Component analysis of a new solid state x-ray image intensifier (SSXII) using photon transfer and instrumentation noise equivalent exposure (INEE) measurements

Kuhls-Gilcrist, Andrew; Bednarek, Daniel R.; Rudin, Stephen

doi:10.1117/12.813957

Cited by 13 publications

(10 citation statements)

References 27 publications

(32 reference statements)

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“…Measurements were also performed on several different clinical imaging technologies, including an x-ray image intensifier ͑XII͒ and a FPD, as well as a custom-built solid-state x-ray image intensifier ͑SSXII͒, 40,[43][44][45] which is an electron-multiplying CCD ͑EMCCD͒-based detector with very high-resolution capabilities ͑greater than 10 lp/mm͒. Results from the noise-response method were compared with those obtained using the standard edge-response method.…”

Section: Introductionmentioning

confidence: 99%

Accurate MTF measurement in digital radiography using noise response

et al. 2010

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Purpose:The authors describe a new technique to determine the system presampled modulation transfer function ͑MTF͒ in digital radiography using only the detector noise response. Methods: A cascaded-linear systems analysis was used to develop an exact relationship between the two-dimensional noise power spectrum ͑NPS͒ and the presampled MTF for a generalized detector system. This relationship was then utilized to determine the two-dimensional presampled MTF. For simplicity, aliasing of the correlated noise component of the NPS was assumed to be negligible. Accuracy of this method was investigated using simulated images from a simple detector model in which the "true" MTF was known exactly. Measurements were also performed on three detector technologies ͑an x-ray image intensifier, an indirect flat panel detector, and a solid state x-ray image intensifier͒, and the results were compared using the standard edge-response method. Flat-field and edge images were acquired and analyzed according to guidelines set forth by the International Electrotechnical Commission, using the RQA 5 spectrum. Results: The presampled MTF determined using the noise-response method for the simulated detector system was in close agreement with the true MTF with an averaged percent difference of 0.3% and a maximum difference of 1.1% observed at the Nyquist frequency ͑f N ͒. The edgeresponse method of the simulated detector system also showed very good agreement at lower spatial frequencies ͑less than 0.5 f N ͒ with an averaged percent difference of 1.6% but showed significant discrepancies at higher spatial frequencies ͑greater than 0.5 f N ͒ with an averaged percent difference of 17%. Discrepancies were in part a result of noise in the edge image and phasing errors. For all three detector systems, the MTFs obtained using the two methods were found to be in good agreement at spatial frequencies less than 0.5 f N with an averaged percent difference of 3.4%. Above 0.5 f N , differences increased to an average of 20%. Deviations of the experimental results largely followed the trend seen in the simulation results, suggesting that differences between the two methods could be explained as resulting from the inherent inaccuracies of the edgeresponse measurement technique used in this study. Aliasing of the correlated noise component was shown to have a minimal effect on the measured MTF for the three detectors studied. Systems with significant aliasing of the correlated noise component ͑e.g., a-Se based detectors͒ would likely require a more sophisticated fitting scheme to provide accurate results. Conclusions: Results indicate that the noise-response method, a simple technique, can be used to accurately measure the MTF of digital x-ray detectors, while alleviating the problems and inaccuracies associated with use of precision test objects, such as a slit or an edge.

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Section: Introductionmentioning

confidence: 99%

Accurate MTF measurement in digital radiography using noise response

et al. 2010

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“…For further investigation, the two-dimensional MTF was measured for two detector systems, a clinical Varian Paxscan 2020+ flat panel detector (FPD) (Palo Alto, CA) and a high-resolution, high-sensitivity solid state x-ray image intensifier (SSXII) 21, 25–26. The FPD implements a 600 μm-thick CsI(Tl) phosphor and has a pixel pitch of 194 μm.…”

Section: Methodsmentioning

confidence: 99%

A method for the determination of the two-dimensional MTF of digital radiography systems using only the noise response

2010

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We present a new method that enables the determination of the two-dimensional MTF of digital radiography systems using the noise response measured from flat-field images. Unlike commonlyused methods that measure the one-dimensional MTF, this new method does not require precisionmade test-objects (slits/edges) or precise tool alignment. Although standard methods are dependent upon data processing that can result in inaccuracies and inconsistencies, this method based on the intrinsic noise response of the imager is highly accurate and less susceptible to such problems. A cascaded-linear-systems analysis was used to derive an exact relationship between the noise power spectrum (NPS) and the presampled MTF of a generalized detector system. The NPS was then used to determine the two-dimensional MTF for three systems: a simulated detector in which the "true" MTF was known exactly, a commercial indirect flat-panel detector (FPD), and a new solid-state x-ray image intensifier (SSXII). For the simulated detector, excellent agreement was observed between the "true" MTF and that determined using the noise response method, with an averaged deviation of 0.3%. The FPD MTF was shown to increase on the diagonals and was measured at 2.5 cycles/mm to be 0.086±0.007, 0.12±0.01, and 0.087±0.007 at 0, 45, and 90°, respectively. No statistically significant variation was observed for the SSXII as a function of angle. Measuring the two-dimensional MTF should lead to more accurate characterization of the detector resolution response, incorporating any potential non-isotropy which may result from the physical characteristics of the sensor, including the active-area shape of the pixel array.

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“…The SSXII is a new high-resolution, high-sensitivity x-ray imager that has been developed by our group to improve upon the inherent limitations of current state-of-the-art radiographic and fluoroscopic detectors, such as flat panel detectors and x-ray image intensifiers 3–6. Superior imaging performance has been demonstrated for traditional EI applications, in particular for endovascular image guided interventions 7.…”

Section: Methodsmentioning

confidence: 99%

The solid state x-ray image intensifier (SSXII) in single photon counting (SPC) mode

et al. 2010

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The new Solid State X-Ray Image Intensifier (SSXII) has the unique ability to operate in single photon counting (SPC) mode, with improved resolution, as well as in traditional energy integrating (EI) mode. The SSXII utilizes an electron-multiplying CCD (EMCCD), with an effective pixel size of 32μm, which enables variable signal amplification (up to a factor of 2000) prior to digital readout, providing very high-sensitivity capabilities. The presampled MTF was measured in both imaging modes using the standard angulated-slit method. A measured detector entrance exposure of 24μR per frame was used to provide approximately 0.8 interaction events per pixel in the 10μm-wide slit area. For demonstration purposes, a simple thresholding technique was used to localize events in SPC mode and a number of such frames were summed to provide an image with the same total exposure used for acquiring the EI image. The MTF for SPC mode, using a threshold level of 15% of the maximum 12-bit signal and 95% of the expected events, and for EI mode (in parentheses) was 0.67 (0.20), 0.37 (0.07), 0.20 (0.03), and 0.11 (0.01) at 2.5, 5, 7.5, and 10 cycles/mm, respectively. Increasing the threshold level resulted in a corresponding increase in the measured SPC MTF and a lower number of detected events, indicating a tradeoff between resolution and count efficiency is required. The SSXII in SPC mode was shown to provide substantial improvements in resolution relative to traditional EI mode, which should benefit applications that have demanding spatial resolution requirements, such as mammography.

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Component analysis of a new solid state x-ray image intensifier (SSXII) using photon transfer and instrumentation noise equivalent exposure (INEE) measurements

Cited by 13 publications

References 27 publications

Accurate MTF measurement in digital radiography using noise response

Accurate MTF measurement in digital radiography using noise response

A method for the determination of the two-dimensional MTF of digital radiography systems using only the noise response

The solid state x-ray image intensifier (SSXII) in single photon counting (SPC) mode

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