Abstract: Noncontact sensing of subject motion using Doppler radar within a magnetic resonance imaging (MRI) apparatus transmits a band-pass filtered continuous wave radio signal at a microwave frequency and receives a band-pass filtered reflected radio signal. The subject motion is detected from the received band-pass filtered reflected radio signal using a quadrature radio receiver with a software defined radio implementing Doppler radar. A first antenna, used for transmission and reception, is connected to the quadrature radio using band-pass filters and an RF coupler. A second antenna, used for reception, is connected directly to the quadrature radio using band-pass filters. The antennas are positioned in a bore of the MRI apparatus.

Abstract: The present invention provides a radiotherapy treatment apparatus that includes a treatment beam, a magnetic field disposed parallel collinear to the treatment beam, and a target that is disposed along the treatment beam. The treatment beam can be a charged particle beam, a proton beam, an electron beam, or a linear accelerator (Linac) beam. The magnetic field is from a magnetic resonance imager (MRI), a megavolt x-ray imager, or a kilovolt x-ray imager and is disposed to operate in coordination with operation of the treatment beam and to narrow the beam. The tumor is disposed to rotate with respect to the treatment beam and the magnetic field, or the treatment beam and the magnetic field are disposed to rotate up to 360° with respect to the target when mounted to a ring gantry. The apparatus can include a rotation angle dependent shim disposed to account for Earth's magnetic field.

Abstract: A method for detecting coupled RF current magnetic resonance (MR) objects in a body and determining MR risk is provided. The body is scanned with reverse circularly polarized RF. MR signals generated by coupling of the reverse circularly polarized RF with the RF current MR objects are detected. The detected MR signals are used to determine a risk value.

Abstract: An amplifier system providing improved Cartesian feedback is provided. A complex band pass error amplifier is provided. A quadrature up converter is connected to the complex band pass error amplifier so as to receive as input, output from the complex band pass error amplifier. An amplifier is connected to the quadrature up converter so as to receive as input, output from the quadrature up converter. A quadrature down converter is connected at or beyond the amplifier output so as to receive as input a signal proportional to that delivered by the amplifier as output to a load, wherein the complex band pass error amplifier is connected to the quadrature down converter so as to receive as a first input, output from the quadrature down converter and as a second input, a quadrature reference signal.

Abstract: An amplifier system providing improved Cartesian feedback is provided. A complex band pass error amplifier is provided. A quadrature up converter is connected to the complex band pass error amplifier so as to receive as input, output from the complex band pass error amplifier. An amplifier is connected to the quadrature up converter so as to receive as input, output from the quadrature up converter. A quadrature down converter is connected at or beyond the amplifier output so as to receive as input a signal proportional to that delivered by the amplifier as output to a load, wherein the complex band pass error amplifier is connected to the quadrature down converter so as to receive as a first input, output from the quadrature down converter and as a second input, a quadrature reference signal.

Abstract: The present invention provides a radiotherapy treatment apparatus that includes a treatment beam, a magnetic field disposed parallel collinear to the treatment beam, and a target that is disposed along the treatment beam. The treatment beam can be a charged particle beam, a proton beam, an electron beam, or a linear accelerator (Linac) beam. The magnetic field is from a magnetic resonance imager (MRI), a megavolt x-ray imager, or a kilovolt x-ray imager and is disposed to operate in coordination with operation of the treatment beam and to narrow the beam. The tumor is disposed to rotate with respect to the treatment beam and the magnetic field, or the treatment beam and the magnetic field are disposed to rotate up to 360° with respect to the target when mounted to a ring gantry. The apparatus can include a rotation angle dependent shim disposed to account for Earth's magnetic field.

Abstract: A method for detecting coupled RF current magnetic resonance (MR) objects in a body and determining MR risk is provided. The body is scanned with reverse circularly polarized RF. MR signals generated by coupling of the reverse circularly polarized RF with the RF current MR objects are detected. The detected MR signals are used to determine a risk value.

Abstract: In a MRI system having a FID detector unit and a computer unit for processing FID signals, phase errors introduced into the FID signal at the detector unit are corrected at the computer unit by transmitting a pilot signal from the computer unit to the detector unit, processing the pilot unit along with a detected FID signal at the detector unit, transmitting the processed signals to the computer unit, obtaining the pilot signal and FID signal at the computer unit, and combining the pilot signal and the FID signal whereby phase errors cancel.

Abstract: A device and method with miniature and tunable MRI receiver coil for catheters is provided that can be used in minimally invasive procedures and intravascular imaging. An MRI receiver coil for catheter procedures is provided having an impedance matching element that includes at least one miniature transmission line cable which are interconnected to construct the impedance matching element. In a particular embodiment, the miniature transmission line cables are constructed to make an inductance matching element defining an inductance L. In another particular embodiment, the miniature transmission line cable is a capacitance matching element defining a capacitance C. The present invention provides a system and method that allows local fine-tuning with a higher signal-to-noise ratio. Transmission line cables also overcome the minimum size limits of fixed components. The shielded and balance techniques further reduce noise and improve safety.

Abstract: The tuning of an interventional receiver coil for magnetic resonance imaging signals is tuned by coupling a varactor tuned circuit with the coil and adjusting a DC voltage applied to the varactor to alter the tuning whereby the coil is tuned to the Larmor frequency of the MRI signals.

Abstract: A coil for magnetic resonance imaging includes at least two spaced electrodes positionable within an object in proximity to a region of interest with feed wires coupling the electrodes to a signal detector. The electrodes and feed wire cooperatively function with tissue and fluid of the object to form an RF signal detecting coil. The electrodes can be needles or rings around the circumference of a catheter or electrodes which extend from and are retractable within a catheter.

Abstract: Transmission Line Techniques for MRI Catheter Coil Miniaturization and Tuning. The present invention provides a device and method for miniature and tunable MRI receiver coil for catheters that can be used in minimally invasive procedures and intravascular imaging. An MRI receiver coil for catheter procedures is provided having an impedance matching element that includes at least one miniature transmission line cable which are interconnected to construct the impedance matching element. In a particular embodiment, the miniature transmission line cables are constructed to make an inductance matching element defining an inductance L. In another particular embodiment, the miniature transmission line cable is a capacitance matching element defining a capacitance C. The present invention provides a system and method that allows fine-tuning locally with a higher signal-to-noise ratio. Transmission line cables also overcome the minimum size limits of fixed components.