Radiation Imaging Group harvests rewards from summer's work

9/8/2015 Susan Mumm, Editor

Written by Susan Mumm, Editor

Radiation Imaging Group harvests rewards from summer's work


Associate Prof. Ling-Jian Meng, middle, and his students.
Associate Prof. Ling-Jian Meng, middle, and his students.

NPRE’s Radiation Imaging Group had a successful summer, with awards and recognitions for several student research contributions.


Second Place, Best Poster Presentation Award, Society of Nuclear Medicine and Medical Imaging (SNMMI) 2015 Annual Meeting

Graduate student Xiaochun Lai was recognized for his poster presentation on the group’s development of simultaneous imaging using Single-Photon Emission Computed Tomography (SPECT) and Magnetic Resonance Imaging (MRI).

While the MRI is a powerful tool in producing high resolution imaging of soft tissues, it is a slow sensitive imaging tool. On the other hand, SPECT and Positron Emission Tomography (PET) are high sensitive imaging tools, equipped with probes to study bioprocesses on the molecular level. Meng’s group has been able to overcome challenging technological issues of strong interference in the two techniques’ modalities to enable them to work simultaneously.

“The (SPECT) detector has to work inside the MRI, where it is a tough environment for the radiation detector,” Lai said. “(The MRI’s) magnetic field is about 60,000 times higher than the one of Earth, and this strong magnetic field will make the convection detector malfunction. Besides, the detector is not allowed to degrade the performance of the MRI: the MRI field requires very high uniformity, with the difference less than several parts per million. Any magnetic component in the detector will distort this field and consequently affect the performance of MRI imaging.”

Over the past five years, Meng’s group has constructed an ultrahigh resolution stationary magnetic resonance-compatible SPECT system for small animal imaging using second-generation energy-resolved photon-counting (ERPC) detectors. The system can achieve very high resolution with relatively high sensitivity.

A potential application for the system is in tracking neuro stem cells, being considered by scientists as possible carriers for targeted delivery of therapeutics to brain tumors.

“Non-invasive imaging approaches using our SPECT/MRI with high sensitivity and high spatial resolution can provide invaluable information of the dynamics and distribution of stem cells in the normal brain and malignant tissue,” Lai said. “With collaborators from the University of Chicago, we have demonstrated the capability of tracking several hundred neuron stem cells in mice brain.”

Finalists for Young Investigator Award, SNMMI 2015 Annual Meeting

Graduate students Andrew Groll and Jonathan George both were picked to be among the top five finalists and were recognized with Honorable Mentions in competition for the Young Investigator Award in the SNMMI Conference’s Computer and Instrumentation competition.

Groll’s work, “Evaluation of Hybrid Pixel-Waveform (HPWF) CdTe and CZT Detectors for Sub-500 μm Resolution PET Imaging for Mouse Brain Studies,” explored the use of CdTe semiconductor detectors for use in small animal PET imaging.

“Semiconductor detectors have been seen as a challenge to the field that is filled with scintillation detectors,” Groll said. “Prof. Meng and I have been pushing toward acceptance of semiconductor detectors for imaging transgenic mouse models, which can represent some form of neurodegenerative disease. In order to adequately investigate the biology of these models, higher resolution imaging systems are necessary, which is what semiconductor PET would offer.”

George’s project, “Evaluation of X-ray Fluorescence Emission Tomography for Real-time Assessment of Photodynamic Therapy Effect,” studies the use of x-ray fluorescence emission tomography (XFET) for assessing the therapeutic effect of x-ray induced photodynamic therapy (PDT) in real-time.

According to George, “X-ray fluorescence occurs when an incident x-ray interacts with a high atomic weight, freeing an electron from an orbital. Another electron moves into the vacant orbital, and the energy difference between orbitals emits a fluorescent x-ray of known energy. These fluorescent x-rays can be detected and imaged in a process called XFET.”

In PDT treatment, a photosensitizer compound uses a specific wavelength of light or x-rays to active a drug and kill nearby cells. “X-ray induced PDT, as compared to typical optically induced PDT, can penetrate into deeper parts of the body to precisely activate the PDT effect in a deeply embedded tumor,” George said.

George’s experimental study evaluated XFET’s feasibility for this purpose.

The SNMMI Annual Meeting was a gathering of leading molecular imaging and nuclear medicine physicians, radiologists, cardiologists, pharmacists, scientists, lab professionals, and technologists, representing the world’s top medical and academic institutions and centers.

Engineering at Illinois Scholars Undergraduate Research (ISUR) Program

Senior Dan Strat has been selected for this program for his project to combine two imaging methods: X-ray induced luminescence-computed tomography (XLCT) and X-ray induced fluorescence computed tomography (XFCT).

“X-ray luminescence uses X-rays to induce the emission of visible light, while X-ray fluorescence uses X-rays to induce the emission of other X-rays,” Strat said. “The major concept of these methods is that nanoparticles would be injected into the body near a region of interest. These nanoparticles get excited inside the body via stimulation by an X-ray beam and then emit either visible light or other X-rays. The emitted photons are detected by special detectors and are then processed into an image.”

While X-ray induced luminescence has a higher sensitivity, it lacks in tissue penetration because visible light cannot pass through tissue easily. Conversely, fluorescence has higher tissue penetration, but lower sensitivity. Combining the two will allow researchers to accentuate the strengths of each.

“Naturally, a system where the strengths of one modality make up for the weaknesses in the other seems like the next logical step in the evolution of X-ray stimulated emission tomography,” Strat said.

ISUR offers selected students a two-semester experience with a research learning community. Through ISUR, students become familiar with research methodologies, develop research skills, gain exposure to what graduate school entails, and gain experience needed for graduate school acceptance. ISUR scholars present their research in an annual expo held in the spring.

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This story was published September 8, 2015.