Technical and clinical results of an experimental flat dynamic (digital) x-ray image detector (FDXD) system with real-time corrections

Bruijns, Tom J. C.; Alving, P. L.; Baker, Edmund L.; Bury, R.F.; Cowen, Arnold R.; Jung, Norbert; Luijendijk, Hans A.; Meulenbrugge, Henk J.; Stouten, Hans

doi:10.1117/12.317038

Cited by 22 publications

(20 citation statements)

References 5 publications

(1 reference statement)

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“…To calculate K(s) for each pixel, we assume VB to be a constant, and fit Vj(s) to a curve within the calibration ADU range (2700 s then extend the curve for s < 2700 and s >4700 to cover the 14-bit ADU range as shown in Figure 2 (2-16) For each pixel not in bad pixel map, we estimate the signal value by s=N(r) and calculate R(r) according to (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13), then R(r) will be checked against a given gain variation limit and the threshold for maximum allowable gain variation. As shown in Figure 2-2, there are three threshold-ranges: hi ( 1-E, i+E), h2 ( < 1-E-t4) and h3 ( > 1++t5 ) , where t4 and t5 are two gaps between these three threshold-ranges.…”

Section: Bad Pixel Mapmentioning

confidence: 99%

“…Gm_1(r)=N(r)/S(r) (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12) Where N(r) is the bias field value of S(r), which was approximated by a B-spline surface using least square fitting method to smooth the high frequency random noise sources in S(r). Gm_I is able to reduce the influence of incident xray distribution, however, it is accurate only within a narrow exposure range near the calibration exposure level.…”

Section: Gain Calibrationmentioning

confidence: 99%

“…During the past few years new ideas have been proposed and examined for applying this new technology. While most reported works concern digital radiography and digital fluoroscopy [5][6][7][8][9][10][11][12], however, one paper was presented by our research group [13], describing an STFT array-based VTA imaging system.…”

Section: Introductionmentioning

confidence: 95%

See 2 more Smart Citations

<title>Accurate and efficient calibration method for a selenium flat-panel-detector-based volume tomographic angiography imaging system</title>

Zhang

Ning

Chen

et al. 1999

Medical Imaging 1999: Physics of Medical Imaging

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The flat panel detector (FPD) has become a highly promising candidate for a wide variety of applications. A prototype selenium thin film transistor (STFT) array-based volume tomographic angiography (VTA) imaging system has been constructed for the feasibility study. This experimental set-up uses a 14" x 17" STFT detector with a 2560 x 3072 array of 14 bit pixels. While an STFT detector offers high resolution digital images, there will always be some defects on the detector. These defects will result in severe streaks and ring artifacts, which have been found in reconstructed images of preliminary phantom studies. It is obvious that the stationary noise sources of the FPD are enhanced by the reconstruction procedure. In this paper, an accurate and efficient FPD calibration method for the VTA imaging system is proposed to reduce the artifacts. An improved gain map and a bad pixel detection method with an adaptive threshold are introduced based on statistical models of the FPD. A more efficient localized and sensitive bad pixel detection ability is obtained by sub-dividing the detector array into sub-arrays, classifying bad pixels as different regional patterns, and then optimizing an interpolation scheme for each pattern. The real-time background correction, gain correction, bad-pixel correction, and methods to generate calibration maps are described in detail. The calibration technique is examined through phantom studies and evaluated by comparing the artifacts and noise in reconstructed images. Improvement of image quality is obtained utilizing the calibration technique. It has been clearly verified that the streaks and ring artifacts in reconstructed VTA images are significantly reduced. Finally, the advantages of our method and future works are also discussed.

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Section: Bad Pixel Mapmentioning

confidence: 99%

Section: Gain Calibrationmentioning

confidence: 99%

See 1 more Smart Citation

<title>Accurate and efficient calibration method for a selenium flat-panel-detector-based volume tomographic angiography imaging system</title>

Zhang

Ning

Chen

et al. 1999

Medical Imaging 1999: Physics of Medical Imaging

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“…5 The idea is that immediately after a radiograph is taken one captures a single image without illumination, which will contain the lag information for each pixel. This frame should be taken two or three frames after the initial exposure so that complete TFT charge transfer can be assumed.…”

Section: Array Transient Behaviormentioning

confidence: 99%

<title>High-performance amorphous silicon image sensor for x-ray diagnostic medical imaging applications</title>

Weisfield

Hartney

Schneider

et al. 1999

Medical Imaging 1999: Physics of Medical Imaging

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Following our previous report' concerning the development ofa 127 im resolution, 7.4 million pixel, 30 x 40 cm2 active area, flat panel amorphous Silicon (a-Si) x-ray image sensor, this paper describes enhancements in image sensor performance in the areas of image lag, linearity, sensitivity, and electronic noise. New process improvements in fabricating a-Si thin film transistor (TFT)/photodiode arrays have reduced first-frame image lag to less than 2%, and uniformity in photoresponse to < 5% over the entire 30 x 40 cm2 active area. Detailed analysis of image lag vs. time and x-ray dose will be discussed. An improved charge amplifier has been introduced to suppress image cross-talk artifacts caused by charge amplifier saturation, and system linearity has been optimized to eliminate banding effects among charge amplifiers. Preliminary sensitivity improvements through the deposition of CsI(Tl) directly on the arrays are reported, as well as overall imaging characteristics of this improved image sensor.

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“…This widely perceived need has, in turn, stimulated considerable innovation resulting in a remarkable variety of [3] 450 256x240 61440 11.5x10.8 124 [4] 450 512x560 286720 23.0x25.2 580 [5] 450 512x560 286720 23.0x25.2(x4) 2318 [6] 270 64x40 2560 1.7x1.1 1.9 [2] 200 192x192 36864 3.8x3. 8 14.4 [7] 200 1024x1024 1048576 20x20 400 [8] 127 1536x1920 2929920 19.5x24.4 476 [9] 127 1536x1920 2929920 19.5x24.4 476 [10] 127 1536x1920 2929920 19 [13] 100 notavailable n.a. n.a.…”

Section: Introductionmentioning

confidence: 97%

Large-area 97-μm pitch indirect-detection active-matrix flat-panel imager (AMFPI)

et al. 1998

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The development of the highest resolution, large-area, active-matrix, flat-panel imager (AMFPI) thus far reported is described. This imager is based on a 97 jtm pixel pitch array with each pixel comprising a single a-Si:H TFT coupled to a discrete a-Si:H n-i-p photodiode. While the initial configuration chosen for fabrication is a 2048x2048 pixel array, a larger monolithic array format of 3072x4096 pixels is also permitted by the design. When coupled to an overlying scintillator such as a phosphor screen or CsI:Tl, the array allows indirect detection of incident radiation. The array is operated in conjunction with a recently completed electronic acquisition system featuring asynchronous operation, a large addressing range, fast analog signal extraction and digitization, and 16-bit digitization. This imager, whose empirical characterization will be reported in a subsequent paper, was developed as an engineering prototype to allow investigation of the performance limits of the most aggressive array designs permitted by present active-matrix technology. The development of this new imager builds upon knowledge acquired from the iterative design, fabrication, and quantitative evaluation of earlier engineering prototypes based on a series of 127 im pitch arrays. This paper summarizes the general program of research leading to this new device and puts this in the context of world-wide developments in indirect and direct detection AMFPI technology. Some limitations of present AMFPI technology are described, and possible solutions are discussed.Specifically, the incorporation of multiplexers based on poly-crystalline silicon circuitry into the array design, to facilitate very high resolution imagers, are proposed. In addition, strategies to significantly improve AMFPI performance at very low exposures, such as those commonly encountered in fluoroscopy, involving the reduction of additive noise (such as through lower preamplifier noise) and the enhancement of system gain (such as through the use of lead iodide) are discussed and initial calculations illustrating potential levels ofperformance are presented.

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Technical and clinical results of an experimental flat dynamic (digital) x-ray image detector (FDXD) system with real-time corrections

Cited by 22 publications

References 5 publications

<title>Accurate and efficient calibration method for a selenium flat-panel-detector-based volume tomographic angiography imaging system</title>

<title>Accurate and efficient calibration method for a selenium flat-panel-detector-based volume tomographic angiography imaging system</title>

<title>High-performance amorphous silicon image sensor for x-ray diagnostic medical imaging applications</title>

Large-area 97-μm pitch indirect-detection active-matrix flat-panel imager (AMFPI)

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