Mr. Ivan P. Mollov Profile

Ivan P. Mollov

Advanced Development Manager at Varex Imaging Corp

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Author

Publications (11)

Proceedings Article | 1 April 2024 Poster + Paper

An alloyed a-Se-Te indirect flat panel imager for improved performance in a dual-layer x-ray detector

Kaitlin Hellier, Kellii Fusari, Paul Pryor, Ivan Mollov, Shiva Abbaszadeh

Proceedings Volume 12925, 1292537 (2024) https://doi.org/10.1117/12.3007292

KEYWORDS: Tellurium, Sensors, Alloys, Scintillators, X-ray detectors, External quantum efficiency, Imaging systems, Emission wavelengths, X-rays, Selenium

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Proceedings Article | 7 April 2023 Poster + Paper

A dual-layer direct/indirect flat panel detector for improved material decomposition: first studies of the indirect layer

Kaitlin Hellier, Ivan Mollov, Paul Pryor, Shiva Abbaszadeh

Proceedings Volume 12463, 124632E (2023) https://doi.org/10.1117/12.2653390

KEYWORDS: X-rays, X-ray detectors, X-ray imaging, Photocurrent, Polyimides, Selenium, Quantum detection, Imaging systems, Dark current, Tissues

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Proceedings Article | 9 March 2018 Presentation + Paper

X-ray performance of new high dynamic range CMOS detector

Arundhuti Ganguly, P. Gerhard Roos, Tom Simak, J. Michael Yu, Steven Freestone, Donald Hondongwa, Richard Colbeth, Ivan Mollov

Proceedings Volume 10573, 105730N (2018) https://doi.org/10.1117/12.2293771

KEYWORDS: Sensors, X-rays, CMOS sensors, Imaging systems, X-ray imaging, X-ray detectors, Modulation transfer functions, Scintillators, Image resolution, Semiconducting wafers

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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 | 25 March 2008 Paper

Photodiode forward bias to reduce temporal effects in a-Si based flat panel detectors

Ivan Mollov, Carlo Tognina, Richard Colbeth

Proceedings Volume 6913, 69133S (2008) https://doi.org/10.1117/12.769951

KEYWORDS: Photodiodes, Sensors, Amorphous silicon, Modulation, Capacitors, Transistors, Amplifiers, Diodes, X-rays, Fluoroscopy

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Proceedings Article | 18 March 2008 Paper

Parameter investigation and first results from a digital flat panel detector with forward bias capability

Jared Starman, Carlo Tognina, Gary Virshup, Josh Star-lack, Ivan Mollov, Rebecca Fahrig

Proceedings Volume 6913, 69130L (2008) https://doi.org/10.1117/12.772356

KEYWORDS: Photodiodes, X-rays, Sensors, Scintillators, Amorphous silicon, Diodes, Switches, X-ray detectors, CT reconstruction, Data acquisition

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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 | 20 April 2005 Paper

Flat panel CT detectors for sub-second volumetric scanning

Richard Colbeth, Ivan Mollov, Pieter Roos, Edward Shapiro

Proceedings Volume 5745, (2005) https://doi.org/10.1117/12.595631

KEYWORDS: Sensors, Computed tomography, X-rays, Scanners, Imaging systems, Photodiodes, X-ray computed tomography, Fluoroscopy, Scintillators, Electronics

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Proceedings Article | 6 May 2004 Paper

Multiple-gain-ranging readout method to extend the dynamic range of amorphous silicon flat-panel imagers

Pieter Roos, Richard Colbeth, Ivan Mollov, Peter Munro, John Pavkovich, Edward Seppi, Edward Shapiro, Carlo Tognina, Gary Virshup, J. Micheal Yu, George Zentai, Wolfgang Kaissl, Evangelos Matsinos, Jeroen Richters, Heinrich Riem

Proceedings Volume 5368, (2004) https://doi.org/10.1117/12.535471

KEYWORDS: Imaging systems, Amplifiers, Capacitors, Calibration, Image processing, Signal processing, X-rays, Amorphous silicon, Gain switching, Image quality

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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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Showing 5 of 11 publications

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