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Non-Conventional Multi-Source X-Ray Imaging: Cardiac, Breast Imaging and Cone Beam CT

T Zhang
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O Zhou
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M Speidel
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S Hsieh

T Zhang1*, O Zhou2*, M Speidel3*, S Hsieh4*, (1) Washington University School of Medicine, St. Louis, MO, (2) The University of North Carolina at Chapel Hill, Chapel Hill, NC, (3) University of Wisconsin - Madison, Madison, WI, (4) UCLA, Anaheim, CA


4:30 PM : Tetrahedron Beam Computed Tomography based on multi-pixel x-ray source and its application in IGRT - T Zhang, Presenting Author
4:52 PM : Stationary digital tomosynthesis using carbon nanotube x-ray source array - O Zhou, Presenting Author
5:14 PM : Scanning-beam digital x-ray technology for fluoroscopy and angiography - M Speidel, Presenting Author
5:36 PM : Spatially distributed x-ray sources for inverse geometry CT - S Hsieh, Presenting Author

TU-H-601-0 (Tuesday, August 1, 2017) 4:30 PM - 6:00 PM Room: 601

Tetrahedron Beam Computed Tomography Based on Multi-pixel X-Ray Source and its Application in IGRT - Tiezhi Zhang

Cone beam CT (CBCT) is an important online imaging modality for image-guided intervention and radiotherapy. But its image quality is significantly inferior to fan-beam CT and compromises the quality of radiation treatment and intervention procedures. Based on the emerging multi-pixel x-ray source technology, we are developing a novel Tetrahedron Beam CT (TBCT) which rapidly scans a stack of fan-beams in axial direction while the gantry slowly rotates about the subject. Besides its scatter-rejecting fan-beam geometry, TBCT also employs the same high quality discrete x-ray detector as helical CT, which has a faster speed, higher dynamic range and detective quantum efficiency (DQE) compared to flat-panel detector of CBCT. We are also developing high power multi-pixel thermionic emission x-ray (MPTEX) source for TBCT, which comprises up to 50 oxide-coated cathodes and an elongated fixed anode. This talk will introduce the principles and limitations of TBCT and MPTEX technologies.

Stationary Digital Tomosynthesis Using Carbon Nanotube X-Ray Source aArray - Otto Zhou

The purpose of this work is to develop a spatially distributed field emission x-ray source array technology and to evaluate its applications in digital tomosynthesis imaging. Recent progresses in both the source technology and imaging devices will be summarized.

Spatially distributed x-ray source array provides the possibility of recording the projection images needed for tomosynthesis reconstruction by electronically activating the individual x-ray beams without any mechanical movement of either the source, detector or patient. It can potentially reduce the tomosynthesis imaging time and increase the image resolution by removing/minimizing image blurs caused by the x-ray source and patient motion. Using the carbon nanotubes (CNT) as the electron field emitters, we have developed x-ray source arrays with various configurations and constructed prototype stationary tomosynthesis imaging systems based on this unique source array technology.

Since the initial report of the CNT x-ray array technology, considerable progress has been made in terms of the source stability, consistency, and output power. Dedicated electronics have been developed to compensate the variations between the individual emitters. Prototype stationary tomosynthesis systems for breast, lung, and dental imaging have been constructed and are under clinical evaluation. In this talk we will discuss the performance of these imaging systems with the emphasis on the digital breast tomosynthesis system and report the initial clinical imaging results.

Digital tomosynthesis using the spatially distributed CNT x-ray source array technology increases the image resolution and reduces the imaging time.

Scanning-beam Digital X-Ray Technology for Fluoroscopy and Angiography - Michael Speidel

X-ray fluoroscopy and angiography remain essential imaging tools for cardiac interventional procedures. However radiation dose is an ongoing source of concern, and the conventional x-ray projection geometry cannot portray device positions in three dimensions. The scanning-beam digital x-ray (SBDX) system is a technology under development which uses a multisource x-ray tube in order to improve dose efficiency and achieve depth-resolved imaging at fluoroscopic frame rates. The components of the system are an x-ray tube with an electron beam that scans over an array of focal spot positions, a multihole collimator, a high-speed photon-counting detector, and a real-time reconstructor. Each image frame is reconstructed from a high speed tomosynthesis scan of a narrow x-ray beam over the patient. Advantages of this design include a reduction in detected x-ray scatter, a reduction in primary x-ray fluence at the skin entrance, and the ability to perform real-time 3D catheter tracking. The multisource tube also allows for tailoring of output from individual focal spots. Technical challenges include output limitations imposed by the use of tight beam collimation. This talk will introduce the principles and limitations of SBDX technology and present results from recent studies.

Spatially Distributed X-Ray Sources for Inverse Geometry CT - Scott Hsieh

Inverse geometry CT (IGCT) is a possible architecture for next-generation CT scanners that deploys an array of small x-ray sources opposite a small detector. These x-ray sources are energized in sequence to build up the sinogram and would enable dose reduction by modulating the power on each individual source (“virtual bowtie”) and cone beam artifact reduction by using several sources distributed in the z-direction. Challenges include the need for flux requirements necessary to compensate for the reduced size of the detector. In this talk, we will describe the design rationale for the existing versions of IGCT, including multiple-detector, stationary-source, and multi-source. Results of a recent prototype system using dispenser cathode emitters will also be presented. IGCT presents a development pathway for modern CT scanners that presents several advantages over standard architectures and which leverages advances in distributed source technology. It is well suited for pediatric populations because of its improved dose efficiency, or whole-organ perfusion imaging because of its ability to acquire large volumes in an axial scan without cone beam artifacts.

Learning Objectives:
1. Learn how multi-source x-ray tube design may provide clinical benefit in CT, mammography, and fluoroscopy applications.
2. Understand the different approaches to multi-source x-ray tube design and the associated imaging geometries.
3. Understand the advantages and limitations of multi-source imaging system design relative to conventional design.

Funding Support, Disclosures, and Conflict of Interest: Zhou was partially supported by the NCI CCNE at UNC and NCI,NIDCR,UNC and Carestream Health grants. Zhou is a board director of XinRay Systems which develops and commercializes CNT x-ray source technology. Speidel was supported by NIH Grant R01HL084022. Work reported by Hsieh was supported by NIH Grant R01EB006837.


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