Research Highlight
Research Highlights
High resolution physiologically gated micro-computed tomography for in vivo small animal imaging
The aim of this research is to develop a dynamic micro-computed tomography (micro-CT) system with enhanced spatial and temporal resolution and more versatile imaging capabilities compared to the current commercial micro-CT scanners, and to explore its applications for biomedical research. The goal is to provide a scanner which will maximize image resolution for in vivo scanning of mice. The proposed system will utilize a micro-focus field-emission x-ray source recently demonstrated in our laboratory. Compared to the conventional micro-focus x-ray sources with thermionic cathodes, the new carbon nanotube (CNT) based field emission x-ray source offers high resolution at significantly reduced size, fast pulsation capability currently not possible, and the potential for higher flux. The proposed CT scanner with the gated field-emission x-ray source, digital 2D x-ray detector and motorized object stage can synchronize x-ray exposure, data collection, objection rotation and the physiological signal of the object. The system will enable triggered and gated imaging at the rate of ~10 millisecond (msec) per image, and will have a high spatial resolution. These capabilities will provide new imaging modalities for biomedical research such as dynamic cardiac and pulmonary imaging of small animals.
This research is funded by grants from NIBIB and NCI CCNE.
Digital breast tomosynthesis for early detection of human breast cancer
Mammography is currently the most effective screening and diagnostic tool for early detection of breast cancer, and has been attributed to the recent reduction of breast cancer mortality rate. However the current 2-view mammography method lacks sensitivity and has a very high false alarm rate with 70-90% biopsies performed turning out negative. X-ray digital breast tomosynthesis (DBT) is an emerging technique for producing multi-slice images to provide depth resolution and improved contrast. It has the potential to allow radiologists to see tumors at an early stage even in very dense breasts using a similar dose as the common two-view mammography. It is generally expected that DBT scanners will replace a large fraction of conventional mammography systems in the coming years. Currently several DBT scanners from commercial vendors are under clinical trial.
The goal of this project is to develop the next generation DBT scanner with significantly improved system performance at potentially reduced dose and cost. All current commercial prototype DBT scanners use a regular full-field digital mammography (FFDM) system to generate a series of projection views from a limited angle range using a single x-ray source that moves along an arc above the compressed breast. Such scanners have several intrinsic limitations: 1) the source rotation leads to long scanning time and discomfort for patients from breast compression; and 2) the slow motion of the source leads to motion blurring and system instability that limited the spatial resolution. In addition the long scanning time prevents the adaptation of advanced imaging methods such as dual energy, quasi-monochromatic, and k-edge imaging which can potentially provide better contrast and reduce imaging dose.
We propose to develop a novel stationary DBT scanner to mitigate the above limitations. This proposed device is based on the new carbon nanotube (CNT) multi-pixel field emission x-ray (MBFEX) technology demonstrated by our team. The pixilated and spatially distributed MBFEX source can generate x-ray radiation from multiple views without any mechanical motion of the source, detector, or object. This enables the design of tomography systems with great flexibility in source configuration and imaging sequence. It further enables multiplexing imaging – simultaneously collection of multiple images using one detector.
This research is currently supported by the following grants. NCI R01, NCI CCNE, UNC Lineberger Comprehensive Cancer Center, and DoD.
Microbeam Radiation Therapy for Potential Treatment of Brain Tumor
The fundamental challenge of radiotherapy is to treat cancer patient effectively and safely. Today, state-of-the-art radiotherapy provides excellent benefits for patients with early stage and radiosensitive cancers. These benefits diminish for patients with radioresistant tumors, such as brain or pancreas cancers, and patients with late stage tumors. For these patients radiation needed to eradicate radioresistant tumor can cause intolerable or fatal radiation damage to normal tissue. This is especially the case for pediatric patients, whose rapidly developing normal tissues are often more radiosensitive than their tumors, and who therefore cannot tolerate radiotherapy that would be curative for adults with the same disease. Microbeam Radiotherapy (MRT) is a unique form of radiation that has shown an extraordinary ability to eradicate tumor and spare normal tissue in numerous animal studies. Despite of its enormous clinical impact MRT has not been used on human, partially due to the lack of understanding of the underlying mechanism, which in turn is hindered by the lack of MRT devices. MRT radiation is technically extreme difficult to produce and it is performed in only two institutions in the world with synchrotron facilities.
We propose to develop the world first desktop image-guided MRT system for cancer research and treatment. The device is based on the carbon nanotube (CNT) field emission technology pioneered by our team at UNC. To carry out the proposed research we assembled a highly multidisciplinary and well-integrated research team including physicists, engineers, medical physicists, and cancer biologists at UNC and a local startup company, XinRay Systems. We have already carried out initial feasibility studies and they indicate that the novel desktop system is capable of producing characteristic MRT radiation comparable to the MRT radiation produced by the synchrotron facilities. The potential impact of the proposed work to cancer patients and health care system is inconceivably high. If human patients response to MRT in similar ways as reported in numerous MRT animal studies, MRT will literally revolutionize cancer treatment.
This project is current supported by grants from the National Cancer Institute Grand Opportunity program (RC2), and the NCI funded NC Center for Translational Research Clinical Sciences.