Optical target, optical calibration system and medical system

Abstract

Optical target (20, 20', 20'', 20''') for calibrating a medical imaging device (30), comprising: a target body (40, 40', 40'', 40'''); and at least one conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54'') formed in and / or on the target body (40, 40', 40'', 40''') and configured to convert light with a first wavelength at least partially into light with a second wavelength different from the first wavelength; wherein at least the conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54'') is additively manufactured, wherein the target body (40, 40', 40'', 40''') is embedded in a dispersion element (55).

Description

[0001] The present application relates to an optical target, an optical calibration system and a medical system.

[0002] In medical imaging, endoscopes and exoscopes are state-of-the-art tools that can generate magnified images of an area under examination. Furthermore, medical imaging with endoscopes and / or exoscopes allows for the visualization of different layers, such as organs, blood vessels, and / or other tissue, at varying depths beneath the skin and / or beneath the organs into which the endoscope is inserted.

[0003] Fluorescence imaging techniques are used to better identify and visualize the depth and size of the different layers. For this, the patient is administered a fluorescein-containing medication that accumulates in one of the different layers. This means that one of the layers may exhibit additional fluorescence properties during medical imaging, which can be identified by the endoscope and / or exoscope. This allows for a more precise determination, using medical imaging, of the depth and size of the fluorescent layer beneath the skin and / or organs into which the endoscope is inserted. Furthermore, multimodal medical imaging techniques can also be employed.For this purpose, the patient is administered several medications with different fluorescences, each marking different layers with different fluorescences.

[0004] In summary, medical imaging provides surgeons with highly precise information about the depth to which they need to cut in order to reach and remove the desired tissue layers. This allows them to more intuitively assess and / or monitor their actions on a screen. In particular, multimodal medical imaging techniques can visualize not only the tissue layers that need to be removed, but also layers that must not be damaged under any circumstances.

[0005] To test and evaluate whether endoscopes and / or exoscopes can correctly identify fluorescence at sufficient penetration depth and / or distance from the endoscope and / or exoscope, a silicone tube filled with a specific concentration of fluorescent dye is inserted into the scattering medium in known test setups. However, a problem arises because the concentration of the fluorescent dye decreases over time due to photobleaching. This means that the fluorescence properties of the silicone tube vary considerably depending on the storage time. Furthermore, the test setup described above is so sensitive that even minor errors in mixing the fluorescent dye for the silicone tube, and subsequent storage on the day of the experiment due to photobleaching, can lead to highly inaccurate test conditions.

[0006] Furthermore, the above arrangement does not allow for the simulation of more complex test setups. However, more complex test setups are urgently needed to evaluate multimodal medical imaging procedures in order to test whether different fluorescences at different penetration depths can be realistically reproduced by the medical imaging procedure.

[0007] From the publication RUIZ, A. [et al.]: 3D printing fluorescent material with tunable optical properties. In: Scientific Reports, 11, 2021, 17135. - ISSN 2045-2322. [DOI: 10.1038 / 5s41598-021-96496-0], a 3D-printed target with fluorescent properties is known that can have the shape of an anatomical structure.

[0008] KHATRI, B [et al.]: Development of a Multi-Material Stereolithography 3D Printing Device. In: Micromachines, 11, 2020, 5, - ISSN 2072-666X. [DOI: 10.3390 / mi11050532] describes a stereolithography device for 3D printing components from different materials.

[0009] Based on the prior art, the invention aims to provide a simple way to check an imaging device.

[0010] This problem is solved according to the invention by an optical target, an optical calibration system and a medical system as described herein and defined in the claims.

[0011] The present invention provides an optical target for calibrating a medical imaging device. The optical target comprises a target body and at least one conversion structure formed in and / or on the target body. Furthermore, the conversion structure is configured to convert light with a first wavelength, at least partially, into light with a second wavelength different from the first. The conversion structure is also additively manufactured.

[0012] The optical target can be used for stereoscopic calibration of the medical imaging device and / or for calibrating the fluorescence imaging techniques of the medical imaging device. In particular, the optical target can be used to calibrate the stereo zero plane of the stereoscopic imaging of the medical imaging device.

[0013] The medical imaging device can be, in particular, an exoscope. Alternatively or additionally, the imaging device can be, for example, an endoscope. The medical imaging device can be configured to acquire images of an examination area. In some embodiments, the imaging device can be configured to generate magnified images of the examination area. The image can be viewed during a medical procedure and / or during a diagnostic procedure. The medical imaging device can be mobile and / or movable. It can be designed, for example, to be movable within an operating room. If a user requires imaging support, the imaging device can be moved to the point of use, i.e., to a patient. The imaging device can also be movable within itself.The imaging device may, for example, include a movable support arm and / or the imaging device may be arranged on the movable support arm.

[0014] The target body defines, in particular, at least one outer surface of the optical target. Light can be coupled or introduced into the optical target through the target body from at least one spatial direction. Preferably, light can be coupled or introduced into the optical target through the target body from all spatial directions. For example, light is coupled or introduced into the optical target through at least one outer surface of the target body, preferably from all outer surfaces of the target body.

[0015] Additive manufacturing describes, in particular, a process by which an object is built up layer by layer, for example, a 3D printing process. Starting materials for additive manufacturing are, in particular, molding sands, polymer gypsum, acrylic resins, plastics, metals, and / or acrylic glass. Preferably, acrylic glass is used for additive manufacturing in the present invention.

[0016] Furthermore, the conversion structure can be partially transparent to light of the first wavelength. For example, the conversion structure can be configured to convert 10% to 100%, in particular 30% to 80%, preferably 40% to 60% of the amount of light and / or the luminous flux of the light of the first wavelength into light of the second wavelength. In addition, the conversion structure can be configured to convert light into narrow spectral bands, according to the other features. Narrow can mean that the converted spectral band is, for example, up to 200 nm, in particular 100 nm, preferably 50 nm, and particularly preferably 20 nm wide. The conversion structure can, in particular, be configured to emit light of the second wavelength. The emitted light can be used to illuminate the optical target. Alternatively or additionally, light of the first wavelength can be used to illuminate the optical target.For example, the conversion structure can be set up to alternately convert and allow light to pass through over time.

[0017] The conversion structure can include filters configured for light conversion. In particular, the conversion structure can be configured to absorb light of the first wavelength and emit light of the second wavelength. Furthermore, in some embodiments, the wavelength of the light of the first wavelength can alternatively or additionally be halved by means of the conversion, for example, by frequency doubling (second harmonic generation, SHG) and / or frequency multiplication using non-linear optical processes. For example, the second wavelength can be a wavelength from the ultraviolet range. Furthermore, quantum dots can be provided for light conversion, or the conversion area can include quantum dots.

[0018] According to the invention, daylight and / or an external light source, which is also provided for illuminating the room, can be sufficient to illuminate the optical target adequately for calibrating the medical imaging device.

[0019] In particular, the features according to the invention can provide an optical target that has comparable properties over an extended period of time, is user-friendly and cannot be negatively affected by user errors.

[0020] For simple and cost-effective manufacturing, the target body can be cast around the conversion structure.

[0021] Furthermore, the target body can be manufactured additively together with the conversion structure. For example, the target body can be printed simultaneously with the conversion structure by switching appropriately between two materials during the 3D printing process.

[0022] Furthermore, the target body can be made of acrylic gas so that light can easily be introduced into the optical target.

[0023] For example, at least one conversion structure has a rectangular and / or round shape and / or the shape of an anatomical vessel, such as a blood vessel. The shape of the conversion area can be modeled after a blood vessel. For example, the conversion area can be cylindrical and / or tubular. This allows the use of optical targets during the calibration of the medical imaging device that replicate realistic structures or, if necessary, simplified but realistic structures that are recorded by the optical imaging device during surgery.

[0024] To create more complex, realistic structures, the optical target can have at least two conversion structures. Furthermore, the first and / or second wavelengths of the two conversion structures can be different. For example, a first conversion structure can be configured to convert light with a first wavelength, at least partially, into light with a second wavelength that differs from the first. A second conversion structure can be configured to convert light with a third wavelength, at least partially, into light with a fourth wavelength that differs from the third. In this case, the first wavelength can differ from the third wavelength. Alternatively or additionally, the second wavelength can differ from the fourth wavelength.

[0025] To ensure that the medical imaging device has the desired penetration depth, for example, the penetration depth necessary for surgery, the optical target can have several conversion structures arranged one above the other and / or next to each other.

[0026] To achieve a more realistic calibration of the medical imaging device, at least two conversion structures can be used to at least partially replicate a blood vessel and / or organ and / or body part. Furthermore, to simulate an organ and / or to replicate different markers / fluorescence solutions dissolved in different parts / layers of the organs or vessels, the optical target can have multiple conversion structures with different wavelength conversion properties.

[0027] In a particularly simple and cost-effective embodiment of the optical target, the conversion structure can fill the target body at least substantially, and in particular completely. The target body can be made, in particular completely, of a material designed to convert light with a first wavelength, at least partially, into a second light with a second wavelength different from the first.

[0028] To enable better identification of the optical target by the medical imaging device, particularly without the use of additional external light sources, and / or to create a realistic calibration environment, particularly to replicate the scattering of skin, the surface of the target body can, in particular, scatter light.

[0029] For cost-effective manufacturing, the surface of the target body can be roughened and / or sandblasted.

[0030] To make the optical target more visible to the medical imaging device, especially without the use of additional external light sources, and / or to create a realistic calibration environment, the target body is further embedded, in particular, in a scattering element.

[0031] In particular, the scattering element and / or the target body replicates the scattering of human tissue to create a realistic calibration environment.

[0032] Furthermore, an optical calibration system can be provided. The optical calibration system comprises a target according to the invention and a holder designed to allow the optical target to be coupled to the stereoscopic medical imaging device under test. The holder enables the geometric calibration to be checked reproducibly. Moreover, the holder makes the calibration system easy to operate, in particular by allowing the calibration system to be aligned efficiently, easily, and / or simply with respect to the imaging device.

[0033] The mount can also include a spacer that defines a distance between the medical imaging device under test and the target. This distance can, for example, correspond approximately to the distance that the imaging device, in particular an image acquisition unit and / or the input optics of the imaging device, typically has in operation relative to an object under examination. Furthermore, the distance can be specifically tunable with the optical target and / or with the imaging device. The distance can correspond at least substantially to the focal length of a first image acquisition unit and / or a focal length of a second image acquisition unit of the medical imaging device. In some embodiments, the distance can be at least 5 cm, at least 10 cm, or at least 20 cm and / or at most 100 cm, at most 80 cm, or at most 50 cm. This can increase the reproducibility of the inspection.Furthermore, the verification process can be standardized.

[0034] Furthermore, the mounting can be designed to support the weight of the calibration system when coupled to the medical imaging device being calibrated. This means that the calibration system can be coupled to the imaging device in such a way that it does not rest on the floor. In other words, the calibration system does not need to include a stand or similar support. This allows for a more dynamically efficient coupling of the system, particularly between the calibration system and the imaging device. Advantageously, fewer vibrations and / or less vibrational energy can be transmitted to the calibration system via the floor. This can improve the accuracy of the verification. Additionally, the calibration system can be designed more compactly.

[0035] The mount may also have openings through which ambient light can reach the target body, or to ensure that the ambient light falls on the target body. For example, additional mirrors may be attached to the mount to increase the proportion of ambient light that falls on the target body.

[0036] The mount can also include a coupling section for connecting to the medical imaging device under test, wherein the coupling section includes a projection configured to hold the calibration system by engaging behind it. The imaging device can also include a holding section to which the mount can be coupled. For example, the projection can engage behind the holding section, at least partially. Furthermore, the projection can be configured to hold the calibration system during coupling by engaging behind it, in particular at least partially behind the holding section. The calibration system can be rotated about the projection during coupling, particularly while the projection is partially engaging behind the holding section. The projection can be rotatably mounted in the holding section.The calibration system, in particular the coupling section and / or the projection, and the imaging device, in particular the holding section, can jointly form a connection. The connection can, for example, include a dovetail joint. This can result in a compact and / or efficient calibration system.

[0037] The coupling section can further comprise a movable retaining element designed to selectively fix the mount to or detach it from the medical imaging device under test. For example, the retaining element can clamp the mount to the imaging device. Alternatively or additionally, the movable retaining element can be designed to engage the imaging device, particularly the mounting section, section by section. The movable retaining element can include, for example, a tensionable retaining element, in particular a clamping spring, a spring adjuster, and / or the like, a screw, and / or a locking lug. This allows the calibration system to be easily and selectively fixed to and / or detached from the imaging device. Coupling can be performed quickly and / or flexibly.

[0038] The invention further comprises a medical system with a medical imaging device and an optical target for verifying the stereoscopic calibration of the medical imaging device. The medical imaging device to be tested may further comprise a fluorescence channel and / or a white light channel.

[0039] The present invention is described below by way of example with reference to the accompanying figures. The drawing, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and use them meaningfully in combination within the scope of the claims.

[0040] If more than one instance of a particular object exists, only one of them may be identified with a reference symbol in the figures and description. The description of this instance can then be applied to the other instances of the object. If objects are named using numerical terms, such as first, second, third object, etc., these serve to identify and / or classify objects. Thus, for example, a first object and a third object, but not a second object, may be included. However, numerical terms could also indicate a number and / or sequence of objects.

[0041] They show: Fig. 1 an exemplary embodiment of an optical target according to the invention; Fig. 2 another exemplary embodiment of an optical target according to the invention; Fig. 3 another exemplary embodiment of an optical target according to the invention; Fig. 4 an exemplary embodiment of a medical system according to the invention comprising a medical imaging device and an optical target according to the invention for verifying a stereoscopic calibration of the medical imaging device.

[0042] Fig. Figure 1 shows an exemplary embodiment of an optical target 20 with a target body 40. The target body 40 can, for example, be made of glass and / or acrylic glass. For example, the target body 40 is manufactured using an additive manufacturing process, in particular a 3D printing process. The entire target body 40 can form a conversion structure.

[0043] Fig. Figure 2 shows another exemplary embodiment of a further optical target 20' with a target body 40'. At least one conversion structure 50', 52', and / or 54'' is incorporated into the target body 40'. As shown, several conversion structures 50', 52', and / or 54'' can be incorporated into the target body 40'. For example, as shown, the conversion structures 50' and 52'' can be arranged side by side, and the conversion structure 54' can be arranged below and, if necessary, between the conversion structures 50' and 52''. However, many shapes, arrangements, and / or numbers of conversion structures are possible, particularly to ensure a realistic calibration environment for the medical imaging device. The conversion structures 50', 52', and / or 54'' can be connected to one another by a connecting element 60'.In particular, the conversion structures 50', 52' and / or 54'' and the connecting elements 60' can be manufactured using an additive manufacturing process, especially a 3D printing process. Subsequently, for example, the target body 40' can be cast around the conversion structures 50', 52' and / or 54'' and / or the connecting element 60' with the target body 40'.

[0044] Fig. Figure 3 shows a further exemplary embodiment of another optical target 20'', comprising a target body 40'', conversion structures 50'', 52'' and 54'' and a connecting element 60''. In principle, the conversion structures 50'', 52'' and 54'' and the connecting element 60'' are arranged similarly to the exemplary embodiment shown in Figure 3. Fig. Figure 2 illustrates this. However, many shapes, arrangements, and / or numbers of conversion structures are possible, particularly to ensure a realistic calibration environment for the medical imaging device. The target body 40'' can, for example, be a prefabricated body that is hollow and open on at least one side. The target body 40'' can be made of glass and / or acrylic glass. The conversion structures 50'', 52'', and / or 54'' and / or the connecting element 60'' are incorporated into the target body 40''. Furthermore, the conversion structures 50'', 52'', and / or 54'' and / or the connecting element 60'' can be surrounded within the target body 40'' by a scattering element 55''.The scattering element 55'' can, for example, be cast around the conversion structures 50'', 52'' and / or 54'' and / or the connecting element 60'' and / or be additively manufactured together with the conversion structures 50'', 52'' and / or 54'' and / or the connecting element 60'' and / or the target body 40''.

[0045] Fig.Figure 4 shows a schematic representation of a medical system 10 with a medical imaging device 30 and an optical target 20'''. The optical target 20''' comprises a target body 40''' and a conversion structure 50''', which is shown as a round shape. The optical target 20''' is part of an optical calibration system 12. The optical target 20''' also includes a holder 70 into which the target body 40''' can be inserted. In this case, the holder 70 has a receptacle 72 for the optical target 20'''. One end of a spacer 80 is attached to the receptacle 72. The medical imaging device 30 is attached to the opposite end of the spacer 80, which is connected to the receptacle 72. The spacer 80 allows a distance 90° to be established between the target body 40''' and the medical imaging device 30.The spacer bracket 80 has further holes 85 to allow more ambient light to hit the target body 40''' or to prevent shadows from being cast on the target body 40''.

[0046] The medical imaging device 30 can comprise a first image acquisition unit and a second image acquisition unit, each of which is light-sensitive in the first spectral range. Furthermore, the medical imaging device 30 can comprise a third image acquisition unit and a fourth image acquisition unit, each of which is light-sensitive in the wider spectral range. Using the first and second image acquisition units, for example, stereoscopic image acquisition can be performed in the first spectral range. Using the third and fourth image acquisition units, for example, stereoscopic image acquisition can be performed in the second spectral range. In particular, the second spectral range lies in the near-infrared range.This makes it possible to perform fluorescence stereo image acquisition using the third image acquisition device and the fourth image acquisition device.

[0047] To enable fluorescence imaging, the image acquisition devices can include further image sensors that are light-sensitive in different spectral ranges. The first and second image acquisition devices can each include a first image sensor that is light-sensitive, at least predominantly, in the first spectral range, which is primarily associated with visible light. That is, image acquisition in the wavelength range of visible light is possible using the first image sensor. This corresponds approximately to conventional image acquisition. Image acquisition in the wavelength range of near-infrared light is possible using the second image sensor.

[0048] The second and fourth image acquisition devices can each comprise a second image sensor. The second image sensor can be light-sensitive, at least predominantly, in the second spectral range, and in particular light-insensitive in the wavelength range of visible light. For the calibration of such a medical imaging device 30, the optical target 20''' can provide light in both spectral ranges by means of, for example, several, in particular two, conversion structures in order to verify the geometric calibration of the medical imaging device 30. To verify the geometric calibration, the medical imaging device 30 captures the target 20''' or the at least one conversion structure 50'''. In particular, each of the image acquisition devices captures at least one image of the target body 40''' with at least one conversion structure 50'''.For example, the user can check the optical calibration of the image acquisition devices using the images of at least one conversion structure 50''' of the optical target 20'''. Reference symbol list 10 medical system 20, 20', 20'', 20'' optical target 30 medical imaging devices 40, 40', 40'', 40''' Target body 50, 50', 50'', 50''' conversion structure 52', 52'' conversion structure 54', 54'' conversion structure 55 Dispersion element 60 connecting element 70 bracket 72 recording 80 spacers 90 distance

Claims

[1] Optical target (20, 20', 20'', 20''') for calibrating a medical imaging device (30), comprising: a target body (40, 40', 40'', 40'''); and at least one conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54'') formed in and / or on the target body (40, 40', 40'', 40''') and configured to convert light with a first wavelength at least partially into light with a second wavelength different from the first wavelength; wherein at least the conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54'') is additively manufactured, wherein the target body (40, 40', 40'', 40''') is embedded in a dispersion element (55). [2] Optical target according to claim 1, wherein the target body (40, 40', 40'', 40''') is cast around the conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54''); and / or wherein the target body (40, 40', 40'', 40''') is manufactured additively together with the conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54''). [3] Optical target (20, 20', 20'', 20''') according to claim 1 or 2, wherein the optical target is formed from acrylic gas. [4] Optical target (20, 20', 20'', 20''') according to any of the preceding claims, wherein the at least one conversion structure (50, 50', 50'', 50''', 52', 52'', 54', 54'') has a rectangular and / or round shape or the shape of an anatomical vessel. [5] Optical target (20, 20', 20'', 20''') according to any one of the preceding claims, further comprising: at least two conversion structures (50, 50', 50'', 50''', 52', 52'', 54', 54''), wherein the first and / or second wavelengths of the at least two conversion structures (50, 50', 50'', 50''', 52', 52'', 54', 54'') are different. [6] Optical target (20, 20', 20'', 20''') according to one of the preceding claims, wherein several conversion structures (50, 50', 50'', 50''', 52', 52'', 54', 54'') are arranged one above the other and / or next to each other. [7] Optical target (20, 20', 20'', 20''') according to one of the preceding claims, wherein the shape of an anatomical vessel and / or organ and / or body part is at least partially replicated by several conversion structures (50, 50', 50'', 50''', 52', 52'', 54', 54''). [8] Optical target (20, 20', 20'', 20''') according to any of the preceding claims, wherein the surface of the target body (40, 40', 40'', 40''') scatters light. [9] Optical target (20, 20', 20'', 20''') according to any of the preceding claims, wherein the surface of the target body (40, 40', 40'', 40''') is roughened and / or sandblasted. [10] Optical target (20, 20', 20'', 20''') according to any of the preceding claims, wherein the scattering element (55) and / or the target body (40, 40', 40'', 40''') replicates the scattering of human tissue. [11] Optical calibration system (12), comprising: an optical target (20, 20', 20'', 20''') according to any one of the preceding claims; and a holder (70) designed to allow the optical target (20, 20', 20'', 20'''') to be coupled to the medical imaging device (30) under test. [12] Optical calibration system (12) according to claim 11, wherein the holder (70) comprises a spacer (80) which defines a distance (90) between the medical imaging device (30) to be tested and the optical target (20, 20', 20'', 20'''). [13] Medical system (10), comprising: a medical imaging device (30); and an optical target (20, 20', 20'', 20''') for verifying a stereoscopic calibration of the medical imaging device (30) according to any one of claims 1 to 10 and / or an optical calibration system (12) according to claim 11 or 12. [14] Medical system (10) according to claim 13, wherein the medical imaging device (30) to be tested has a fluorescence channel and / or a white light channel.

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