MRT Gradient Amplifier Circuit With Integrated Voltage Limiting

Solution Overview

Problem

Magnetic resonance tomography (MRT) systems face challenges in safely examining patients with metallic implants due to potential risks from induced voltages and magnetic fields, requiring complex and costly redundancy measures to ensure patient safety.

Innovation Solution

A circuit arrangement for an MRT system incorporating a switch-mode output stage, regulator device, and modulator with a limiter stage integrated into the drive path to control and limit voltages supplied to gradient coils, ensuring patient safety with reduced component and cost overheads.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If comprehensive additional protective measures and full redundancy are implemented to ensure patient safety, then reliability is improved, but device complexity and manufacturing costs worsen

Engineering Contradiction:

Improvepatient safetyVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the control path and drive path into a single integrated circuit arrangement. The modulator serves dual functions: it modulates the control signal for gradient coil operation and simultaneously limits the control signal to prevent hazardous voltage edges. This merging eliminates the need for separate protective circuits while maintaining patient safety

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The modulator is designed to perform multiple functions: signal modulation for gradient coil control and signal limiting for patient safety protection. By making the modulator universal, the patent reduces the number of separate components needed, thereby reducing device complexity while maintaining reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If comprehensive additional protective measures and full redundancy are implemented to ensure patient safety, then reliability is improved, but manufacturing costs worsen

Engineering Contradiction:

Improvepatient safetyVSAvoidmanufacturing costs

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the control path and drive path into a single integrated circuit arrangement. The modulator serves dual functions: it modulates the control signal for gradient coil operation and simultaneously limits the control signal to prevent hazardous voltage edges. This merging eliminates the need for separate protective circuits while maintaining patient safety

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The modulator is designed to perform multiple functions: signal modulation for gradient coil control and signal limiting for patient safety protection. By making the modulator universal, the patent reduces the number of separate components needed, thereby reducing device complexity while maintaining reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If the switch-mode output stage provides high voltage for rapid magnetic field changes, then productivity is improved, but object-affected harmful factors worsen due to induced voltages in implants

Engineering Contradiction:

Improvemeasurement speedVSAvoidinduced voltages

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The modulator limits the control signal before it reaches the switch-mode output stage. By performing the limiting action in advance, the patent prevents hazardous voltage edges from being generated, thereby eliminating induced voltages in implants while still allowing rapid magnetic field changes when safe

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The modulator acts as an intermediary between the control signal source and the switch-mode output stage. It modifies the control signal by imposing a limit, thereby mediating between the need for rapid field changes and the need to prevent induced voltages in implants

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10379182B2Circuit arrangement for an MRT system, MRT system and method for operating an MRT system

Publication Date: 2019.08.13 SIEMENS HEALTHINEERS AG

AI summary

A circuit arrangement for an MRT system and a method for operating an MRT system are disclosed. The circuit arrangement includes a gradient amplifier having a switch-mode output stage, a regulator device, and a modulator connected therebetween in the circuit. To ensure patient safety, a control path is integrated into a drive path of the circuit arrangement or the MRT system provided for driving a gradient coil, the gradient coil being connected to an output of the switch-mode output stage. The control path includes a limiter stage connected downstream of the regulator device, the modulator, the switch-mode output stage and its supply voltage. The limiter stage is connected in the circuit between the regulator device and an input of the modulator, to limit a control signal output by the regulator device and limit the voltage for the gradient coil provided by the switch-mode output stage at its output.