JPH03205030A - Waveform generation device for mr device - Google Patents

Abstract

PURPOSE:To enable the change of amplitude at the arbitrary portion of a waveform by adding information indicative of the update point of an amplitude value, or information assigning specific gain data to the additional data of a waveform memory. CONSTITUTION:Waveform data C and amplitude value update bits A added thereto are stored in a waveform memory 1, and sequentially read out. The waveform data C is sent to an amplitude adjuster 2, while the amplitude value update bits A are sent to a controller 3. This controller 3 accesses a register file 4 for gain data B, depending upon the amplitude value update bits A, and sequentially reads out the gain data B for sending to the amplitude adjuster 2. This adjuster 2, for example, consists of a multiplier, and the multiplying factor or the like thereof is set with the gain data B, thereby changing the amplitude of the waveform data C. When the amplitude value update bits to be added to leading waveform data at a portion desired for the change of waveform amplitude, is set and gain data corresponding to the register file for the gain data B is set at desired amplitude, therefore, the amplitude of the waveform can arbitrarily be changed independently at each portion thereof, according to a real time.

Description

[Detailed description of the invention] [Industrial application field]

This invention is applicable to MRI (nuclear magnetic resonance imaging) and MR
The present invention relates to a waveform generator used in a nuclear magnetic resonance apparatus (MR unit W) that performs 3 (nuclear magnetic resonance spectroscopy).

[Conventional technology]

In an MR apparatus, it is necessary to generate a magnetic field with a specific waveform, such as a gradient magnetic field, or to generate an excitation high-frequency pulse with a specific waveform. Therefore, a waveform generator is used, but conventionally, the data of the waveform to be output is stored in advance in a waveform memory, and the data is sequentially read out and then connected to an external power source such as a gradient magnetic field generation power supply or a high-frequency signal generator. I am trying to output it to the device. The waveform data stored in this waveform memory is normally sampled at a fixed sampling rate, but some models are designed to switch the sampling rate in real time to reduce memory usage. 6
1-20548). By the way, when performing phase encoding, it is necessary to change the amplitude of the same gradient magnetic field waveform little by little, and in such a case, conventionally, as shown in FIG.
The waveform data read out is sent to an amplitude adjuster 2 to adjust its amplitude. For example, when the waveform data stored in the waveform memory 1 is as shown in Figure 6A, if the gain is set to 0 with the amplitude adjuster 2, the overall amplitude will be as shown in Figure 6B. The resulting waveform is output (in FIGS. 6A and 6B, O indicates the position where the amplitude value is O). (Problem to be solved by the invention) However, it is not possible to store the waveform itself to be outputted in a memory as in the past, read it out, and adjust the amplitude using an amplitude adjuster when outputting it to the outside. If you try to change the amplitude of the fundamental waveform, the amplitude will be changed over the entire range of the fundamental waveform as shown in Figures A and B. For example, the positive period will remain the same and only the negative period will be changed. There is a problem in that it is not possible to easily change the amplitude of only a part of a basic waveform. It is an object of the present invention to provide a waveform generator for an MR apparatus that can be easily produced.

[Means to solve the problem]

In order to achieve the above object, the waveform generator for an MR apparatus according to the present invention includes a first storage means storing waveform data for each time point and additional data added thereto, and a plurality of gain data. a second storage means stored therein; a control means for reading out specific gain data from the second storage means in accordance with additional data read out simultaneously when the waveform data is read out in order; and a readout gain. The present invention is characterized in that it includes an amplitude changing means for changing the amplitude of the read waveform data and outputting the same according to the amplitude.

[For production]

The first storage means stores not only simple waveform data but also additional data added to each waveform data at each point in time. When the waveform data is read out in order, this additional data is also read out together with the waveform data. This additional data is then sent to the control means. The control means determines the meaning of this additional data and accesses the second storage means. A plurality of gain data are stored in the second storage means. Therefore, specific gain data is read out in accordance with the input data, and is sent to the amplitude changing means. The amplitude changing means changes the amplitude of the read waveform data and outputs it based on the sent gain data. Therefore, the amplitude of the waveform can be arbitrarily changed at any part of the waveform by providing the additional data with information indicating the update point of the amplitude value or specifying specific gain data. It becomes possible to do so.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings.6 In FIG. 1, a waveform memory 1 stores waveform data as well as amplitude value update bits added to the waveform data. These are read out in order, and the waveform data is sent to the amplitude adjuster 2 and the amplitude value update bit is sent to the controller 3. The controller 3 accesses the gain data register file 4 according to the rubbing amplitude value update bit, reads out the gain data in order, and sends the gain data to the amplitude adjuster 2. The amplitude adjuster 2 is composed of, for example, a multiplier, and its multiplication factor is set based on gain data, thereby changing the amplitude of the waveform data. To explain in more detail, the waveform data represents the amplitude values at each point in the waveform in order. For example, in the case of a waveform as shown in Fig. 2, each amplitude value is numbered n
expressed as amplitude values. Here, the portion of this waveform whose amplitude is desired to be changed independently is divided into, for example, three portions: A block, B block, and C block. The beginning of block A is number 1, the beginning of block B is number 0, and the beginning of block C is number m. In the waveform memory 1, data representing this amplitude value is stored in order from the first to the nth data in a structure as shown in FIG. 3. Each data is stored in the waveform memory 1 with a 1-bit amplitude value update bit added thereto. This amplitude value update bit is set to "1" at the beginning of each block and set to "0" at the other parts. That is, only the data added to the 1st data, the 0th data, and the mth data are "1", and the others are "0". Therefore, when waveform data is sequentially read out from the waveform memory 1 starting from the first waveform data, the amplitude value update bi-soto is also read out at the same time and sent to the controller 3. The controller 3 determines whether this amplitude value update hit is "1" or r□, and if it is r], J, the controller 3 sequentially takes out the gain data stored in the gain data register file 4 and sends the amplitude adjuster 2 give to In this case, the gain data register file 4 contains the fourth
As shown in the figure, it is assumed that the gain value G1 of block A, the gain value G2 of block B, and the gain value G3 of block C are stored in order from the beginning. Then, each time the amplitude value update bit becomes "1", it is changed to 01 . G2,
G3 is given to the amplitude adjuster 2 from the register file 4. This is multiplied by the waveform data read from the waveform memory 1. That is, the waveform data of the A block is multiplied by G1, the waveform data of the B block is multiplied by G2, and the waveform data of the C block is multiplied by G3, so that each part has a different amplitude. The waveform will be output. In this way, set the amplitude value update bit added to the first waveform data of the part where you want to change the amplitude of the waveform to "1", and set the corresponding gain data in the gain data register file to the desired amplitude. By doing so, the amplitude of the waveform can be changed independently for each part in real time. Note that, instead of the 1-bit amplitude value update bit of "1" or "0", an index consisting of multiple bits is added to the waveform data as additional data and is stored in the waveform memory 1.
The information may be stored in the memory. In this case, the index specifies the register storing each gain data, and the gain data extracted from there is sent to the amplitude adjuster 2.
Try to give it to Even with this configuration, by setting the index and setting the contents of each register, the amplitude of the waveform can be changed independently for each part in real time as desired.

【Effect of the invention】

According to the waveform generator for MR equipment of the present invention, the amplitude of a pre-stored waveform can be arbitrarily changed independently for each part, and this can be easily done in real time. .

[Brief explanation of drawings]

Figure 1 is a block diagram of an embodiment of this invention, Figure 2 is a diagram showing stored waveforms and their respective blocks, Figure 3 is a diagram showing the structure of waveform data, and Figure 1 is a diagram showing 4 gains. A diagram showing the structure of a data register file, FIG. 5 is a block diagram of a conventional example, and FIGS. 6A and 6B are diagrams showing waveforms. 1... Waveform memory, 2... Amplitude adjuster, 3... Controller, 1... Register file for gain data.

Claims (1)

[Claims] (1) A first storage means in which waveform data for each point in time and additional data added thereto are stored, a second storage means in which a plurality of gain data are stored, and the waveform data are sequentially stored. control means for reading out specific gain data from the second storage means in accordance with additional data read out at the same time when the data is read out; and control means for changing the amplitude of the read out waveform data in accordance with the read out gain. 1. A waveform generator for an MR apparatus, comprising: amplitude changing means for outputting an amplitude.