The Effect of Amorphous Selenium Thickness on Imaging Performance of Contrast Enhanced Digital Breast Tomosynthesis

Hu, Yue‐Houng; Scaduto, David A.; Zhao, Wei

doi:10.1007/978-3-642-31271-7_2

Cited by 4 publications

(15 citation statements)

References 19 publications

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“…Figure shows a flow chart for the propagation of Φ and S through the DE imaging process according to the CLSM. The detector model was modified with the ability to generate an arbitrary x‐ray spectrum with tube potentials ranging between 23 kVp and 51 kVp and to vary the a‐Se thickness of the detector in an effort to quantify its effect on quantum detective efficiency (QDE) . A projection‐space subtraction step ( Sub ) was also implemented.…”

Section: Theorymentioning

confidence: 99%

“…For CE‐DBT, structural noise is propagated from 2D to 3D by employing the mathematical methods outlined by Gang et al and added after 2D to 3D conversion of the stochastic NPS. The analysis was generalized for a system without focal spot motion since CE‐DM functions without movement of the x‐ray tube and because for DBT acquisitions implementing filtered backprojection (FBP) reconstruction algorithms (as is the case in the present work), Fourier filters act as the dominant source of blur …”

Section: Theorymentioning

confidence: 99%

“…In addition, the thickness of the a‐Se layer of the detector ( d Se ) was increased from 200 to 300 μ m. This was done in order to match the performance of the prototype unit, which houses an experimental, 300 μ m a‐Se detector for improved DQE at HE . The thicker d Se provides higher quantum detective efficiency (QDE), particularly when the high energy spectra are used in CE imaging (both DE and TE subtraction techniques), resulting in reduced quantum noise ( S q ) …”

Section: Theorymentioning

confidence: 99%

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Optimization of contrast‐enhanced breast imaging: Analysis using a cascaded linear system model

Scaduto

Zhao

2017

Medical Physics

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Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

Section: Theorymentioning

confidence: 99%

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Optimization of contrast‐enhanced breast imaging: Analysis using a cascaded linear system model

Scaduto

Zhao

2017

Medical Physics

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“…X‐ray experiments in previous works have validated the MTF degradation due to oblique incidence. The MTF was calculated with a digital breast tomosynthesis (DBT) system using a tungsten edge . Previous works have also shown that increasing the thickness of selenium results in more substantial MTF degradation .…”

Section: Introductionmentioning

confidence: 99%

“…The MTF was calculated with a digital breast tomosynthesis (DBT) system using a tungsten edge . Previous works have also shown that increasing the thickness of selenium results in more substantial MTF degradation . This arises because the incident ray traverses a broader path length through the x‐ray converter, yielding more blurring.…”

Section: Introductionmentioning

confidence: 99%

Nonstationary model of oblique x‐ray incidence in amorphous selenium detectors: II. Transfer functions

Acciavatti

Maidment

2019

Medical Physics

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Purpose One limitation of experimental techniques for quantifying resolution and noise in detectors is that the measurement is made in a region‐of‐interest (ROI). With theoretical modeling, these properties can be measured at a point, allowing for quantification of spatial anisotropy. This paper calculates nonstationary transfer functions for amorphous selenium (a‐Se) detectors in breast imaging. We use this model to demonstrate the performance advantage of a “next‐generation” tomosynthesis (NGT) system, which is capable of x‐ray source motion with more degrees of freedom than a clinical tomosynthesis system. Methods Using Swank's formulation, the optical transfer function (OTF) and presampled noise power spectra (NPS) are determined based on the point spread function derived in Part 1. The modulation transfer function (MTF) is found from the normalized modulus of the OTF. To take into account the presence of digitization, the presampled NPS is convolved with a two‐dimensional comb function, for which the period along each direction is the reciprocal of the detector element size. The detective quantum efficiency (DQE) is then determined from combined knowledge of the OTF and NPS. Results First, the model is used to demonstrate the loss of image quality due to oblique x‐ray incidence. The MTF is calculated along various polar angles, corresponding to different orientations of the input frequency. The MTF is independent of the incidence angle if the polar angle is perpendicular to the ray incidence direction. However, along other polar angles, oblique incidence results in MTF degradation at high frequencies. The MTF degradation is most substantial along the ray incidence direction. Unlike the MTF, the normalized NPS (NNPS) is independent of the incidence angle. To measure the relative signal‐to‐noise, the DQE is also calculated. Oblique incidence yields high‐frequency DQE degradation, which is more pronounced than the MTF degradation. This arises because the DQE is proportionate with the square of the MTF. Ultimately, this model is used to evaluate how the image quality varies over the detector area. For various projection images, we calculate the variation in the incidence angle over this area. With the NGT system, the source can be positioned in such a way that this variation is minimized, and hence the DQE exhibits less anisotropy. To achieve this improvement in the image quality, the source needs to have a component of motion in the posteroanterior (PA) direction, which is perpendicular to the conventional direction of source motion in tomosynthesis. Conclusions In a‐Se detectors, the DQE at high frequencies is degraded due to oblique incidence. The DQE degradation is more pronounced than the MTF degradation. This model is used to quantify the spatial variation in DQE over the detector area. The use of PA source motion is a strategy for minimizing this variation and thus improving the image quality.

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Development of active matrix flat panel imagers incorporating thin layers of polycrystalline HgI₂for mammographic x-ray imaging

et al. 2013

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Active matrix flat-panel imagers (AMFPIs) offer many advantages and have become ubiquitous across a wide variety of medical x-ray imaging applications. However, for mammography, the imaging performance of conventional AMFPIs incorporating CsI:Tl scintillators or a-Se photoconductors is limited by their relatively modest signal-to-noise ratio (SNR), particularly at low x-ray exposures or high spatial resolution. One strategy for overcoming this limitation involves the use of a high gain photoconductor such as mercuric iodide (HgI2) which has the potential to improve the signal-to-noise ratio by virtue of its low effective work function (WEFF). In this study, the performance of direct-detection AMFPI prototypes employing relatively thin layers of polycrystalline HgI2 operated under mammographic irradiation conditions over a range of 0.5 to 16.0 mR is presented. High x-ray sensitivity (corresponding to WEFF values of ~19 eV), low dark current (<0.1 pA/mm2) and good spatial resolution, largely limited by the size of the pixel pitch, were observed. For one prototype, a detective quantum efficiency of ~70% was observed at an x-ray exposure of ~0.5 mR at 26 kVp.

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The Effect of Amorphous Selenium Thickness on Imaging Performance of Contrast Enhanced Digital Breast Tomosynthesis

Cited by 4 publications

References 19 publications

Optimization of contrast‐enhanced breast imaging: Analysis using a cascaded linear system model

Optimization of contrast‐enhanced breast imaging: Analysis using a cascaded linear system model

Nonstationary model of oblique x‐ray incidence in amorphous selenium detectors: II. Transfer functions

Development of active matrix flat panel imagers incorporating thin layers of polycrystalline HgI₂for mammographic x-ray imaging

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The Effect of Amorphous Selenium Thickness on Imaging Performance of Contrast Enhanced Digital Breast Tomosynthesis

Cited by 4 publications

References 19 publications

Optimization of contrast‐enhanced breast imaging: Analysis using a cascaded linear system model

Optimization of contrast‐enhanced breast imaging: Analysis using a cascaded linear system model

Nonstationary model of oblique x‐ray incidence in amorphous selenium detectors: II. Transfer functions

Development of active matrix flat panel imagers incorporating thin layers of polycrystalline HgI2for mammographic x-ray imaging

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Development of active matrix flat panel imagers incorporating thin layers of polycrystalline HgI₂for mammographic x-ray imaging