The effect of amorphous selenium detector thickness on dual‐energy digital breast imaging

Hu, Yue‐Houng; Zhao, Wei

doi:10.1118/1.4897244

Cited by 16 publications

(25 citation statements)

References 37 publications

(45 reference statements)

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“…We show that the MTF is degraded by oblique incidence. This result is consistent with previous works on both direct‐ and indirect‐converting detectors . The MTF degradation is most pronounced along the ray incidence direction.…”

Section: Discussionsupporting

confidence: 92%

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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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Section: Discussionsupporting

confidence: 92%

“…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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“…As a future work, the developed 3D cascaded system analysis described above can be integrated with detectability index calculation by introducing various task functions (Gang et al 2011, Tward and Siewerdsen 2008, Hu and Zhao 2014, Siewerdsen and Jaffray 2000, Gang et al 2012, Richard et al 2005 to evaluate the detectability of objects of interest, such as small microcalcifications and low contrast masses.…”

Section: Page 21 Of 27mentioning

confidence: 99%

“…Previously, 3D cascaded system analysis models have been developed and validated for both cone-beam computed tomography (CT) and DBT (Tward and Siewerdsen 2008, Zhao and Zhao 2008b, Zhao et al 2009, Hu and Zhao 2014, Siewerdsen and Jaffray 2003, Gang et al 2011. We have already reported a 2D cascaded system analysis model for a 50 μm pixel pitch CMOS APS detector named DynAMITe (Zhao et al 2015b).…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

et al. 2017

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Abstract. High-resolution, low-noise x-ray detectors based on the complementary metal-oxide-semiconductor (CMOS) active pixel sensor (APS) technology have been developed and proposed for digital breast tomosynthesis (DBT). In this study, we evaluated the three-dimensional (3D) imaging performance of a 50 μm pixel pitch CMOS APS x-ray detector named DynAMITe (Dynamic Range Adjustable for Medical Imaging Technology). The two-dimensional (2D) angle-dependent modulation transfer function (MTF), normalized noise power spectrum (NNPS), and detective quantum efficiency (DQE) were experimentally characterized and modeled using the cascaded system analysis at oblique incident angles up to 30°. The cascaded system model was extended to the 3D spatial frequency space in combination with the filtered back-projection (FBP) reconstruction method to calculate the 3D and in-plane MTF, NNPS and DQE parameters. The results demonstrate that the beam obliquity blurs the 2D MTF and DQE in the high spatial frequency range. However, this effect can be eliminated after FBP image reconstruction. In addition, impacts of the image acquisition geometry and detector parameters were evaluated using the 3D cascaded system analysis for DBT. The result shows that a wider projection angle range (e.g. ±30°) improves the low spatial frequency (below 5 mm -1 ) performance of the CMOS APS detector. In addition, to maintain a high spatial resolution for DBT, a focal spot size of smaller than 0.3 mm should be used.Theoretical analysis suggests that a pixelated scintillator in combination with the 50 μm pixel pitch CMOS APS detector could further improve the 3D image resolution. Finally, the 3D imaging performance of the CMOS APS and an indirect amorphous silicon (a-Si:H) thin-film A c c e p t e d M a n u s c r i p t transistor (TFT) passive pixel sensor (PPS) detector was simulated and compared.Keywords: CMOS active pixel sensor, x-ray detector, digital breast tomosynthesis, three-dimensional, cascaded system analysis, pixelated scintillator, detective quantum efficiency IntroductionHigh performance x-ray detectors based on the complementary metal-oxide-semiconductor ( Up to now, most studies focus on CMOS APS detector evaluation by measuring the one-dimensional (1D) or 2D modulation transfer function (MTF), noise power spectrum (NPS) and detective quantum efficiency (DQE) using a single x-ray projection at the zero-degree incident angle (perpendicular to the detector). Nevertheless, since DBT is a quasi-three-dimensional (3D) imaging technology, the DBT image quality is influenced by the system geometry and reconstruction algorithms (Sechopoulos 2013a(Sechopoulos , 2013b. Therefore, the 3D imaging performance should be evaluated for the CMOS APS detectors. However, it is difficult to empirically investigate the 3D image quality. To deal with this issue, the 3D cascaded system analysis for CMOS APS detectors was developed and is presented in this study.Cascaded system analysis can accurately model the signal and noise propagation and blurring within ...

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“…In recent years, technological advances on x-ray flatpanel detectors (FPD) enabling large-area digital imaging that have made it become a major of applications in diagnostic imaging (e.g., radiography, mammography) [1,2], interventional procedures (e.g., angiography, image-guided surgery) [3,4], and non-medical imaging (e.g., security screening, non-destructive testing) [5]. Digital detectors in the imaging system, include x-ray image intensifiers, photostimulable phosphors and scintillator-photodiode arrays responds to energy in x-ray photons.…”

Section: Introductionmentioning

confidence: 99%

Compound Poisson noise verification for X-ray flat panel imager

Hsieh

Tseng

et al. 2015

2015 IEEE International Conference on Imaging Systems and Techniques (IST)

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Physical effects that contribute to the noise in digital radiography are possible to be represented as overall variance including Poisson statistics of x-rays. For real system, statement of the noise response must be integrated against a spectrum to get the total response to spectral fluence of x-ray, that the detected x-ray follows a compound-Poisson distribution. To verify the noise property of our x-ray flat-panel detector (FPD), we formulate a compound-Poisson based model to verify the image noise statistic from measured data.Results demonstrate that the FPD noise property is independed from the tube voltage; only 1.6% error is occurred by the model fitting. In this case, the noise property of our FPD can accurately be represented as the modeled function.

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The effect of amorphous selenium detector thickness on dual‐energy digital breast imaging

Cited by 16 publications

References 37 publications

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

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

Three-dimensional cascaded system analysis of a 50µm pixel pitch wafer-scale CMOS active pixel sensor x-ray detector for digital breast tomosynthesis

Compound Poisson noise verification for X-ray flat panel imager

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