KR20080043921A - Method for capsule endoscope tracking based on friendly points and system for performing the same - Google Patents

Abstract

A method and a system for capsule endoscope tracking based on friendly points are provided to accurately check position of lesion by using an ultrasonic wave harmless to a human body to give reliable three-dimensional position information of a capsule endoscope. A method for capsule endoscope tracking based on friendly points includes the steps of: transmitting an ultrasonic wave and an RF(Radio Frequency) signal to a capsule endoscope(10) by ultrasonic generators(31-38) and an RF transmitter of a wearing system(20) when a user swallows the capsule endoscope; starting counting time in an initial state by a time counter when the RF signal transmitted from the wearing system is sensed in an RF receiver of the capsule endoscope and stopping counting time when the ultrasonic signal transmitted from the wearing system is sensed in ultrasonic sensing units of the capsule endoscope; storing a count value of the time counter in a memory(50) of the wearing system through an RF transmitter mounted to an operation unit of the capsule endoscope when the time counter stops counting time; and calculating position information of the capsule endoscope by calculating distances between an ultrasonic sensing system of the capsule endoscope and four ultrasonic transmitting units of the wearing system through the count value of the time counter, selecting the three friendly points among the cross points of circles with radiuses of the distances, and calculating an inner center, an outer center, or a centroid of a triangle composed of the three cross points.

Description

Method for capsule endoscope tracking based on friendly points and system for performing the same}

1 is a schematic diagram for explaining the trigonometric method used in the conventional method for measuring the position of the capsule endoscope.

Figure 2 is a schematic diagram for explaining the triangulation method measured by the distance having an error used in the conventional method for measuring the position of the capsule endoscope.

3 is a simulation diagram of a trigonometry measured by a distance having an error used in a conventional method for measuring the position of a capsule endoscope.

4 is a schematic diagram of a system for calibrated position measurement of a capsule endoscope using a proximity point method according to the present invention.

5 is an internal configuration of a capsule endoscope system using a proximity point method according to the present invention.

7 is a flowchart of a method for measuring a position of a capsule endoscope using a proximity point method according to the present invention.

8 shows a schematic diagram in the case of proximity selection.

9 shows a schematic of a proximity point method.

10 shows a schematic diagram of a proximity method of distance with error.

11A is an example of simulation using the inner core of the proximity point method.

11B is an example of simulation using the outer core of the proximity point method.

11C is an example of simulation using the center of gravity of the proximity point method.

Fig. 12 shows a schematic diagram of forming a group of errors of trigonometry and proximity points.

13 shows a schematic diagram of a positioning environment with rectangular coordinates.

14 shows a schematic diagram of the position measurement in the XY plane.

Fig. 15 shows a positioning schematic in the SZ plane.

<Explanation of symbols for the main parts of the drawings>

10: capsule endoscope 11 ~ 14: ultrasonic detection unit

15: calculator 20: wear system

31 ~ 38: ultrasonic transmitter 40: control unit

41 processor 42 ultrasonic drive circuit

44,45: transceiver 50: memory card

60: cable 70: computer

81,82: RF transceiver 90: Time counter

100: monitor 100: main body

The present invention relates to a method and system for measuring the position of a capsule endoscope using a proximity point method, and the probability of error for position detection by using a proximity point method for more accurate location of the capsule endoscope when performing the capsule endoscope. The present invention relates to a method and a system for measuring a capsule endoscope using a proximity point method for measuring three-dimensional coordinates in space.

In general, when the capsule endoscope is performed in the body, the position measuring methods calculate the position information by triangulation by measuring the distance based on the intensity or delay time of the radiated energy by radiating RF, magnetic field, or ultrasonic wave into the body. However, in the conventional position measuring technique by triangulation, the error due to the following two factors seriously affects the diagnosis accuracy. First, it is an error caused by factors affecting the electromagnetic field changes, such as bones and organs in the human body. Second, there are inherent errors of magnetic fields, RF, and ultrasound that radiate into the body.

The capsule endoscope currently being used is representative of M2A of Giving Imaging, Israel. The M2A measures the position of the capsule endoscope in the human body using RF (Radio Frequency). The position coordinates measured use RF intensity and trigonometry. The strength of RF does not accurately determine the distance according to the medium in the human body, and the position measurement using the trigonometry also has an error. The location information measured in this way has an error of about 3 cm.

In addition, Korean Patent Application No. 10-2002-0027334 'Telemetry capsule and its position detection system' used a magnetic field to grasp the position information of the capsule endoscope. The Miro capsule endoscope measures the position by trigonometry using the strength of the magnetic field. This is impossible to accurately measure the position by the error and the position measurement according to the medium in the human body, such as M2A. The location information measured in this way has an error of about 3 cm.

이다. 이 때의 관측점은 각각

,

,

이다.

에서

까지 실제 거리가

이고, 측정오차가

이면, 측정한 거리는 다음 <식1>과 같다.The conventional method for measuring the position of a capsule endoscope is a triangular method. Trigonometry is the method of finding the position of a point or an object at the same distance from an observation point. The coordinates of the capsule endoscope in the human body

to be. The observation points at this time are

,

,

to be.

in

Until the actual distance

The measurement error

In this case, the measured distance is as follows.

<식 1>

<Equation 1>

에서

을 반지름으로 하는 원은 <식2>와 같다.Viewpoint

in

The circle whose radius is is equal to <Equation 2>.

<식2>

<Equation 2>

의 값을 구한다. 이를 <식 6>과 같이 연산하여

를 구한다.When <Equation 2> is combined, it is expressed as a matrix as in <Equation 3>, <Equation 4>, and <Equation 5>.

Find the value of. Calculate this as <Equation 6>

Obtain

<식3>

<Equation 3>

<식4>

<Equation 4>

<식5>

(Eq. 5)

<식6>

<Equation 6>

에서 거리

로 반지름을 하는 원을 그렸을 때, 원들의 교선이 생긴다. 이 교선들의 교점을 캡슐형 내시경의 위치로 한다. Trigonometry used in the position measurement method calculated by the above equations, as shown in Figure 1, the observation point

Distance from

When you draw a circle with radius, the intersection of circles occurs. The intersection of these intersections is the position of the capsule endoscope.

If the intersection of intersections does not meet at one point due to error, find the center of gravity of the intersections. For example, as shown in FIG. 2, when the measured distance is the same as the dotted line and the actual distance is the same as the solid line, it can be seen that the measured position information has an error. 3 shows an example of the simulation obtained in this way. 3 illustrates a case where the measurement distance has an error of ± 10 mm when the coordinates 250 and 150 are obtained. In the worst case of the simulation results, the positional information was found to be ± 15mm, which is larger than the measurement distance.

The present invention has been invented to solve the above problems, in the procedure of capsule endoscope to overcome the irregularities of the electrical characteristics of the human tissue and to overcome the limitations of the measurement medium to position the camera of the capsule endoscope error range of about 10mm To provide a method and system for measuring the position of a capsule endoscope using a proximity point method for measuring a distance using ultrasonic waves harmless to the human body and using the proximity point method to determine a more accurate location of the lesion. Its purpose is to.

The present invention for achieving such an object,

Iii) when the user swallows the capsule endoscope 10, the ultrasound generator 31-38 and the RF transmitter 44 of the wearing system 20 simultaneously transmit ultrasound and RF signals to the capsule endoscope 10 inside the human body, respectively. ;

Ii) When the RF signal transmitted from the wearing system 20 is detected by the RF receiver 82 of the capsule endoscope, the time counter 90 starts the time count in the initial state, and the ultrasonic wave transmitted from the wearing system 20. When the signal is detected by the ultrasonic sensors 11 to 14 of the capsule endoscope 10, stopping the time coefficient;

Iii) If the time counting of the time counter 90 is stopped in step ii, the value of the counted time counter 90 is transferred to the capsule endoscope 10 through the RF transmitter 81 mounted to the calculation unit 15. Storing in the memory 50 of the wearing system 20; And

Vi) the ultrasonic detection system of the capsule endoscope from the four ultrasonic transmitters 33, 35, 37, 38 of the wearing system 20 by using the value of the time counter stored in the memory 50 in the step iii); Calculates the location information of the capsule endoscope by obtaining three distances, selecting three points close to each other from the intersections of the circles having the radius of the distance, and calculating the inner, outer, or center of gravity of the selected three points. Steps.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the accompanying drawings, Figure 1 is a schematic diagram for explaining the operation of the capsule endoscope system having a posture measuring function according to the present invention, Figures 2a, b and c is the interior of the capsule endoscope system having a posture measuring function according to the present invention It is a block diagram. 3 is an ultrasonic signal detection system of a capsule endoscope system having a posture measuring function according to the present invention.

4 is a schematic diagram of a system for corrected position measurement of a capsule endoscope using a proximity point method according to the present invention, and FIG. 5 is an internal configuration diagram of a capsule endoscope system using a proximity point method according to the present invention. 7 is a flowchart of a position measuring method of the capsule endoscope using the proximity point method according to the present invention.

As shown in FIG. 5, the posture measuring system of the capsule endoscope according to the present invention includes a capsule endoscope 10, a wearing system 20 worn by a user, a capsule endoscope 10, and a wearing system 20. ) Is broadly classified into an image processing system 70 for controlling.

As shown in FIG. 6, the structure of the capsule endoscope 10 according to the present invention forms four ultrasonic sensors 11 to 14 inside the conventional capsule endoscope 10. The calculation unit 15 is electrically connected to each of the ultrasonic sensing units 11 to 14 at the center of the ultrasonic sensing units 11 to 14. Ultrasonic sensing units 11 to 14 are formed in all directions from the inside of the capsule endoscope 10, and the calculating unit 15 is provided with RF transmitters and receivers 81 and 82 and time counters 90 for transmitting and receiving RF signals. do.

As shown in FIG. 5, a plurality of ultrasonic transmitters 31 to 38 are formed from an outer upper portion to a lower portion of a wearing portion (not shown) formed in a vest form as shown in FIG. 5. The outer side of the wearing portion is formed with a control unit 40 for performing various controls for grasping the position of the capsule endoscope 10. As shown in FIG. 7, the control unit 40 transmits / receives 44 and 45 to transmit and receive an RF frequency to and from the capsule endoscope 10 to the processor 41 for controlling the posture control of the capsule endoscope 10. ), Generating an ultrasonic signal transmitted to the ultrasonic detection unit 11 to 14 formed inside the capsule endoscope 10, the memory card 50 for storing the image information and posture information transmitted from the capsule endoscope 10 Ultrasonic driving circuit 42 and a USB 43 port which is a removable data storage means may be formed as necessary.

In addition, the image processing system 70 is electrically connected to the control unit 40 of the wearing system 20 via a cable 60 and the computer 70 for image processing the image information transmitted from the capsule endoscope 10 and And a monitor 100.

The operation of the capsule endoscope 10 according to the present invention configured as described above, as shown in FIG. 5, when the user swallows the capsule endoscope 10, the capsule endoscope 10 moves along the user's intestine. The ultrasonic generator of the wearing system 20 and the receiver of the capsule endoscope communicate with each other to produce mutual distance data. This data value is stored in the vest system along with the image data and then passed to the computer 70. The computer 70 performs location tracking and attitude measurement algorithms and displays them on the monitor 100.

The ultrasonic sensors 11 to 14 embedded in the capsule endoscope 10 detect ultrasonic signals generated from the ultrasonic transmitters 31 to 38 of the wearing system 20 to amplify only signals of a desired ultrasonic frequency band and convert them into digital signals. Convert

The time counter 90 connected to the calculation unit 15 is necessary to calculate the time difference between the RF received signal and the ultrasonic signal received by the RF receiver 82. When the RF receiver 82 receives the RF signal, the value of the time counter 90 is initialized (starts time counting from zero), and when the ultrasonic signal is detected, the time counter value stops. In this case, the time counter value means a difference in arrival time between the ultrasonic signal and the RF signal.

The ultrasonic generators 31-38 and the RF transmitters 44 of the wearing system 20 simultaneously transmit ultrasonic waves and RF signals to the capsule endoscope 10 inside the human body. When the RF signal is detected at the RF receiver 82 of the capsule endoscope, the value of the time counter 90 starts counting from zero. In addition, the counting of the time counter 90 is stopped when the ultrasonic signal of the capsule endoscope 10 is detected. The speed of the RF signal for performing the time counting operation in the initialization state of the time counter 90 is 3 x 10 ⁸ m. / s On the other hand, the speed of the ultrasonic wave that stops the time counting operation of the time counter 90 is 340 m / s in the air and 1625 m / s in the human body. Therefore, the RF signal speed is about 106 times in the air compared to the ultrasonic signal and in the human body. 2 x 10 ⁵ times faster Therefore, even if the ultrasound generator 31-38 and the RF transmitter 44 of the wearing system 20 simultaneously transmit ultrasound and RF signals to the capsule endoscope 10 inside the human body, the RF signal first receives the RF receiver of the capsule endoscope ( 82, the time counter 90 starts counting the time, and when the ultrasonic signal is detected later, the time counting (counting) of the time counter 90 is stopped.

When the counting of the time counter 90 is stopped, the value of the time counter 90 counted in the meantime is transmitted to the wearing system 20 through the RF transmitter 81 mounted on the calculation unit 15 in the capsule endoscope 10. And stored in the memory 50 of the wearing system 20.

Subsequently, as shown in FIG. 5 using the value of the time counter stored in the memory 50, the four ultrasonic transmitters 33, 35, 37, 38 of the wearing system 20 and the ultrasonic endoscope system of the capsule endoscope are used. Find the distance. The relationship between these distances is used to extract the 3D coordinates of the ultrasonic sensing system of the capsule endoscope.

That is, a value proportional to the distance is calculated by the following Equation 7 based on the value of the time counter stored in the memory 50. The average speed of the ultrasonic waves in the human body is 1625 m / s, and the speed is the human body temperature, This value takes into account pressure and density.

<식 7>

<Equation 7>

=초음파의 지연 속도,

=초음파 속도,

=비열,

=압력,

= 밀도)(

= Ultrasonic delay rate,

= Ultrasonic speed,

= Specific heat,

= Pressure,

= Density)

The position measurement of the capsule endoscope is made in the sequence as shown in Figure 7, the distance from the ultrasonic generator 31 to 38 of the wearing system 20 to the ultrasonic sensing unit 11 to 14 of the capsule endoscope 10 Calculate the delay time of the ultrasonic wave as shown in <Equation 7>. The location information is calculated by the proximity point method using the measured distance and the designated number of the ultrasonic transmitter.

이다. 이 때의 관측점은 각각

,

,

이다.

에서

까지 실제 거리가

이고, 측정오차가

이면, 측정한 거리는 다음 <수식8>과 같다.Proximity point method is to find the position of the point or the object at the same distance from the observation point. The coordinates of the capsule endoscope in the human body

to be. The observation points at this time are

,

,

to be.

in

Until the actual distance

The measurement error

In this case, the measured distance is as shown in Equation 8.

<수식 8>

<Equation 8>

에서

을 반지름으로 하는 원은 <수식 9>와 같다. Viewpoint

in

The circle whose radius is is equal to <Equation 9>.

<수식9>

<Equation 9>

라고 할 때,

은 <수식10>과 같다. 이를 <수식 9>에 대입하면 <수식 11>이 산출된다. <수식 11>을 변형함으로 <수식 12>를 구할 수 있으며, 이를 <수식 10>에 대입하여 두 원간의 교점을 찾는다.Find the intersection of two circles in the equation (9). The intersection of two circles

When I say

Is the same as <Equation 10>. Substituting this into Equation 9 yields Equation 11. By transforming <Equation 11>, <Equation 12> can be obtained, and substituting it into <Equation 10> to find the intersection point between two circles.

<수식10>

<Equation 10>

<수식11>

<Equation 11>

<수식12>

<Equation 12>

라고 했을 때, 최대 6개의

가 생긴다. 이러한 교점을 이용하여 교점간의 최대 거리가 작은 것을 선택한다. 방법은 표 1과 같이 6개의

가 생겼을 때를 가정한다. Find the intersection

Up to six

Occurs. Using these intersections, the one with the smallest maximum distance between the intersections is selected. Six methods are shown in Table 1.

Suppose you have a

<Table 1> Intersection of Circle

에 의해 생긴 원의 교점 :

관측점

에 의해 생긴 원의 교점:

관측점

에 의해 생긴 원의 교점:

Viewpoint

The intersection point of the circle caused by:

Viewpoint

The intersection point of the circle caused by:

Viewpoint

The intersection point of the circle caused by:

When selecting an intersection point, as shown in FIG. 8, the total distance is calculated and the smallest distance is selected. The selected point becomes the proximity point. Form a triangle with three points of proximity to find the inner, outer and center of gravity. One of these points is the location of the capsule endoscope.

The inner core of a triangle is calculated as shown in Equation 13. The outer core is calculated as shown in Equation 14. The center of gravity is calculated as shown in Equation 15.

<수식 13>

<Equation 13>

<수식 14>

<Equation 14>

<수식 15>

<Equation 15>

에서 오차를 갖는 거리

을 반지름으로 하는 원을 형성한다. 형성된 원의 교점 중에서 근접한 3개의 점을 선택한다. 선택된 점을 삼각형으로 하는 무게중심, 내심, 외심을 구한다. 도 9에서는 무게 중심을 표현한다. 근접점 방법은 도 10와 같이 삼각법보다 정확한 측정이 가능하다. 도 10과 같이 근접법 방법의 시뮬레이션 예를 들 수 있다. 도 11a, 11b, 11c는 내심, 외심, 무게중심으로 측정한 위치측정의 시뮬레이션이다. 시뮬레이션에서 (a), (b), (c) 방법에 따라 위치정보 좌표의 분포가 다르다. 이와 같은 좌표의 분포를 이용하여 도 12과 같이 위치정보좌표의 분포가 삼각법보다 작아지게 함으로서 보다 정확한 캡슐형 내시경의 위치측정이 가능하다.An example of a proximity point method is an observation point as shown in FIG.

Distance with error

Form a circle with radius. Select three adjacent points from the intersections of the circles formed. Find the center of gravity, inward and outward with the selected point as the triangle. 9 expresses the center of gravity. The proximity method can be measured more accurately than the trigonometric method as shown in FIG. A simulation example of the proximity method can be given as shown in FIG. 10. 11A, 11B, and 11C are simulations of position measurement measured by the inner core, outer core, and center of gravity. In the simulation, the distribution of location coordinates differs according to the methods (a), (b), and (c). By using such a distribution of coordinates, as shown in FIG. 12, the distribution of the location information coordinates is smaller than the triangulation method, thereby making it possible to more accurately measure the position of the capsule endoscope.

Positioning in three dimensions is calculated assuming the coordinate axis in space as a plane. In the environment as shown in FIG. 14, the ultrasonic wave transmitting apparatus of the binder has specific coordinates by the user. For example, a three-dimensional spatial coordinate axis is configured as shown in FIG. 14. The coordinate axis in space can be projected onto the XY plane and the YZ plane. If the ultrasonic transmitters are called P1, P2, P3, and P4, and the measuring distances from each of the capsule endoscopes are L1, L2, L3, and L4, the ultrasonic transmitters Pn (n = 1, 2, 3, 4) By selecting three or more points, the corresponding measurement distances are converted into distances in the XY plane and the YZ plane. When three points P1, P2 and P3 are selected in the XY plane as shown in Fig. 14, the selected L1, L2 and L3 are transformed into L1 ', L2' and L3 '. With the modified distance, the position in the XY plane is calculated via the proximity method. In this way, when the XY plane is regarded as one S axis, the same plane as the YZ axis is configured. As shown in Fig. 15, L1 ', L2', and L4 'are obtained from P1, P2, and P4 selected in the SZ plane, and the position measurement in the SZ plane can be performed by the proximity point method. Since S is the same as the XY plane, the coordinates in the XYZ space are represented by the coordinates at this time.

As described above, the present invention according to the present invention by providing an accurate position measurement method and system of the capsule endoscope using ultrasonic waves harmless to the human body to provide reliable three-dimensional position information of the capsule endoscope to provide accurate location of the lesion There is an effect that can be grasped.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited thereto and may be improved or modified by those skilled in the art within the scope of the technical idea of the present invention.

Claims (3)

Iii) when the user swallows the capsule endoscope 10, the ultrasound generator 31-38 and the RF transmitter 44 of the wearing system 20 simultaneously transmit ultrasound and RF signals to the capsule endoscope 10 inside the human body, respectively. ; Ii) When the RF signal transmitted from the wearing system 20 is detected by the RF receiver 82 of the capsule endoscope, the time counter 90 starts the time count in the initial state, and the ultrasonic wave transmitted from the wearing system 20. When the signal is detected by the ultrasonic sensors 11 to 14 of the capsule endoscope 10, stopping the time coefficient; Iii) If the time counting of the time counter 90 is stopped in step ii, the value of the counted time counter 90 is transferred to the capsule endoscope 10 through the RF transmitter 81 mounted to the calculation unit 15. Storing in the memory 50 of the wearing system 20; And Vi) the ultrasonic detection system of the capsule endoscope from the four ultrasonic transmitters 33, 35, 37, 38 of the wearing system 20 by using the value of the time counter stored in the memory 50 in the step iii); Calculates the location information of the capsule endoscope by obtaining three distances, selecting three points close to each other from the intersections of the circles having the radius of the distance, and calculating the inner, outer, or center of gravity of the selected three points. Position measuring method of the capsule endoscope using the proximity point method comprising the step. The method of claim 1, wherein the step (b) comprises: calculating a value proportional to a distance by using Equation 1 using a value of a time counter stored in the memory 50;

<Equation 1> (

= Ultrasonic delay rate,

= Ultrasonic speed,

= Specific heat,

= Pressure,

= Density) Using Equation 1, the coordinates of the capsule endoscope in the human body are

Viewpoint

,

,

Until the actual distance

The measurement error

If it is, the step of calculating the distance measured by the following formula (2);

<Equation 2> Observation point in <Equation 2>

in

Calculating a circle with a radius by <Equation 3>;

<Equation 3> Intersection between two circles in <Equation 3>

To obtain, and according to <Equation 4>

To calculate the equation 5 by substituting the calculated intersection into Equation 3, transforming Equation 5 to yield Equation 6, and substituting it into Eq. Finding an intersection;

<Equation 4>

(Eq. 5)

<Equation 6> Calculating a proximity point by selecting a smallest maximum distance between intersections among the maximum six nodes found in the step; The inner core of the triangle is calculated as in <Equation 7>, the outer core is calculated as in <Equation 8>, and the center of gravity is calculated as in <Equation 9>. Position measuring method of the capsule endoscope using the proximity point method comprising the step of setting one point of the position information of the capsule endoscope.

<Eq. 7>

(Eq. 8)

<Eq. 9> It has four ultrasonic sensing units 11 to 14 formed in all directions from the inside, and an arithmetic unit 15 is formed at the center of the ultrasonic sensing units 11 to 14, and the RF unit transmits and receives an RF signal. Capsule endoscope 10 is formed for the RF transmitter, the receiver (81, 82) and the time counter 90; The capsule endoscope 10 is worn on the user to transmit and receive a signal, a plurality of ultrasonic transmitters 31 to 38 are formed from the outer top to the bottom, and various controls for grasping the position of the capsule endoscope 10 A control unit 40 composed of a processor 41 for performing the operation, and a transceiver 44 for transmitting and receiving an RF frequency with the capsule endoscope 10 is formed on one side, and is transmitted from the capsule endoscope 10. A memory card 50 for storing image information and posture information and an ultrasonic driving circuit 42 for generating an ultrasonic signal transmitted to the ultrasonic sensors 11 to 14 formed inside the capsule endoscope 10. Wearing system 20; And An image including a computer 70 and a monitor 100 for image processing image information transmitted from the capsule endoscope 10 electrically connected to the control unit 40 of the wearing system 20 via a cable 60. Pose measuring system of the capsule endoscope consisting of a processing system (70).

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