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Integration of X-ray and MRI systems.

Stanford University.

Integration of X-ray and MRI systems.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Integration of X-ray and MRI systems.
Author:	Wen, Zhifei.
Description:	156 p.
Notes:	Adviser: Norbert J. Pelc.
Notes:	Source: Dissertation Abstracts International, Volume: 66-08, Section: B, page: 4268.
Contained By:	Dissertation Abstracts International66-08B.
Subject:	Physics, General.
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3186417
ISBN:	9780542287206

Integration of X-ray and MRI systems.
Wen, Zhifei.

Integration of X-ray and MRI systems. - 156 p.

Adviser: Norbert J. Pelc.

Thesis (Ph.D.)--Stanford University, 2005.

X-ray fluoroscopic imaging provides two-dimensional (2D) projection images with high temporal and spatial resolutions, while magnetic resonance imaging (MRI) has the ability to image any plane in 3D space with excellent soft tissue contrast and powerful physiological information. Integration of these two complementary imaging modalities can greatly benefit numerous image-guided minimally invasive procedures. At Stanford, an x-ray/MR hybrid system has been developed by placing an x-ray tube and detector inside the magnet of an open-bore interventional MR scanner in a configuration without requiring patient movement. However, the proximity of the two systems can cause one to degrade the performance of the other. The influence on the x-ray system by the MR system mainly results from its magnetic field at the location of the x-ray tube. If the magnetic field is parallel to the axis of the tube, it can change the size and shape of the x-ray focal spot by affecting the trajectories of the primary electrons, and increase the tube output by confining the backscattered electrons. If the magnetic field is misaligned with the tube axis, the electron beam can be deflected. These effects are studied analytically, numerically and experimentally. Experimental data agree well with theoretic analysis and computer simulations. Modifications to the x-ray tube are proposed to make it more robust for working in a misaligned magnetic field. The impact on the MR system from the x-ray system stems from the x-ray detector placed underneath the patient table near the MR imaging volume. Magnetic components inside the detector can be magnetized in the magnetic field and create an additional magnetic field that degrades the field homogeneity of the MR system. We use rare-earth permanent magnets located proximate to the detector to compensate for the unwanted field. The strengths and locations of the magnets are optimized with the measured detector field and the MR image quality is significantly improved after shim magnets are deployed. Our work effectively minimized interferences between the x-ray and MR systems. Clinical procedures performed with our system show great promise for enhanced diagnosis and improved guidance of therapy.

ISBN: 9780542287206Subjects--Topical Terms:

227017
Physics, General.

Integration of X-ray and MRI systems.
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