Method and apparatus for measuring vibration of a magnetic resonance imaging system
First Claim
1. A method for acquiring data indicating variation of a magnetic field produced by an electromagnet of a magnetic resonance imaging system, said method comprising the steps of:
- generating a first signal having a predefined wavelength λ
;
directing the first signal to impinge upon part of the magnetic resonance imaging system which is physically connected to the electromagnet;
receiving a second signal formed by a portion of the first signal which is reflected by the part of the magnetic resonance imaging system;
processing the first and second signals to produce an output signal which represents movement of the electromagnet; and
delivering the output signal to circuitry of the magnetic resonance imaging system for use in compensating for effects that variation of a magnetic field has on images produced by the magnetic resonance imaging system.
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Accused Products
Abstract
Vibration of the magnet assembly in a MRI system perturbs the magnetic field and adversely affects the images produced by the system. The perturbation of the magnetic field can be sensed by an apparatus having a source which emits a first signal that is reflected off the magnet assembly. A receiver detects a second signal formed by the reflected portion of the first signal. The first and second signals are processed to produce an output signal representing movement of the electromagnet and thus variation of the magnetic field. That output signal can be used by to components of the magnetic resonance imaging system to compensate for the effects that the vibration has on the images.
13 Citations
19 Claims
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1. A method for acquiring data indicating variation of a magnetic field produced by an electromagnet of a magnetic resonance imaging system, said method comprising the steps of:
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generating a first signal having a predefined wavelength λ
;
directing the first signal to impinge upon part of the magnetic resonance imaging system which is physically connected to the electromagnet;
receiving a second signal formed by a portion of the first signal which is reflected by the part of the magnetic resonance imaging system;
processing the first and second signals to produce an output signal which represents movement of the electromagnet; and
delivering the output signal to circuitry of the magnetic resonance imaging system for use in compensating for effects that variation of a magnetic field has on images produced by the magnetic resonance imaging system. - View Dependent Claims (2, 3, 4, 5, 6, 7)
mixing the first and second signals to produce an intermediate signal l(t) given by the expression;
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8. A method for acquiring data indicating variation of a magnetic field produced by an electromagnet of a magnetic resonance imaging system, said method comprising the steps of:
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generating a first signal having a predefined wavelength λ
;
transmitting the first signal toward part of the magnetic resonance imaging system which is physically connected to the electromagnet;
detecting interaction of the part of the magnetic resonance imaging system with the first signal which produces a second signal;
processing the second signal to produce an output signal which represents movement of the electromagnet; and
delivering the output signal to circuitry of the magnetic resonance imaging system for use in compensating for effects that variation of a magnetic field has on images produced by the magnetic resonance imaging system. - View Dependent Claims (9, 10, 11)
mixing the first and second signals to produce a resultant signal;
low-pass filtering the resultant signal to produce an intermediate signal; and
applying quadrature detection to the intermediate signal to produce the output signal.
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12. In a magnetic resonance imaging system having a magnet assembly which produces a magnetic field, an apparatus for acquiring data related to variation of a magnetic field, said apparatus comprising:
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a source of a first signal having a predefined wavelength λ
;
an emitter which directs the first signal toward the magnet assembly;
a receiver which receives a second signal formed by a portion of the first signal which is reflected by the magnet assembly;
circuitry which processes the first and second signals to produce an output signal representing movement of the electromagnet; and
conductors which deliver the output signal to components of the magnetic resonance imaging system for use in compensating for effects that variation of a magnetic field has on images produce d by the magnetic resonance imaging system. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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Specification