DE102009009165A1 - Method and device for determining a path traveled by an endoscopy capsule in a patient - Google Patents

Abstract

In a method for determining a path (w) traveled by an endoscopy capsule (2) in a patient (4), the endoscopy capsule (2) containing a light source (8) and a light sensor (10), transmitting at a first time ( t1) the light source (8) emits light of a known first quantity (M1) reflected from an inner surface (6) of the patient (4), and the light sensor (10) receives a second quantity (M2) of reflected light and first (M1) and second quantities (M2), a reflection factor (R) of the inner surface (6) irradiated with light in the patient (4) is determined, - at a second time (t2) the light source (8) again transmits light of a third quantity ( M3) toward the inner surface (6), and the light sensor (10) receives a fourth quantity (M4) of reflected light, and from the third (M3) and fourth quantities (M4) and the reflection factor (R) the t1) and the second time (t2) path as changes ng of the distance (d2-d1) to the inner surface (6) determined. A device for determining a path (w) traveled by an endoscopy capsule (2) in a patient (4) comprises an endoscopy capsule (2) with light source (8) and light sensor (10) and a control and evaluation unit (12) with a this implemented program (13) for the implementation of the above Process.

Description

The The invention relates to a method and a device for determination a path that an endoscopy capsule travels in a patient.

An endoscopy capsule in question is z. B. from the DE 101 42 253 known. The present endoscopy capsule includes at least a light source and a light sensor. Such capsules may also include various inspection, diagnostic or therapeutic devices. This can z. As a video camera, a biopsy forceps, a clip or a drug reservoir. The capsule further contains a magnetizable or permanent magnetic element by means of which the capsule is moved wirelessly in the patient. For this purpose, the patient lies wholly or partially in an electric coil system of several, z. B. 14 individual coils. From the coil system suitable magnetic fields or gradient magnetic fields are generated which generate forces or torques on the capsule located in the patient or on the magnetic element. Thus, the capsule can be selectively moved in the patient in any direction. Areas of use are mainly hollow organs, in particular z. B. the human gastrointestinal tract, which is traversable with the capsule in a single pass in its entirety.

The The above-mentioned overall system or examination method will also MGCE (magnetically guided capsule endoscopy). At a first generation of these devices or capsules is the respective spatial location of the capsule in or relative to Coil system not known because the system does not have a expensive and complex location system has.

Of the Operator of the plant, which controls the capsule manually, can not see these from the outside. For certain therapeutic or diagnostic purposes, eg. B. in the evaluation of images that the capsule provides or when navigating the Capsule to a desired location, however, it is very useful or desirable from the endoscopy capsule in the patient to know the way traveled.

in principle could such a capsule in the patient with the help of X-ray or fluoroscopy can be easily visualized, However, the X-ray exposure of the patient and the cost of a corresponding system expansion opposite. Rather, the user must be purely on the basis of the Capsule or additionally introduced into the patient Orient the endoscope supplied images to the capsule in a desired Direction or to a desired location in the patient to control can. An estimate of the distance traveled by the capsule Way succeed only on the basis of the on-board camera supplied image material and thanks to the experience of a user of the system.

task The invention therefore, an improved method or a Device for determining one of an endoscopy capsule in a Patients to travel.

Regarding of the method, the object is achieved by a method according to claim 1.

The Invention is based on the fundamental idea, the distance measurement to realize that the distance traveled by the Capsule as a relative change in distance to one in the patient selected fixed point is measured. The absolute distance must not be known here. For this purpose, funds, namely a light source and a light sensor, used in the usual Capsules are present anyway.

According to the invention at a first time light of a known first set of the light source emitted. This light is from an inner surface Reflected the patient. The backscattered from the inside surface Part of the emitted light is from the light sensor as a second Received amount of reflected light. From the first and second Amount of emitted and reflected light becomes a reflection factor determined in the patient irradiated with light area. At one or any of several second times, the light source transmits then again light a respective known third amount in the direction the same inner surface. The light will be back on the Inner surface reflected, the light sensor receives a fourth amount of reflected light. On the basis of the third and fourth quantity and the previously determined reflection factor will now the change in distance of the endoscopy capsule or light source and light sensor to the inner surface determined. The change the distance corresponds between the first and second time covered Path of endoscopy capsule.

Under In the present case, a quantity of light is to be understood as follows: The amount of light is integrated over solid angle and / or time measured or it becomes the spatial and / or temporal density determined. Here are any combinations of spatial and temporal behavior of the measurement possible.

The invention is based on the recognition that substantially the same point or inner surface of the patient are irradiated with light for the first and second times. It is assumed that the reflection factor of the inner surface does not change and the orientation of the capsule and thus the orientation of the light source and the light sensor also between the first and the second time did not change significantly. This can be achieved by selecting the time intervals between successive measurements, ie first and second or between successive further second times, to be so small that the position and orientation can not change so much that the inner surface would migrate out of the light cone of the light source.

With In other words: So, starting from a position of the Capsule for the first time the optical reflection properties Measured quantitatively in the patient and then removed or approaching the capsule to the inner surface the reflected amount of light in turn measured, evaluated and under Consideration of the optical properties of the lens converted into a distance change relative to the first time.

Nonlinear optical properties of light source or light sensor, lens, Glass dome, etc. are at the o. G. Calculations taken into account. For faster mathematical consideration of nonlinearities is z. B. used in a reference measurement look-up table used.

In a preferred embodiment of the method is for first time the absolute distance of the endoscopy capsule to the inner surface known. From the known distance and inventively determined Path change becomes so at the second time by the way the actual distance to the inner surface is determined.

Of the absolute distance of the endoscopy capsule from the inner surface may in a preferred embodiment of the method be particularly easily determined so that the endoscopy capsule for first time on the inner surface is applied. The distance the endoscopy capsule to the inner surface is then zero.

light sensor and light source are usually under in an endoscopy capsule a glass dome, also called Dom housed. When concerns of the dome on the inner surface then corresponds to the distance from light source or light sensor to the inner surface of the distance to the adjacent to the inner surface glass dome. First Time is thus the reflection factor directly in relation to absolute known distance.

In A preferred embodiment of the method is described as Light sensor uses a camera. Such is usually in contain an endoscopy capsule anyway. The camera is then mostly a lighting device, for. B. a surrounding the camera lens LED wreath available. This is then in a further embodiment as Light source used. The inventive method can then use a standard endoscopy capsule for video observation be performed.

In a further advantageous embodiment of the method is the first and third amount of light coming from the light source is sent out. thereby changing that the light source is operated in pulse width mode. This offers z. B. in the o. g. Variant on when an LED ring serves as a light source. Whose Brightness can then be switched to a desired one by pulsed operation Amount of light to be dimmed.

In a further embodiment of the method remain light source and light sensor during movement of the endoscopy capsule aligned with the same area of the patient's internal surface. Thus, a path measurement in the patient even when moving a capsule over long distances take place as long as the capsule has a line of sight to the originally chosen inner surface has.

Regarding the device, the object of the invention is achieved by a device according to claim 7. This includes an endoscopy capsule with light source and light sensor and a control and evaluation unit, which is a program for execution the above method including its embodiments includes.

In an advantageous embodiment of the device is the light sensor a camera and / or the light source a LED wreath of the camera.

In A further advantageous embodiment is the light source a pulse width modulator operating in pulse width mode assigned.

For a further description of the invention will be made to the embodiments the drawings referenced. They show, in each case in a schematic outline sketch:

1 an endoscopy capsule in a patient operating according to the method of the invention,

2 an endoscopy capsule in an alternative mode of operation.

1 shows an endoscopy capsule 2 which are in a patient 4 is located, of which only an inner surface 6 is shown in the form of his stomach wall. The endoscopy capsule 2 carries a light source 8th in the form of a light emitting diode and a light sensor 10 in the form of a camera.

The endoscopy capsule 2 is a tax and evaluation 12 associated with a program 13 includes, which performs the method described below.

1 shows the endoscopy capsule 2 at a first time t ₁ , to which they are at a distance d ₁ to the inner surface 6 located. This distance is not known. At time t ₁ sends the endoscopy capsule 2 or the light source 8th a first known amount of light M ₁ to the inner wall 6 out. Part of the light is on the inner wall 6 reflected and towards light sensor 10 reflected back in the form of a quantity of light M ₂ .

The endoscopy capsule 2 sends the numerical values of the quantities M ₁ and M ₂ to a control and evaluation unit assigned to it 12 , From the quantities M ₁ and M ₂ , the reflection factor R of the inner wall 6 certainly.

1 shows a situation in which the patient 4 just with the help of endoscopy capsule 2 is examined. Therefore, the endoscopy capsule 2 from an operator, not shown, in the patient 4 navigates, for example, to the inner wall 6 too moved. At a time t ₂ , the capsule has the inner wall 6 approximated, so that they now have a distance d ₂ from each other, which, however, is also unknown. At time t ₂ sends the light source 8th again another known amount M ₃ of light to the inner surface 6 out, which in turn partially reflects the light and a lot of M ₄ of light to the light sensor 10 scatters back. The quantities M ₃ and M ₄ are returned to the control and evaluation unit 12 transfer. This is calculated on the basis of the quantities M ₃ and M ₄ and that as constant for the inner surface 6 assumed reflection factor R, the change in distance of the endoscopy capsule 2 to the inner surface 6 , This difference of the distances d ₂ - d ₁ corresponds to that of the endoscopy capsule 2 between the times t ₁ and t ₂ traveled path w. The method thus provides the information as to which path w the endoscopy capsule 2 has traveled without their distance to the inner surface 6 to know.

2 shows an alternative embodiment of the method, in which initially the endoscopy capsule 2 manually at time t ₁ until it touches the inside surface 6 is approached. The distance d ₁ between the light source 8th or light sensor 10 and inner surface 6 is thus known as the known distance between these and the front end of the glass dome 14 , Subsequently, the endoscopy capsule 2 from the inner surface 6 moved away and the procedure accordingly 1 executed. As per 1 At time t _2, the distance traveled w is determined. Since, in contrast to the above at time t ₁ but the absolute distance d _{1 was} known, thus also results in the absolute distance of the endoscopy capsule 2 from the inner surface 6 at time t ₂ as d ₂ = w + d ₁ .

In. 1 corresponds to the amount of emitted light M1 and M3 of a constant amount, since the light source 8th lit in continuous operation. In one embodiment in 2 is the light source 8th a pulse width modulator 16 assigned. Thus, at the times t ₁ and t ₂ different amounts of light M ₁ and M _{3 can be} emitted, which of the duty cycle of the pulse width modulator 16 depend. For example, in 2 At time t _1, a small amount of light M _{1 is} used, which is used to determine the reflection factor R, to the light sensor 10 near the inner surface 6 not to oversteer.

In 1 is still a variant of the method shown, in which for the calculation of the path W also a look-up table 18 is used. This contains information about the non-linear properties of the entire optical system, eg. B. from light source 8th , Glass dome 14 , Light sensor 10 and the reflection properties of the inner surface 6 at different einstrahlenden amounts of light. The corresponding look-up table was z. B. once under laboratory conditions at known distances from endoscopy capsule 2 and models of the inner surface 6 measured in a reference method.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 10142253 [0002]

Claims (9)

Method for determining one of an endoscopy capsule ( 2 ) in a patient ( 4 ) (w), whereby the endoscopy capsule ( 2 ) a light source ( 8th ) and a light sensor ( 10 ), in which: - at a first time (t1) the light source ( 8th ) Emits light of a known first quantity (M1), which from an inner surface (M1) 6 ) of the patient ( 4 ) and the light sensor ( 10 ) receives a second quantity (M2) of reflected light and, on the basis of the first (M1) and second quantities (M2), a reflection factor (R) in the patient ( 4 ) with light-irradiated inner surface ( 6 ) is determined, - at a second time (t2) the light source ( 8th ) again light of a third quantity (M3) in the direction of the inner surface ( 6 ), and the light sensor ( 10 ) receives a fourth quantity (M4) of reflected light and uses the third (M3) and fourth quantity (M4) and the reflection factor (R) of the distance traveled between the first (t1) and second time (t2) as a change in the distance (d2 - d1) to the inner surface ( 6 ) is determined. Method according to claim 1, in which - at the first time (t1) the distance (d1) of the endoscopy capsule ( 2 ) to the inner surface ( 6 ) is known and - at the second time (t2) on the basis of the path (w) the actual distance (d2) to the inner surface ( 6 ) is determined. Method according to Claim 2, in which, at the first time (t1), the endoscopy capsule ( 2 ) on the inner surface ( 6 ) is created. Method according to one of the preceding claims, in which as a light sensor ( 10 ) a camera is used. Method according to one of the preceding claims, in which the amount (M1, 3) of emitted light is determined by pulse width operation of the light source ( 8th ) is determined. Method according to one of the preceding claims, wherein the light source ( 8th ) and light sensor ( 10 ) during a movement of the endoscopy capsule ( 6 ) to the same point of the inner surface ( 6 ) stay aligned. Device for determining one of an endoscopy capsule ( 2 ) in a patient ( 4 ) path (w), with an endoscopy capsule ( 2 ) with light source ( 8th ) and light sensor ( 10 ), and with a control and evaluation unit ( 12 ) with an implemented program ( 13 ) for carrying out a method according to one of the claims 1 to 6. Device according to Claim 7, in which the light sensor ( 8th ) is a camera. Apparatus according to claim 7 or 8, with a light source ( 10 ) in a pulse width operating pulse width modulator ( 16 ).