&lt;title&gt;Storage phosphor-based digital mammography using a low-dose x-ray system optimized for screen-film mammography&lt;/title&gt;

Jennings, Robert J.; Jafroudi, Hamid; Gagné, Robert M.; Fewell, Thomas R.; Quinn, P. W.; Artz, Dorothy E. Steller; Vucich, James J.; Freedman, Matthew T.; Mun, Seong Ki

doi:10.1117/12.237785

Cited by 11 publications

(9 citation statements)

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“…For this reason, the limited number of studies employing this approach have used ''thick'' slices made by extracting NPS data near to, but not directly on, the primary axes. 20,21 As will be demonstrated below, in some digital detectors this approach can overlook structures that occur only at zero frequency in the orthogonal dimension ͑i.e., they are constant in the orthogonal spatial direction, such as a stripe or band͒.…”

Section: B One-dimensional Npsmentioning

confidence: 99%

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Noise power spectra of images from digital mammography detectors

1999

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Noise characterization through estimation of the noise power spectrum (NPS) is a central component of the evaluation of digital x-ray systems. We begin with a brief review of the fundamentals of NPS theory and measurement, derive explicit expressions for calculation of the one- and two-dimensional (1D and 2D) NPS, and discuss some of the considerations and tradeoffs when these concepts are applied to digital systems. Measurements of the NPS of two detectors for digital mammography are presented to illustrate some of the implications of the choices available. For both systems, two-dimensional noise power spectra obtained over a range of input fluence exhibit pronounced asymmetry between the orthogonal frequency dimensions. The 2D spectra of both systems also demonstrate dominant structures both on and off the primary frequency axes indicative of periodic noise components. Although the two systems share many common noise characteristics, there are significant differences, including markedly different dark-noise magnitudes, differences in NPS shape as a function of both spatial frequency and exposure, and differences in the natures of the residual fixed pattern noise following flat fielding corrections. For low x-ray exposures, quantum noise-limited operation may be possible only at low spatial frequency. Depending on the method of obtaining the 1D NPS (i.e., synthetic slit scanning or slice extraction from the 2D NPS), on-axis periodic structures can be misleadingly smoothed or missed entirely. Our measurements indicate that for these systems, 1D spectra useful for the purpose of detective quantum efficiency calculation may be obtained from thin cuts through the central portion of the calculated 2D NPS. On the other hand, low-frequency spectral values do not converge to an asymptotic value with increasing slit length when 1D spectra are generated using the scanned synthetic slit method. Aliasing can contribute significantly to the digital NPS, especially near the Nyquist frequency. Calculation of the theoretical presampling NPS and explicit inclusion of aliased noise power shows good agreement with measured values.

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Section: B One-dimensional Npsmentioning

confidence: 99%

“…Noise power spectra are sometimes presented normalized by the square of the large-area ͑average͒ output signal. 20,21 This normalization has the effect of compensating for difference in gain between two systems which are being compared, and of simplifying the expression for the DQE. With this normalization, Eq.…”

Section: Figmentioning

confidence: 99%

Noise power spectra of images from digital mammography detectors

1999

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“…16 To date, several x-ray detectors have been developed and employed for digital mammography. These digital detectors are based on computed radiography systems (CR), [17][18][19][20][21] charge-coupled devices (CCD), [20][21][22][23][24][25] or amorphous silicon flat-panel systems (FP). 20,21,[26][27][28][29] Computed radiography with storage phosphors was developed in the early 1980's and has been widely used in clinical practice.…”

Section: Introductionmentioning

confidence: 99%

Visibility of simulated microcalcifications—A hardcopy‐based comparison of three mammographic systemsa)

et al. 2004

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Full-field digital mammography systems are currently available for clinical use. These digital systems offer improved image quality, flexible image processing, display, storage, retrieval, and transmission. These systems employ a variety of different x-ray detectors based on storage phosphors (in computed radiography), charge-coupled devices (CCDs), or amorphous silicon flat panels (FPs). The objective of this study is to compare three different types of mammographic detectors: screenfilm (SF) combination, a CsI-based FP detector, a CCD and x-ray phosphor-based detector for their performance in detection of simulated microcalcifications. Microcalcifications (MCs) were simulated with calcium carbonate grains of various sizes (90-355 microm). They were overlapped with a slab of simulated 50% adipose/50% glandular breast tissue for a uniform background or an anthropomorphic breast phantom for a tissue structure background. Images of the phantoms, acquired with and without magnification, were reviewed by mammographers, physicists, and students. A five-point confidence level rating was given for each MC reviewed. Average ratings from the mammographers were used to compare the performances of the three imaging systems, various MC size groups, and two magnification modes. The results indicate that with uniform background and no magnification, the FP system performed the best while the SF system did slightly better than the CCD system. With magnification added, all detection tasks were improved except for the smallest and largest one or two size groups. In particular, detection in the SF and CCD images was significantly improved over that in the FP images. With tissue structure background and no magnification, the FP system was outperformed by the SF and the CCD systems. With magnification added, the performance of the FP and the CCD systems was improved significantly. With this improvement, the SF and FP systems were outperformed by the CCD system.

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“…Some of the CR systems of different makes and models have been characterized in terms of their image quality characteristics by previous studies. [3][4][5][6][7][8][9][10][11][12][13][14][15] However, as the methodologies for such characterizations have not been standardized, the results of these studies cannot be directly compared. Ideally, such comparisons should be undertaken using identical methodologies, an objective that has not been widely pursued in prior investigations.…”

Section: Introductionmentioning

confidence: 99%

An experimental comparison of detector performance for computed radiography systems

2002

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The intrinsic resolution, noise, and signal-to-noise transfer characteristics of five commercial digital computed radiography (CR) systems were compared using identical experimental methods. The reader/screen combinations evaluated were Agfa ADC-Compact/MD-10, Agfa ADC-Compact/MD-30, Agfa ADC-Solo/MD-10, Agfa ADC-Solo/MD-30, Lumisys CR-2000/MD-10, Fuji FCR-9501 (HQ)/ST-Va, Kodak CR-400/GP-25, and Kodak CR-400/HR. Measurements were made at 70 and 115 kVp with 19 mm added aluminum filtration. The presampled modulation transfer functions (MTFs) of the systems were measured using an edge method. The noise power spectra (NPS) were determined by 2D Fourier analysis of uniformly exposed radiographs. The frequency-dependent detective quantum efficiencies (DQEs) were computed from the MTF, NPS, exposure measurements, and computational estimates of the ideal signal-to-noise ratios. Using 70 kVp and 0.1-0.12 mm pixel sizes, spatial frequencies of 2.1, 2.0, 2.2, 1.9, 2.0, 2.0, 2.3, 2.3, and 3.5 cycles/mm were measured at 0.2 MTF for the eight reader/screen combinations, respectively. Using 70 kVp, 7.74 x 10(-8) C/kg (0.3 mR), and 0.1-0.12 mm pixel sizes, DQE(0.15) values of 20.3%, 22.9%, 24.6%, 28.6%, 22.2%, 30.0%, 29.5%, and 17.3% were obtained for the eight combinations, respectively. The corresponding values at 115 kVp were 15.9%, 18.5%, 21.5%, 21.8%, 15.3%, 23.1%, 22.3%, and 13.8%, respectively. The findings of the study demonstrate the pixel size, orientation, beam quality, screen, and reader dependencies of image quality in CR systems. The physical performance of the systems having standard-resolution screens demonstrated similar resolution performance but more notable variations in DQE. The one high-resolution screen tested had reduced DQE and increased MTF at high frequencies.

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<title>Storage phosphor-based digital mammography using a low-dose x-ray system optimized for screen-film mammography</title>

Cited by 11 publications

References 0 publications

Noise power spectra of images from digital mammography detectors

Noise power spectra of images from digital mammography detectors

Visibility of simulated microcalcifications—A hardcopy‐based comparison of three mammographic systemsa)

An experimental comparison of detector performance for computed radiography systems

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