公开(公告)号：US06313630B1

公开(公告)日：2001-11-06

申请号：US09382905

申请日：1999-08-25

申请人： Alexander Ganin ,  Kevin F. King

发明人： Alexander Ganin ,  Kevin F. King

IPC分类号： G01U300

CPC分类号： G01R33/385 ,  G01R33/3852

摘要： An MRI system has two sets of gradient coils driven by two corresponding sets of gradient amplifiers. Logical gradient waveforms produced during a pulse sequence are rotated to produce corresponding physical gradient waveforms and these are distributed to drive both sets of coils simultaneously. Each distributed set of physical gradient waveforms is separately compensated for Eddy current errors, and a polarizing field Eddy current compensation signal is produced and used to modulate the RF reference frequency of the system transceiver.

摘要翻译： MRI系统具有由两组对应的梯度放大器驱动的两组梯度线圈。 在脉冲序列期间产生的逻辑梯度波形被旋转以产生相应的物理梯度波形，并且它们被分配以同时驱动两组线圈。 每个分布的物理梯度波形组分别补偿涡流电流误差，并产生偏振场涡流补偿信号，并用于调制系统收发器的RF参考频率。

公开(公告)号：US06211675B1

公开(公告)日：2001-04-03

申请号：US09191862

申请日：1998-11-12

申请人： Alexander Ganin ,  Kevin F. King

发明人： Alexander Ganin ,  Kevin F. King

IPC分类号： G01V300

CPC分类号： G01R33/56518 ,  G01R33/58

摘要： An MRI system automatically performs a calibration procedure to calculate optimal compensation parameter values for all three gradient pre-emphasis filters. A single fixture is employed to measure the errors caused by gradient pulses produced by each of the three gradient systems. The measured errors are used to calculate a gradient error function and the optimal compensation parameter values are calculated for each pre-emphasis filter by finding the minimum in the gradient error function.

摘要翻译： MRI系统自动执行校准程序，以计算所有三个梯度预加重滤波器的最佳补偿参数值。 采用单个夹具来测量由三个梯度系统中的每一个产生的梯度脉冲引起的误差。 测量误差用于计算梯度误差函数，并通过求出梯度误差函数中的最小值，为每个预加重滤波器计算最优补偿参数值。

公开(公告)号：US6025715A

公开(公告)日：2000-02-15

申请号：US990610

申请日：1997-12-15

申请人： Kevin F. King ,  Alexander Ganin

发明人： Kevin F. King ,  Alexander Ganin

IPC分类号： G01R33/387 ,  A61B5/055 ,  G01R33/385 ,  G01R33/48 ,  G01V3/00

CPC分类号： G01R33/385

摘要： An MRI system performs a calibration procedure to calculate optimal compensation parameter values for a pre-emphasis filter that alters the shape of gradient waveforms. The gradient field errors are measured using a series of pulse sequences in which different compensation parameter values are sampled. The measured errors are used to calculate a gradient error function and the optimal compensation parameter values are calculated by finding the minimum in the gradient error function.

摘要翻译： MRI系统执行校准程序，以计算改变梯度波形形状的预加重滤波器的最佳补偿参数值。 使用其中对不同的补偿参数值进行采样的一系列脉冲序列来测量梯度场误差。 测量误差用于计算梯度误差函数，并通过求出梯度误差函数中的最小值来计算最优补偿参数值。