WO2021128868A1

WO2021128868A1 - Method and system for controlling ray dose in ct system

Info

Publication number: WO2021128868A1
Application number: PCT/CN2020/108834
Authority: WO
Inventors: 王青强
Original assignee: 南京安科医疗科技有限公司
Priority date: 2019-12-27
Filing date: 2020-08-13
Publication date: 2021-07-01
Also published as: CN110881995A; CN110881995B

Abstract

A method and system for controlling a ray dose in a CT system. The method comprises: constructing a relational expression between the weight of an examinee and an output current of a driver; then reading the output current of the driver during a CT examination process, and converting same into the equivalent weight of the examinee according to the relational expression between the weight of the examinee and the output current of the driver; and finally, dynamically adjusting a ray dose at different scanning positions according to the calculated equivalent weight value of the examinee, so that a scanned image is clearer, and rays received by the patient are smaller and more rational.

Description

A method and system for controlling radiation dose in CT system

Technical field

The present invention relates to the field of CT scanning technology, in particular to a method and system for controlling radiation dose in a CT system.

Background technique

CT stands for electronic computer tomography. It uses a precisely collimated X-ray beam to scan a certain part of the human body together with a highly sensitive detector. It has the characteristics of fast scanning time and clear images. Can be used for inspections of a variety of diseases. The CT is mainly composed of frame, examination table and workstation. Normally, by scanning the CT equipment in the shielded room at the workstation, the operator will select different scan modes according to different parts of the scan. Different scan modes will have different dose output. The quality of imaging is closely related to the dose of the scan. However, the existing scanning technology has certain defects, and can only adjust the dose according to different parts. For examiners of different weights, the workstation cannot automatically control the scanning dose according to the examiner's weight.

In the prior art, there is a method of collecting the weight of the patient through a pressure sensor, or obtaining the weight of the patient in advance, and then adjusting the radiation dose according to the weight of the patient. However, in the prior art, the measured weight is the patient's natural weight. When the dosage adjustment formula is substituted into the dosage adjustment formula, the influence of the patient's different postures, body positions, and movement status of the examination table on the dosage requirement is not considered. In the actual scanning process, the patient’s different postures, positions, and movement status of the examination table will require different radiation doses. That is to say, what we actually have to consider is the patient’s equivalent weight. The larger the equivalent weight, the larger the equivalent weight. The longer the time for the same body part to pass through the same position, the dose needs to be increased to ensure the accuracy of the scan data; on the contrary, the smaller the equivalent weight, the less time the patient stays at this position during the entire scanning process. The same tissue can be penetrated with a smaller dose, and the radiation dose can be reduced at this time to prevent the patient from undergoing too many radiation scans.

In addition, because the pressure sensor is outside the entire CT system, monitoring the weight of the patient by adding an additional pressure sensor will cause data collection to be out of sync; secondly, CT scanning requires the rotation of the gantry to match the advancement of the bed, and the pressure sensor is in the bed It is troublesome to collect and install during exercise, and it cannot reflect the dynamic changes of human body weight based on factors such as speed.

Summary of the invention

Objective of the invention: In order to overcome the shortcomings of the prior art, the present invention proposes a method and system for controlling the radiation dose in a CT system, which can obtain different equivalent weight values according to the patient's different body positions during the CT scanning process, and then adjust the radiation dose .

Technical solution: In order to achieve the above-mentioned purpose, the technical solution proposed by the present invention is as follows:

A method for controlling radiation dose in a CT system. The CT system includes an examination table, a driver, and a driving motor, and the driving motor drives the examination table to move horizontally according to the pulse output by the driver;

The control method includes the steps:

(1) Construct the relationship between the equivalent weight of the examinee and the output current of the driver:

Among them, m represents the equivalent weight of the examinee, U represents the rated voltage of the drive, I represents the output current of the drive, R represents the drive radius of the drive motor, n represents the motor speed, g represents the acceleration of gravity, and μ represents the movement of the examination table Coefficient of friction;

(2) During the inspection process, when the examination table is moving at a constant speed, read the drive parameters, including the rated voltage, output current, and read the speed of the drive motor; then, according to the formula

Calculate the equivalent weight of the current examinee, and then adjust the radiation dose according to the calculated m.

The present invention also provides a radiation dose control system in a CT system, including: an examination table, an examination table control board, a driver, a driving motor, and a workstation; among them,

The examination table control panel provides a user interaction window, which generates the control signal of the driver according to the motion control parameters of the examination table input by the user; and reads the driver parameters and the speed of the driving motor, and calculates the equivalent weight of the examinee based on the read data. Send to the workstation; the formula for calculating the equivalent weight of the examinee is:

Among them, U represents the rated voltage of the drive, I represents the output current of the drive, R represents the drive radius of the drive motor, n represents the motor speed, g represents the acceleration of gravity, and μ represents the friction coefficient when the examination table is moving;

The driver generates a pulse waveform according to the control signal issued by the examination bed control board, and outputs the pulse waveform to the drive motor, controls the rotation of the drive motor, and drives the examination bed to move horizontally;

The workstation receives the weight value of the examinee sent by the control panel of the examination table, and adjusts the radiation dose during the scanning process according to the weight value.

Further, the control board of the examination table collects the rotational speed of the driving motor through an electronic encoder.

Further, the examination table control board reads the parameters of the driver through the CANOPEN protocol, and the parameters include: rated voltage and output current.

Further, the examination table control board exchanges data with the workstation through a custom CAN bus protocol.

Beneficial effects: Compared with the prior art, the present invention has the following advantages:

The invention can obtain different equivalent weight values according to different body positions of the patient during the CT scanning process, and then adjust the radiation dose, so that the scanned image is clearer, and the radiation received by the patient is smaller and more reasonable.

Description of the drawings

Fig. 1 is a structural diagram of an embodiment of a radiation dose control system in a CT system related to the present invention.

Detailed ways

The present invention will be further described below with reference to the drawings and specific embodiments. However, it should be understood that the present invention can be implemented in various forms. The exemplary and non-limiting embodiments shown in the accompanying drawings and described below are not intended to limit the present invention to the specific embodiments described. .

This embodiment provides an implementation of a radiation dose control method in a CT system according to the present invention. The CT system includes an examination table, a driver, and a driving motor. The driving motor drives the examination table to move horizontally according to the pulse output by the driver. ; The method includes the following steps:

Calculate the equivalent weight of the current examinee, and then adjust the radiation dose according to the calculated weight m.

The specific method for adjusting the radiation dose according to the equivalent weight is: the larger the equivalent weight, the longer the time for the same body part to pass through the same position, and the dose needs to be increased to ensure the accuracy of the scan data; conversely, the smaller the equivalent weight is , It means that the less time the patient stays at this position during the whole scanning process, the less dose can be used to penetrate the same tissue, at this time, the radiation dose can be reduced and the patient can avoid too much radiation scanning. The specific adjustment dose depends on the specific scanning protocol used for the scan, or based on the doctor's experience.

In step (1), specifically, the formula

The derivation principle is:

Formula 1: P=FV, where P represents the output power of the driver, F represents the force applied by the drive motor to the examination table, and V represents the movement speed of the examination table (that is, the linear velocity of the drive motor).

Formula 2: T=FR, where T represents the torque of the drive motor, and R represents the radius of action of the drive motor. Since the bed plate of the examination bed moves horizontally, it can be obtained: F=mgμ, μ is the friction when the examination bed moves coefficient.

Formula 3: V=2πRn, where n represents the rotation speed of the driving motor.

Formula 4: P=UI, where U represents the rated voltage and I represents the output current.

The relationship between the equivalent weight of the examinee and the output current of the driver can be obtained from the above four formulas:

In step (2), specifically, when reading the drive parameters, including rated voltage, output current, and reading the speed of the drive motor, the values of U, I, and n can be obtained, and the radius of action of the drive motor R is related to the drive motor model and is a known parameter. Both the pi rate π and the gravitational acceleration g are constants, and μ is the coefficient of friction that can be obtained through experiments in advance. Therefore, at this time, just substitute U, I, n into the formula

Then the equivalent weight value can be calculated.

The invention also proposes a control system for the radiation dose in the CT system. Fig. 1 shows a schematic block diagram of an embodiment of a radiation dose control system in a CT system according to the present invention. As shown in Figure 1, a radiation dose control system in a CT system includes: an examination table, an examination table control board, a driver, a driving motor, and a workstation; among them,

The examination table control board provides a user interaction window, which generates the control signal of the driver according to the motion control parameters of the examination table input by the user; and reads the driver parameters and the rotation speed of the driving motor, calculates the weight of the examinee based on the read data and sends it to Workstation; the formula for calculating the equivalent weight of the examinee is:

The workstation receives the equivalent weight value of the examinee sent by the control panel of the examination table, and adjusts the radiation dose during the scanning process according to the equivalent weight value.

Preferably, the control board of the examination table collects the rotational speed of the driving motor through an electronic encoder.

Preferably, the examination table control board reads the parameters of the driver through the CANOPEN protocol, and the parameters include: rated voltage and output current.

Preferably, the examination table control board exchanges data with the workstation through a custom CAN bus protocol.

It should be understood that, where technically feasible, the technical features listed above for different embodiments can be combined with each other to form additional embodiments within the scope of the present invention. In addition, the specific examples and embodiments described in the present invention are non-limiting, and corresponding modifications may be made to the structure, steps, and sequence set forth above without departing from the protection scope of the present invention.

The above-mentioned embodiments, especially any "preferred" embodiments, are possible examples of implementations, and are presented only for a clear understanding of the principles of the present invention. Many changes and modifications can be made to the above embodiments without basically departing from the spirit and principle of the technology described in the present invention, and these changes and modifications should also be regarded as the protection scope of the present invention.

Claims

A method for controlling radiation dose in a CT system, wherein the CT system includes an examination table, a driver, and a driving motor, and the driving motor drives the examination table to move horizontally according to the pulse output by the driver;

The control method includes the steps:

(1) Construct the relationship between the equivalent weight of the examinee and the output current of the driver:

Among them, m represents the equivalent weight of the examinee, U represents the rated voltage of the drive, I represents the output current of the drive, R represents the drive radius of the drive motor, n represents the motor speed, g represents the acceleration of gravity, and μ represents the movement of the examination table Coefficient of friction;

(2) During the inspection process, when the examination table is moving at a constant speed, read the drive parameters, including the rated voltage, output current, and read the speed of the drive motor; then, according to the formula
Calculate the equivalent weight of the current examinee, and then adjust the radiation dose according to the calculated m.
A control system for radiation dose in a CT system, which is characterized by comprising: an examination table, an examination table control board, a driver, a driving motor, and a workstation; wherein,

The examination table control panel provides a user interaction window, which generates the control signal of the driver according to the motion control parameters of the examination table input by the user; and reads the driver parameters and the speed of the driving motor, and calculates the equivalent weight of the examinee based on the read data. Send to the workstation; the formula for calculating the equivalent weight of the examinee is:

Among them, U represents the rated voltage of the drive, I represents the output current of the drive, R represents the drive radius of the drive motor, n represents the motor speed, g represents the acceleration of gravity, and μ represents the friction coefficient when the examination table is moving;

The driver generates a pulse waveform according to the control signal issued by the examination bed control board, and outputs the pulse waveform to the drive motor, controls the rotation of the drive motor, and drives the examination bed to move horizontally;

The workstation receives the weight value of the examinee sent by the control panel of the examination table, and adjusts the radiation dose during the scanning process according to the weight value.
The radiation dose control system in the CT system according to claim 2, wherein the control board of the examination table collects the rotation speed of the driving motor through an electronic encoder.
The radiation dose control system in a CT system according to claim 2, wherein the examination table control board reads the parameters of the driver through the CANOPEN protocol, and the parameters include: rated voltage and output current.
The radiation dose control system in the CT system according to claim 2, wherein the examination table control board exchanges data with the workstation through a custom CAN bus protocol.