We propose to research and design an MR compatible rotating anode x-ray tube that can function immediately adjacent to a high field, 1.5T closed bore (CB) magnet, in order to maximize flexibility of X-ray/MR hybrid system design. Such an x-ray tube, integrated with other already proven components such as digital flat panel and high-frequency generator, would enable MRI information to be accessible during x-ray image-guided critical interventional procedures such as cardiac stem cell delivery, stroke treatment and liver cancer management. With a short travel distance limited only by the length of the magnet, the proposed design would minimize patient travel. This will allow the best utilization of the high resolution, high contrast and real-time imaging capabilities of angiography to be combined with excellent physiology assessment (flow, perfusion, soft tissue motion) and 3D soft tissue imaging of MRI, so that changes during a procedure can be assessed. Previously we successfully demonstrated the clinical use of a static anode x-ray system placed in the bore of a 0.5T GE Signa-SP open magnet (SP-XMR) for guiding a range of challenging procedures including creation of neo-vagina, and sclerotherapy for arteriovenous malformations. For many of the ~50 patient cases, intervention under x-ray alone had not been successful or was considered too risky;conversely, the clinicians could not have carried out the intervention under MR guidance alone. Presence of the closely integrated system enabled a minimally invasive approach. However, the SP-XMR system has modest x-ray output and a specialized magnet design which restrict wide clinical acceptance. On the other hand, operating a rotating anode x-ray tube adjacent to a high-field magnet produces significant challenges. We therefore propose innovative research to develop x-ray tube sub-components including new, MR compatible motors, and electron optics, with appropriate feedback mechanisms, so as to create a truly MR-compatible rotating-anode x-ray tube. This x-ray tube could be placed adjacent to the shortest bore magnets currently available (e.g. Siemens Espree, 4 ft. in length) allowing a translation between fields-of-view of x-ray and MR of as little as three feet. This table translation is seen often in the x-ray fluoroscopy suite when, for example, guiding catheters from the groin into the neurovasculature. Initial research and design of the new x-ray tube will include finite element modeling of both electron beam and motor components, modeling of heat distribution properties, and then using FE models as a guide, construction and testing of the components within known fields. The most efficient and MR compatible components will then be combined into an x-ray tube, and testing of the tube will be carried out to verify that tube output, focal spot distribution and lifetime are equivalent to current state-of-the-art x-ray tubes used in the fluoroscopy suite for the range of MR fields of interest. This x-ray tube will enable the next generation of hybrid XMR systems.

National Institute of Health (NIH)
National Institute of Biomedical Imaging and Bioengineering (NIBIB)
Research Project (R01)
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Biomedical Imaging Technology Study Section (BMIT)
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Lopez, Hector
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Stanford University
Schools of Medicine
United States
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Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo et al. (2014) Electrostatic focal spot correction for x-ray tubes operating in strong magnetic fields. Med Phys 41:112302
Shin, Mihye; Lillaney, Prasheel; Hinshaw, Waldo et al. (2013) Design optimization of MR-compatible rotating anode x-ray tubes for stable operation. Med Phys 40:111913
Lillaney, Prasheel; Shin, Mihye; Hinshaw, Waldo et al. (2013) Novel motor design for rotating anode x-ray tubes operating in the fringe field of a magnetic resonance imaging system. Med Phys 40:022302
Lillaney, Prasheel; Shin, Mihye; Conolly, Steven M et al. (2012) Magnetostatic focal spot correction for x-ray tubes operating in strong magnetic fields using iterative optimization. Med Phys 39:5567-83
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Bracken, John A; Komljenovic, Philip; Lillaney, Prasheel V et al. (2009) Closed-bore XMR (CBXMR) systems for aortic valve replacement: x-ray tube imaging performance. Med Phys 36:1086-97
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