Dr. Martin Clajus Profile

Dr. Martin Clajus

at Nova R&D Inc

SPIE Involvement:

Author

Publications (8)

SPIE Journal Paper | 28 April 2015

Evaluation of position-estimation methods applied to CZT-based photon-counting detectors for dedicated breast CT

Andrey Makeev, Martin Clajus, Scott Snyder, Xiaolang Wang, Stephen Glick

JMI, Vol. 2, Issue 02, 023501, (April 2015) https://doi.org/10.1117/12.10.1117/1.JMI.2.2.023501

KEYWORDS: Sensors, X-rays, Photodetectors, X-ray detectors, Detection and tracking algorithms, Photons, X-ray computed tomography, Breast, Spatial resolution, Computer simulations

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Semiconductor photon-counting detectors based on high atomic number, high density materials [cadmium zinc telluride (CZT)/cadmium telluride (CdTe)] for x-ray computed tomography (CT) provide advantages over conventional energy-integrating detectors, including reduced electronic and Swank noise, wider dynamic range, capability of spectral CT, and improved signal-to-noise ratio. Certain CT applications require high spatial resolution. In breast CT, for example, visualization of microcalcifications and assessment of tumor microvasculature after contrast enhancement require resolution on the order of 100 μm. A straightforward approach to increasing spatial resolution of pixellated CZT-based radiation detectors by merely decreasing the pixel size leads to two problems: (1) fabricating circuitry with small pixels becomes costly and (2) inter-pixel charge spreading can obviate any improvement in spatial resolution. We have used computer simulations to investigate position estimation algorithms that utilize charge sharing to achieve subpixel position resolution. To study these algorithms, we model a simple detector geometry with a 5×5 array of 200 μm pixels, and use a conditional probability function to model charge transport in CZT. We used COMSOL finite element method software to map the distribution of charge pulses and the Monte Carlo package PENELOPE for simulating fluorescent radiation. Performance of two x-ray interaction position estimation algorithms was evaluated: the method of maximum-likelihood estimation and a fast, practical algorithm that can be implemented in a readout application-specific integrated circuit and allows for identification of a quadrant of the pixel in which the interaction occurred. Both methods demonstrate good subpixel resolution; however, their actual efficiency is limited by the presence of fluorescent K-escape photons. Current experimental breast CT systems typically use detectors with a pixel size of 194 μm, with 2×2 binning during the acquisition giving an effective pixel size of 388 μm. Thus, it would be expected that the position estimate accuracy reported in this study would improve detection and visualization of microcalcifications as compared to that with conventional detectors.

Proceedings Article | 19 March 2013 Paper

Achieving sub-pixel resolution using CZT-based photon counting detectors for dedicated breast CT

Andrey Makeev, John McGrath, Martin Clajus, Scott Snyder, Stephen Glick

Proceedings Volume 8668, 86680T (2013) https://doi.org/10.1117/12.2008351

KEYWORDS: Sensors, X-rays, Detection and tracking algorithms, Breast, Electrons, Semiconductors, X-ray detectors, Spatial resolution, X-ray computed tomography, Electrodes

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Proceedings Article | 2 September 2010 Paper

Design of a coded aperture Compton telescope imaging system (CACTIS)

Alexander Volkovskii, Martin Clajus, Stephen Gottesman, Hans Malik, Kenneth Schwartz, Evren Tumer, Tumay Tumer, Shi Yin

Proceedings Volume 7805, 78051V (2010) https://doi.org/10.1117/12.862995

KEYWORDS: Sensors, Coded apertures, Prototyping, Signal detection, Telescopes, Imaging systems, Gamma radiation, Data acquisition, Computing systems, Control systems

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Proceedings Article | 10 September 2008 Paper

New two-dimensional ASICs for solid state pixel detectors

Tumay Tumer, Victoria Cajipe, Martin Clajus, Satoshi Hayakawa, Alexander Volkovskii

Proceedings Volume 7079, 707913 (2008) https://doi.org/10.1117/12.799392

KEYWORDS: Sensors, Solid state electronics, Image sensors, Detector arrays, Detector development, Integrated circuits, X-rays, Spatial resolution, Photography, Silicon

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Proceedings Article | 4 September 2008 Paper

Performance of an improved readout IC for multi-energy photon-counting x-ray detector arrays

Martin Clajus, Victoria Cajipe, Satoshi Hayakawa, Tümay Tümer

Proceedings Volume 7079, 707911 (2008) https://doi.org/10.1117/12.795607

KEYWORDS: Amplifiers, Sensors, X-ray detectors, Detector arrays, Signal detection, X-rays, Analog electronics, X-ray imaging, Statistical analysis, Photonic integrated circuits

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Proceedings Article | 4 September 2008 Paper

Performance of RENA-3 IC with position-sensitive solid-state detectors

Tumay Tumer, Victoria Cajipe, Martin Clajus, Satoshi Hayakawa, Alexander Volkovskii

Proceedings Volume 7079, 70791F (2008) https://doi.org/10.1117/12.797750

KEYWORDS: Sensors, Solid state electronics, Capacitance, Signal detection, Analog electronics, Electronics, Gamma radiation, Spectroscopy, Imaging spectroscopy, Photography

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Proceedings Article | 30 August 2006 Paper

High-resolution imaging 1D and 2D solid state detector systems

Tümay Tumer, Victoria Cajipe, Martin Clajus, Satoshi Hayakawa, Alexander Volkovskii

Proceedings Volume 6319, 63190P (2006) https://doi.org/10.1117/12.684168

KEYWORDS: Sensors, Solid state electronics, Imaging systems, X-rays, Image sensors, Detector arrays, Amplifiers, Detector development, Silicon, X-ray detectors

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Proceedings Article | 21 November 2000 Paper

Scanned x-ray images from a linear CdZnTe pad array with monolithic readout electronics

Martin Clajus, Tumay Tumer, Gerald Visser, Shi Yin, Paul Willson, Lawrence D'Aries, Kevin Parnham, Bruce Glick, John Perry, Thomas Gamble, Geoffrey Creede, Eric Worthington, John Sparling, Dale Maeding, Dan Gorzen

Proceedings Volume 4141, (2000) https://doi.org/10.1117/12.407590

KEYWORDS: Sensors, Detector arrays, Signal detection, Prototyping, Amplifiers, X-rays, X-ray imaging, X-ray detectors, Electronics, Inspection

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Showing 5 of 8 publications

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