With the rapid advancement of medical technology, magnetic resonance imaging (MRI) has become a crucial technique in the field of medical imaging. Compared with traditional imaging methods, MRI uses magnetic fields and radio waves to produce high-resolution images of internal body structures, without the need for harmful ionizing radiation, making it highly favored by both patients and physicians. However, the stability and accuracy of MRI systems increasingly demand stringent current control. The application of high-precision current sensors enables effective monitoring and regulation of currents within the magnet, thereby ensuring the system’s stability and precision.
Magnetic resonance imaging (MRI) equipment is a high-precision medical imaging device that generates images by exploiting the phenomenon of nuclear spin resonance. In an MRI system, the gradient amplifier unit refers to all circuitry associated with the gradient magnetic field. The gradient amplifier is one of the key components responsible for generating gradient magnetic field signals in MRI imaging; it produces magnetic field gradient signals in different directions by controlling the magnitude and direction of the current, thereby enabling spatial encoding and localization of MRI images. An MRI system typically requires three gradient amplifiers to generate gradient magnetic fields along three orthogonal axes, allowing for the encoding and localization of signals in three-dimensional space. Consequently, each MRI system usually incorporates three current-control loops, each corresponding to the gradient amplifiers for the X, Y, and Z directions.
Each current control loop comprises a current source, a current amplifier, and a current sensor. The current source provides the current signal, the current amplifier amplifies this signal and generates the gradient magnetic field via the gradient coils, while the current sensor monitors the current signal to ensure that the generated gradient magnetic field matches the preset gradient field. The current sensor senses the current signal in the gradient amplifier and transmits it to the control system, enabling monitoring and control of the current signal. The precision and accuracy of the current sensor directly affect the precision and accuracy of the gradient magnetic field signal produced by the gradient amplifier, thereby significantly impacting the quality, sharpness, and resolution of MRI images.
The CTB and CTF series of high-precision current sensors, developed by Wuxi nGV Technology Co., Ltd. for high-precision, high-performance applications such as MRI equipment, offer the following advantages over conventional Hall-effect sensors:
High precision: 10ppm
Full range: The accuracy of a single product 1%-100% remains consistent.
Low temperature drift: Good consistency; temperature effects, 0.1PPM/K
Linearity: Achieves 2ppm
Wide bandwidth: (up to 500kHz @±3 dB)
Response time: 1μs
Operating temperature range: -40..+85 °C
Stability (0.2 ppm/month)
AC/DC universal: Can measure AC, DC, and pulse currents.
Intelligent: Load-starting overload protection, self-recovery
The fluxgate current sensor enables more precise current control, thereby enhancing MRI image quality; moreover, its high stability ensures imaging accuracy. The high-precision fluxgate current sensor can also be applied to other high‑precision electrical measurement applications, such as precision power supply control, power analysis, calibration equipment, and laboratory metrology instruments.