Frequency-dependent DQE in dual-screen CR imaging

Shaw, Chris C.; Liu, Xingming; Chardon, Sophie; Herron, John M.

doi:10.1117/12.317074

Cited by 4 publications

(9 citation statements)

References 1 publication

(1 reference statement)

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“…10-12. As has been demonstrated in other works, 14,16 the dual-side read capability of System A contributes a great deal to the improved noise characteristics. Significant improvements in the noise characteristics of System A compared to System B were especially apparent in the low-frequency NPS components.…”

Section: Discussionmentioning

confidence: 56%

“…The general principles involved with adding two spatially correlated images together to produce an image with improved image quality have been published. [15][16][17] The 5000MA can accept one storage phosphor plate for readout at a time. After the cassette is placed in the reader, the stored energy image is read out and then any latent image is erased with high-intensity light.…”

Section: A Imaging Equipmentmentioning

confidence: 99%

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Performance evaluation of a “dual‐side read” dedicated mammography computed radiography system

Fetterly

Schueler

2003

Medical Physics

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The image quality of a dedicated mammography computed radiography (CR) system was characterized. A unique feature of this system is that it collects image signals from both sides of the storage phosphor. Measurements of the modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) were made. This work included improvements in our measurement methods to specifically account for the detrimental effects of system glare on the MTF and to accurately characterize the low-frequency NPS components. Image quality measurements were performed using a 25 kVp beam filtered with 2 mm Al and an exposure range of 1 to 100 mR (87 to 870 microGy). The DQE was found to decrease with increasing exposure due to an increased contribution of storage phosphor structure noise. The DQE of this system was compared to similar measurements made using a standard CR system. The dual-side read system demonstrated superior DQE compared to the standard system. The decrease in DQE with increasing exposure was more severe for the standard system than the dual-side read system. This finding suggests that the CR system noise was reduced for the dual-side read system compared to the standard system.

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Section: Discussionmentioning

confidence: 56%

Section: A Imaging Equipmentmentioning

confidence: 99%

Performance evaluation of a “dual‐side read” dedicated mammography computed radiography system

Fetterly

Schueler

2003

Medical Physics

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“…Objective measures such as the modulation transfer function ͑MTF͒, noise power spectrum ͑NPS͒ and the detective quantum efficiency ͑DQE͒ have been used to characterize the performance of imaging systems. Such objective measures detailing the performance of imaging systems developed for mammography [1][2][3][4] and radiography [5][6][7][8][9][10][11][12] have been reported. Similar measures of image quality for fluoroscopic imaging systems based on image intensifiers, [13][14][15][16][17] amorphous silicon, 18 -22 amorphous selenium, 7,[23][24][25][26] and CCDs coupled to scintillator using fiberoptic tapers 27,28 have also been reported.…”

Section: Introductionmentioning

confidence: 99%

Solid‐state fluoroscopic imager for high‐resolution angiography: Physical characteristics of an 8 cm×8 cm experimental prototype

et al. 2004

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In this paper, the performance of an 8 cm x 8 cm three-side buttable charge-coupled device (CCD)-based imager specially designed for high-resolution fluoroscopy and operating in fluoroscopic (30 frames/second) mode is presented in terms of the presampling modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE). The 8 cm x 8 cm CCD imager is coupled to a 450 microm thick CsI:Tl scintillator by nondemagnifying (straight, 1:1) fiberoptics. The CCD imager has a fundamental pixel pitch of 39 microm and incorporates an optically opaque interline (data) channel. The CCD imager was operated at 156 microm pixel pitch by binning 4 x 4 adjacent pixels prior to readout. The fluoroscopic image lag was measured and accounted for in the DQE estimate to provide lag-corrected DQE. The measured limiting spatial resolution at 10% presampling MTF with the imager operated at 156 microm pixel pitch (Nyquist sampling limit: 3.21 cy/mm) was 3.6 cy/mm. In the pulsed fluoroscopic mode, the first-frame image lag was less than 0.9%. The lag-corrected DQE(0) of approximately 0.62 was achieved even at a low fluoroscopic exposure rate of 1 microR/frame. Grid phantom measurements indicate no appreciable distortion. Results from DQE and image lag measurements at fluoroscopic exposure rates combined with the high spatial resolution observed from the MTF suggest that this type of imager or its variants may be a potential candidate for high-resolution neuro-interventional imaging, cardiovascular imaging, pediatric angiography, and small animal imaging. Since the CCD is three-side buttable, four such CCD modules can be joined to form a 2 x 2 matrix providing a field of view of 16 cm x 16 cm.

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“…[3][4][5] The dual-screen CR imaging techniques have been proposed and investigated for improvement of the image SNR and CNR while maintaining the image MTFs in various imaging applications. [24][25][26][27] With this technique, two CR plates are placed in a cassette for simultaneous exposure ͑Fig. 1͒.…”

Section: Introductionmentioning

confidence: 99%

“…24,25 When an HR screen is used with an ST screen for dual-screen CR imaging, both MTF and SNR can be improved over those of a single ST image. [27][28][29] An example of MTF improvement by using HR-ST screen combination over ST-ST screen combination or a single ST screen is shown in Table I. A dual-side readout system has also been developed and investigated.…”

Section: Introductionmentioning

confidence: 99%

Regional improvement of signal‐to‐noise and contrast‐to‐noise ratios in dual‐screen CR chest imaging—a phantom study

Liu

Shaw

2001

Medical Physics

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The improvement of signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) in dual-screen computed radiography (CR) has been investigated for various regions in images of an anthropomorphic chest phantom. With the dual-screen CR technique, two image plates are placed in a cassette and exposed together during imaging. The exposed plates are separately scanned to form a front image and a back image, which are then registered and superimposed to form a composite image with improved SNRs and CNRs. The improvement can be optimized by applying specifically selected weighting factors during superimposition. In this study, dual-screen CR images of an anthropomorphic chest phantom were acquired and formed with four different combinations of standard resolution (ST) and high-resolution (HR) screens: ST-ST, ST-HR, HR-ST, and HR-HR. SNRs and their improvements were measured and compared over twelve representative regions-of-interest (ROIs) in these images. A 19.1%-45.7% increase of the SNR was observed, depending on the ROI and screen combination used. The optimal weighting factors were found to vary by only 4.5%-12.4%. Largest improvement was found in the lung field for all screen combinations. Improvement of CNRs was investigated over two ROIs in the lung field using the rib bones as the contrast objects and a 29.2%-43.9% improvement of the CNR was observed. Among the four screen combinations, ST-ST resulted in the most SNR and CNR improvement, followed in order by HR-ST, HR-HR, and ST-HR. The HR-ST combination yielded the lowest spatial variation of the optimal weighting factors with improved SNRs and CNRs close to those of the ST-ST combination.

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Frequency-dependent DQE in dual-screen CR imaging

Cited by 4 publications

References 1 publication

Performance evaluation of a “dual‐side read” dedicated mammography computed radiography system

Performance evaluation of a “dual‐side read” dedicated mammography computed radiography system

Solid‐state fluoroscopic imager for high‐resolution angiography: Physical characteristics of an 8 cm×8 cm experimental prototype

Regional improvement of signal‐to‐noise and contrast‐to‐noise ratios in dual‐screen CR chest imaging—a phantom study

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