Detective quantum efficiency of imaging systems with amplifying and scattering mechanisms

Rabbani, Majid; Shaw, Rodney; Metter, Richard Van

doi:10.1364/josaa.4.000895

Cited by 191 publications

(207 citation statements)

References 8 publications

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“…Each stage consists of several interaction substages, where the quanta undergo one of three processes: 48 Amplification, blurring, or addition of noise. A brief summary of the parallel cascade model analysis is presented below.…”

Section: Iia Theoretical Development Of the Noise-response Methodsmentioning

confidence: 99%

Accurate MTF measurement in digital radiography using noise response

et al. 2010

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Purpose:The authors describe a new technique to determine the system presampled modulation transfer function ͑MTF͒ in digital radiography using only the detector noise response. Methods: A cascaded-linear systems analysis was used to develop an exact relationship between the two-dimensional noise power spectrum ͑NPS͒ and the presampled MTF for a generalized detector system. This relationship was then utilized to determine the two-dimensional presampled MTF. For simplicity, aliasing of the correlated noise component of the NPS was assumed to be negligible. Accuracy of this method was investigated using simulated images from a simple detector model in which the "true" MTF was known exactly. Measurements were also performed on three detector technologies ͑an x-ray image intensifier, an indirect flat panel detector, and a solid state x-ray image intensifier͒, and the results were compared using the standard edge-response method. Flat-field and edge images were acquired and analyzed according to guidelines set forth by the International Electrotechnical Commission, using the RQA 5 spectrum. Results: The presampled MTF determined using the noise-response method for the simulated detector system was in close agreement with the true MTF with an averaged percent difference of 0.3% and a maximum difference of 1.1% observed at the Nyquist frequency ͑f N ͒. The edgeresponse method of the simulated detector system also showed very good agreement at lower spatial frequencies ͑less than 0.5 f N ͒ with an averaged percent difference of 1.6% but showed significant discrepancies at higher spatial frequencies ͑greater than 0.5 f N ͒ with an averaged percent difference of 17%. Discrepancies were in part a result of noise in the edge image and phasing errors. For all three detector systems, the MTFs obtained using the two methods were found to be in good agreement at spatial frequencies less than 0.5 f N with an averaged percent difference of 3.4%. Above 0.5 f N , differences increased to an average of 20%. Deviations of the experimental results largely followed the trend seen in the simulation results, suggesting that differences between the two methods could be explained as resulting from the inherent inaccuracies of the edgeresponse measurement technique used in this study. Aliasing of the correlated noise component was shown to have a minimal effect on the measured MTF for the three detectors studied. Systems with significant aliasing of the correlated noise component ͑e.g., a-Se based detectors͒ would likely require a more sophisticated fitting scheme to provide accurate results. Conclusions: Results indicate that the noise-response method, a simple technique, can be used to accurately measure the MTF of digital x-ray detectors, while alleviating the problems and inaccuracies associated with use of precision test objects, such as a slit or an edge.

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Section: Iia Theoretical Development Of the Noise-response Methodsmentioning

confidence: 99%

Accurate MTF measurement in digital radiography using noise response

et al. 2010

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“…The basic aspects of cascaded linear systems analysis have been discussed in detail in previous work [24][25][26] as has its application in a variety of 2D imaging applications. [2][3][4][5][6][7][8][9][10][11][12] The basic concepts and derivation of the 2D projection NPS are briefly summarized below.…”

Section: Iia Background: Cascaded Linear Systems Analysismentioning

confidence: 99%

Cascaded systems analysis of the 3D noise transfer characteristics of flat‐panel cone‐beam CT

2008

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The physical factors that govern 2D and 3D imaging performance may be understood from quantitative analysis of the spatial-frequency-dependent signal and noise transfer characteristics ͓e.g., modulation transfer function ͑MTF͒, noise-power spectrum ͑NPS͒, detective quantum efficiency ͑DQE͒, and noise-equivalent quanta ͑NEQ͔͒ along with a task-based assessment of performance ͑e.g., detectability index͒. This paper advances a theoretical framework based on cascaded systems analysis for calculation of such metrics in cone-beam CT ͑CBCT͒. The model considers the 2D projection NPS propagated through a series of reconstruction stages to yield the 3D NPS and allows quantitative investigation of tradeoffs in image quality associated with acquisition and reconstruction techniques. While the mathematical process of 3D image reconstruction is deterministic, it is shown that the process is irreversible, the associated reconstruction parameters significantly affect the 3D DQE and NEQ, and system optimization should consider the full 3D imaging chain. Factors considered in the cascade include: system geometry; number of projection views; logarithmic scaling; ramp, apodization, and interpolation filters; 3D back-projection; and 3D sampling ͑noise aliasing͒. The model is validated in comparison to experiment across a broad range of dose, reconstruction filters, and voxel sizes, and the effects of 3D noise correlation on detectability are explored. The work presents a model for the 3D NPS, DQE, and NEQ of CBCT that reduces to conventional descriptions of axial CT as a special case and provides a fairly general framework that can be applied to the design and optimization of CBCT systems for various applications.

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“…Cascaded system analysis [46][47][48] has been widely used in a variety of 2D (Refs. [49][50][51][52][53][54][55][56] and 3D (Refs.…”

Section: Iiia Cascaded System Model For Dpc-ct and Act Acquisitionsmentioning

confidence: 99%

Fundamental relationship between the noise properties of grating-based differential phase contrast CT and absorption CT: Theoretical framework using a cascaded system model and experimental validation

Bevins

Zambelli

et al. 2013

Med. Phys.

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Purpose: Using a grating interferometer, a conventional x-ray cone beam computed tomography (CT) data acquisition system can be used to simultaneously generate both conventional absorption CT (ACT) and differential phase contrast CT (DPC-CT) images from a single data acquisition. Since the two CT images were extracted from the same set of x-ray projections, it is expected that intrinsic relationships exist between the noise properties of the two contrast mechanisms. The purpose of this paper is to investigate these relationships. Methods: First, a theoretical framework was developed using a cascaded system model analysis to investigate the relationship between the noise power spectra (NPS) of DPC-CT and ACT. Based on the derived analytical expressions of the NPS, the relationship between the spatial-frequencydependent noise equivalent quanta (NEQ) of DPC-CT and ACT was derived. From these fundamental relationships, the NPS and NEQ of the DPC-CT system can be derived from the corresponding ACT system or vice versa. To validate these theoretical relationships, a benchtop cone beam DPC-CT/ACT system was used to experimentally measure the modulation transfer function (MTF) and NPS of both DPC-CT and ACT. The measured three-dimensional (3D) MTF and NPS were then combined to generate the corresponding 3D NEQ. Results: Two fundamental relationships have been theoretically derived and experimentally validated for the NPS and NEQ of DPC-CT and ACT: (1) the 3D NPS of DPC-CT is quantitatively related to the corresponding 3D NPS of ACT by an inplane-only spatial-frequency-dependent factor 1/f 2 , the ratio of window functions applied to DPC-CT and ACT, and a numerical factor C g determined by the geometry and efficiency of the grating interferometer. Note that the frequency-dependent factor is independent of the frequency component f z perpendicular to the axial plane. (2) The 3D NEQ of DPC-CT is related to the corresponding 3D NEQ of ACT by an f 2 scaling factor and numerical factors that depend on both the attenuation and refraction properties of the image object, as well as C g and the MTF of the grating interferometer. Conclusions: The performance of a DPC-CT system is intrinsically related to the corresponding ACT system. As long as the NPS and NEQ of an ACT system is known, the corresponding NPS and NEQ of the DPC-CT system can be readily estimated using additional characteristics of the grating interferometer.

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Detective quantum efficiency of imaging systems with amplifying and scattering mechanisms

Cited by 191 publications

References 8 publications

Accurate MTF measurement in digital radiography using noise response

Accurate MTF measurement in digital radiography using noise response

Cascaded systems analysis of the 3D noise transfer characteristics of flat‐panel cone‐beam CT

Fundamental relationship between the noise properties of grating-based differential phase contrast CT and absorption CT: Theoretical framework using a cascaded system model and experimental validation

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