Research

The National Institutes of Health

A dual-layer flat panel x-ray detector based on an engineered amorphous chalcogenide alloy for quantifying coronary artery calcium, 2022, R01, PI

Identification of Coronary artery calcification (CAC) is clinically important because it is used for cardiovascular risk and therapy decision making. Currently, CAC is quantified by computed tomography (CT), however, CT-based population screening is not widely utilized due to cost and radiation burden. Chest x-rays (CXR) are the most common medical imaging procedure and have higher availability than CT in low-resource settings, lower radiation dose, and higher patient throughput that could be used for screening purposes. Unfortunately, due to the lack of quantification in CXR, only qualitative descriptors are possible. The objective of this proposal is therefore to bring much-needed quantification to CXR, particularly for detecting and quantifying CAC by combining a new dual-layer x-ray detector and artificial-intelligence based image processing. The proposed dual-layer detector utilizes alloys of amorphous selenium (a-Se) that achieve favorable electro-optical properties (e.g., higher charge carrier mobilities and higher gain) compared to conventional a-Se based x-ray detectors. This technology has four major components: (1) a top layer direct convection a-Se alloys on an imaging backplane, (2) a bottom layer indirect conversion a-Se alloy with intrinsic gain on an imaging backplane coupled to a scintillator, (3) top panel and bottom panel integration into a dual-layer detector, and (4) a machine learning algorithm that enhances accuracy of the quantitative information from the dual-layer detector. The detector development leverages a mature platform from Varex Imaging, a leading manufacturer of x-ray detectors. We expect to show that the proposed system has higher spatial resolution images and higher sensitivity to detect small, high contrast features (calcifications) and to separate materials such as calcium from soft tissue. This approach will allow accurate quantification of predictive factors and will have immense impact in proactive healthcare, improving the clinical outcomes of patients, and reducing the number of deaths associated with cardiovascular disease.

Enabling Brain Parametric Imaging of Alzheimer’s disease with organ-dedicated PET, 2021, R01-Supplement, PI

Dynamic positron emission tomography (PET) imaging with tracer kinetic modeling has the potential to enable quantitative characterization of Alzheimer’s disease and related dementias (ADRD) but suffers from invasive blood sampling and limited spatial resolution for imaging small brain vasculature. We will augment our high spatial resolution dedicated scanner to evaluate spillover and partial volume effects from the carotid-derived input function for brain kinetic quantification. An optimization-derived input function method will have the potential to further improve the performance of our dedicated system and it can be applied to many existing brain-dedicated scanners and clinical scanners for ADRD imaging.

High spatial resolution dedicated head and neck PET system based on cadmium zinc telluride detectors, 2018, R01-PI

Current head and neck cancer diagnosis and treatment planning suffers from poor spatial resolution of whole-body positron emission tomography (WB-PET) scans. In the neck, where tissue layers are thin, the spatial resolution of WB-PET (4-6 mm) is not sufficient to evaluate small lymph nodes (<5 mm), establish how far the tumor has invaded locally, and guide the decision to resect a tumor rather than irradiate and deliver chemotherapy. This proposal, responsive to PAR-18-009, “Academic-Industrial Partnerships to Translate and Validate in vivo Cancer Imaging Systems,” seeks to address this problem by translating high resolution radiation detection technology to head and neck imaging. The project research team consists of researchers from the Department of Nuclear, Plasma, and Radiological Engineering at the University of Illinois at Urbana-Champaign and eV Products Inc., a world leader in semiconductors for radiation detection. To achieve its goal, this research will pursue the design, development, optimization, characterization, and validation of a dedicated head and neck PET scanner. The proposed system will be the first head and neck scanner to exhibit features as small as 1 mm with high photon sensitivity, enabled by the use of high energy and spatial resolution properties of cadmium zinc telluride (CZT) crystals. This system will be integrated into a transportable stage and is designed to not interfere with the conventional workflow of the WB- PET scan procedure, and has the additional attraction of being used for dynamic PET studies. We expect that this dedicated head and neck PET imaging system will deliver the following new capabilities: i) detection and evaluation of small lymph nodes, ii) improved treatment planning and determining the extent of the tumor growth, and iii) improved confidence in differentiating post-treatment change from tumor recurrence. The system will consist of two panels and have an adjustment for panel-to-panel separation distance. Each panel contains 150, 4x4x0.5 cm3 cross-strip CZT crystals covering a 20×15 cm2 panel area. The crystals will be mounted in an edge-on configuration for increased photon detection efficiency. A novel event recovery scheme based on the 3D position sensitive cross-strip crystals will be developed to recover multiple interaction photon events, reject random events, and significantly increase the photon sensitivity of the system. In the final year of the project, a study consisting of 20 patients will be conducted to evaluate the performance of the developed prototype and validate the potential benefits.

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The Department of Energy

Development and Characterization of a Large Area Selenium Avalanche Photodetector for Photon Detection from Ultraviolet to Infrared Wavelengths, 2021, DOE, PI

Over the last few years, silicon photomultiplier (SiPM) technology has advanced tremendously in terms of cost and performance, and there has been a growing interest to replace photomultiplier tubes (PMTs) in high-energy and nuclear physics experiments. However, SiPMs still require improvements to enhance quantum efficiency (QE) of ultraviolet (UV) and blue wavelengths, reduce dark counts, and increase uniformity and size. Enhancing QE to UV-blue wavelengths has been identified as an important technological advancement to enable the next generation of experiments in high energy physics (HEP). In addition, a subset of experiments requires large area detectors for more complete coverage of the scintillators (e.g., multiple faces of a crystal calorimeter), water, or liquid argon to ensure sufficient light detection (e.g., Cherenkov light and/or scintillation light).

We propose to adapt cutting-edge thin-film semiconductor evaporation techniques to develop new photodetectors for high-energy physics applications. We envision engineering a comprehensive, breakthrough research program that combines engineering material interfaces, electrodes configurations, and device structures to advance selenium-based detector technology for enabling an extended wavelength sensitivity over large area in future HEP applications. Amorphous selenium (a-Se) is a glass-former capable of deposition at high rates by thermal evaporation over a large area. It has a bandgap of 2.2 eV and can achieve a photodetection efficiency of approximately 90% at a wavelength of 400 nm. Our main objectives are to: (i) determine material and interfaces to improve the a-Se radiation tolerance and prevent radiation-induced damage, (ii) optimize pixel configuration and device structures for picosecond timing resolution and simple fabrication, and (iii) enable detection of photons with spectral coverage from UV to red wavelengths over a large area utilizing amorphous selenium with doping gradient based on wavelength-dependent absorption coefficient.

Non-destructive, three-dimensional Imaging of processes in rhizosphere utilizing high energy photons, 2021, DOE, PI

The interactions between plant roots and soils are extensively complex. Most of these interactions occur in the rhizosphere. The field of rhizosphere studies has increasingly gained wide attention, because many biological and physicochemical processes at multiple scales in the Earth system are critically linked to rhizosphere activities. However, existing approaches often rely on taking disturbed samples from the root-soil system, which fundamentally deviates from reality.  We are collaborating with Stanford (Dr.  Craig Levin and Dr. Adam Wang)  to demonstrate the capability of the developed PET and micro-CT scanners in imaging rhizosphere systems for in situ, 3D images.

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The Department of Defense

Amorphous selenium avalanche photodetector for isotope identification, 2020, DTRA, PI

A new approach to stand-off detection of special nuclear material using big data analytics, 2018, DARPA, Co-PI

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Real-time AI for Programmable Training Arrays, 2022, PI, RCSA Scialog Advanced BioImaging

The Scialog program was created in 2010 by RCSA, which oversees its administration. Scialog – short for “science + dialog” – funds early career scientists to pursue transformative research with their fellow grantees on crucial issues of
scientific inquiry.

Basic science of avalanche behavior in chalcogenide alloys, 2021, PI Western Digital Technologies, INC

Amorphous selenium is a leading material for next generation X-ray detectors. The high device sensitivity is due to avalanche breakdown when an X-ray hits the selenium layer under high electric fields. A similar mechanism may occur in other chalcogenide alloys currently under investigation for a variety of applications. Development of X-ray or light detectors based on these films could provide insight into the general transport physics and it may also lead to improved X-ray medical detectors.

Investigation of flexible substrates for stable, large-area UV & X-ray detectors, Collaboration with Esmaeelpour Group at Missouri S&T

Submersible, data-driven lab-on-a-chip for real-time monitoring of water quality, 2020, CITRIS and the Banatao Institute, PI

Precision robotic-assisted implantation for preclinical stereotactic neuro-surgery, 2019, Zhejiang University-University of Illinois at Urbana-Champaign Institute Research Program, PI

Spatio-Temporal Socio-Technical risk analysis for agriculture networks, 2017, US Army, Co-PI

Improving quantitative molecular imaging accuracy in clinical practice and assessing response to therapy, 2017, Carle Illinois Collaborative Research Seed Funding Program, PI