Simulation and experimental validation of high-resolution test objects for evaluating a next-generation digital breast tomosynthesis prototype

Vent, Trevor L.; Barufaldi, Bruno; Maidment, Andrew D. A.

doi:10.1117/12.2511304

Cited by 10 publications

(15 citation statements)

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“…There are many possibly ways in which VCTs can be conducted. For example, we have conducted VCTs in which no machine observer is used; rather, we have used quantitative tools such as breast density 50 ; similarly, we have recently begun to use physics VCTs 24 in which quantitative measures such as phantom score 25 or spatial resolution 24 are evaluated. While physics VCTs were developed as a pass–fail step in moving a VCT‐designed imaging system into real clinical trials, they have proven to be useful in their own right.…”

Section: Discussionmentioning

confidence: 99%

“…Although there are many uses for VCTs, as a research group which develops imaging devices, we have primarily used VCTs to design and test novel devices and imaging algorithms. 5,[23][24][25][26] In our research, we first calibrate the VCT in terms of patient population, lesion admixture, and case difficulty to an existing study of a predicate device such that the VCT matches the existing clinical trial in terms of the study design and observed AUC. 1,5,14 We can then use this calibrated VCT dataset to evaluate a novel study device with the goal of demonstrating either equivalency or superiority to the predicate technology.…”

Section: Rationalementioning

confidence: 99%

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Computer simulations of case difficulty in digital breast tomosynthesis using virtual clinical trials

et al. 2022

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Purpose Virtual clinical trials (VCTs) require computer simulations of representative patients and images to evaluate and compare changes in performance of imaging technologies. The simulated images are usually interpreted by model observers whose performance depends upon the selection of imaging cases used in training evaluation models. This work proposes an efficient method to simulate and calibrate soft tissue lesions, which matches the detectability threshold of virtual and human readings. Methods Anthropomorphic breast phantoms were used to evaluate the simulation of four mass models (I–IV) that vary in shape and composition of soft tissue. Ellipsoidal (I) and spiculated (II–IV) masses were simulated using composite voxels with partial volumes. Digital breast tomosynthesis projections and reconstructions of a clinical system were simulated. Channelized Hotelling observers (CHOs) were evaluated using reconstructed slices of masses that varied in shape, composition, and density of surrounded tissue. The detectability threshold of each mass model was evaluated using receiver operating characteristic (ROC) curves calculated with the CHO's scores. Results The area under the curve (AUC) of each calibrated mass model were within the 95% confidence interval (mean AUC [95% CI]) reported in a previous reader study (0.93 [0.89, 0.97]). The mean AUC [95% CI] obtained were 0.94 [0.93, 0.96], 0.92 [0.90, 0.93], 0.92 [0.90, 0.94], 0.93 [0.92, 0.95] for models I to IV, respectively. The mean AUC results varied substantially as a function of shape, composition, and density of surrounded tissue. Conclusions For successful VCTs, lesions composed of soft tissue should be calibrated to simulate imaging cases that match the case difficulty predicted by human readers. Lesion composition, shape, and size are parameters that should be carefully selected to calibrate VCTs.

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Section: Discussionmentioning

confidence: 99%

Section: Rationalementioning

confidence: 99%

Computer simulations of case difficulty in digital breast tomosynthesis using virtual clinical trials

et al. 2022

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“…One of the earliest applications of VCTs was in the area of breast imaging for investigations of image quality, dosimetry, optimization, and technology evaluation. 30,213,[278][279][280][281][282][283][284][285][286][287][288][289] Recent VCTs have attempted to predict the ranking and the magnitude of improvement of breast imaging technologies as seen by human observers. 26,278,[290][291][292] In one example, VCTs were used in the Optimam project to evaluate the smallest detectable diameter of various lesions, showing that digital breast tomosynthesis (DBT) is superior to digital mammography (DM) for masses, 290 while the converse is true for calcifications.…”

Section: Breast Imagingmentioning

confidence: 99%

“…One of the earliest applications of VCTs was in the area of breast imaging for investigations of image quality, dosimetry, optimization, and technology evaluation. 30 , 213 , 278 – 289 Recent VCTs have attempted to predict the ranking and the magnitude of improvement of breast imaging technologies as seen by human observers. 26 , 278 , 290 – 292 …”

Section: Vct Applicationsmentioning

confidence: 99%

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Virtual clinical trials in medical imaging: a review

et al. 2020

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The accelerating complexity and variety of medical imaging devices and methods have outpaced the ability to evaluate and optimize their design and clinical use. This is a significant and increasing challenge for both scientific investigations and clinical applications. Evaluations would ideally be done using clinical imaging trials. These experiments, however, are often not practical due to ethical limitations, expense, time requirements, or lack of ground truth. Virtual clinical trials (VCTs) (also known as in silico imaging trials or virtual imaging trials) offer an alternative means to efficiently evaluate medical imaging technologies virtually. They do so by simulating the patients, imaging systems, and interpreters. The field of VCTs has been constantly advanced over the past decades in multiple areas. We summarize the major developments and current status of the field of VCTs in medical imaging. We review the core components of a VCT: computational phantoms, simulators of different imaging modalities, and interpretation models. We also highlight some of the applications of VCTs across various imaging modalities.

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Line‐based iterative geometric calibration method for a tomosynthesis system

Choi,

Vent,

Acciavatti

et al. 2024

Medical Physics

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BackgroundA next generation tomosynthesis (NGT) system, capable of two‐dimensional source motion, detector motion in the perpendicular direction, and magnification tomosynthesis, was constructed to investigate different acquisition geometries. Existing position‐based geometric calibration methods proved ineffective when applied to the NGT geometries.PurposeA line‐based iterative calibration method is developed to perform accurate geometric calibration for the NGT system.MethodsThe proposed method calculates the system geometry through virtual line segments created by pairs of fiducials within a calibration phantom, by minimizing the error between the line equations computed from the true and estimated fiducial projection pairs. It further attempts to correct the 3D fiducial locations based on the initial geometric calibration. The method's performance was assessed via simulation and experimental setups with four distinct NGT geometries: X, T, XZ, and TZ. The X geometry resembles a conventional DBT acquisition along the chest wall. The T geometry forms a “T”‐shaped source path in mediolateral (ML) and posteroanterior (PA) directions. A descending detector motion is added to both X and T geometries to form the XZ and TZ geometries, respectively. Simulation studies were conducted to assess the robustness of the method to geometric perturbations and inaccuracies in fiducial locations. Experimental studies were performed to assess the impact of phantom magnification and the performance of the proposed method for various geometries, compared to the traditional position‐based method. Star patterns were evaluated for both qualitative and quantitative analyses; the Fourier spectral distortions (FSDs) graphs and the contrast transfer function (CTF) were extracted. The limit of spatial resolution (LSR) was measured at 5% modulation of the CTF.ResultsThe proposed method presented is highly robust to geometric perturbation and fiducial inaccuracies. After the line‐based iterative method, the mean distance between the true and estimated fiducial projections was [X, T, XZ, TZ]: [0.01, 0.01, 0.02, 0.01] mm. The impact of phantom magnification was observed; a contact‐mode acquisition of a calibration phantom successfully provided an accurate geometry for 1.85× magnification images of a star pattern, with the X geometry. The FSD graphs for the contact‐mode T geometry acquisition presented evidence of super‐resolution, with the LSR of [0°‐quadrant: 8.57, 90°‐quadrant: 8.47] lp/mm. Finally, a contact‐mode XZ geometry acquisition and a 1.50× magnification TZ geometry acquisition were reconstructed with three calibration methods—position‐based, line‐based, and iterative line‐based. As more advanced methods are applied, the CTF becomes more isotropic, the FSD graphs demonstrate less spectral leakage as super‐resolution is achieved, and the degree of blurring artifacts reduces significantly.ConclusionsThis study introduces a robust calibration method tailored to the unique requirements of advanced tomosynthesis systems. By employing virtual line segments and iterative techniques, we ensure accurate geometric calibration while mitigating the limitations posed by the complex acquisition geometries of the NGT system. Our method's ability to handle various NGT configurations and its tolerance to fiducial misalignment make it a superior choice compared to traditional calibration techniques.

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Simulation and experimental validation of high-resolution test objects for evaluating a next-generation digital breast tomosynthesis prototype

Cited by 10 publications

References 9 publications

Computer simulations of case difficulty in digital breast tomosynthesis using virtual clinical trials

Computer simulations of case difficulty in digital breast tomosynthesis using virtual clinical trials

Virtual clinical trials in medical imaging: a review

Line‐based iterative geometric calibration method for a tomosynthesis system

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