US-20260126509-A1 - MAGNETIC RESONANCE IMAGING APPARATUS, GRADIENT MAGNETIC POWER SUPPLY APPARATUS, AND ABNORMALITY DETECTION METHOD

US20260126509A1US 20260126509 A1US20260126509 A1US 20260126509A1US-20260126509-A1

Abstract

A magnetic resonance imaging apparatus includes a gradient coil, a gradient magnetic field power supply, and processing circuitry. The gradient coil generates a gradient magnetic field. The gradient magnetic field power supply includes a power supply device configured to supply power, a capacitor configured to accumulate power supplied from the power supply device, and an amplifier configured to operate based on power supplied from at least one of the power supply device and the capacitor and amplify an input signal, and outputs the amplified signal to the gradient coil. The processing circuitry is configured to detect a voltage across the capacitor, determine a value corresponding to an impedance of the gradient coil, measure a period required for the voltage across the capacitor to decrease from a first predetermined value to a second predetermined value by self-discharge based on the detected voltage, and detect an abnormality in at least one of the capacitor and the gradient coil based on the determined value corresponding to the impedance and the measured period.

Inventors

Yoshinobu Shinozaki
Makoto Takanaka
Koichi Yamakawa
Masao Ito

Assignees

CANON MEDICAL SYSTEMS CORPORATION

Dates

Publication Date: 20260507
Application Date: 20251030
Priority Date: 20241101

Claims (19)

1 . A magnetic resonance imaging apparatus comprising: a gradient coil configured to generate a gradient magnetic field; a gradient magnetic field power supply including a power supply device configured to supply power, a capacitor configured to accumulate power supplied from the power supply device, and an amplifier configured to amplify an input signal and operate based on power supplied from at least one of the power supply device and the capacitor, the gradient magnetic field power supply being configured to output the amplified signal to the gradient coil; and processing circuitry configured to: detect a voltage across the capacitor; determine a value corresponding to an impedance of the gradient coil; measure a period required for the voltage across the capacitor to decrease from a first predetermined value to a second predetermined value by self-discharge based on the detected voltage; and detect an abnormality in at least one of the capacitor and the gradient coil based on the determined value corresponding to the impedance and the measured period.
2 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to, in a case where the determined value corresponding to the impedance is greater than a predetermined value and the measured period is less than a predetermined period, determine that an abnormality is detected in the capacitor.
3 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to, in a case where the determined value corresponding to the impedance is greater than a predetermined value and the measured period is more than or equal to a predetermined period, determine that an abnormality is detected in the gradient coil.
4 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to, in a case where the determined value corresponding to the impedance is less than or equal to a predetermined value and the measured period is less than a predetermined period, determine that an abnormality is detected in the capacitor.
5 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to provide information to prompt to replace the capacitor in a case where an abnormality is detected in the capacitor.
6 . The magnetic resonance imaging apparatus according to claim 5 , wherein the processing circuitry is further configured to predict time when the period will be less than a predetermined period based on a temporal change of the period, wherein the information about the predicted time is provided as time for replacement of the capacitor.
7 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to provide information about an abnormality in the gradient coil in a case where an abnormality is detected in the gradient coil.
8 . The magnetic resonance imaging apparatus according to claim 1 , wherein the processing circuitry is further configured to determine a frequency characteristic of an impedance of the gradient coil to be the value corresponding to the impedance based on the detected voltage.
9 . The magnetic resonance imaging apparatus according to claim 8 , wherein processing of measuring the period is executed after processing of determining the frequency characteristic is executed.
10 . A gradient magnetic power supply apparatus comprising: a power supply device configured to supply power; a capacitor configured to accumulate power supplied from the power supply device; an amplifier configured to operate based on power supplied from at least one of the power supply device and the capacitor, amplify an input signal, and output the amplified signal to a gradient coil configured to generate a gradient magnetic field; and processing circuitry configured to: detect a voltage across the capacitor; determine a value corresponding to an impedance of the gradient coil; measure a period required for the voltage across the capacitor to decrease from a first predetermined value to a second predetermined value by self-discharge based on the detected voltage; and detect an abnormality in at least one of the capacitor and the gradient coil based on the determined value corresponding to the impedance and the measured period.
11 . An abnormality detection method to be performed by a gradient magnetic power supply apparatus comprising: a power supply device configured to supply power; a capacitor configured to accumulate power supplied from the power supply device; an amplifier configured to operate based on power supplied from at least one of the power supply device and the capacitor, amplify an input signal, and output the amplified signal to a gradient coil configured to generate a gradient magnetic field; and processing circuitry configured to detect a voltage across the capacitor, the abnormality detection method comprising: determining a value corresponding to an impedance of the gradient coil; measuring a period required for the voltage across the capacitor to decrease from a first predetermined value to a second predetermined value by self-discharge based on the detected voltage; and detecting an abnormality in at least one of the capacitor and the gradient coil based on the determined value corresponding to the impedance and the measured period.
12 . The abnormality detection method according to claim 11 , wherein, in a case where the determined value corresponding to the impedance is greater than a predetermined value and the measured period is less than a predetermined period, it is determined that an abnormality is detected in the capacitor.
13 . The abnormality detection method according to claim 11 , wherein, in a case where the determined value corresponding to the impedance is greater than a predetermined value and the measured period is more than or equal to a predetermined period, it is determined that an abnormality is detected in the gradient coil.
14 . The abnormality detection method according to claim 11 , wherein, in a case where the determined value corresponding to the impedance is less than or equal to a predetermined value and the measured period is less than a predetermined period, it is determined that an abnormality is detected in the capacitor.
15 . The abnormality detection method according to claim 11 , wherein, in a case where an abnormality is detected in the capacitor, information to prompt to replace the capacitor is provided.
16 . The abnormality detection method according to claim 15 , wherein time when the period will be less than the predetermined period is predicted based on a temporal change of the period, and wherein information about the predicted time is provided as time for replacement of the capacitor.
17 . The abnormality detection method according to claim 11 , wherein, in a case where an abnormality is detected in the gradient coil, information about the abnormality in the gradient coil is provided.
18 . The abnormality detection method according to claim 11 , wherein a frequency characteristic of the impedance of the gradient coil is determined to be the value corresponding to the impedance based on the detected voltage.
19 . The abnormality detection method according to claim 18 , wherein processing of measuring the period is executed after processing of determining the frequency characteristic is executed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2024-193082, filed Nov. 1, 2024, the entire contents of which are incorporated herein by reference. FIELD Embodiments of this application relate to a magnetic resonance imaging apparatus, a gradient magnetic power supply apparatus, and an abnormality detection method. BACKGROUND In a magnetic resonance imaging apparatus of related art, a gradient coil cannot fulfill its original function due to an increase in the impedance of the gradient coil. In this regard, for example, Japanese Patent Laid-Open No. 2017-108968 describes a technique in which performance degradation (abnormality) of a gradient coil is detected based on the impedance of the gradient coil. However, a change in the impedance of a gradient coil may be caused due to an abnormality in a capacitor provided in a gradient magnetic field power supply even in a case where no abnormality is detected in the gradient coil. In other words, in the configuration of related art, it has been difficult to determine whether an abnormality has occurred in the gradient coil, or whether an abnormality has occurred in the capacitor. Therefore, there is a demand for providing a configuration for identifying an abnormality section. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram illustrating a configuration example of a magnetic resonance imaging apparatus according to one embodiment; FIG. 2 is a block diagram illustrating a schematic configuration example of a gradient magnetic field power supply and the like according to the embodiment; FIG. 3 illustrates a schematic circuitry configuration example relating to a gradient coil according to the embodiment; FIG. 4 illustrates a circuitry configuration example in the gradient magnetic field power supply according to the embodiment; FIG. 5 illustrates an example of a connection relation between a capacitor bank and a measurement device according to the embodiment; FIG. 6 is a graph illustrating an example of each of a voltage Vc, a supplied current Ip, and an output current I of the capacitor bank during a current supply period according to the embodiment; FIG. 7 is a graph illustrating an example of frequency dependencies of a voltage Vc(t) (R is constant) and a drop voltage Vc(t) of the capacitor bank when the resistance of the gradient coil is constant (frequency-independent) according to the embodiment; FIG. 8 is a graph illustrating a relationship between the drop voltage Vc(t) of the capacitor bank with respect to a frequency ω of an output current I(t) and a resistance R(ω) of the gradient coil according to the embodiment; FIG. 9 is a graph illustrating frequency dependencies of a resistance-frequency curve R(ω) and an inductance L(ω) in the gradient coil according to the embodiment; FIG. 10 is a graph illustrating an example of a discharge characteristic of the capacitor bank at the time of installation according to the embodiment; FIG. 11 is a graph illustrating an example of the discharge characteristic of the capacitor bank at the time of degradation according to the embodiment; FIG. 12 illustrates an example of a graph relating to the detection of an abnormality in at least one of the gradient coil and the capacitor bank according to the embodiment; FIG. 13 is a flowchart illustrating an example of processing to be performed by the magnetic resonance imaging apparatus according to the embodiment; and FIG. 14 is a flowchart illustrating an example of processing to be performed by the magnetic resonance imaging apparatus according to the embodiment. DETAILED DESCRIPTION A magnetic resonance imaging apparatus according to an embodiment of the present disclosure includes a gradient coil, a gradient magnetic field power supply, and processing circuitry. The gradient coil generates a gradient magnetic field. The gradient magnetic field power supply includes a power supply device configured to supply power, a capacitor configured to accumulate power supplied from the power supply device, and an amplifier configured to operate based on power supplied from at least one of the power supply device and the capacitor and amplify an input signal, and outputs the amplified signal to the gradient coil. The processing circuitry is configured to detect a voltage across the capacitor, determine a value corresponding to an impedance of the gradient coil, measure a period required for the voltage across the capacitor to decrease from a first predetermined value to a second predetermined value by self-discharge based on the detected voltage, and detect an abnormality in at least one of the capacitor and the gradient coil based on the determined value corresponding to the impedance and the measured period. Various Embodiments will be described hereinafter with reference to the accompanying drawings. A magnetic resonance imaging apparatus, a gradient magnetic power supply appar