JPH0884709A - Magnetic resonance video apparatus - Google Patents

Abstract

PURPOSE: To keep rising time and falling time of electric current constant by arranging a gradient magnetic field power source for supplying power to a gradient magnetic field coil to accumulate the power supplied from a power source unit by a plurality of power accumulation means. CONSTITUTION: A capacitor for resonance which is charged with a proper voltage is selected with an S4 from among capacitor banks 3b. An input waveform different in amplitude between the same amplitude side on a positive/negative basis and the same polarity side on the positive/negative basis is inputted into a gradient magnetic field amplifier 3a from a pulse generation source 21 and S2 and S3 are turned ON. Here, electric current rises at a time constant determined by resonance conditions of the capacitor for resonance and a gradient coil L1 and when it reaches a desired current value, the S2 is turned OFF. With this OFF operation, the current flows to a D1 and the S3 and furthermore, the S3 is turned Off at a specified time so that electromagnetic energy stored in the gradient coil L1 is accumulated again in the capacitor C4 for resonance as electric charge energy. This allows the keeping of the rising and falling time of the electric current constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic resonance imaging apparatus, and more particularly to the structure of a power supply circuit for generating a gradient magnetic field.

[0002]

2. Description of the Related Art A high-speed magnetic resonance imaging technique using a magnetic resonance imaging apparatus switches a gradient magnetic field at high speed to collect data necessary for imaging in several tens of milliseconds. In this technique, the gradient magnetic field amplifier is a component for controlling the current flowing through the gradient coil and is indispensable.

In the conventional imaging method, the inductance component as a load is 1 millihenry (resistance component 200
When a gradient coil of about (mΩ) is connected and an attempt is made to raise a current of 150 A in about 1 millisecond, a voltage of 180 V is generated at the output end of the gradient magnetic field amplifier.

When a current of 150 A is to be raised in 200 microseconds with the same structure for high speed imaging, a voltage of 780 V is generated at the output terminal.
Regarding the performance of the gradient magnetic field amplifier that has been conventionally used, since the withstand voltage at the output stage is about 200 V, the gradient magnetic field amplifier has been structurally devised for high-speed imaging.

As a method therefor, for example, US Pat.
In No. 5,287, one side of each of the bridge circuits forming a diagonal pair as shown in FIG.
D4) and one switch (S1 to S4) are combined in parallel, and the gradient magnetic field amplifier 3 via the gradient coil L1 is arranged diagonally to the resonance capacitor CR connected to this bridge circuit. ing.

Next, the operation in the EPI (echo planar imaging) mode (SIN waveform: t1 to t5) will be described with reference to FIG. (In the figure, the white parts are the operation of the switches (S1 to S4), and the shaded parts are the diodes (D1 to D4).
The operation of 4) is shown. ) The resonance capacitor CR is charged with a high voltage, and the input waveform shown in the figure is input from the pulse generation source 21 to the gradient magnetic field amplifier 3 and at time t1.
Then turn on S2 and S3. The current rises with a time constant determined by the resonance condition of the resonance capacitor CR and the gradient coil L1. The input waveform from the above-mentioned pulse generation source is based on this. The current flows in the direction of "A" in FIG. Then, when the desired current value (+ Ip) is reached at time t2, S2 and S3 are turned off. At this time, the charge energy from the resonance capacitor CR is stored as electromagnetic energy in the gradient coil L1, and therefore passes through D1 and D4 and is again stored as charge energy in the resonance capacitor CR. After that, the current of the gradient coil L1 becomes “0” at time t3, and S1 and S4 are turned on here.

Then, the waveform input from the pulse generation source 21 to the gradient magnetic field amplifier 3 is inverted in polarity, and the gradient coil L1
The current flowing in the direction B flows in the direction of "B" in FIG. afterwards,
When the desired current value (-Ip) is reached at time t4, S1,
Turn off S4. At this time, since the charge energy from the resonance capacitor CR is stored in the gradient coil L1 as electromagnetic energy, it passes through D2 and D3 and is stored again in the resonance capacitor CR as charge energy.

Further, in the figure, the FLAT mode (startup /
The fall will be described with respect to the operation at the time of SIN waveform + flat waveform: t5 to t14). First, at time t5, S2 and S3 are turned on. The current rises with a time constant determined by the resonance condition of the resonance capacitor CR and the gradient coil L1. When the desired current value (+ I ') is reached at time t6, S2 is turned off.
The current flowing through the gradient coil L1 passes through D1 and S3,
It flows at a constant value in the direction of "A". When S3 is also turned off at time t7, the electromagnetic energy stored in the gradient coil L1 during t5 to t6 passes through D1 and D4, and is stored again in the resonance capacitor CR as charge energy. At time t8, the current of the gradient coil L1 becomes “0”, where S
Turn on S1 and S4. The waveform input from the pulse generation source 21 to the gradient magnetic field amplifier 3 is inverted in polarity, and the gradient coil L1
The current flowing through the device flows in the direction of "B". When the desired current value (-I ') is reached at time t9, S4 is turned off. The current flowing through the gradient coil L1 passes through S1 and D3, and becomes “B”.
Flows at a constant value in the direction of. When S1 is also turned off at time t10, the electromagnetic energy stored in the gradient coil L1 during t8 to t9 passes through D2 and D3 and is stored again in the resonance capacitor CR as charge energy. Time t1
At 1, the current of the gradient coil L1 becomes "0", and S1 and S4 are turned on again here.

The waveforms input from the pulse generation source to the gradient magnetic field amplifier have the same polarity, and the current flowing through the gradient coil L1 also flows in the "B" direction. Hereinafter, t12 to t14 are t
The same operation as 9 to t11 is performed, and the currents in the same polarity direction can be continuously supplied.

In the two modes described above, when the desired current values | Ip | and | I '| are the same, the time for controlling the switch from the outside (t1 to t2, t3 to t).
4, t5 to t6, t8 to t9, t11 to t12) may be set to be the same. However, in the FLAT mode, "| I '
When "|" is set to "| Ip |" or less, the time (t5 to t6, t8 to t9, t1) for controlling the switch from the outside is set.
It is necessary to set 1 to t12) short. In this case, the rise / fall time changes each time the desired current value changes, which is not suitable for oblique imaging.

Further, since the eddy current generated in the magnetic shield in the static magnetic field coil is compensated at the time of switching the gradient magnetic field, it is not suitable to use the compensation method in which the compensation component is superimposed on the current from the gradient magnetic field amplifier 3. . There is also a method of using a self-shield type gradient coil so that it is not necessary to consider this compensation, but it is expensive.

Further, in Japanese Patent Application No. 3-155833, a high voltage power source and a conventionally used gradient amplifier are switched by a switch so that the high voltage power source is connected during the rising and falling periods. . This method is based on EPI
It is suitable for switching currents of the same positive and negative amplitudes as in the (echo planar imaging) method, but not suitable for outputting asymmetrical positive and negative current values.

[0013]

As described above, the gradient magnetic field power supply circuit which has been conventionally used can be used for a sequence in which the pulse amplitude does not change, such as the EPI calling pulse. However, it is not suitable for control in which the amplitude is changed in a series of gradient magnetic field pulse sequences. The present invention has been made to solve such conventional problems, and an object thereof is to make the rise time and the fall time of the current constant regardless of the change of the output current value. It is an object of the present invention to provide a magnetic resonance imaging apparatus having a gradient magnetic field power supply that can be used.

[0014]

In order to achieve the above object, the present invention applies a high frequency magnetic field and a gradient magnetic field to a subject placed in a uniform static magnetic field according to a predetermined pulse sequence, In a magnetic resonance imaging apparatus for collecting and imaging a magnetic resonance signal detected from within a specimen, a gradient magnetic field power supply for supplying electric power to the gradient magnetic field coil stores a power supply device and electric power supplied from the power supply device. A plurality of power storage means, a plurality of switches connected to each power storage means, the power supply device, and each power storage means selected to generate a gradient magnetic field related to the predetermined pulse sequence. Switching connection and turning on each switch
And a control means for controlling the off state.

[0015]

The present invention has a plurality of capacitors having the same capacitance value, a function of charging the capacitors, a function of discharging the charged voltage at high speed, and a function of controlling charging / discharging by detecting the voltage across the capacitor. The current supplied to the gradient coil can be switched at high speed. Since the rise / fall time can be made constant by selecting a resonance capacitor suitable for the inductance value of the gradient coil, high-speed oblique imaging can be performed.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a magnetic resonance imaging apparatus equipped with a high-speed gradient magnetic field control function according to an embodiment of the present invention. In FIG. 1, the static magnetic field magnet 1 applies a uniform static magnetic field to the patient 4. The gradient magnetic field coil 2 is driven by a gradient magnetic field amplifier 3a and a capacitor bank circuit 3b controlled by the system controller 10, and is directed to the patient 4 in orthogonal X and Y directions in a desired tomographic plane of interest and perpendicular thereto. Gradient magnetic fields Gx, Gy, Gz whose magnetic field strength linearly changes in the Z direction are applied.

The patient 4 also has a system controller 1
Under the control of 0, a high-frequency magnetic field generated by applying a high-frequency signal from the transmitter 7 to the transmitting probe 6 is applied. By applying such a static magnetic field, a gradient magnetic field, and a high-frequency magnetic field, a magnetic resonance signal regarding proton nuclei is generated from the patient 4. The magnetic resonance signal of the nuclide is received by the RF irradiation / reception probe 8 and is received by the reception unit 9.
After being amplified and detected by the system controller 10,
Is sent to the data collection unit 11 under the control of. The data collection unit 11 collects the magnetic resonance signals input via the reception unit 9 under the control of the system controller 10, performs A / D conversion of the signals, and sends them to the electronic computer 12 as image reconstruction data.

The electronic computer 12 is controlled by the console 13 and performs image reconstruction processing including Fourier transform on the image reconstruction data input from the data collection unit 11. Further, the electronic computer 12 is the system controller 10
It also controls. The image data obtained by the electronic computer 12 is sent to the image display 14 and the image is displayed. As the image display 14, for example, a CRT display is used.

2 and 3 show four semiconductor switch elements (D1 to D4, S1 to S4) and a capacitor bank 3b.
FIG. 4 is a circuit diagram showing an example in which the rise time and fall time of the gradient magnetic field current are accelerated by using (see FIG. 4).

Waveform peak current (Ip) = 150 A, rise time to peak current = 200 μsec, magnitude of magnetic field by gradient coil = 1 m henry, gain of gradient amplifier = 150 times, flat portion time 500 μsec, and above When the input current as shown in FIG. 3 is supplied to the gradient coil L1 under the condition of No. 1, first, the switch 22 shown in FIG.
Charge energy (voltage) is stored in each of the capacitors C1 to Cn of the bank so that the black circles have a positive potential.

The voltage can be calculated if the value of the current flowing through the gradient coil L1 is known in advance. Therefore, the plurality of capacitors C1 to Cn are connected to the switches SW1 to S
A capacitor bank that can be selected by Wn is configured so that each of the capacitors C1 to Cn is charged with a different voltage so that the optimum capacitor can be selected for the calculated voltage value.

In this case, since the peak current of the waveform is 150 A, the initial voltage Vs is given by the following equation (1).

[0023]

[Expression 1] I = Ipsin (ωt) | Vs | = −L (dI / dt) = − L · Ip · ω · cos (ωt) = − L · Ip · ω (1) ω = 2πf = 2 × 3.14 × 1.25 × 103 f = 1 / T T = 200 μs * 4 L = 1 mH Gradient coil value Ip = 150 A Waveform peak current Vs = 1178
Therefore, the resonance capacitor Cn, which is charged with an appropriate voltage, is selected from the capacitor bank by the switch SWn. Then, a current having the input waveform of FIG. 3 is input from the pulse generation source 21 to the gradient magnetic field amplifier 3a. Then, at time t1, S2 and S3 are turned on. The current rises with a time constant determined by the resonance condition of the resonance capacitor Cn and the gradient coil L1. Desired current value + Ip at time t2
When it reaches, S2 is turned off. The current flowing through the gradient coil L1 passes through D1 and S3 and flows at a constant value in the direction of arrow A in the figure.

After that, when S3 is also turned off at time t3,
The electromagnetic energy stored in the gradient coil L1 between t1 and t2 is stored again as charge energy in the resonance capacitor Cn. At time t4, the current of the gradient coil L1 becomes “0”, and S1 and S4 are turned on here. As a result, the waveform input from the pulse generation source 21 to the gradient magnetic field amplifier 3a is inverted, and the current flowing through the gradient coil L1 flows in the direction of arrow B in the figure. Desired current value at time t5 −
When Ip is reached, S4 is turned off. The current flowing through the gradient coil L1 passes through S1 and D3 and flows at a constant value in the direction of arrow B. Then, when S1 is also turned off at time t6, the electromagnetic energy stored in the gradient coil L1 between t4 and t5 is stored again in the resonance capacitor Cn as charge energy. Then, at time t7, the current of the gradient coil L1 becomes “0”. After the series of operations, since the initial charging voltage remains in the resonance capacitor Cn, the switch SWn is disconnected.

As explained above, the electric charges of the individual capacitors C1 to Cn stored in the capacitor bank 3b complement the energy required for rising and falling. Conventionally, a high voltage is generated at the output of the gradient magnetic field amplifier 3a at the time of rising and falling. However, since the initial charging voltage of the resonance capacitor is compensated for, a high voltage is not generated at the output end of the gradient magnetic field amplifier, and a conventional gradient magnetic field amplifier having an output characteristic of about several hundred volts is used in combination. It becomes possible.

Further, when the peak current is changed, the charge energy may be varied. Therefore, Q = CV (2) Q: charge, C: capacitance (constant), V: voltage It suffices to change the initial charging voltage of the capacitor.

The voltage required at the output terminal of the gradient magnetic field amplifier 3a (energy supplied / consumed from the gradient magnetic field amplifier 3a) supplies current to the resistance component of the gradient coil L1 when the current rises and falls. It is for. Therefore, from the relationship shown by V = R · I (3) V: generated voltage, R: resistance component of gradient coil, I: peak current, a voltage of about 30 V is generated in this case. Further, since the voltage is generated even when the initial charging voltage of the resonance capacitor and the current value flowing in the gradient coil L1 are not optimal, the voltage actually generated at the output end of the gradient magnetic field amplifier 3a is superposed. It becomes a thing.

Therefore, the number of capacitors n prepared in the capacitor bank 3b is substantially determined by the voltage value required when the maximum peak current flows and the allowable output voltage value of the gradient magnetic field amplifier 3a to be used. Further, considering the voltage generated by the resistance component of the gradient coil L1 as described above, the initial charging voltage of the resonance capacitor and the voltage generated when the current value flowing in the gradient coil is not optimum, the formula (4) is considered. It is desirable to prepare N pieces calculated by.

N = Vsp ÷ Vmax × 1.5 to 2 (4) N: the number of capacitors in the capacitor bank, Vsp:
The voltage value required to flow the maximum peak current, Vmax: Allowable output voltage value of the gradient magnetic field amplifier x 2 The charging voltage to each capacitor in the capacitor bank is proportional to the peak current in the above equation (1). Vsn = n × Vs ÷ N (5) n: capacitor number, Vs: initial voltage at maximum peak current, N: number of capacitors, Vsn: charging voltage for nth capacitor It is sufficient to charge the voltage Vsn calculated in.

Table 1 shows the charging voltage for each capacitor in the capacitor bank shown in FIG. 3 (1) to (5).
It was calculated using the formula. N = 6

[Table 1] It should be noted that the gradient magnetic field amplifier 3a is equipped with a protection circuit at the time of generation of a voltage higher than the rated value, and even if a voltage exceeding the rated value is generated, the gradient magnetic field amplifier 3a is not damaged. .

Next, another embodiment of the present invention will be described. FIG. 5 is a time chart for explaining the operation of the gradient magnetic field amplifier 3a according to this embodiment.

First positive peak current of input waveform = + 100
A, negative first peak current = -100A, negative second peak current = -80A, rise time to peak value = 20
0 μsec, the magnitude of the magnetic field by the gradient coil = 1 mHenry, the gain of the gradient amplifier = 100 times, the time of the flat portion = 500 μsec, and the positive and negative equal amplitudes as shown in FIG. 5 under the above conditions,
A case where gradient magnetic fields having different amplitudes on the same polarity side are output will be described.

First, the time from t0 to t1 is shown in FIG.
The switch 22 shown in FIG. 2 is selectively controlled, and the high-voltage power supply 23 stores charge energy (voltage) in the capacitors C1 to Cn of the capacitor bank so that the black circles have a positive potential.

In this case, the peak current of the waveform = + 100A
Is. Therefore, the resonance capacitor C4, which is charged with an appropriate voltage, is selected from the capacitor bank by SW4. Then, the input waveform shown in FIG. 5 is input from the pulse generation source 21 to the gradient magnetic field amplifier 3a, and at time t1, S
Turn on S2 and S3. Then, the resonance capacitor C4
The current rises with a time constant determined by the resonance condition of the gradient coil L1. Then, at time t2, the desired current value +10
When it reaches 0 A, S2 is turned off. The current flowing through the gradient coil L1 passes through D1 and S3 and flows at a constant value in the direction of arrow A. If S3 is also turned off at time t3, t1 to t
The electromagnetic energy stored in the gradient coil L1 during 2 is stored again in the resonance capacitor C4 as charge energy.

At time t4, the current in the gradient coil L1 is "0".
Then, S1 and S4 are turned on. Pulse source 2
The waveform input from 1 to the gradient magnetic field amplifier 3a is inverted in polarity, and the current flowing through the gradient coil L1 flows in the direction of arrow B. When the desired current value of -100A is reached at t5, S4 is turned off. The current flowing through the gradient coil L1 is S1 and D
Flows through 3 at a constant value in the direction of arrow B. Time t6
If S1 is also turned off at, the gradient coil L will be between t4 and t5.
The electromagnetic energy stored in 1 is again stored in the resonance capacitor C4 as charge energy. At time t7, the current of the gradient coil L1 becomes “0”.

Then, C4 (FIG. 4) and C3 in the capacitor bank are switched. Here, S1 and S4 are turned on again. The waveforms input from the pulse generation source to the gradient magnetic field amplifier have the same polarity, but the amplitude is smaller than that at the time of t4 to t7. The current flowing through the gradient coil L1 flows in the direction of arrow B. When the desired current value −80 A is reached at t5, S1
Turn off. The current flowing through the gradient coil L1 passes through S1 and D3 and flows at a constant value in the direction of arrow B. Time t
When S1 is also turned off at 6, the electromagnetic energy stored in the gradient coil L1 between t4 and t5 is stored again as charge energy in the resonance capacitor C3. Time t7
Then, the current of the gradient coil L1 becomes "0". After the series of operations, since the initial charging voltage remains in the resonance capacitors C1 to Cn, SW1 to SWn are disconnected.

Next, still another embodiment of the present invention will be described. FIG. 6 is a block diagram of a capacitor bank according to this embodiment,
FIG. 7 is a time chart diagram for explaining the operation of this embodiment.

In advance, desired current values | I1 |, | I2 |,
The optimum resonance capacitors for passing | I3 | and | I4 | are determined as C1, C2, C3, and C4, respectively.
However, the resonance capacitor is selected so that the voltage generated at the output of the gradient magnetic field amplifier 3a is within the allowable voltage even if the amplitude amounts of + I1 and -I1 are strictly different. t
Before 1 turn on SW4 in the capacitor bank.

At time t1, S2 and S3 are turned on. At this time, the resonance capacitor C4 is selected and the current rises. The current flowing through the gradient coil L1 flows in the direction of arrow A. When the current value + I4 is reached at time t2, S2,
Turn off S3. Due to the electromagnetic energy of the gradient coil L1, D1 and D4 are turned on, and the resonance capacitor C4 is turned on again.
The voltage rises and the current falls. Eventually, at time t3, the current of the gradient coil L1 becomes “0”. At time t4, the waveform input from the pulse generation source 21 to the gradient magnetic field amplifier 3a is inverted in polarity. At the same time, S1 and S4 are turned on. The current flowing in the gradient coil L1 flows in the direction of arrow B and rises. When the current value −I4 is reached at time t5, S1 and S4 are turned off. D due to the electromagnetic energy of the gradient coil L1
2, D3 are turned on, the voltage of the resonance capacitor C4 rises again, and the current falls. Eventually, the current of the gradient coil L1 becomes “0” at time t6. The switch in the capacitor bank is switched from SW4 to SW3 between t6 and t7.

Next, at time t7, S2 and S3 are turned on. At this time, the resonance capacitor C3 is selected,
The current rises. The current flowing through the gradient coil L1 flows in the direction of arrow A. When the current value + I3 is reached at time t8, S2 and S3 are turned off. Due to the electromagnetic energy of the gradient coil L1, D1 and D4 are turned on, the voltage of the resonance capacitor C3 again rises, and the current falls. Eventually, the current of the gradient coil L1 becomes “0” at time t9.

At time t10, the waveform input from the pulse generation source to the gradient magnetic field amplifier is inverted in polarity. At the same time S1, S
Turn on 4. The current flowing through the gradient coil L1 is indicated by the arrow B.
It rises in the direction of. When the current value −I3 is reached at time t11, S1 and S4 are turned off. Due to the electromagnetic energy of the gradient coil L1, D2 and D3 are turned on, the voltage of the resonance capacitor C3 again rises, and the current falls.
Eventually, the current of the gradient coil L1 becomes “0” at time t12. The switch in the capacitor bank is switched from SW3 to SW2 between times t12 and t13.

At time t13, S2 and S3 are turned on. The resonance capacitor C2 is selected and the current rises. The current flowing through the gradient coil L1 flows in the direction of arrow A. When current value + I2 is reached at time t14, S2, S3
Turn off. D due to the electromagnetic energy of the gradient coil L1
1, 1 and D4 are turned on, the voltage of the resonance capacitor C2 rises again, and the current falls. Eventually, at time t15, the current of the gradient coil L1 becomes “0”.

At time t16, the waveform input from the pulse generation source to the gradient magnetic field amplifier 3a is inverted. At the same time S
Turn on S1 and S4. The current flowing through the gradient coil L1 flows in the direction of arrow B and rises. When the current value −I2 is reached at time t17, S1 and S4 are turned off. Due to the electromagnetic energy of the gradient coil L1, D2 and D3 are turned on,
The voltage of the resonance capacitor C2 again rises, and the current falls. Eventually, at time t18, the current in the gradient coil L1 becomes “0”. The switch in the capacitor bank is switched from SW2 to SW1 between times t18 and t19.

At time t19, S2 and S3 are turned on. The resonance capacitor C1 is selected and the current rises. The current flowing through the gradient coil L1 flows in the direction of arrow A. When current value + I1 is reached at time t20, S2, S3
Turn off. D due to the electromagnetic energy of the gradient coil L1
1, 1 and 4 are turned on, the voltage of the resonance capacitor C1 rises again, and the current falls. Eventually, at time t21, the current of the gradient coil L1 becomes “0”.

At time t22, the waveform input from the pulse generator 21 to the gradient magnetic field amplifier 3a is inverted between positive and negative. At the same time, S1 and S4 are turned on. The current flowing through the gradient coil L1 flows in the direction of arrow B and rises. When the current value −I1 is reached at time t23, S1 and S4 are turned off. Due to the electromagnetic energy of the gradient coil L1, D2 and D3 are turned on, the voltage of the resonance capacitor C1 rises again, and the current falls. Eventually, at time t24, the current of the gradient coil L1 becomes “0”.

After a series of operations, the resonance capacitors C1 to C
Since the voltage remains in n, SW1 to SWn are disconnected.

[0047]

According to the present invention, the rise and fall times can be set to be the same at any current value and the gradient magnetic field can be switched at high speed, so that image data can be collected at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a magnetic resonance imaging apparatus according to the present invention.

FIG. 2 is a configuration diagram of a gradient magnetic field power supply circuit according to an embodiment of the present invention.

FIG. 3 is a timing chart showing the operation of the gradient magnetic field power supply circuit according to the first embodiment.

FIG. 4 is a configuration diagram showing a configuration of a capacitor bank according to the first embodiment.

FIG. 5 is a timing chart showing the operation of the gradient magnetic field power supply circuit according to the second embodiment.

FIG. 6 is a configuration diagram showing a configuration of a capacitor bank according to a third embodiment.

FIG. 7 is an explanatory diagram showing the operation of the third embodiment.

FIG. 8 is a configuration diagram of a conventional gradient magnetic field power supply circuit.

FIG. 9 is a timing chart showing the operation of a conventional gradient magnetic field power supply circuit.

[Explanation of symbols]

 1 Static magnetic field magnet 2 Gradient magnetic field coil 3 Gradient magnetic field power supply circuit 3a Gradient magnetic field amplification section 3b Capacitor bank 4 Patient 5 Excitation power supply 6 Transmitting probe 7 Transmitting section 8 Receiving probe 9 Receiving section 10 System controller 11 Data collecting section 12 Electronic calculator 13 Console 14 Image display 21 Power supply 22 Switching unit 23 High voltage power supply 24 Control circuit

Claims (2)

[Claims] 1. A high-frequency magnetic field and a gradient magnetic field are applied to a subject placed in a uniform static magnetic field according to a predetermined pulse sequence, and magnetic resonance signals detected from inside the subject are collected and imaged. In the magnetic resonance imaging apparatus described above, the gradient magnetic field power supply for supplying power to the gradient magnetic field coil includes a power supply device and a plurality of power storage means for storing the power supplied from the power supply device. Magnetic resonance imaging device. 2. A high-frequency magnetic field and a gradient magnetic field are applied to a subject placed in a uniform static magnetic field according to a predetermined pulse sequence, and magnetic resonance signals detected from inside the subject are collected and imaged. In the magnetic resonance imaging apparatus, the gradient magnetic field power supply for supplying power to the gradient magnetic field coil,
A power supply device, a plurality of power storage means for storing power supplied from the power supply device, a plurality of switches connected to each of the power storage means, the power supply device and a gradient magnetic field related to the predetermined pulse sequence. A magnetic resonance imaging apparatus comprising: a switching unit for controlling connection switching with each of the power storage units selected for generation and controlling ON / OFF of each of the switches.