Current Research Projects
Imaging and Tracking Radiolabeled Stem Cells for Targeting Glioblastoma in Mouse Brain Models
We will perform in vivo SPECT Imaging of Stem Cells, functionalized with radiolabeled mesoporous silica nanoparticles for dynamic tracking of the most aggressive primary malignant brain tumor: the glioblastoma multiforme. The study will take advantage of the excellent performaces provided by the state-of-art MRC-SPECT-I system, developed in our lab.
[3-D rendering of fused SPECT/CT images of a mouse head acquired with MR-SPECT-I and Inveon microPET/SPECT/CT. Two small populations of radiolabeled stem cells injected in two hemisferes are visible in the image]
Next Generation of SPECT Imaging System based on Artificial Inverted Compound-Eye Gamma Cameras
As an ommatidium is the photoreceptor unit in the natural compound eye, the basic element in the MRC-SPECT-II system is the micro-pinhole-camera-element (MPCE) that consists of a narrow-open-angle pinhole which projects a small fraction of the object volume onto the active area of the high-resolution gamma ray detector. A Synthetic Innverted Compound Eye (S-ICE) gamma camera is a 3D arrangement of several S-ICE camera modules, dense 2D arrays of independent MCPEs. The uniqueness of this system design is the ability to combine attractive features: a dramatically improved sensitivity, an excellent imaging resolution, an unprecedented density of angular sampling in the field-of-view (FOV) and an increased flexibility in imaging performance. Moreover, the compact system design could be placed inside small-bore pre-clinical MRI scanners allowing simultaneous MRI and SPECT imaging.
[ A triple-head detector prototype setup for experimental evaluation of the MRC-SPECT-II system]
Statistical Techniques for the Design and Optimization of Complex Imaging Systems
Given the increasing complexity of modern radiological imaging systems, how do we know whether a given system has the most efficient configuration for collecting useful imaging information? and if not, how do we optimize the system that is characterized by hundreds or thousands of system parameters and by an infinite number of possible combinations? We have asnwered developing a statistical technique, based on the Modified Uniform Cramer-Rao bound (M-UCRB), to model the responses of any radiological imaging system to an arbitrarily given object, and to predict the properties provided by the system. Then we have integrated it in a general system optimization strategy that could accommodate almost any system parameter. It implements a systematic search through a very large parameter space to construct designs that provide the most statistical information possible and have low variances.
[ The Inverted Compound Eye Gamma Camera design as a challenging platform for applying the hardware optimization technique]
Hybrid X-ray Fluorescence, Luminescence and Transmission Computed Tomography
We develop a hybrid imaging modality that relies on X-ray fluorescence (XF), X-ray luminescence (XL), and X-ray transmission (XCT) measurements to produce 3-D multicolor images for guiding and monitoring nanoparticle-mediated microbeam therapy. During the microbeam therapeutic delivery process, a highly collimated X-ray beam irradiates the object. The pre-administrated metal-containing nanoparticles (NPs) preferably absorb the X-rays to produce therapeutic effects or directly from radiation effects induced by low-energy secondary electrons. Combining these three imaging techniques would provide a unique tool for guiding therapeutic delivery with highly detailed spatial and functional information: (1) the XF signal could determine the distribution of the NPs in the object, (2) the XL signal could provide quantitative information and indirect spatial mapping of the scintillation process induced by the X-ray irradiation of nanophosphors conjugated with photosensitizers and,finally, (3) the micro-CT images provide structural details of the object for confirmation of the delivery of the beam to the target area.
[ Preliminary imaging studies of a NP-loaded double-tube phantom that was filled with yttrium oxide nanoparticles in powder on the inside and sodium bromide aqueous solution on the outside]
A Prototype Ultrahigh Resolution PET Imaging System based on Hybrid Pixel-Waveform (HPWF) CdTe Detectors
Our work has focused on the development of an application specific high resolution semiconductor PET imaging system. While potentially not a substitute for scintillation based modalities, the ultrahigh resolution offered by pixelated anode CdTe detectors is an extremely attractive option for the preclinical environments where animal mouse model studies can be performed. In our efforts to prove the resolution potential, we have also gone forward to address the challenges imposed through the use of semiconductor detectors for PET imaging. Through the implementation of an approach which utilizes information from both the cathode side and the anode side, known as the hybrid pixel-waveform (HPWF) method, we are able to (A) derive the depth of interaction (DOI), (B) improve overall system energy resolution, (C) improve system timing resolution, and (D) reduce the overall complexity of the readout circuitry. This method makes the application of ultrahigh resolution an attractive option for imaging for preclinical imaging with a focus on neurodegenerative disease, such as Alzheimer's (AD) and Parkinson's Disease (PD)
[PET Reconstruction Image of three Capillary Tubes and relative Sinogram in a Photon Count Study]
Ultrahigh-Performance Gamma Ray Imaging Detectors
We develop different high performance gamma ray imaging detectors for radiological imaging applications. We have combined compact CZT or CdTe semiconductor imaging detectors with custom-designed CMOS readout ASICs. These detectors provide excellent spatial, energy and timing resolution, and an adequate stopping power for medical applications.
Past Research Projects
Imaging and tracking T-cells for brain cancer immunotherapy
A collaboration with Dr. Ed Roy's group at the University of Illinois
[3-D rendering of a fused SPECT/CT image of a mouse head. A small number (down to 1500) of radiolabeled T-cells are visible in the image]
Imaging of pancreatic beta-cell beta cells with combined SPECT/MR systems
A collaboration with Dr. Chin-Tu Chen's group at the Department of Radiology of the University of Chicago
3-D mapping of naturally occurring trace-metal in the brain
A collaboration with Dr. Patrick La Riviere's group at the University of Chicago
[3-D rendering of CT images from a Zebrafish Sample with 1% osmium tetroxide acquired using our X-Ray Stimulated Emission Tomography System]
Superhigh resolution PET imaging of mouse brain
A collaboration with Dr. Y-C. Tai's group at the Washington University in St Louis, and Dr. Q Z Li's group at the Massachussetts General Hospital