Resolution Properties Of A Computed Radiographic System

Fujita, Hiroshi; Morishita, Junji; Ueda, Katsuhiko; Tsai, Du-Yih; Ohtsuka, Akiyoshi; Fujikawa, Toru

doi:10.1117/12.953211

Cited by 22 publications

(8 citation statements)

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“…8,29 Previous investigators have slightly angulated their slit test devices with respect to the pixel array in order to deduce the non-aliased, socalled presampled, 8 response from various phase shifts of the slit opening with respect to the image array. 10,12,14,[30][31][32][33] In order to determine the perpendicular distance from each pixel to the test device, the exact angle and position of the test device must be known. In many previous studies, either the angulation of the test device has been ignored or the method used to determine this angle has not been fully disclosed.…”

Section: Introductionmentioning

confidence: 99%

A method for measuring the presampled MTF of digital radiographic systems using an edge test device

1998

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The modulation transfer function (MTF) of radiographic systems is frequently evaluated by measuring the system's line spread function (LSF) using narrow slits. The slit method requires precise fabrication and alignment of a slit and high radiation exposure. An alternative method for determining the MTF uses a sharp, attenuating edge device. We have constructed an edge device from a 250-microm-thick lead foil laminated between two thin slabs of acrylic. The device is placed near the detector and aligned with the aid of a laser beam and a holder such that a polished edge is parallel to the x-ray beam. A digital image of the edge is processed to obtain the presampled MTF. The image processing includes automated determination of the edge angle, reprojection, sub-binning, smoothing of the edge spread function (ESF), and spectral estimation. This edge method has been compared to the slit method using measurements on standard and high-resolution imaging plates of a digital storage phosphor (DSP) radiography system. The experimental results for both methods agree with a mean MTF difference of 0.008. The edge method provides a convenient measurement of the presampled MTF for digital radiographic systems with good response at low frequencies.

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Section: Introductionmentioning

confidence: 99%

A method for measuring the presampled MTF of digital radiographic systems using an edge test device

1998

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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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“…A number of improvements in DSP screens and instrumentation for reading screens have been introduced since earlier reports of DSP image quality were published. [1][2][3][4][5] We report in this paper the measured image quality of a DSP instrument with features for scanning 35 by 43 cm phosphor screens with 100 m pixels ͑3520ϫ4280 array size͒ rather than with standard 200 m pixels ͑1760ϫ2140 array size͒. This work was largely motivated by a desire to understand the relative performance of 2k and 4k DSP systems for chest radiography.…”

Section: Introductionmentioning

confidence: 99%

Experimental comparison of noise and resolution for 2k and 4k storage phosphor radiography systems

1999

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The purpose of this study was to compare the image quality for a digital storage phosphor system using 1760 x 2140 (2k) and 3520 x 4280 (4k) image arrays. Measurements were made on a chest radiography system (Fuji FCR-9501) with special provisions to be operated in both 2k (standard) and 4k (HQ) modes. Presampled modulation transfer functions (MTF) were measured using an edge method. Noise power spectra (NPS) were determined for different input exposures by two-dimensional Fourier analysis. These measures along with exposure measurements and an x-ray spectral model were used to determine the frequency-dependent detective quantum efficiency DQE (f) of the system for the 4k and the 2k modes. The magnitude of the NPS for the 4k mode was about 1/2 that of the 2k mode. A MTF value of 0.5 was found at 1.25 cycles/mm for the 4k system and 1.50 cycles/mm for the 2k system. The 4k images had an extended MTF of 0.1 at 4.5 cycles/mm in the plate-scan direction. Overall, the DQE (f) of the 4k mode was slightly better than that for the 2k mode by about 0.02 due primarily to its better noise characteristics.

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Resolution Properties Of A Computed Radiographic System

Cited by 22 publications

References 0 publications

A method for measuring the presampled MTF of digital radiographic systems using an edge test device

A method for measuring the presampled MTF of digital radiographic systems using an edge test device

An experimental comparison of detector performance for computed radiography systems

Experimental comparison of noise and resolution for 2k and 4k storage phosphor radiography systems

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