Multi-channel real-time phase modulation for EMI reduction in an ultrasound device
Inventors
Kurtz, Ron • Leonard, Patrick • Zhang, Xiaoyu
Assignees
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Publication Number
US-11806554-B2
Publication Date
2023-11-07
Expiration Date
Abstract
Methods for reducing electromagnetic interference arising from use of multiple ultrasound transducers in an array, particularly inside a human body that is inside a magnetic resonance imaging device. Electrical signals driving the transducers are offset in phase with respect to one another so as to achieve maximum offset of electrical and magnetic fields arising from such signals and transducers. Phase offsets are dynamically adjusted to respond to changes in driving amplitudes and frequencies so as to maintain optimal reduction of electromagnetic interference.
Core Innovation
The invention concerns reducing electromagnetic interference when operating an electrically-driven ultrasound thermal therapy apparatus. A computer-based host unit determines a common driving frequency and an amplitude for each of a plurality of transducer elements, and each transducer element is driven with a driving signal that includes the common driving frequency, the amplitude, and a respective phase angle.
Phase angles are determined based, at least in part, on the amplitude of the corresponding driving signal. Before modifying the phase angle, the method multiplies each amplitude and a respective phase offset value of +1 or −1 to determine a respective amplitude-phase product, where each phase offset represents a two-state phase assignment of 0 degrees (+1) or 180 degrees (−1). The respective amplitude-phase products are summed to calculate a residual Ri, and the repeating of these computations over 2^N−1 possible combinations determines a plurality of residuals R2^N−1 for a residual minimum.
Residual selection is used to set phase angles according to the two-state phase assignment that corresponds to the minimum residual Rmin. When the minimum residual Rmin is not equal to 0, the respective phase angles of the driving signals are set according to the two-state assignment for the minimum residual, thereby driving the net electromagnetic output toward reduction.
Claims Coverage
The document provides one independent claim describing a method for reducing electromagnetic interference, with a two-stage structure: phase-angle determination via a two-state 0°/180° residual minimization search based on amplitude-phase products, and setting phase angles according to the minimum residual.
Two-state phase residual minimization using amplitude-phase products
Determining a minimum residual Rmin by multiplying each amplitude and a respective phase offset value of +1 or −1 to form amplitude-phase products, summing the products to calculate residual Ri, repeating for 2^N−1 combinations of two-state (0°/180°) phase assignments, and comparing residuals to find the minimum residual Rmin.
Common frequency per-element phase modulation to reduce net electromagnetic output
Driving a plurality of transducer elements using a respective driving signal generated by a respective voltage source, the driving signal for each element comprising a common driving frequency, an amplitude, and a respective phase angle, and modifying at least one phase angle based on the amplitude of the corresponding driving signal to reduce a net electromagnetic output of the thermal therapy apparatus.
Setting phase angles according to minimum residual two-state assignment
When the minimum residual Rmin is not equal to 0, setting the respective phase angles according to the two-state phase assignment that corresponds to the minimum residual Rmin.
Overall, the claim coverage centers on computing residuals from amplitude-phase products under a two-state 0°/180° phase assignment search to obtain a minimum residual, then using that minimum residual to set per-element phase angles to reduce a net electromagnetic output during operation of an electrically-driven ultrasound thermal therapy apparatus.
Stated Advantages
Reduces electromagnetic interference by reducing a net electromagnetic output of the thermal therapy apparatus.
Documented Applications
Electrically-driven ultrasound thermal therapy apparatus operation in an MRI-guided ultrasound thermal therapy context to reduce EMI during operation.
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