Mr. Isaias D. Job Profile

Isaias D. Job

Imaging Scientist at Varex Imaging Corp

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Publications (12)

Proceedings Article | 16 March 2020 Paper

Analysis of a new indium gallium zinc oxide (IGZO) detector

Steven Freestone, Richard Weisfield, Carlo Tognina, Isaias Job, Richard Colbeth

Proceedings Volume 11312, 113123W (2020) https://doi.org/10.1117/12.2549469

KEYWORDS: Sensors, Amorphous silicon, Imaging systems, Field emission displays, Modulation transfer functions, Spatial frequencies, CMOS sensors, Signal to noise ratio, Sensor performance, X-rays

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Proceedings Article | 3 April 2019 Presentation + Paper

Comparison of CMOS and amorphous silicon detectors: determining the correct selection criteria, to optimize system performance for typical imaging tasks

Isaias Job, Arundhuti Ganguly, Don Vernekohl, Richard Weisfield, Elena Muñoz, Jin Zhang, Carlo Tognina, Rick Colbeth

Proceedings Volume 10948, 109480F (2019) https://doi.org/10.1117/12.2513500

KEYWORDS: Amorphous silicon, Sensors, CMOS sensors, Scintillators, X-rays, Modulation transfer functions, Imaging systems, X-ray imaging

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Complementary metal-oxide-semiconductors (CMOS) flat panel detectors (FPD) have steadily gained acceptance into medical imaging applications1-15. Selecting the proper detector technology for the imaging task requires optimization to balance the cost and the image quality. To facilitate this, fundamental detector performance of CMOS and a-Si panels were evaluated using the following quantitative imaging metrics: X-ray sensitivity, Noise Equivalent Dose (NED,) Noise Power Spectrum (NPS), Modulation Transfer Function (MTF), and Detective Quantum Efficiency (DQE). Imaging task measurements involved high-contrast and low-contrast resolution assessment. Varex FPDs evaluated for this study included: CMOS 3131 (150 μm pixel), a-Si 3030X (194 μm pixel), a-Si XRpad2 3025 (100 μm) and CMOS 2020 (100 μm pixel). Performance comparisons were organized by pixel size: large pixels, 150 μm CMOS and 194 μm a-Si, and small pixels, 100 μm in a-Si and CMOS technology. The results showed high dose DQE of the a-Si 3030X was about 10% higher than the CMOS 3131 between 0 - 1.8 cycles/mm, while beyond 1.8 cycles/mm, the CMOS performed better. The 3030X low dose DQE was higher than the 3131 between 0-1.3 cycles/mm, while the CMOS performance was higher beyond 1.3 cycles/mm. The high dose DQE of 100 μm a-Si was higher than the 100 μm CMOS for all frequencies. However, the low dose DQE of 100 μm CMOS was higher beyond 0.6 cycles/mm, while the 100 μm a-Si pixel had higher DQE only between 0 – 0.6 cycles/mm. Large pixel image quality (IQ) assessment favored a-Si pixel with 7% higher Contrast-to-Noise-Ratio (CNR) results for both high and low contrast-detail at 500 nGy. Small pixel CNR favored CMOS with ~38% better high contrast-detail and 12% greater low contrast-detail at ~500 nGy. Through these measurements that combine imaging metrics and image quality, we demonstrated a practical method for selecting the appropriate detector technology based on the requirements of the imaging applications.

Proceedings Article | 1 March 2019 Paper

Flat panel design and performance of a new a-Si mammography imaging system

Steve Wettstein, Carlo Tognina, Isaias Job

Proceedings Volume 10948, 109483F (2019) https://doi.org/10.1117/12.2513473

KEYWORDS: Imaging systems, Signal to noise ratio, Mammography, Tomography, X-rays, Sensors, Modulation transfer functions

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Proceedings Article | 31 March 2016 Paper

A comparison of quantum limited dose and noise equivalent dose

Isaias Job, Sarah Boyce, Michael Petrillo, Kungang Zhou

Proceedings Volume 9783, 97833T (2016) https://doi.org/10.1117/12.2216888

KEYWORDS: Sensors, Modulation transfer functions, Image sensors, Image quality, Data acquisition, Signal to noise ratio, Field emission displays, X-rays, X-ray imaging, Quantum electronics, Calibration, Image processing, Interference (communication), X-ray detectors

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Proceedings Article | 3 March 2012 Paper

Improved DQE by means of X-ray spectra and scintillator optimization for FFDM

Isaias Job, Nima Taie-Nobraie, Richard Colbeth, Ivan Mollov, Keith Gray, Chris Webb, John Pavkovich, Fred Zoghi, Carlo Tognina, Pieter Roos

Proceedings Volume 8313, 83135T (2012) https://doi.org/10.1117/12.911795

KEYWORDS: Scintillators, X-rays, Sensors, Modulation transfer functions, Signal to noise ratio, X-ray imaging, Spatial resolution, Molybdenum, Aluminum, Tissues

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The focus of this work was to improve the DQE performance of a full-field digital mammography (FFDM) system by means of selecting an optimal X-ray tube anode-filter combination in conjunction with an optimal scintillator configuration. The flat panel detector in this work is a Varian PaxScan 3024M. The detector technology is comprised of a 2816 row × 3584 column amorphous silicon (a-Si) photodiode array with a pixel pitch of 83μm. The scintillator is cesium iodide and is deposited directly onto the photodiode array and available with configurable optical and x-ray properties. Two X-ray beam spectra were generated with the anode/filter combinations, Molybdenum/Molybdenum (Mo/Mo) and Tungsten/Aluminum (W/Al), to evaluate the imaging performance of two types of scintillators, high resolution (HR) type and high light output (HL) type. The results for the HR scintillator with W/Al anode-filter (HRW/ Al) yielded a DQE(0) of 67%, while HR-Mo/Mo was lower with a DQE(0) of 50%. In addition, the DQE(0) of the HR-W/Al configuration was comparable to the DQE(0) of the HL-Mo/Mo configuration. The significance of this result is the HR type scintillator yields about twice the light output with the W/Al spectrum, at about half the dose, as compared to the Mo/Mo spectrum. The light output or sensitivity was measured in analog-to-digital convertor units (ADU) per dose. The sensitivities (ADU/uGy) were 8.6, 16.8 and 25.4 for HR-Mo/Mo, HR-W/Al, HL-Mo/Mo, respectively. The Nyquist frequency for the 83 μm pixel is 6 lp/mm. The MTF at 5 lp/mm for HR-Mo/Mo and HR-W/Al were equivalent at 37%, while the HL-Mo/Mo MTF was 24%. According to the DQE metric, the more favorable anodefilter combination was W/Al with the HR scintillator. Future testing will evaluate the HL-W/Al configuration, as well as other x-ray filters materials and other scintillator optimizations. While higher DQE values were achieved, the more general conclusion is that the imaging performance can be tuned as required by the application by modifying optical and x-ray properties of the scintillator to match the spectral output of the chosen anode-filter combination.

Proceedings Article | 15 March 2007 Paper

Multidetector-row CT with a 64–row amorphous silicon flat panel detector

Edward Shapiro, Richard Colbeth, Earl Daley, Isaias Job, Ivan Mollov, Todor Mollov, John Pavkovich, Pieter Roos, Josh Star-Lack, Carlo Tognina

Proceedings Volume 6510, 65103X (2007) https://doi.org/10.1117/12.713682

KEYWORDS: Sensors, Scintillators, Diagnostics, Signal to noise ratio, Scanners, Ceramics, Modulation transfer functions, X-rays, Amorphous silicon, X-ray computed tomography

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Proceedings Article | 6 May 2004 Paper

Design and performance of a new a-Si flat-panel imager for use in cardiovascular and mobile C-arm imaging systems

Carlo Tognina, Ivan Mollov, Jiann Yu, Chris Webb, Pieter Roos, Mark Batts, Delenah Trinh, Robert Fong, Nima Taie-Nobraie, Boris Nepo, Isaias Job, Keith Gray, Sarah Boyce, Richard Colbeth

Proceedings Volume 5368, (2004) https://doi.org/10.1117/12.536054

KEYWORDS: Imaging systems, Amorphous silicon, Fluoroscopy, Electronics, Medical imaging, Modulation transfer functions, Physics, Sensors, Image resolution, Scintillators

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Proceedings Article | 28 June 2001 Paper

40 x 30 cm flat-panel imager for angiography, R&F, and cone-beam CT applications

Richard Colbeth, Sarah Boyce, Robert Fong, Keith Gray, Richard Harris, Isaias Job, Ivan Mollov, Boris Nepo, John Pavkovich, Nima Taie-Nobarie, Edward Seppi, Edward Shapiro, Michael Wright, Chris Webb, Jiann Yu

Proceedings Volume 4320, (2001) https://doi.org/10.1117/12.430917

KEYWORDS: Imaging systems, X-rays, Signal to noise ratio, Receptors, Calibration, Modulation transfer functions, Angiography, X-ray computed tomography, Radiography, Fluoroscopy

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Proceedings Article | 28 May 1999 Paper

Characterization of a third-generation multimode sensor panel

Richard Colbeth, Virgil Cooper, David Gilblom, Richard Harris, Isaias Job, Martin Klausmeier-Brown, Marcel Marc, John Pavkovich, Edward Seppi, Edward Shapiro, Michael Wright, Jiann Yu

Proceedings Volume 3659, (1999) https://doi.org/10.1117/12.349527

KEYWORDS: Imaging systems, X-rays, Sensors, Video, Signal to noise ratio, Receptors, Radiography, Control systems, Spatial frequencies, Fluoroscopy

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Proceedings Article | 24 July 1998 Paper

Amorphous silicon dual-mode medical imaging system

Michael Wright, Maxwell Allen, Richard Colbeth, Derek Day, David Gilblom, Richard Harris, Isaias Job, Martin Klausmeier-Brown, John Pavkovich, Edward Seppi, Edward Shapiro, Jiann Yu

Proceedings Volume 3336, (1998) https://doi.org/10.1117/12.317052

KEYWORDS: Amorphous silicon, Imaging systems, Sensors, Electronics, Digital filtering, Modulation transfer functions, Medical imaging, X-rays, Image intensifiers, X-ray imaging

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Proceedings Article | 24 July 1998 Paper

Flat-panel imaging system for fluoroscopy applications

Richard Colbeth, Maxwell Allen, Derek Day, David Gilblom, Richard Harris, Isaias Job, Martin Klausmeier-Brown, John Pavkovich, Edward Seppi, Edward Shapiro, Michael Wright, Jiann Yu

Proceedings Volume 3336, (1998) https://doi.org/10.1117/12.317037

KEYWORDS: Imaging systems, Sensors, Receptors, Interference (communication), Amorphous silicon, Fluoroscopy, X-rays, Resistance, Image resolution, Image processing

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Proceedings Article | 12 March 1998 Paper

Real-time image processing in a flat-panel solid state medical fluoroscopic imaging system

Martin Klausmeier-Brown, Maxwell Allen, Sarah Boyce, Richard Colbeth, David Gilblom, Isaias Job, M. Koenig, John Pavkovich, Michael Wright, Jiann Yu

Proceedings Volume 3303, (1998) https://doi.org/10.1117/12.302414

KEYWORDS: Image processing, Imaging systems, Sensors, Real time image processing, Solid state electronics, X-ray imaging, Image sensors, Medical imaging, Amorphous silicon, Image filtering

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Showing 5 of 12 publications

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