Magnetic resonance imaging apparatus and gradient power supply apparatus

1. A magnetic resonance imaging apparatus comprising:

a gradient coil configured to generate a gradient magnetic field;

power supply circuitry configured to supply power to the gradient coil, the power being required by the gradient coil; and

control circuitry configured to temporarily change an upper limit value of power to be supplied by the power supply circuitry to a second value higher than a first value as a rated value based on the power required by the gradient coil,

wherein the control circuitry is further configured to calculate a reference value of power supply during a period in which the upper limit value is set to the second value, the reference value being at least one of a duration of time when the upper limit value is set to the second value, an integrated value of the power during the time, and a mean value of the power during the period in which the upper limit value of the power is set to the second value.

2. The magnetic resonance imaging apparatus according to claim 1 , wherein the control circuitry is further configured to change the upper limit value set to the second value to the first value in accordance with power supplied during a period that the upper limit value of the power is set to the second value.

3. The magnetic resonance imaging apparatus according to claim 1 , wherein the control circuitry is further configured to monitor the power to be supplied by the power supply circuitry, and power to be supplied to at least one of a plurality of axis coils, the axis coils being included by the gradient coil.

4. The magnetic resonance imaging apparatus according to claim 1 , wherein the control circuitry is further configured to change the upper limit value from the second value to the first value when the reference value reaches a predetermined threshold, and control the upper limit value not to be changed to the second value.

5. The magnetic resonance imaging apparatus according to claim 4 , wherein the control circuitry is further configured to stop limiting the upper limit to the second value when the mean value of the power is below the first value.

6. The magnetic resonance imaging apparatus according to claim 1 , wherein the control circuitry is further configured to:

calculate a temperature of the power supply circuitry based on the power supplied to the gradient coil by the power supply circuitry;

change the upper limit value from the second value to the first value when the temperature reaches a first temperature threshold, and control the upper limit value not to be changed to the second value, and

stop limiting the upper limit to the second value when the temperature reaches a second temperature threshold lower than the first temperature threshold, and

the magnetic resonance imaging apparatus further comprises display circuitry configured to display the temperature, together with the first temperature threshold and the second temperature threshold.

7. The magnetic resonance imaging apparatus according to claim 1 , further comprising processing circuitry configured to estimate, based on an imaging condition, prior to starting imaging, at least one of the power required by the gradient coil, a time when the upper limit value is permitted to be changed, and the duration of time.

8. The magnetic resonance imaging apparatus according to claim 7 , wherein the processing circuitry is further configured to control a display to display an alert based on the estimation.

9. The magnetic resonance imaging apparatus of claim 7 , wherein the processing circuitry is further configured to optimize an imaging sequence related to the imaging condition based on the estimation.

10. A magnetic resonance imaging apparatus, comprising:

a gradient coil configured to generate a gradient magnetic field;

power supply circuitry configured to supply power to the gradient coil, the power being required by the gradient coil; and

control circuitry configured to temporarily change an upper limit value of power to be supplied by the power supply circuitry to a second value higher than a first value as a rated value based on the power required by the gradient coil;

a temperature measuring sensor configured to measure a temperature of the power supply circuitry; and

display circuitry configured to display the temperature, together with a first temperature threshold and a second temperature threshold lower than the first temperature threshold, wherein

the control circuitry is further configured to

change the upper limit value set to the second value to the first value when the temperature reaches the first temperature threshold, and control the upper limit value not to be changed to the second value, and

stop limiting the upper limit to the second value when the temperature reaches a second temperature threshold lower than the first temperature threshold.

11. A gradient power supply apparatus, comprising:

power supply circuitry configured to supply power required by a gradient coil, the gradient coil being configured to generate a gradient magnetic field; and

control circuitry configured to temporarily change an upper limit value of power from a first value as a rated value to a second value higher than the first value based on the power required by the gradient coil, the upper limit value being set by the power supply circuitry,

wherein the control circuitry is further configured to calculate a reference value of power supply during a period in which the upper limit value is set to the second value, the reference value being at least one of a duration of time when the upper limit value is set to the second value, an integrated value of the power during the time, and a mean value of the power during the period in which the upper limit value of the power is set to the second value.