DE29613103U1 - Endoscope head - Google Patents

Description

Endoscope head
Description

The invention relates to an endoscope head for an endoscope suitable for diagnostic or therapeutic purposes in body cavities with a lighting device, an endoscope optics, an image capture device and signal transmission lines.

In endoscopes, an endoscope tube is used to examine or treat objects in body cavities and tubes, such as the lungs, stomach and intestinal tract, where there is no outside light, especially for the detection of early-stage cancer.

It is known that a photosensitive substance that has an affinity for tumors, such as a hematoporphyrin derivative (HpD), can be used to examine cancer in the early stages. However, this method is not advisable due to the side effects of a substance such as a hematoporphyrin derivative on the human body. In addition, the use of laser light requires an expensive laser light generator and an endoscope specially designed for this purpose. Such a system is therefore very expensive. In addition, the possible selective damage to the tissue by the pulsed dye laser light plays a special role. This is why such devices are ideal for treating vascular constrictions.

From DE-OS 41 33 493 a diagnostic device for the detection of &ogr; cancer in the early stages is known, which has an endoscope in which illumination light emanating from an external illumination light source is projected onto an object via an illumination window arranged at the distal end of an insertion part and in which an object image which is generated by a

optical lens system arranged at the distal end of the insertion part, is transmitted out of the insertion part via an image transmission means so that image viewing is possible.

The wavelength required for an excitation light between 400 nm and 100 nm for the illumination light at which a living organism produces fluorescent light is obtained by means of a wavelength selection filter arranged in the illumination path between the illumination light source and the object. A second wavelength selection filter, designed to transmit the fluorescent light between 500 nm and 600 nm, but not the light transmitted via the first filter, is provided in the viewing path at the outer end of the eyepiece. In a variant of the device, the image transmission means is designed as a solid-state image generating device which transmits the image to be viewed in the form of electrical signals. The main disadvantage of this device is the use of an external light source and optical fiber bundles for transmitting the illumination light and the image transmission light, which, in addition to low image resolution and lack of space, results in a lack of image resolution and a lack of space. in the endoscope tube means that the endoscope tube must be relatively thick and its flexibility is low.

DE-PS 41 10 228 describes an arrangement for the endoscopic detection of cancerous tissue marked by a substance that can be excited to fluorescence by light, with a first light guide that is connected to an external light source and via which the tissue can be illuminated intermittently, and a second light guide via which the fluorescence light excited by the light is fed to an optoelectronic converter in the form of a video camera to which an evaluation device with at least two video memories is connected. Due to the total exposure times available for the individual image and thus the total recording time for the fluorescence, with sufficient dynamics it is also possible to work with lower HPD doses and thus with less stress on the patient. The light source for exciting the dye

An argon ion laser with the two main lines 514 and 488 nm can be used for fluorescence. These two wavelengths in the green range stimulate a one-photon process that fluoresces in a wavelength range of 600 to 700 nm and the green light still has a good penetration depth. The main disadvantage of this device is the use of an external light source and fiber optic bundles to transmit the illumination light and the image transmission light, resulting in low image resolution and a thick endoscope tube with little flexibility.

The company Olympus Optical Co GmbH, Hamburg, DE currently offers a large number of endoscopes in the form of colonoscopes, duodenoscopes, gastroscopes and bronchoscopes in numerous brochures, some of which can also be used for electronic recording, storage and evaluation of the observation results using an extracorporeal video camera, for example the Olympus video camera OTV-F2. The camera is equipped with CCD elements (charge coupled devices) in order to achieve a small design with high image resolution, but the endoscopes used in this device also have the disadvantage of using an external light source and the use of optical fiber bundles to transmit the illumination light and the image transmission light, which results in a relatively low image resolution despite the stated large number of optical fibers. The problems with the endoscope tube and the device costs described above still exist here.

The DD patent specification 233 299 theoretically describes a device and a method for eye examination, in which emitters for electromagnetic waves in the frequency range from UV radiation to 0 infrared radiation, the frequency of which can be continuously changed, are provided. An optical system that has optoelectronic components, arranged in different configurations, as receivers in order to detect reflections, especially when examining sections of the eye, and

The possibility of subsequently processing the data electronically is also mentioned. However, the device cannot function without an additional optical system or without optical fibers, so that the disadvantages of light loss discussed above also apply here. If this system were used in an endoscope-like device, the disadvantages of low image resolution and lack of space in the endoscope tube would also occur.

A combined optoelectronic component is also known from DD patent specification 233 463, in which light-emitting diodes or laser diodes are arranged with CCD elements in a common component and can be controlled and read out together in groups or individually. With the help of the components arranged in many different possible configurations, it should be possible to obtain colored screen images in the multispectral range, which can be used in the medical field to recognize and observe pathological manifestations and can also be stored electronically. This component is used to recognize and scan structural shapes or to view objects that can be accessed from the outside and is largely unsuitable for use in endoscopes. It is intended in particular for measuring reflection angles and not for viewing objects in body cavities and tubes where there is no external light.

Both DD documents describe theoretical systems that have not been tested in practice and suffer from a lack of feasibility.

The present invention is therefore based on the problem of improving conventional endoscopes of the types mentioned, increasing the image resolution and significantly reducing the costs compared to known devices, for example those with laser light devices.

The problem is solved by the features of claims 1 and 14. Advantageous further developments of the invention are covered in the subclaims.

The endoscope head according to the invention, which is suitable for attachment to a commercially available endoscope, is provided on its distal end with light-emitting elements as well as with an integrated, e.g. opto-electronic detection device for image generation, an upstream endoscope optics and, in special embodiments, with a polarization filter. It also has channels for passing a fluid through to cool the image generation device.

Light-emitting diodes (LEDs) are advantageously used as light-emitting elements, but electroluminescent lamps (ELL) can also be used as light-emitting elements. These can be installed directly as semiconductor components without the need for commercially available housings or glass capsules.

The image generation device is advantageously designed as a CCD element, expediently in the form of a CCD matrix or other group-based arrangement. A CCD element is generally defined as an assembly or a chip with CCD cells for pixel-oriented detection of light emissions.

By dispensing with an optical fiber bundle, an image resolution that is about 10 times higher can be achieved because the entire pixel surface of the chip, which is densely packed with 1032 CCDs, can be used.

However, high-quality, densely staggered photodiode arrays with subdivided structures and high image resolution can also be used as image generation devices. Differential, quadrant, circular, and ϳ circular ring photodiodes and arrays can be used for this purpose.

Further advantages can be provided by the use of wavelength-sensitive avalanche photodiodes, in particular through the advantage of

inexpensive image-intensifier-like effect, which allows modulations up to 200 MHz and in some cases even higher. The photodiodes are supplied with a sinusoidally modulated voltage, which, depending on the frequency applied, leads to a short-term electronic closure of the diode. With the help of this modulation in the range of preferably 10 to 100 MHz, the separation of fast and slow decaying fluorescence is possible. By using photodiodes, it is possible to quantitatively record light scattering phenomena due to their potentially high readout speed and thus to detect ballistic photons if necessary. With higher frequency modulations, the scattered light, which travels a longer path due to its deflection, can be separated from photons that hit the diode directly, for example to detect a biological sample in a milky, cloudy liquid.

The fluorescence excitation can be carried out with single-color, for example blue, green or red LED chips in conjunction with a black and white CCD chip with dichroic filters (transmission > 56 nm). With the help of the colored LED chips mentioned, fluorescence excitation of natural or administered porphyrins is possible in the respective absorption bands in the blue, green and red range. This enables fluorescence emission in the range of 680 nm via the black and white CCD chip equipped with the filter mentioned. A high-frequency control of the LED, in conjunction with the also controlled CCD chip, allows the separation of the various fluorescences according to their decay time. The preferred goal is the quantitative measurement of red porphyrin fluorescence with half-lives between 10 and 15 ns.

By combining and individually controlling different chip colors, additional information can be identified. The penetration depth of the green or red light is considerably higher than that of the blue light, which makes it possible, for example, to make submucosal tumors visible or to show the depth extension superficially with blue light.

visualizable tumors can be detected noninvasively.

Another preferred application is the use of different colored, red, green and blue LEDs in conjunction with a black and white CCD chip without a filter. By sequentially illuminating with the colors red, green and blue and a correspondingly synchronized triggering of the black and white CCD chip, it is possible to generate very high-resolution color images, since the entire CCD chip is available for one spectral color at a time.

&iacgr;&ogr; Although endoscopic arrangements are known in which black and white CCD chips are also used, the illumination is conventionally provided by a fiber optic cable and a xenon light source, between which a filter wheel with red, green and blue filters is arranged. The intended use of colored LEDs would thus make it possible to dispense with expensive analog light sources and their image transmission cables. The freely selectable, very short shutter speeds of the LED also prevent the occurrence of motion artifacts.

A third possible preferred application is the combination of different colored red, green and blue LEDs in conjunction with a color CCD chip. Since the CCD chip already has color filters, it is possible to evaluate a fluorescence image by reading the red channel after blue and green excitation, or to obtain a conventional color image by simultaneously exciting red, green and blue. The advantage of such an arrangement would be the easy switching between color and fluorescence display. The disadvantage, however, is that the light sensitivity is reduced by a factor of 5 compared to the black and white CCD chip, as well as a lower resolution, since the color images are already on the chip and thus reduce the effective resolution by a factor of 3.

The light-emitting elements are conveniently arranged in a ring around the CCD or photodiode arrangement to ensure good illumination of the object to be viewed.

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From a particular point of view, it may be advantageous to control the light-emitting elements individually, in groups or all at the same time, for example in segments in order to obtain a spatial impression by illuminating them from different directions, or to control them individually or in groups alternately or in the manner of a circulating light.

The fluid passed through the endoscope head to cool the image generation device can be either a gas or a liquid.

&iacgr;&ogr; The gaseous fluid passed through can flow in through one channel and out through another channel, flowing freely around the elements in the endoscope head. If the fluid passed through is a liquid, it must be guided through the endoscope head in a closed circuit. It is then sensible to provide the image generation device with thermal dissipation devices that are introduced into the cooling fluid circuit or at least coupled to corresponding heat exchanger surfaces. This thermal dissipation can be expediently designed as a wire or strip made of a good heat-conducting material, preferably silver or copper, which can be connected to the chip &ogr; and the heat exchanger using conventional bonding or soldering connections.

To supply the coolant to the endoscope head, the channels originally provided for the light guides in the endoscope tube or in endoscopes according to the state of the art can be used advantageously, without the tube losing its flexibility.

The invention will be explained in more detail below with reference to the preferred embodiments shown schematically in the accompanying figures.
Show it:

0 Fig. 1 a first endoscope head according to the invention with gas cooling and

CCD elements and LED lighting; Fig. 2 shows a second endoscope head according to the invention with liquid cooling and photodiodes and ELL lighting.

Identical or equivalent parts are provided with the same reference symbols below.

The endoscope head 1 according to the invention according to Fig. 1 with coupling 20 for an endoscope tube (not shown) is provided with light-emitting elements 3 and an image generation device 4, for example a CCD matrix, on its front side 2 facing the object 18 to be examined, and has an endoscope optics 5 and a transparent cover, here a polarization filter 6. The supply lines 8 to the light-emitting elements 3, here a ring of LED diodes, and the signal or readout line 9 of the CCD matrix 4, which is connected to extracorporeal electronics, are led to them through a channel 7. Furthermore, channels 10 and 11 are provided for passing a gaseous fluid through to cool the image generation device 4. The gaseous fluid passed through can flow in through one of the channels 10 and back through the other channel 11 - to a processing and feeding device that is also extracorporeal. The elements of the image generation device 4 in the endoscope head 1 are freely flowed around or contacted on at least one side in order to dissipate the heat that is generated, as indicated by the arrows. When the endoscope head 1 is attached to a conventional endoscope tube 12 with a manipulator channel 13, through which, for example, a biopsy forceps 14 can be guided to the object 18, the channels provided for the light guides in endoscopes according to the state of the art can be used as coolant channels 10, 11. With the aid of the device according to the invention, it is possible to diagnose an early carcinoma 19 present on an organ surface 18 and to take a tissue sample with the biopsy forceps 14.

As an alternative to gas recirculation, inert liquid gas can be used and fed through line 10 to the image capture device and expanded there in space 22. Instead of a return flow through channel 11, the resulting gas can be fed through branch 21 via channel 13 to object 18. This results in two applications. The gas can be used to prevent local icing for a

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subsequent therapy or the changed emission of the locally cooled object can be included in an observation. This results in a contrast image to an object under normal temperature conditions, whereby polarizing filters 6 with suitable polarization planes can also have a supporting effect.

Additionally, local heating of the object caused by the lighting can be compensated by cooling.

According to Fig. 2, the optical-electronic elements of the endoscope head 25, here ELL arrays 23, comprise a polarization filter 26 that only covers the optics block 5, and a photodiode chip 24. The cooling fluid here is a liquid, e.g. cooling water. It is guided through the endoscope head 1 in a closed circuit 15. It is useful for the photodiode arrangement to be provided with a thermal dissipation, for example in the form of heat sinks or cooling plates 16, from which thermal dissipation devices 17 are introduced into the cooling circuit 15 for heat exchange when the cooling fluid cannot flow directly past the heat sinks or cooling plates. These thermal dissipations can be expediently designed as a wire or strip made of a good heat-conducting material, preferably silver or copper.

Alternative embodiments combining the functions of illumination, polarization, image generation and cooling - possibly also other components in sub-combination can also be provided by the person skilled in the art, e.g. ELL illumination, CCD element, liquid cooling, without departing from the scope of the invention.

These endoscope designs or diagnostic procedures offer the following advantages in conjunction with a control and regulating circuit (not shown) for the light control and the signal evaluation of the image generation device 4 as well as the other device parameters: By dispensing with fiber optic bundles! a higher image resolution is achieved,

by a factor of 10. By using high-performance LEDs, which can be modulated in the range of up to 15 MHz, in the endoscope head, extremely inexpensive fluorescence excitation is possible, since there are no light losses in the optical fibers. The LEDs are operated directly by applying a high-frequency sinusoidally modulated voltage. Depending on the design of the LED, a very short light emission time (flash) can be achieved. The direct modulation of the light source otherwise requires a considerably higher effort. For example, it is common to introduce so-called acousto-optical modulations into a collimated laser beam, the

&iacgr;&ogr; Light diffraction behavior is changed by applying a high-frequency voltage. These changes in the diffraction behavior can be used to modulate the laser light. The advantage of this LED described here is the direct modulation of the semiconductor without any additional technical aids. Something similar is also possible with various semiconductor lasers that can be modulated accordingly.

The LED itself and not just the optics can be fitted with polarization filters. This enables time-resolved anisotropy measurements of fluorescence markers.

With state-of-the-art white light endoscopy, it is often not possible to detect any changes in the tissue. The advantage of variable penetration depths of different colored light that can be used according to the invention has already been described, e.g. for the detection of preinvasive bronchial carcinomas, which are diagnosed by fluorescence endoscopic imaging after excitation with blue light.

The sequential illumination with the colors red, green and blue and a correspondingly synchronous triggering of the black and white chip makes it possible to generate very high-resolution color images for special measurements. Time-resolved anisotropy measurements refer to the simultaneous determination of the depolarization of the fluorescence and its temporal behavior. Since the depolarization of fluorescent molecules depends strongly on the molecule size or on a possible binding to cell structures, it is possible to use time-resolved anisotropy measurements to also

To determine rotation polarization half-lives. By measuring the depolarization of fluorescein-labeled monoclonal antibodies, it is therefore possible to indirectly determine whether an antibody has bound by determining fluorescence rotation half-lives. One possible area of application is the direct in-vivo quantification of membrane-bound cell antigens in patients, which makes it possible to obtain information about lung epithelial inflammation processes and their drug-induced influence, for example. This eliminates the need for in-vitro quantifications, which could potentially lead to falsified results.

Today, comparable examinations are generally only possible through biopsies and corresponding immunofluorescence staining by the pathologist. By combining the time-resolved fluorescence measurement according to the heterodyne "box car method", which refers to a "frequency-domain fluorescence lifetime imaging method" for the phase-selective representation of certain fluorescence components (explained in: G. Wagnieres et al., Endoscopic Frequency-Domain Fluorescence Lifetime Imaging for Clinical Cancer Photodetection: Apparatus Design in: Progress in Biomedical Optics, Volume 2392, the disclosure content of which is included by citation) and the polarization measurements described above, an additional increase in the measurement sensitivity is possible, for example by suppressing scattered light.

The invention not only allows endogenous porphyrins to be selectively detected as a result of their delayed fluorescence decay time, but also allows statements to be made about their intracellular aggregation. This involves the formation of microaggregates from porphyrin derivatives that have different fluorescence half-lives than freely mobile porphyrin derivatives.

0 By cooling the interline transfer CCD sensor preferably used in the invention to approx. 4 ° C, an effective increase in resolution from 8 to 12 bits is possible, while at the same time drastically reducing the photon dark current. The interline transfer system is

It is a readout method that, in contrast to the frame transfer method, can address individual shift register rows and thus enables a prerequisite for the direct substrate modulation of the CCD chip. This cannot be achieved with frame transfer CCD.

Overall, the arrangement replaces a laser in the frequency range up to 40 MHz, as well as a multi-channel plate amplifier and its phosphor screen. This reduces the price by a factor of around 10. A particularly advantageous feature is the fact that the standard control of a color CCD chip can be retained in parallel, so that the examining doctor has two viewing options (fluorescence and native image) available using the same instrument. By switching the CCD chip above the fusion frequency of the human eye, two monitors can be operated simultaneously during an examination. The only known system described in EPA 512 965 by Xillix Technologies Inc. offers firstly no time resolution, secondly no digital image amplification and thirdly the examining doctor has to change the bronchoscope during the examination in order to view a suitable native image.

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Reference list Endoscope head 1 Front side 5 2 light-emitting elements 3 Image forming device 4 Endoscope optics 5 Polarizing filter 6 channel 10 7 Supply line 8th Reading line 9 channel 10 channel 11 Endoscope optics 15 12 Manipulator channel 13 Biopsy forceps 14 Cycle 15 Heatsink 16 thermal dissipation device 20 17 Organ surface 18 Early carcinoma 19 coupling 20 branch 21 Space 25 22 ELL array 23 Photodiode chip 24 Endoscope head 25 Polarizing filter 26 30

Claims (14)

Protection claims 1. Endoscope head for a diagnostic or therapeutic purpose in Endoscope suitable for body cavities with lighting device, a Endoscope optics, an image capture device and signal transmission lines, characterized by light-emitting elements (3) arranged on its distal front side (2), an integrated image generation device (4) behind the endoscope optics (5) and &iacgr;&ogr; optionally a polarization filter (6) and/or channels (10, 11) for Passing a fluid to cool the imaging device. 2. Endoscope head according to claim 1, characterized in that the light-emitting elements are light-emitting diodes (LED) or electroluminescent lamps (ELL). 3. Endoscope head according to one of the preceding claims, characterized by an opto-electronic image generation device comprising CCD elements or photodiodes, each of which is arranged in group form or in a matrix. 4. Endoscope head according to one of the preceding claims, characterized in that the light-emitting elements are arranged in a ring shape around the image generating device. 5. Endoscope head according to one of the preceding claims, characterized in that the light-emitting elements can be controlled individually, in groups or all at the same time. 0 6. Endoscope head according to one of the preceding claims, characterized in that the light-emitting elements can be controlled in segments to produce a spatial impression by illumination from different directions. 7. Endoscope head according to one of the preceding claims, characterized in that the light-emitting elements can be controlled individually or in groups, alternately or in the manner of a circulating light. 8. Endoscope head according to one of the preceding claims, characterized in that the fluid passed through for cooling is a gas, a liquefied gas or a liquid at normal pressure. &iacgr;&ogr; 9. Endoscope head according to one of the preceding claims, characterized in that the gaseous fluid passed through for cooling flows in through one channel and out through another channel and thereby flows freely along the image generating device. 10. Endoscope head according to one of the preceding claims, characterized in that a liquid fluid is guided through the endoscope head in a closed circuit. 11. Endoscope head according to one of the preceding claims, characterized characterized in that the image forming device is provided with a thermal dissipation device which is in contact with the cooling circuit. 12. Endoscope head according to one of the preceding claims, characterized characterized in that the thermal dissipation device is designed as a wire or strip made of good heat-conducting material. 13. Endoscope head according to one of the preceding claims, characterized in that the material with good heat conduction is silver or copper. 14. Use of light-emitting diodes (LED) to illuminate an intracorporeal examination field by arranging the LED directly on an endoscope head in combination with a detection of the electromagnetic reflection of the field by means of CCD or photodiode elements integrated in the endoscope head.