Magnetic resonance imaging apparatus and operating method
AssigneeHitachi Medical Corporation
InventorMunetaka Tsuda
Life of this patent
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Abstract
In order to extend the lifetime of a cooler and reduce down periods of an MRI apparatus due to the maintenance, a cooling capacity of the cooler 107 of the superconducting magnet is controlled so that cooling heat absorption almost equivalent to an amount of heat penetrating into the refrigerant vessel 202 of the superconducting magnet is exerted, and pressure in the refrigerant vessel 202 is maintained within an acceptable pressure range. In addition to this, at least either change amount of magnetic field strength or magnetic field homogeneity in an imaging space due to a pressure change in the refrigerant vessel 202 is compensated by the magnetic field adjustment unit.
Claims12
A magnetic resonance imaging apparatus, comprising:
- a superconducting magnet that generates a static magnetic field in an imaging space;
- a gradient magnetic field coil that applies a gradient magnetic field to the imaging space;
- a high-frequency coil that applies a high-frequency magnetic field to the imaging space;
- and
- a control unit that controls operations of the gradient magnetic field coil and the high-frequency coil to execute a predetermined imaging sequence,
- wherein the superconducting magnet includes a refrigerant vessel to accommodate a refrigerant and a superconducting coil, a cooler that is connected to the refrigerant vessel and re-condenses refrigerant gas vaporized in the refrigerant vessel, and a detector to detect pressure in the refrigerant vessel, and
- the control unit compares a pressure value detected by the detector with a predetermined set pressure value and continuously performs feedback control that increases a cooling capacity of the cooler if the pressure value is higher than the set pressure value and that reduces a cooling capacity of the cooler if the pressure value is lower than the set pressure value to maintain a thermal equilibrium state at the set pressure value.
(canceled)
The magnetic resonance imaging apparatus, comprising:
- a superconducting magnet that generates a static magnetic field in an imaging space;
- a gradient magnetic field coil that applies a gradient magnetic field to the imaging space;
- a high-frequency coil that applies a high-frequency magnetic field to the imaging space;
- a magnetic field adjustment unit that adjusts at least either of magnetic field strength or magnetic field homogeneity in the imaging space;
- and
- a control unit that controls operations of the gradient magnetic field coil and the high-frequency coil to execute a predetermined imaging sequence,
- wherein the superconducting magnet includes a refrigerant vessel to accommodate a refrigerant and a superconducting coil and a cooler that is connected to the refrigerant vessel and re-condenses refrigerant gas vaporized in the refrigerant vessel, and
- the control unit controls a cooling capacity of the cooler so as to exert cooling heat absorption almost equivalent to an amount of heat penetrating into the refrigerant vessel and maintains pressure in the refrigerant vessel within an acceptable range as well as compensates at least either change amount of magnetic field strength or magnetic field homogeneity in the imaging space due to a pressure change in the refrigerant vessel.
A operation method of the magnetic resonance imaging apparatus that includes a superconducting magnet that generates a static magnetic field in an imaging space;
- a gradient magnetic field coil that applies a gradient magnetic field to the imaging space;
- a high-frequency coil that applies a high-frequency magnetic field to the imaging space;
- a magnetic field adjustment unit that adjusts at least either of magnetic field strength or magnetic field homogeneity in the imaging space;
- and a control unit that controls operations of the gradient magnetic field coil and the high-frequency coil to execute a predetermined imaging sequence, the operation method comprising:
- controlling a cooling capacity of a cooler of the superconducting magnet so that cooling heat absorption almost equivalent to an amount of heat penetrating into a refrigerant vessel of the superconducting magnet is exerted;
- maintaining pressure in the refrigerant vessel within an acceptable pressure range;
- and
- compensating at least either change amount of magnetic field strength or magnetic field homogeneity in the imaging space due to a pressure change in the refrigerant vessel by the magnetic field adjustment unit.
Dependencies are inferred from the claim text.