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There are concerns about workers repeatedly exposed to magnetic fields exceeding regulatory limits with respect to modern magnetic resonance imaging (MRI). As a result, there is need for an ambulatory magnetic field dosimeter capable of measuring these fields in and around an MRI scanner in order to evaluate the regulatory guidelines and determine any(More)
PURPOSE This article aims to present a fast, efficient and accurate multi-layer integral method (MIM) for the evaluation of complex spatiotemporal eddy currents in nonmagnetic and thin volumes of irregular geometries induced by arbitrary arrangements of gradient coils. METHODS The volume of interest is divided into a number of layers, wherein the(More)
Recent studies have shown that rotating a single RF transceive coil (RRFC) provides a uniform coverage of the object and brings a number of hardware advantages (i.e. requires only one RF channel, averts coil-coil coupling interactions and facilitates large-scale multi-nuclear imaging). Motion of the RF coil sensitivity profile however violates the standard(More)
In MRI, healthcare workers may be exposed to strong static and dynamic magnetic fields outside of the imager. Body motion through the strong, non-uniform static magnetic field generated by the main superconducting magnet and exposure to gradient-pulsed magnetic fields can result in the induction of electric fields and current densities in the tissue. The(More)
While recent studies have shown that rotating a single radio-frequency (RF) coil during the acquisition of magnetic resonance (MR) images provides a number of hardware advantages (i.e., requires only one RF channel, avoids coil-coil coupling and facilitates large-scale multinuclear imaging), they did not describe in detail how to build a rotating RF coil(More)
A new passive shim design method is presented which is based on a magnetization mapping approach. Well defined regions with similar magnetization values define the optimal number of passive shims, their shape and position. The new design method is applied in a shimming process without prior-axial shim localization; this reduces the possibility of(More)
MRI-LINAC is a new image-guided radiotherapy treatment system that combines magnetic resonance imaging (MRI) and a linear particle accelerator (LINAC) into a single unit. Moving (i.e., rotating or translating) the patient inside the strong magnetic field of the split MRI-LINAC magnet can potentially induce high levels of electric fields and corresponding(More)
Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) was capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo sensitivity profiles (B1(-)) become(More)
Conventionally, magnetic resonance imaging (MRI) is performed by pulsing gradient coils, which invariably leads to strong acoustic noise, patient safety concerns due to induced currents, and costly power/space requirements. This modeling study investigates a new silent, gradient coil-free MR imaging method, in which a radiofrequency (RF) coil and its(More)
MRI-LINAC is a new image-guided radiotherapy treatment system that combines magnetic resonance imaging (MRI) with a linear accelerator (LINAC) in a single unit. One drawback is that the pulsing of the split gradient coils of the system induces an electric field and currents in the patient which need to be predicted and evaluated for patient safety. In this(More)