An edge spread technique for measurement of the scatter‐to‐primary ratio in mammography

Cooper, Virgil N.; Boone, John M.; Seibert, J. Anthony; Pellot‐Barakat, Claire

doi:10.1118/1.598950

Cited by 43 publications

(39 citation statements)

References 24 publications

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“…17 The spatial distribution of scatter is appreciable only at very low spatial frequencies. Because we need the scatter MTF all the way up to the Nyquist frequency of each detector for further calculations in generalized system parameters, we used an exponential tail extrapolation up to the Nyquist frequency of each detector.…”

Section: Scatter Mtfmentioning

confidence: 99%

Generalized performance evaluation of x-ray image intensifier compared with a microangiographic system

Yadava

Kyprianou

Rudin

et al. 2005

Medical Imaging 2005: Physics of Medical Imaging

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Standard objective parameters such as MTF, NPS, NEQ and DQE do not reflect complete system performance, because they do not account for geometric unsharpness due to finite focal spot size and scatter due to the patient. The inclusion of these factors led to the generalization of the objective quantities, termed GMTF, GNNPS, GNEQ and GDQE defined at the object plane. In this study, a commercial x-ray image intensifier (II) is evaluated under this generalized approach and compared with a high-resolution, ROI microangiographic system previously developed and evaluated by our group. The study was performed using clinically relevant spectra and simulated conditions for neurovascular angiography specific for each system. A head-equivalent phantom was used, and images were acquired from 60 to 100 kVp. A source to image distance of 100 cm (75 cm for the microangiographic system) and a focal spot of 0.6 mm were used. Effects of varying the irradiation field-size, the air-gaps, and the magnifications (1.1 to 1.3) were compared. A detailed comparison of all of the generalized parameters is presented for the two systems. The detector MTF for the microangiographic system is in general better than that for the II system. For the total x-ray imaging system, the GMTF and GDQE for the II are better at low spatial frequencies, whereas the microangiographic system performs substantially better at higher spatial frequencies. This generalized approach can be used to more realistically evaluate and compare total system performance leading to improved system designs tailored to the imaging task.

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Section: Scatter Mtfmentioning

confidence: 99%

Generalized performance evaluation of x-ray image intensifier compared with a microangiographic system

Yadava

Kyprianou

Rudin

et al. 2005

Medical Imaging 2005: Physics of Medical Imaging

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show abstract

“…[38][39][40][41][42][43] Among them, the beam stop method has been widely used to measure the scatter component at a given point while the slat or edge spread method allows the scatter component to be measured along a straight line ͑for scatter distribution͒. In this study, we used a method referred to as the beam aperture array method to indirectly estimate the scatter component at selected locations.…”

Section: Iid Measurement Of Primary Scatter Signals and Sprsmentioning

confidence: 99%

Scatter rejection and low‐contrast performance of a slot‐scan digital chest radiography system with electronic aft‐collimation: A chest phantom study

et al. 2008

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Anti-scatter grids have been widely used to reject scatter and increase the perceptibility of lowcontrast object in chest radiography; however they also attenuate the primary x-rays, resulting in a substantial degradation of primary information. Compensation for this degradation requires the use of higher exposure technique hence higher dose to the patient. A more efficient approach to reject scatter is the slot-scan imaging technique which employs a narrow scanning x-ray fan beam in conjunction with a slit or slot shaped solid state detector or an area detector used with an aftcollimator. With this approach, scatter can be rejected effectively without the need to attenuate primary x-rays. This paper demonstrates an electronic aft-collimation method, referred to as the alternate line erasure and readout ͑ALER͒ technique, for implementing the slot-scan digital radiography with a modern flat-panel detector. With this technique, instead of first exposing the detector and then reading the image line by line, the image line on the leading edge of the scanning fan beam is reset to erase the scatter accumulated prior to the arrival of the fan beam x-rays, while the image line on the trailing edge of the scanning fan beam is read out to acquire the image signals following the fan-beam exposure. These reset and readout processes are alternated and repeated as the x-ray fan beam scans across the detector. An anthropomorphic chest phantom was imaged to evaluate the scatter rejection ability and the low-contrast performance for the ALER technique and compare them with those for the anti-scatter grid method in full-field chest imaging. With a projected beam width of 16 mm, the slot-scan/ALER technique resulted in an average reduction of the scatter-toprimary ratios by 81%, 84%, 82%, and 86% versus 65%, 73%, 74%, and 73% with the anti-scatter grid method in the lungs, mediastinum, retrocardium, and subdiaphragm, respectively. The average CNR for the slot-scan/ALER technique was found to improve by 135%, 133%, 176%, and 87% versus 15%, 15%, 38%, and −11% with the anti-scatter grid method in the mediastinum, retrocardium, subdiaphragm, and lungs, respectively. These results demonstrated that the slot-scan/ALER technique can be used to achieve equally effective scatter rejection but substantially higher lowcontrast performance than the anti-scatter grid method.

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“…For example, Seibert et al (1984) modelled image-intensifiers and used a deconvolution method to 295 remove veiling-glare. Also, Cooper III et al (2000) applied the deconvolution method to a flat-panel mammography imaging system. Notably, however, our parameterization of the LSF differs and we explore the implications for cone-beam CT reconstructions.…”

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confidence: 99%

Removal and effects of scatter-glare in cone-beam CT with an amorphous-silicon flat-panel detector

et al. 2011

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Abstract.Scatter in a detector and its housing can result in image degradation. Typically, such scatter leads to a low-spatial frequency 'glare' superimposed on the primary 10 signal. We infer the glare-spread-function (GSF) of an amorphous-silicon flat-panel detector via an edge-spread technique. We demonstrate that this spread (referred to as 'scatter-glare' herein) causes a low-spatial-frequency drop in the associated modulationtransfer-function. This results in a compression of the range of reconstructed CTnumbers and is an impediment to accurate CT-number calibration. We show that 15 it can also lead to visual artefacts. This explains previously unresolved CT-number discrepancies in an earlier work (Poludniowski et al 2009a Phys. Med. Biol. 54 3847). We demonstrate that after deconvolving the GSF from the projection images, in conjunction with a correction for phantom-scatter, the CT-number discrepancies disappear. We show results for an in-house-built phantom with inserts of tissue-20 equivalent materials and for a patient scan. We conclude that where scatter-glare has not been accounted for the calibration of cone-beam CT-numbers to material density will be compromised. The scatter-glare measurement method we propose is simple and requires no special equipment. The deconvolution process is also straight-forward and relatively quick (60 ms per projection on a desktop PC).

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An edge spread technique for measurement of the scatter‐to‐primary ratio in mammography

Cited by 43 publications

References 24 publications

Generalized performance evaluation of x-ray image intensifier compared with a microangiographic system

Generalized performance evaluation of x-ray image intensifier compared with a microangiographic system

Scatter rejection and low‐contrast performance of a slot‐scan digital chest radiography system with electronic aft‐collimation: A chest phantom study

Removal and effects of scatter-glare in cone-beam CT with an amorphous-silicon flat-panel detector

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