Dr. Ian A. Cunningham Profile

Dr. Ian A. Cunningham

Scientist at Robarts Research Institute

SPIE Involvement:

Author | Instructor

Publications (47)

PROCEEDINGS ARTICLE | March 9, 2018

Cascaded systems analysis of photon-counting field-shaping multi-well avalanche detectors (SWADs)

Proc. SPIE. 10573, Medical Imaging 2018: Physics of Medical Imaging

KEYWORDS: Photon counting, Imaging systems, Sensors, X-rays, Quantum efficiency, Monte Carlo methods, Modulation transfer functions, Spatial resolution, X-ray imaging, X-ray detectors, Systems modeling, Photon counting theory

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PROCEEDINGS ARTICLE | March 31, 2016

Detective quantum efficiency: a standard test to ensure optimal detector performance and low patient exposures

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Spatial frequencies, Sensors, X-rays, Quantum efficiency, Radiography, Sensor performance, Image quality, Image quality, Modulation transfer functions, X-ray imaging, X-ray detectors, X-ray detectors, Image quality standards

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PROCEEDINGS ARTICLE | March 29, 2016

Theoretical and Monte Carlo optimization of a stacked three-layer flat-panel x-ray imager for applications in multi-spectral diagnostic medical imaging

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Tissues, Imaging systems, Sensors, Photons, X-rays, Scintillators, Radiography, Diagnostics, Medical imaging, Monte Carlo methods, Image quality, X-ray imaging, X-ray detectors, Signal detection, Dual energy imaging

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PROCEEDINGS ARTICLE | March 22, 2016

A novel x-ray detector design with higher DQE and reduced aliasing: Theoretical analysis of x-ray reabsoprtion in detector converter material

Proc. SPIE. 9783, Medical Imaging 2016: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Sensors, Photons, Quantum efficiency, Interference (communication), Image quality, X-ray imaging, Selenium, X-ray detectors

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PROCEEDINGS ARTICLE | March 18, 2015

Apodized-aperture pixel design to increase high-frequency DQE and reduce noise aliasing in x-ray detectors

Proc. SPIE. 9412, Medical Imaging 2015: Physics of Medical Imaging

KEYWORDS: CMOS sensors, Spatial frequencies, Sensors, X-rays, Interference (communication), Modulation transfer functions, X-ray imaging, Selenium, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 18, 2015

Signal and noise analysis of flat-panel sandwich detectors for single-shot dual-energy x-ray imaging

Proc. SPIE. 9412, Medical Imaging 2015: Physics of Medical Imaging

KEYWORDS: Electronics, Sensors, Photons, X-rays, Interference (communication), Photodiodes, Modulation transfer functions, X-ray imaging, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 18, 2015

Theoretical and experimental comparison of image signal and noise for dual-energy subtraction angiography and conventional x-ray angiography

Proc. SPIE. 9412, Medical Imaging 2015: Physics of Medical Imaging

KEYWORDS: Signal to noise ratio, Quantum wells, Sensors, X-rays, Interference (communication), Iodine, Angiography, Image enhancement, X-ray imaging, X-ray detectors

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Cardiovascular disease is currently the leading cause of mortality worldwide. Digital subtraction angiography (DSA) is widely used to enhance the visibility of small vessels and vasculature obscurred by overlying bone and lung fields by subtracting a mask and contrast image. However, motion between these mask and contrast images can introduce artifacts that can render a study non-diagnostic. This makes DSA particularly unsuccessful for cardiac imaging. A method called dual-energy, or energy subtraction angiography (ESA), was proposed in the past as an alternative for vascular imaging, however it was not pursued because experimental results suggested that image quality was deemed as poor and inferior to DSA. Image quality for angiography comes down to iodine signal and noise. In this paper we investigate the fundamental iodine signal and noise analysis of ESA and compare it to DSA. Method: We developed a polyenergetic and monoenergetic theoretical model for iodine signal and noise for both ESA and DSA. We validated our polyenergetic model by experiment where ESA and DSA images of a vascular phantom were acquired using an x-ray system with a flat panel CsI Xmaru1215CF-MPTM (Rayence Co., Ltd., Republic of Korea) detector. For ESA low and high applied tube voltages of 50 kV and 120 kV (2.5 mmCu), respectively, and for DSA the applied tube voltage was 80 kV. Iodine signal-to-noise ratio (SNR) per entrance exposure was calculated for each iodine concentration for both ESA and DSA. Results: Our measured iodine SNR agreed well with theoretical calculations. Iodine SNR for ESA was relatively higher than DSA for low iodine mass loadings, and as iodine mass loading increases iodine SNR decreases. Conclusions: We have developed a model for iodine SNR for both DSA and ESA. Our model was validated with experiment and showed excellent agreement. We have shown that there is potential for obtaining iodine-specific images using ESA that are similar to DSA.

PROCEEDINGS ARTICLE | March 17, 2015

Three-dimensional segmentation of pulmonary artery volume from thoracic computed tomography imaging

Proc. SPIE. 9417, Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging

KEYWORDS: Gold, Medicine, Image segmentation, Arteries, Lung, 3D metrology, Computed tomography, Pulmonary hypertension, Chronic obstructive pulmonary disease, 3D image processing

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PROCEEDINGS ARTICLE | March 17, 2015

Principal component analysis of the CT density histogram to generate parametric response maps of COPD

Proc. SPIE. 9417, Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging

KEYWORDS: Gold, Principal component analysis, Medicine, X-ray computed tomography, Signal attenuation, Magnetic resonance imaging, Diffusion, Lung, Emphysema, Chronic obstructive pulmonary disease

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PROCEEDINGS ARTICLE | March 17, 2015

Fourier-based linear systems description of free-breathing pulmonary magnetic resonance imaging

Proc. SPIE. 9417, Medical Imaging 2015: Biomedical Applications in Molecular, Structural, and Functional Imaging

KEYWORDS: Signal to noise ratio, Imaging systems, Magnetic resonance imaging, Fourier transforms, Image registration, Lung, Image quality, Systems modeling, Pulmonary function tests, Chronic obstructive pulmonary disease

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PROCEEDINGS ARTICLE | March 19, 2014

Amorphous selenium direct detection CMOS digital x-ray imager with 25 micron pixel pitch

Proc. SPIE. 9033, Medical Imaging 2014: Physics of Medical Imaging

KEYWORDS: Gold, CMOS sensors, Imaging systems, Sensors, X-rays, Modulation transfer functions, Spatial resolution, X-ray imaging, Selenium, X-ray detectors

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PROCEEDINGS ARTICLE | March 19, 2014

Feasibility of active sandwich detectors for single-shot dual-energy imaging

Proc. SPIE. 9033, Medical Imaging 2014: Physics of Medical Imaging

KEYWORDS: Tissues, Sensors, Photons, X-rays, Copper, Monte Carlo methods, Image quality, Aluminum, X-ray imaging, X-ray detectors

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PROCEEDINGS ARTICLE | March 19, 2013

Cascaded-systems analyses of photon-counting x-ray detectors

Proc. SPIE. 8668, Medical Imaging 2013: Physics of Medical Imaging

KEYWORDS: Sensors, Photons, X-rays, Interference (communication), Bismuth, X-ray imaging, Selenium, X-ray detectors, Signal detection, Stochastic processes

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PROCEEDINGS ARTICLE | March 19, 2013

Cascaded-systems analyses of the DQE of double-Z x-ray detectors including photoelectric, coherent and incoherent interactions

Proc. SPIE. 8668, Medical Imaging 2013: Physics of Medical Imaging

KEYWORDS: Scattering, Sensors, Chemical species, X-rays, Interference (communication), Monte Carlo methods, Modulation transfer functions, X-ray detectors, Signal detection, Absorption

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Image quality in diagnostic x-ray detectors is limited by statistical properties governing how, and where, x-ray energy is deposited in a detector. This in turn depends on the physics of underlying x-ray interactions, and the development of theoretical models of x-ray interaction physics is therefore a critical step in optimal detector design and assessment. While cascaded-systems analyses are often used to describe image signal and noise in many systems, it has always been assumed there is only a single element (single Z) with which all x rays interact even though most commonly used and promising candidates are compound materials. In addition, coherent and incoherent scattering and their effects on image quality are usually ignored but may be important in some situa- tion such as in low-Z atoms with high x-ray energies. We present a theoretical model of energy deposition within a double-Z x-ray detector material that addresses the nature of energy absorption following photoelectric and incoherent interactions and the effects of coherent scatter prior to energy deposition by photoelectric interactions. A cascaded systems approach is used to describe the transfer of signal and noise in terms of the modulation transfer function (MTF), Wiener noise power spectrum (NPS), and detective quantum efficiency (DQE). The model is validated by comparing Monte Carlo simulation results with CsI and PbI2 double-Z materials. Excellent agreement is obtained for each metric over the entire diagnostic energy range up to 10 cycles/mm. It is shown that in all cases tested, a combination of two single-Z models weighted by the atomic density of each atom type gives equivalent results to the more comprehensive double-Z model within a few percent. This result suggests the simpler model is adequate and may be preferred for the optimal design of conventional radiography detectors and the estimation of x-ray imaging performance of novel photoconductor materials.

PROCEEDINGS ARTICLE | March 6, 2013

Characterization of a digital x-ray detector for region of interest tuberculosis screening

Proc. SPIE. 8668, Medical Imaging 2013: Physics of Medical Imaging

KEYWORDS: Amorphous silicon, Chest, Imaging systems, Sensors, X-rays, Radiography, Diagnostics, Modulation transfer functions, X-ray detectors, Chest imaging

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PROCEEDINGS ARTICLE | March 9, 2012

Extension of cascaded systems analysis to single-photon-counting x-ray detectors

Proc. SPIE. 8313, Medical Imaging 2012: Physics of Medical Imaging

KEYWORDS: Radon, Imaging systems, Sensors, Image processing, Interference (communication), Medical imaging, Signal processing, X-ray imaging, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 9, 2012

A robust approach to measuring the detective quantum efficiency of radiographic detectors in a clinical setting

Proc. SPIE. 8313, Medical Imaging 2012: Physics of Medical Imaging

KEYWORDS: Sensors, Image processing, X-rays, Copper, Quantum efficiency, Data processing, Image enhancement, Modulation transfer functions, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 17, 2011

A novel method to measure the zero-frequency DQE of a non-linear imaging system

Proc. SPIE. 7961, Medical Imaging 2011: Physics of Medical Imaging

KEYWORDS: Imaging systems, Spatial frequencies, Sensors, Image processing, Copper, Quantum efficiency, Physics, Medical imaging, X-ray detectors, Current controlled current source

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PROCEEDINGS ARTICLE | March 16, 2011

The case for single-exposure angiography using energy-resolving photon-counting detectors: a theoretical comparison of signal and noise with conventional subtraction angiography

Proc. SPIE. 7961, Medical Imaging 2011: Physics of Medical Imaging

KEYWORDS: Photodetectors, Sensors, X-rays, Interference (communication), Iodine, Angiography, Artificial intelligence, X-ray imaging, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 23, 2010

An aging study of the signal and noise characteristics in large-area CMOS detectors

Proc. SPIE. 7622, Medical Imaging 2010: Physics of Medical Imaging

KEYWORDS: CMOS sensors, Sensors, X-rays, Interference (communication), Photodiodes, Image analysis, Image quality, Image sensors, Modulation transfer functions, Signal detection

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PROCEEDINGS ARTICLE | March 23, 2010

Modeling of pulse signals in photon-counting detectors

Proc. SPIE. 7622, Medical Imaging 2010: Physics of Medical Imaging

KEYWORDS: Semiconductors, Photodetectors, Sensors, X-rays, Amplifiers, Photonics systems, Signal processing, Signal generators, Signal detection, Digital x-ray imaging

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PROCEEDINGS ARTICLE | March 23, 2010

Phosphor-filled micro-well arrays for digital x-ray imaging: effects of surface treatments

Proc. SPIE. 7622, Medical Imaging 2010: Physics of Medical Imaging

KEYWORDS: Silica, Sensors, Photons, X-rays, Silicon, Scintillators, Quantum efficiency, Reflectivity, Photodiodes, Modulation transfer functions

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PROCEEDINGS ARTICLE | March 22, 2010

Noise in energy-discriminating photon-counting x-ray imaging detectors

Proc. SPIE. 7622, Medical Imaging 2010: Physics of Medical Imaging

KEYWORDS: Imaging systems, Sensors, X-rays, Interference (communication), Image sensors, Signal processing, X-ray imaging, Selenium, X-ray detectors, Signal detection

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PROCEEDINGS ARTICLE | March 18, 2008

Temporal modulation transfer function of fluoroscopic systems: small-signal versus large-signal approaches

Proc. SPIE. 6913, Medical Imaging 2008: Physics of Medical Imaging

KEYWORDS: Point spread functions, Imaging systems, Sensors, Signal attenuation, X-rays, Copper, Quantum efficiency, Precision measurement, Modulation transfer functions, X-ray imaging

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PROCEEDINGS ARTICLE | March 18, 2008

Use of the detective quantum efficiency in a quality assurance program

Proc. SPIE. 6913, Medical Imaging 2008: Physics of Medical Imaging

KEYWORDS: Chest, Imaging systems, Spatial frequencies, Sensors, X-rays, Quantum efficiency, Medical imaging, Image quality, Modulation transfer functions, X-ray imaging

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PROCEEDINGS ARTICLE | March 13, 2007

Development of a portable instrument for automated measurements of the detective quantum efficiency of x-ray detectors

Proc. SPIE. 6510, Medical Imaging 2007: Physics of Medical Imaging

KEYWORDS: Imaging systems, Spatial frequencies, Sensors, X-rays, Quantum efficiency, Manufacturing, Modulation transfer functions, X-ray imaging, X-ray detectors, Prototyping

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PROCEEDINGS ARTICLE | March 2, 2006

A method to measure the temporal MTF to determine the DQE of fluoroscopy systems

Proc. SPIE. 6142, Medical Imaging 2006: Physics of Medical Imaging

KEYWORDS: Point spread functions, Sensors, Video, X-rays, Quantum efficiency, Data acquisition, Image intensifiers, Modulation transfer functions, Fluoroscopy, X-ray imaging

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PROCEEDINGS ARTICLE | April 20, 2005

Comparison of air space measurement imaged by CT, small-animal CT, and hyperpolarized Xe MRI

Proc. SPIE. 5745, Medical Imaging 2005: Physics of Medical Imaging

KEYWORDS: Optical spheres, Tissues, Magnetic resonance imaging, Image processing, Medical research, Lung, Xenon, Solids, Computed tomography, Spherical lenses

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PROCEEDINGS ARTICLE | May 6, 2004

Penalty on the detective quantum efficiency from off-axis incident x rays