CN111721243A

CN111721243A - Horizontal position monitoring device for spiral CT carrier

Info

Publication number: CN111721243A
Application number: CN202010560636.7A
Authority: CN
Inventors: 陈牧; 孙方伟
Original assignee: Shandong Dacheng Medical Technology Co ltd
Current assignee: Shandong Dacheng Medical Technology Co ltd
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2020-09-29

Abstract

The invention provides a horizontal position monitoring device for a spiral CT carrier, which comprises: a stationary member, a rotatable member, and a slip ring member; the stationary member is interconnected with the slip ring member, the slip ring member is interconnected with the rotatable member; the fixed component comprises a horizontal encoder, a rotary encoder, a level conversion circuit, an encoding logic circuit and a level conversion circuit; the rotatable member includes level shifting circuitry and decoding logic circuitry. The invention adopts the programmable logic circuit to encode the pulse signal of the horizontal encoder of the sickbed and other pulse signals to form a serial signal, the serial signal is sent to the data acquisition system of the rotor part through the slip ring together, and the data acquisition system bypasses the motion control system to directly obtain the encoder information, thereby realizing the real-time accurate report of the horizontal position of the sickbed, being beneficial to optimizing reconstructed images and eliminating horizontal motion artifacts.

Description

Horizontal position monitoring device for spiral CT carrier

Technical Field

The invention relates to the technical field of spiral CT (computed tomography), in particular to a horizontal position monitoring device for a spiral CT carrier.

Background

When the spiral CT acquires a group of image data, the data acquisition system needs to mark corresponding scanning position information, such as angle information of rotational motion and horizontal position information of a patient bed, and accurate position monitoring is one of the necessary conditions for image reconstruction. Because the data acquisition system of the spiral CT system is positioned at the rotating part, the motion control system of the spiral CT system and the fixed part need to be communicated through a slip ring. If the position signal fed back by the encoder is directly transmitted to the data acquisition system, a separate slip ring channel needs to be occupied, so that the cost of the slip ring is increased. Because the horizontal movement rate is low, in order to save the cost of the slip ring, a common CAN bus or a serial bus and other information of a movement control system are sent to a data acquisition system of a rotating part together, a special transmission channel is not provided for horizontal coding information independently, but the method has large delay, so that the feedback accuracy is reduced. In the prior art, the motion state of the spiral CT is mainly controlled and acquired by a pc (ipc) plus motion control card or by an ARM + FPGA (patent application No. 201910373970.9, which discloses a CT PET-CT motion control system with configurable peripherals).

The motion control system sends out horizontal position information in various modes, one mode is to tell the system the speed of horizontal motion, and the data acquisition system DMS stamps a timestamp on each frame of data to be used as a mark. The disadvantage of this method is that when the drive chain of the patient bed is not able to keep the patient bed moving absolutely at a constant speed due to friction and vibration, motion artifacts are generated due to inaccurate motion information being not available during image reconstruction. The other method is that the position information is sent to the DMS uninterruptedly through the CAN bus or the serial port bus, the DMS directly marks the position of the data, the method has the defect that the communication signals are not real-time, the processor performs operation processing and then packs the data after receiving the position signals fed back by the encoder, and then the data are sent out through the interface, the delay time in the process is uncontrollable, so that the horizontal position cannot be marked accurately, and the quality of the reconstructed image CAN be influenced finally.

Patent document CN101917160A (application No. 201010278388.3) discloses a method and system for controlling the synchronization of spiral CT for safety inspection, in which a time pulse of one rotation of a rotation mechanism is transmitted to a horizontal mechanism, and a horizontal mechanism controller adjusts the speed of the horizontal mechanism to a desired constant speed during the time. The system for realizing the method comprises a rotating mechanism and a horizontal mechanism, wherein the horizontal mechanism comprises a conveyor belt and a conveying gear, the horizontal mechanism is connected with an alternating current servo motor, and the alternating current servo motor is controlled by a servo driver; the rotary mechanism is provided with an encoder, the encoder transmits pulses corresponding to one circle of rotation of the rotary mechanism to the servo driver, and the servo driver controls the horizontal mechanism to move through the servo motor and keeps synchronous with the rotation of the rotary mechanism.

Disclosure of Invention

In view of the defects in the prior art, the present invention provides a horizontal position monitoring device for a spiral CT carrier.

The invention provides a horizontal position monitoring device for a spiral CT carrier, which comprises:

a stationary member, a rotatable member, and a slip ring member; the stationary member is interconnected with the slip ring member, the slip ring member is interconnected with the rotatable member;

the fixed component comprises a horizontal encoder, a rotary encoder, a level conversion circuit, an encoding logic circuit and a level conversion circuit;

the rotatable member comprises a level shifting circuit and a decoding logic circuit;

the output ends of the horizontal encoder and the rotary encoder are respectively interconnected with the input end of the level switching circuit; the output end of the level conversion circuit is interconnected with the input end of the coding logic circuit;

the output end of the coding logic circuit is interconnected with the input end of the level conversion circuit;

an output of the level shifting circuit is interconnected with the slip ring member;

an output of the slip ring member is interconnected with an input of the level shifting circuit;

the output of the level shifting circuit is interconnected with the input of the decoding logic circuit.

Preferably, the horizontal encoder and the rotary encoder emit pulse signals for indicating motion displacement information.

Preferably, the level conversion circuit performs level conversion on the input pulse signal into a level pattern that can be recognized by the input terminal of the coding logic circuit.

Preferably, the coding logic circuit uses a programmable logic device CPLD or FPGA to sample the input horizontal position pulse signal and the rotation position pulse signal, and codes the sampled pulse signals into a channel of serial data signal, and then sends out the serial data signal through the output end of the coding logic circuit.

Preferably, the level conversion circuit converts the serial data signal from a single-ended level mode to a differential level mode and transmits the converted serial data signal from the output terminal.

Preferably, the slip ring member sends the serial data signal from the input end to the output end, completes the signal transmission from the fixed member to the rotatable member, and sends the serial data signal to the level conversion circuit.

Preferably, the level conversion circuit converts the input serial data signal from a differential level mode to a single-ended level mode, and the single-ended level mode after conversion is recognized by the decoding logic circuit.

Preferably, the decoding logic circuit uses a programmable logic device CPLD or FPGA to recognize and receive the serial data signal and decode the serial data signal, and restores the pulse signals sent by the horizontal encoder and the rotary encoder.

Preferably, the decoding logic circuit calculates a horizontal position and a rotational position from the pulse numbers of the horizontal encoder and the rotational encoder, and records horizontal position and rotational position information when the CT machine performs data acquisition.

Preferably, the CT projection data in different directions are continuously acquired at equal angles, and the acquired data and the position information are uploaded to an image reconstruction computer of the CT for image reconstruction.

Compared with the prior art, the invention has the following beneficial effects:

1. the pulse signal of the horizontal encoder of the sickbed and other pulse signals are encoded to form a serial signal by adopting the programmable logic circuit, and the serial signal is sent to the data acquisition system of the rotor part through the slip ring together, bypasses the motion control system, and enables the data acquisition system to directly obtain the encoder information, thereby realizing the real-time accurate report of the horizontal position of the sickbed, being beneficial to optimizing reconstructed images and eliminating horizontal motion artifacts;

2. the transmission of two pulse signals of rotation angle signals TickA and TickB is realized by adopting a pair of slip ring channels, both TickA and TickB can be used for triggering the acquisition of a detector, the number of image views can be doubled, the time interval between the views is shortened, and the time resolution of the scanned image is improved;

3. the invention only outputs one path of serial data signal by adopting a mode of mixed coding of horizontal position and rotary position, and only needs to occupy one pair of slip ring channels, thereby realizing the improvement of the utilization efficiency of the slip ring channels and saving the cost of slip ring components.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic structural view of the present invention;

in the figures, 10-the fixation member; 11-a horizontal encoder; 12-a rotary encoder; 13-a level shift circuit; 14-a coded logic circuit; 15-a level shift circuit; 20-a rotatable member; 21-a level shift circuit; 22-decode logic circuitry; 30-slip ring member.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

FIG. 1 is an embodiment that operates by:

the horizontal encoder 11 and the rotary encoder 12 contained in the fixed component 10 both indicate displacement operation through pulse signals, and each time the fixed distance is moved, one pulse signal is triggered, and the system can judge position information according to the number of monitoring pulses. The pulse signals sent by the encoders can be two groups of pulse signals of TICK A and TICK B, the moving direction can be judged according to the sequence of triggering the two groups of pulses, the precision of displacement detection can also be improved, and the two encoders in the embodiment have four groups of pulse signals in total. The pulse signal directly sent from the encoder is generally a level signal in a differential mode, which has the capability of suppressing common mode noise, but cannot be directly input into the programmable logic device, and therefore needs to be converted into a level mode that can be recognized by the level conversion circuit 13. In the embodiment of fig. 1, the level shift circuit 13 may use an RS422 to TTL level shifter, and may also use a comparator or other circuits to implement the level shift function. The pulse signals are input to the input terminal of the coding logic circuit 14 through the level shift circuit 13, and four pulse signals in this embodiment 1 are input to the coding logic circuit 14 in parallel.

The encoded logic circuit 14 may be implemented using a CPLD or an FPGA with more logic resources and higher speed. In order to identify the pulse signal, the encoding logic circuit 14 needs to internally generate a set of sampling clocks, which have a much higher clock frequency than the input pulse signal, and according to the sampling theorem, the sampling result can contain all the information of the original signal, and the sampled signal can be restored to the original signal without distortion. The same sampling clock is used for synchronously sampling the four paths of pulse input signals, and 4-bit parallel data can be obtained. The 4 groups of parallel data signals are converted into serial data signals through logic coding, and a simple conversion mode is that the 4 groups of parallel data are spliced into 4-bit data in a fixed sequence, a 1-bit start bit is added in front of the data, a 1-bit stop bit is added behind the data, and the start bit and the stop bit are respectively 0 and 1 or respectively 1 and 0. If the working rate of data coding and the working rate of data transmission are far higher than the frequency of the pulse signal, the delay on the time sequence can be reduced, in addition, the delay can be generated when the serial signal is transmitted on a physical transmission line, and because the delay of the time sequence and the delay of the transmission line are fixed, the compensation and correction can be carried out later.

The encoded serial data signal is output from the transmitting end of the encoding logic circuit 14, and in order to improve the anti-interference capability of the signal, the serial data signal is converted from a single-ended level mode to a differential level mode by the level conversion circuit 15 and then transmitted. Since the stationary member 10 is stationary during operation and the rotatable member 20 is continuously revolving during operation, they cannot be interconnected directly by cables, and therefore communication is required by means of the slip ring member 30, which slip ring member 30 establishes an electrically conductive path through carbon brushes and annular metal tracks. A differential serial data signal needs to occupy two signal tracks on the slip ring structure 30, which is electrically equivalent to a communication cable, and can transmit the signal from the output of the level shift circuit 15 to the input of the level shift circuit 21 without loss. Level shifter 21 converts the serial data signal from differential level mode to single-ended level mode, which is sent from the output and interconnected to the input of decode logic 22.

The decode logic circuit 22 may be implemented as a CPLD or FPGA for reading and decoding the serial data signal. When the decode logic circuit 22 detects the start bit of the serial data signal, it immediately reads the following 4 bits of data, identifies which TICK signal is triggered, and counts. Based on the number of pulses that occur in the horizontal encoder and the rotary encoder, the decode logic 22 can calculate the current travel distance and, in comparison to the reference position, the current actual position. The decoding logic circuit 22 is located at the rotating part of the CT machine and is a part of the data acquisition system, and the system performs data acquisition of one view each time the decoding logic circuit 22 receives a TICK signal of a rotating motion, so that CT projection data in different directions can be continuously acquired at equal angles after the system continuously works. When the spiral scanning is carried out, the data acquisition system needs to mark an angle position and a horizontal position on a data stream every time acquisition is carried out, and the system can obtain accurate and real-time position information through the circuit design of the embodiment. The data acquisition system uploads the data and the position information of each view to the image reconstruction computer of the CT, and because the reported position of the sickbed is real and accurate, the motion artifact caused by the horizontal motion error of the sickbed can not be generated during image reconstruction.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

Those skilled in the art will appreciate that, in addition to implementing the systems, apparatus, and various modules thereof provided by the present invention in purely computer readable program code, the same procedures can be implemented entirely by logically programming method steps such that the systems, apparatus, and various modules thereof are provided in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers and the like. Therefore, the system, the device and the modules thereof provided by the present invention can be considered as a hardware component, and the modules included in the system, the device and the modules thereof for implementing various programs can also be considered as structures in the hardware component; modules for performing various functions may also be considered to be both software programs for performing the methods and structures within hardware components.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims

1. A spiral CT carrier horizontal position monitoring device is characterized by comprising:

a stationary member (10), a rotatable member (20) and a slip ring member (30); the stationary member (10) is interconnected with the slip ring member (30), the slip ring member (30) is interconnected with the rotatable member (20);

the fixed member (10) comprises a horizontal encoder (11), a rotary encoder (12), a level conversion circuit (13), an encoding logic circuit (14) and a level conversion circuit (15);

the rotatable member (20) comprises a level shift circuit (21) and a decode logic circuit (22);

the output ends of the horizontal encoder (11) and the rotary encoder (12) are respectively interconnected with the input end of the level conversion circuit (13); the output end of the level conversion circuit (13) is interconnected with the input end of the coding logic circuit (14);

the output end of the coding logic circuit (14) is interconnected with the input end of the level conversion circuit (15);

an output of the level shifting circuit (15) is interconnected with the slip ring member (30);

an output of the slip ring member (30) is interconnected with an input of the level shifting circuit (21);

the output of the level shift circuit (21) is interconnected with the input of the decoding logic circuit (22).

2. The spiral CT carrier horizontal position monitoring device according to claim 1, wherein said horizontal encoder (11) and said rotary encoder (12) emit pulse signals for indicating movement displacement information.

3. The spiral CT carrier horizontal position monitoring device according to claim 2, wherein said level shifting circuit (13) level shifts the input pulse signal into a level pattern recognizable by the input of said coding logic circuit (14).

4. The spiral CT carrier horizontal position monitoring device according to claim 3, wherein said coding logic circuit (14) uses a programmable logic device CPLD or FPGA to sample the input horizontal position pulse signal and the rotation position pulse signal, and codes the sampled pulse signals into a serial data signal, and then sends out the serial data signal through the output end of said coding logic circuit (14).

5. The spiral CT carrier horizontal position monitoring device as claimed in claim 4, wherein the level conversion circuit (15) converts the serial data signal from a single-ended level mode to a differential level mode and transmits the converted signal from an output terminal.

6. The spiral CT carrier horizontal position monitoring device according to claim 5, wherein said slip ring member (30) sends serial data signals from an input end to an output end, completing signal transmission from said fixed member (10) to said rotatable member (20), and then to said level shifting circuit (21).

7. The spiral CT carrier horizontal position monitoring device according to claim 6, wherein said level conversion circuit (21) converts the input serial data signal from differential level mode to single-ended level mode, and the single-ended level mode after conversion is identified by said decoding logic circuit (22).

8. The spiral CT carrier horizontal position monitoring device according to claim 7, wherein said decoding logic circuit (22) uses a programmable logic device CPLD or FPGA to recognize and receive serial data signals and decode them to recover the pulse signals sent by said horizontal encoder (11) and said rotary encoder (12).

9. The spiral CT carrier horizontal position monitoring device as claimed in claim 8, wherein said decoding logic circuit (22) calculates the horizontal position and the rotation position according to the number of pulses of said horizontal encoder (11) and said rotation encoder (12), and records the horizontal position and the rotation position information when the CT machine performs data acquisition.

10. The spiral CT carrier horizontal position monitoring device of claim 9, wherein CT projection data of different directions are continuously collected at equal angles, and the collected data and position information are uploaded to a CT image reconstruction computer for image reconstruction.