomosynthesis from enjoying significant utilization earlier. In the past decade, tomosynthesis imaging has been investigated in a variety of clinical imaging situations, but the two most prominent have been in breast and chest imaging. Tomosynthesis has the potential to substantially change the way in which breast cancer and pulmonary nodules are detected and managed. Commercial tomosynthesis devices are now available or on the horizon. Many of the remaining research activities with tomosynthesis will be translational in nature and will involve physicist and clinician alike. This overview article provides a forwardlooking assessment of the translational questions facing tomosynthesis imaging and anticipates some of the likely research and clinical activities in the next five years. © 2009 American Association of Physicists in Medicine. ͓DOI: 10.1118/1.3120285͔ Key words: tomosynthesis, breast imaging, chest imaging, tomography I. OVERVIEWDigital tomosynthesis is a simple and relatively inexpensive method of producing section images using conventional digital x-ray equipment. It is a form of limited angle tomography that produces section, or "slice," images from a series of projection images acquired as the x-ray tube moves over a prescribed path. The total angular range of movement is often less than 40°. Because the projection images are not acquired over a full 360°rotation about the patient, the resolution in the z direction ͑i.e., in the depth direction perpendicular to the x-y plane of the projection images͒ is limited, and thus tomosynthesis does not produce the isotropic spatial resolution achievable with computed tomography ͑CT͒. However, the resolution of images in the x-y plane of the reconstructed slices is often superior to CT, and the ease of use in conjunction with conventional radiography makes tomosynthesis a potentially quite useful imaging modality.There has been a high degree of research interest in tomosynthesis imaging in the past decade, and at least two commercial products have recently been approved by the Food and Drug Administration ͑FDA͒ and released on the market. It is expected that other approved devices will soon follow. As such, tomosynthesis imaging is in a period of a high rate of change, with an increasing number of investigators and manufacturers nearing completion of projects involving both the physics and clinical aspects of the technique. If one were to compare the current state of tomosynthesis imaging to a metaphorical calendar year, the field is firmly in the middle of spring. It has moved beyond the "winter" of initial research ...

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Optimizing breast-tomosynthesis acquisition parameters with scanning model observers

Cited by 17 publications

References 0 publications

Visual‐search observers for assessing tomographic x‐ray image quality

Visual‐search observers for assessing tomographic x‐ray image quality

A virtual trial framework for quantifying the detectability of masses in breast tomosynthesis projection data

Tomosynthesis imaging: At a translational crossroads

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