Exploring advanced 2D acquisitions in breast tomosynthesis: T-shaped and Pentagon geometries.

In this study, we investigate the performance of advanced 2D acquisition geometries - Pentagon and T-shaped - in digital breast tomosynthesis (DBT) and compare them against the conventional 1D geometry. Unlike the conventional approach, our proposed 2D geometries also incorporate anterior projections away from the chest wall. Implemented on the Next-Generation Tomosynthesis (NGT) prototype developed by X-ray Physics Lab (XPL), UPenn, we utilized various phantoms to compare three geometries: a Defrise slab phantom with alternating plastic slabs to study low-frequency modulation; a Checkerboard breast phantom (a 2D adaptation of the Defrise phantom design) to study the ability to reconstruct the fine features of the checkerboard squares; and the 360° Star-pattern phantom to assess aliasing and compute the Fourier-spectral distortion (FSD) metric that assesses spectral leakage and the contrast transfer function.

Line-based iterative geometric calibration method for a tomosynthesis system.

Background: A 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.

Purpose: A line-based iterative calibration method is developed to perform accurate geometric calibration for the NGT system.

Non-Isocentric Geometry for Next-Generation Tomosynthesis With Super-Resolution.

Our lab at the University of Pennsylvania (UPenn) is investigating novel designs for digital breast tomosynthesis. We built a next-generation tomosynthesis system with a non-isocentric geometry (superior-to-inferior detector motion). This paper examines four metrics of image quality affected by this design.

Spatial dependency of multiplanar reconstruction in digital breast tomosynthesis.

Tomosynthesis acquires projections over a limited angular range, resulting in anisotropic sampling in the Fourier domain. The volume of the sampled space is therefore spatially dependent; different Fourier components are sampled for the same object, depending upon where the object is located relative to the system origin. A next-generation tomosynthesis (NGT) system was developed at the University of Pennsylvania to increase the spatial isotropy in DBT, by incorporating additional system motions.

Spatial dependency of lesion detectability in digital breast tomosynthesis.

X-ray imaging results in inhomogeneous irradiation of the detector and distortion of structures in the periphery of the image; yet the spatial dependency of tomosynthesis image-quality metrics has not been extensively investigated. In this study, we use virtual clinical trials to quantify the spatial dependency of lesion detectability in our lab's next-generation tomosynthesis (NGT) system. Two geometries were analyzed: a conventional geometry with mediolateral source motion, and a NGT geometry with T-shaped motion.

Achieving Isotropic Super-Resolution with a Non-Isocentric Acquisition Geometry in a Next-Generation Tomosynthesis System.

We have constructed a prototype next-generation tomosynthesis (NGT) system that supports a non-isocentric acquisition geometry for digital breast tomosynthesis (DBT). In this geometry, the detector gradually descends in the superior-to-inferior direction. The aim of this work is to demonstrate that this geometry offers isotropic super-resolution (SR), unlike clinical DBT systems which are characterized by anisotropies in SR.

Signal-to-Noise Ratio and Contrast-to-Noise Ratio Measurements for Next Generation Tomosynthesis.

It is standard for the x-ray source in conventional digital breast tomosynthesis (DBT) acquisitions to move strictly along the chest wall of the patient. A prototype, next-generation tomosynthesis (NGT) system has been developed that is capable of acquiring customized geometries with source motion parallel and perpendicular to the chest wall. One well-known consequence of acquiring projections with the x-ray source anterior to the chest wall is that a small volume of tissue adjacent to the chest wall is missed.

Analysis of Digital Breast Tomosynthesis Acquisition Geometries in Sampling Fourier space.

Tomosynthesis acquires projections over a limited angular range and thus samples an incomplete projection set of the object. For a given acquisition geometry, the extent of tomosynthesis sampling can be measured in the frequency domain based on the Fourier Slice Theorem (FST). In this paper we propose a term, "sampling comprehensiveness", to describe how comprehensively an acquisition geometry samples the Fourier domain, and we propose two measurements to assess the sampling comprehensiveness: the volume of the null space and the nearest sampled plane.

Development of Magnification Tomosynthesis for Superior Resolution in Diagnostic Mammography.

Our previous work showed that digital breast tomosynthesis (DBT) supports super-resolution (SR). Clinical systems are not yet designed to optimize SR; this can be demonstrated with a high-frequency line-resolution pattern. SR is achieved if frequencies are oriented laterally, but not if frequencies are oriented in the perpendicular direction; .