CN213365348U

CN213365348U - Multichannel PET power automatic calibration circuit

Info

Publication number: CN213365348U
Application number: CN202022587244.8U
Authority: CN
Inventors: 朱银东; 陈汉生; 方泽利莉; 王武斌; 黄振强
Original assignee: FMI Technologies Inc
Current assignee: Minfound Medical Systems Co Ltd; FMI Technologies Inc
Priority date: 2020-11-10
Filing date: 2020-11-10
Publication date: 2021-06-04
Anticipated expiration: 2030-11-10

Abstract

The utility model provides a multichannel PET power automatic calibration circuit belongs to medical instrument technical field, set for circuit, controller, analog switch switching circuit, serial ports communication circuit, LDO output circuit, operation pilot lamp, ISP download circuit including power reference circuit, VBIAS. The calibration method comprises the following steps: ADC filtering, MCU calculating each channel actual bias voltage, obtaining OFFSET by subtracting the actual measured value, saving the calculated parameters to FLASH, electrifying again to read parameters from FLASH and outputting. The utility model discloses compare the tradition and put output difference etc. through receiving the regulation fortune and only lean on the calibration mode that improves the hardware uniformity, the utility model discloses calibration circuit has convenient operation, and labour saving and time saving's characteristics have greatly improved calibration efficiency, have simplified production flow.

Description

Multichannel PET power automatic calibration circuit

Technical Field

The utility model relates to a multichannel PET power automatic calibration circuit belongs to medical instrument technical field.

Background

In the CT equipment used at present, the problem that output errors among a plurality of channels of a PET power supply are large exists, a key SIPM sensor in a PET-CT detector needs power supply with high precision, particularly, when the multichannel PET power supply is adopted, the requirement on the consistency of each channel is high, only when the consistency of each channel is good, the SIPM sensor of each module can obtain consistent parameters, and then the reconstructed reliable data can be obtained.

In order to solve the above-mentioned defects, the prior art usually adopts a single high-power switching power supply to supply power, so that each module obtains the same voltage output. Or by a multi-channel PET power supply using hardware. However, the following problems may occur: although the power supplies of the modules are the same to a certain extent, the power supplies of different modules cannot be automatically adjusted to a fine level according to different temperatures. Especially, when the PET length of some models is long, there are more modules in the detector ring, and if the voltage fine tuning compensation is not performed, the SIPM modules may generate large noise due to temperature difference.

The multi-channel PET power supply designed directly through hardware can cause errors of +/-200 millivolts in actual output of each channel power supply due to operational amplifier errors and device errors of a linear power supply chip, and the image quality is seriously influenced by the large errors.

The present application was made based on this.

SUMMERY OF THE UTILITY MODEL

In order to solve the above-mentioned defect that exists among the prior art, the utility model provides a multichannel PET power automatic calibration circuit realizes unanimously for the output of each passageway, can reach the error within 10 millivolts through the calibration, and this error is the acceptable scope of SIPM module power supply, and easy operation, precision are higher.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

a multi-channel PET power supply automatic calibration circuit comprises a controller, an analog switch switching circuit, a VBIAS setting circuit and a memory which are connected with the controller, a voltage reference circuit connected with the analog switch switching circuit, and an LDO output circuit connected with the output end of the VBIAS setting circuit; ADC sampling is arranged in the controller;

the power reference circuit is connected to the controller through the analog switch after signal amplification and operation, the controller controls the analog switch switching circuit to gate to realize bias voltage AD sampling of each path, the output value calculated by the controller is adjusted and set to VIBIAS through the VBIAS setting circuit DA, and then the output of the LDO is set by the LDO output circuit.

As preferred, the utility model discloses multichannel PET power automatic calibration circuit still include with the serial communication circuit that the controller is connected.

Preferably, the utility model discloses multichannel PET power automatic calibration circuit still include with ISP download circuit that the controller is connected.

Preferably, the utility model discloses multichannel PET power automatic calibration circuit still include with the operation pilot lamp that the controller is connected.

Preferably, the utility model discloses in the multichannel PET power automatic calibration circuit the controller adopts STM32F103 series's CPU.

As preferred, the utility model discloses in multichannel PET power automatic calibration circuit the memory adopts MCU to take FLASH, iron certainly

The utility model discloses a principle and beneficial technological effect:

the utility model discloses a MCU from the ADC of taking carries out the reading of bias voltage to calibrate according to the actual measurement value, bias voltage that reads when the ADC is different automatic calculation error with the actual measurement value and add the OFFSET value that obtains with the initial value as the parameter after the calibration, then put the parameter of each passageway in unified the FLASH that stores MCU inside numerical value, just can use the parameter after this calibration next time power on. Compare the tradition and put output difference etc. through receiving the regulation fortune and only lean on the calibration mode that improves the hardware uniformity, the utility model has the characteristics of convenient operation, labour saving and time saving have greatly improved calibration efficiency, have simplified production flow.

Drawings

FIG. 1 is a circuit block diagram of an automatic calibration circuit of the multi-channel PET power supply of the present embodiment;

FIG. 2 is a flowchart illustrating an automatic calibration method for a multi-channel PET power supply according to the present embodiment;

FIG. 3 is a schematic diagram illustrating the connection of an analog switch circuit in the multi-channel PET power supply auto-calibration circuit according to the present embodiment;

FIG. 4 is a flowchart illustrating a mean filtering process performed on data in the multi-channel PET power supply auto-calibration method according to the present embodiment;

FIG. 5 is a schematic diagram of circuit connections for summing the VREF output of each output of the calibration DAC in the multi-channel PET power supply auto-calibration method according to the embodiment.

Detailed Description

In order to make the technical means and the technical effects achieved by the technical means of the present invention clearer and more complete, the following embodiments are provided and are described in detail with reference to the accompanying drawings as follows:

as shown in fig. 1, the automatic calibration circuit of a multi-channel PET power supply of this embodiment includes a power reference circuit, a VBIAS setting circuit, a controller, an analog switch switching circuit, a serial port communication circuit, an LDO output circuit, an operation indicator lamp, and an ISP downloading circuit. The power reference circuit is connected with a controller (to) through an analog switch after signal amplification and operation, the controller controls the analog switch switching circuit to realize bias voltage AD sampling of each path, the output value calculated by the controller is adjusted and set by a DA (digital-analog converter), and then the output of the LDO is set, the serial communication circuit is used for realizing communication with a setting command and the like of an upper computer, the operation indicating lamp is used for prompting that the system is in a normal or abnormal state, and the ISP downloading circuit is used for realizing one-key downloading of a program.

The utility model discloses preferably, the controller adopts STM32F103 series CPU, and more preferably, this embodiment adopts STM32F103VCT 6.

The utility model discloses preferred, the memory adopts MCU to take FLASH, ferroelectric memory, EEPROM or external FLASH chip from one of, more preferred, and this embodiment adopts MCU to take FLASH from.

The utility model discloses preferred, the analog switch that adopts when the ADC reads the bias voltage is MAX 14757. As shown in fig. 3: in this embodiment, VBIAS (differential voltage) of each channel is sequentially switched by the MCU through the analog switch, and then added to VREF and output in reverse (inverted) to obtain a positive input voltage to the ADC of the MCU, and the MCU performs AD conversion and then calculates to obtain a bias voltage value of each channel.

The utility model discloses when giving the power calibration of multichannel, the concrete calibration process of automatic calibration circuit of above-mentioned multichannel PET power includes: ADC filtering, MCU calculating each channel actual bias voltage, obtaining OFFSET by subtracting the actual measured value, saving the calculated parameters to FLASH, electrifying again to read parameters from FLASH and outputting. As shown in fig. 2: VREF is first initialized to the theoretical value: 28.75V, VREF is amplified in phase from a 2.5V voltage reference to 28.75V, which VREF acts as a fixed value for the common adder for each output. The DAC7578 is used in the DAC chip, which has 8 outputs, and each output is added with VREF as the setting value of the corresponding output, and the specific circuit is shown in fig. 5. Then the output of-30.2V is set for 12 channels according to the theoretical value, and the actual output value can be measured by a multimeter with 4 bits and half or more precision, then the measured value is issued to a power panel (MCU) through a VREF writing command, the power panel will take part in the calculation of the received actual VREF value and control the power output, then respectively reading the AD value of each channel and subtracting the AD value from the theoretical set value to obtain OFFSET, adding the theoretical parameters of each channel and the OFFSET to obtain calibrated parameters for output, at this point a multimeter can be used to again measure whether the actual measurement has been made to within a tolerance of + -10 MV, if the calibration parameters are stored in the FLASH, the calibration parameters can be stored in the FLASH, and if the accuracy is not achieved, the common error of the ADC of each channel and the actual value of VREF can be added, and the VREF is written in by a VREF writing command for calibration again, so that the calibration can be realized.

Preferably, in the embodiment, the single chip microcomputer needs to perform some filtering processes to obtain more stable data, that is, after the ADC bias value of each channel is read, the filtering process is performed first. In the embodiment, the mean filtering process is adopted, and 20 pieces of AD adopted data are obtained first, then bubble sorting is performed, and averaging is performed after the maximum value and the minimum value are removed, so that a relatively stable bias data can be obtained, and the processing flow is shown in fig. 4.

The above is a detailed description of the technical solutions provided in connection with the preferred embodiments of the present invention, and it should not be assumed that the embodiments of the present invention are limited to the above description, and it will be apparent to those skilled in the art that the present invention can be implemented in a variety of ways without departing from the spirit and scope of the present invention.

Claims

1. The utility model provides a multichannel PET power automatic calibration circuit which characterized in that: the device comprises a controller, an analog switch switching circuit, a VBIAS setting circuit and a memory which are connected with the controller, a voltage reference circuit connected with the analog switch switching circuit, and an LDO output circuit connected with the output end of the VBIAS setting circuit; ADC sampling is arranged in the controller;

the voltage reference circuit is connected to the controller through the analog switch after signal amplification and operation, the controller controls the analog switch switching circuit to gate to realize bias voltage AD sampling of each path, the output value calculated by the controller is adjusted and set to VIBIAS through the VBIAS setting circuit DA, and then the output of the LDO is set by the LDO output circuit.

2. The multi-channel PET power supply auto-calibration circuit of claim 1, wherein: the device also comprises a serial port communication circuit connected with the controller.

3. The multi-channel PET power supply auto-calibration circuit of claim 1, wherein: also included is an ISP download circuit connected to the controller.

4. The multi-channel PET power supply auto-calibration circuit of claim 1, wherein: and the running indicator lamp is connected with the controller.

5. The multi-channel PET power supply auto-calibration circuit of claim 1, wherein: the controller employs a CPU of the STM32F103 series.

6. The multi-channel PET power supply auto-calibration circuit of claim 1, wherein: the memory adopts any one of an MCU self-contained FLASH, a ferroelectric memory, an EEPROM or an external FLASH chip.