Control device and method for a surgical microscope

Abstract

A control device (118) for a surgical microscope (100) controls an excitation unit (106) of the surgical microscope (100) to emit excitation light so as to excite a phosphor located within a target region (102) of a patient. The control device (118) controls an optical detection unit (108) of the surgical microscope (100) to receive light from the target region (102) and separate the received light into at least two spectral channels. The first spectral channel corresponds to a first wavelength band, and the second spectral channel corresponds to a second wavelength band. The control device (118) generates at least one image of the target region (102) including a plurality of pixels based on the received light, determines a first intensity for each pixel based on the first spectral channel, and determines a second intensity for each pixel based on the second spectral channel. The control device (118) further determines at least one first image area (122) based on the first intensity and the second intensity, and determines at least one second image area (124) based on the first intensity and the second intensity. The first image area (122) corresponds to an area within the target region (102) that exhibits fluorescence caused by the excited phosphor. The second image area (124) corresponds to an area within the target region (102) that exhibits fluorescence caused by other fluorescent sources other than the excited phosphor.

Description

Technical Field

[0001] The present invention relates to a control device for a surgical microscope and a surgical microscope. The present invention further relates to a method for acquiring an image by a surgical microscope.

Background Art

[0002] In microsurgery, i.e., surgery assisted by a surgical microscope, fluorescence imaging is becoming increasingly important. To label specific substances and structures such as blood vessels or cancer cells, a phosphor is introduced into the patient's body. The phosphor is used to highlight substances and structures that would otherwise be invisible or hardly visible to the naked eye. For example, indocyanine green (ICG) binds to plasma proteins in the blood and can be used to highlight blood vessels (angiography). Other phosphors, such as aminolevulinic acid (5-ALA), bind to cancer cells and can thus be used to highlight the location of cancerous tissue.

[0003] Typically, fluorescence imaging is performed in a single narrow spectral band, for example in the near-infrared region when using ICG as the phosphor, to generate a monochrome image. In a monochrome image, it is impossible to purely distinguish between the diagnostic fluorescence signal, i.e., the fluorescence signal derived from the phosphor used, and the unwanted fluorescence signal, i.e., the signal from any other light source, based solely on fluorescence intensity.

[0004] In the context of microsurgery, there are also other applications that utilize a wider spectral band for fluorescence imaging, such as 5-ALA fluorescence imaging. In such applications, color images are generated, and theoretically, the surgeon can distinguish between the diagnostic fluorescence signal and the unwanted fluorescence signal by color. For example, in the case of 5-ALA fluorescence imaging, the diagnostic fluorescence signal is pink, while the fluorescence of bone is, for example, white. Other objects can potentially have virtually any color and may in particular exhibit the color of the diagnostic fluorescence signal. Therefore, it is not easy to distinguish between the diagnostic fluorescence signal and the unwanted fluorescence signal, especially when the perceived color of the diagnostic fluorescence signal and the perceived color of the unwanted fluorescence signal are similar. In some cases, it is simply impossible to distinguish between diagnostic fluorescence and unwanted fluorescence. For example, the autofluorescence of soft tissue appears in a color similar to 5-ALA fluorescence, especially when the fluorescence intensity is weak. Even when it is possible to distinguish between diagnostic fluorescence and unwanted fluorescence using color information, this task poses an additional burden on the surgeon.

[0005] Augmented reality (AR) platforms that integrate the fluorescence image in the operating room with the reflectance image or the white light image typically display the fluorescence image in a single color. Therefore, it is impossible to distinguish between the diagnostic fluorescence signal and the unwanted fluorescence signal with these platforms. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0006] Accordingly, it is an object to provide a control device for an operating microscope and a method for acquiring an image with an operating microscope that enable a surgeon to easily distinguish between a diagnostic fluorescence signal and an unwanted fluorescence signal. MEANS FOR SOLVING THE PROBLEM

[0007] The above object is achieved by the subject matter of the independent claims. Advantageous embodiments are defined in the dependent claims and the following description.

[0008] The control device according to the present proposal for a surgical microscope is configured to control the excitation unit of the surgical microscope so as to emit excitation light for exciting a phosphor located within the target region of a patient. The control device is configured to control the optical detection unit of the surgical microscope so as to receive light from the target region and separate the received light into at least two spectral channels. The first spectral channel corresponds to a first wavelength band, and the second spectral channel corresponds to a second wavelength band. The control device is configured to generate at least one image of the target region including a plurality of pixels based on the received light, and the control device is configured to determine a first intensity for each pixel based on the first spectral channel and determine a second intensity for each pixel based on the second spectral channel. The control device is further configured to determine at least one first image area based on the first intensity and the second intensity, and to determine at least one second image area based on the first intensity and the second intensity. The first image area corresponds to an area of the target region that exhibits fluorescence caused by the excited phosphor. The second image area corresponds to an area of the target region that exhibits fluorescence caused by other fluorescent sources other than the excited phosphor.

[0009] The first region and the second region may overlap. The overlap between the first region and the second region corresponds to a region in the target area that exhibits fluorescence caused by the excited phosphor and fluorescence caused by at least one other fluorescent source other than the excited phosphor. The first region and the second region may be as small as a single pixel of the image of the target area. In particular, the control device may be configured to determine, for each pixel, whether the pixel corresponds to a region in the target area that exhibits fluorescence caused by the excited phosphor and / or whether the pixel corresponds to a region in the target area that exhibits fluorescence caused by at least one other fluorescent source other than the excited phosphor.

[0010] The received light is separated into at least two distinct spectral channels. This provides additional spectral information regarding the received light as compared to the case of using a single narrow spectral band. Different fluorescent light sources each have different fluorescence spectra. For example, fluorescein has an emission maximum at 560 nm, 5-ALA has an emission maximum at 630 nm for 5-ALA, and ICG has an emission maximum at 830 nm. However, all phosphors emit light at other wavelengths different from their respective emission maxima. By comparing the intensities in a plurality of different spectral channels with the known spectrum of a specific phosphor, it can be determined that the specific phosphor is present. Similarly, other fluorescent light sources, such as the autofluorescence of tissue or bone, also have their own distinct spectral profiles and can thus be identified by comparing the intensities in a plurality of different spectral channels with the known spectral profiles. Therefore, additional spectral information is used to distinguish between diagnostic fluorescent signals and undesired fluorescent signals. Diagnostic fluorescent signals are the fluorescence caused by excited phosphors, such as the location of blood vessels indicated by the presence of ICG or the presence of cancerous tissue indicated by the presence of 5-ALA. Undesired fluorescent signals are the fluorescence caused by other fluorescent light sources other than the excited phosphors, such as the autofluorescence of bone or tissue. By distinguishing between diagnostic fluorescent signals and undesired fluorescent signals, additional mental stress on the surgeon is removed, thereby enabling the surgeon to perform their tasks more efficiently.

[0011] In a preferred embodiment, the control device is configured to determine the first image area and the second image area in real time. In the context of this specification, real time particularly means that no post-processing is performed. This enables the information regarding the first area and the second area, i.e., the information regarding the position of blood vessels or cancerous tissue, to be notified to the surgeon without any noticeable delay. For example, the first area and the second area can be presented to the surgeon as an overlay in an AR environment, thereby expanding the surgeon's vision and assisting the surgeon during microsurgery.

[0012] In another preferred embodiment, the control device is configured to determine the first image area and the second image area by spectral decomposition. Spectral decomposition refers to all techniques that enable the separation of multiple different fluorescent light sources based on the intensities detected in a plurality of different spectral channels. Spectral decomposition can be performed quickly and reliably, enabling the rapid determination of the first image area and the second image area. Techniques for spectral decomposition include, but are not limited to, linear decomposition, principal component analysis, unsupervised learning means for spectra, support vector machines, neural networks, (spectral) phase approaches, and Monte Carlo decomposition algorithms.

[0013] In another preferred embodiment, the control device is configured to control the illumination unit of the surgical microscope so as to emit illumination light for illuminating the target area and to generate at least one reflectance image based on the received light. The reflectance image, also referred to as a white light image, displays the target area so as to be visible to the human naked eye. Using the reflectance image, a composite image can be generated that includes the reflectance image and the first image area and / or the second image area. Such a composite image can assist the surgeon in identifying the position of the first image area and / or the second image area within the target area.

[0014] In another preferred embodiment, the control device is configured to control the optical detection unit so as to separate the received light into at least three spectral channels. The third spectral channel corresponds to a third wavelength band. The third wavelength band is complementary to the first wavelength band and the second wavelength band. The control device is further configured to generate a reflectivity image based at least on the third spectral channel. Thereby, it becomes possible to process the first wavelength band and the second wavelength band separately from the reflectivity image. For example, the first spectral channel and the second spectral channel can be increased or decreased in terms of intensity before being displayed to the surgeon. In this embodiment, the third wavelength band is complementary to the first wavelength band and the second wavelength band, that is, the third wavelength band and the first wavelength band and the second wavelength band do not overlap. In particular, the third wavelength band can include all optical wavelengths except the first wavelength band and the second wavelength band. In such an embodiment, the reflectivity image will not display the first wavelength band and the second wavelength band.

[0015] In another preferred embodiment, the control device is configured to determine a first image area and a second image area based on the reflectivity image. In this embodiment, additional information in the form of the reflectivity image is used to determine the first image area and the second image area. For example, the control device may be configured to detect a non-biological object, such as a glove or a surgical instrument, in the reflectivity image of the target area using image detection, and determine that any fluorescent light emitted by the glove cannot be a diagnostic fluorescent signal. By using additional information in the form of the reflectivity image, the certainty with which the control device can determine the first image area and the second image area is improved.

[0016] In another preferred embodiment, the control device is configured to use machine learning to determine the first image area and the second image area. In this embodiment, the control device uses machine learning to distinguish between diagnostic fluorescence signals and unwanted fluorescence signals. In particular, additional information such as the reflectance image of the target area is used to determine the first image area and the second image area using machine learning. For example, the control device may be configured to perform image detection facilitated by machine learning to detect non-biological objects. In other words, the control device may be configured to perform semantic segmentation of the image of the target area using machine learning. For example, a particular area may be determined to be a non-biological object, such as a glove or a surgical instrument. In that case, the result of the image segmentation can be used to exclude from the image of the target area the source of the diagnostic fluorescence signal, such as a particular area that is the above-mentioned non-biological object. Therefore, by using machine learning, the determination of the diagnostic fluorescence signal can be greatly assisted, thereby greatly improving the reliability of the control device.

[0017] Machine learning techniques include, but are not limited to, support vector machines and neural networks. Most machine learning techniques require supervised training or unsupervised training using an appropriate training data set. The selection of the training data set depends on the specific task of the machine learning technique used. In the above example of detecting non-biological objects in the image of the target area, an appropriate training data set would consist of images of various different foreign objects within the patient's body, particularly images captured by a surgical microscope.

[0018] In another preferred embodiment, the control device is configured to generate a composite image from the first image area and the image of the target area, and the control device is configured to control the output unit of the surgical microscope to display the image of the target area and / or the composite image. The composite image assists the surgeon in identifying the position of the first image area and / or the second image area within the target area, thereby reducing the mental load during microsurgery and enabling the surgeon to perform their tasks more efficiently. In the composite image, the first area and the second area are preferably highlighted so that the first area and the second area can be easily distinguished.

[0019] In another preferred embodiment, the control device is configured to generate a composite image from the first image area, the second image area, and the image of the target area. The first image area has a first color, and the second image area has a second color. The second color is different from the first color. Displaying different areas in different colors helps the surgeon distinguish between diagnostic fluorescence signals and unwanted fluorescence signals. By displaying the second image area, i.e., the area from which the control device has determined that there is an unwanted fluorescence signal, the surgeon can further verify the determination made by the control device, thereby ensuring that all the information needed to make an information-based decision during microsurgery is provided to the surgeon.

[0020] In another preferred embodiment, the control device is configured to generate a composite image from the first image area, the second image area, and the image of the target area. The first image area or the second image area is a blinking overlay that covers the image of the target area. Displaying the second area as a blinking overlay helps the surgeon distinguish between diagnostic fluorescence signals and unwanted fluorescence signals. In particular, this enables the surgeon to verify the determination made by the control device during microsurgery.

[0021] In another preferred embodiment, the first wavelength band and the second wavelength band do not overlap. In this embodiment, the first wavelength band and the second wavelength band are complementary to each other, thereby making it possible to more reliably determine the first image area and the second image area.

[0022] The present invention relates to a surgical microscope, which includes a control device as described above, an excitation unit configured to emit excitation light for exciting a phosphor located within a target area of a patient, and an optical detection unit configured to receive light from the target area and separate the received light into at least two spectral channels. The first spectral channel corresponds to a first wavelength band, and the second spectral channel corresponds to a second wavelength band.

[0023] The surgical microscope includes the control device described above, and thus has the same advantages as the control device.

[0024] In a preferred embodiment, the surgical microscope further includes an illumination unit configured to emit illumination light for illuminating the target area. The illumination unit can be particularly used in the generation of reflectance images.

[0025] According to another preferred embodiment, the surgical microscope includes an output unit. The output unit is particularly one of a screen, an eyepiece, an augmented reality set, and a virtual reality set. The output unit may be configured to display an image of the target area and / or a composite image.

[0026] In another preferred embodiment, the optical detection unit includes at least one microscope objective lens, and the at least one microscope objective lens is directed towards the target area and is configured to receive light from the target area. The microscope objective lens can provide magnification that enables the surgeon to view details of the target area that are smaller than what can be seen with the naked eye. In other words, the magnification enables the surgeon to perform microsurgery, for example, on thin blood vessels or nerves having a diameter of 1 mm or less.

[0027] In another preferred embodiment, the optical detection unit includes at least two detector elements and beam splitting means, and the beam splitting means is configured to direct the received light having a wavelength in the first wavelength band towards the first detector element and the received light having a wavelength in the second wavelength band towards the second detector element. In this embodiment, the beam splitting element, the first detector element, and the second detector element are used as means for generating a first spectral channel and a second spectral channel. Compared with other means for generating the first spectral channel and the second spectral channel, using the beam splitting element, the first detector element, and the second detector element is easy to implement, cost-effective, and reliable.

[0028] In another preferred embodiment, the optical detection unit is configured to separate the received light into at least three spectral channels. The third spectral channel corresponds to a third wavelength band. In particular, the third wavelength band is complementary to the first wavelength band and the second wavelength band. An optical device for separating the received light into three complementary wavelength bands can be easily realized by a beam splitter. Such an optical device has the advantage that the received light is distributed among a plurality of detector elements, and thus, the received light is hardly lost or not lost at all, as may apply in the case of, for example, a multispectral camera.

[0029] In another preferred embodiment, the optical detection unit includes a multispectral camera or a hyperspectral camera configured to generate a first spectral channel and a second spectral channel. The multispectral camera is configured to capture a limited number of wavelength bands, typically less than 10 or about 10 wavelength bands. Each of these wavelength bands may be a spectral channel of the surgical microscope. The hyperspectral camera is configured to capture dozens or hundreds of wavelength bands per pixel. In other words, the hyperspectral image has a very high spectral resolution. With more spectral channels, it becomes possible to distinguish much more finely the fluorescent sources in the image of the target area based on their respective emission spectra, thereby improving the sensitivity and reliability of the surgical microscope.

[0030] The present invention relates to a method for acquiring an image by a surgical microscope, the method comprising exciting a phosphor within a target area of a patient, receiving light from the target area, separating the received light into at least two spectral channels, namely a first spectral channel corresponding to a first wavelength band and a second spectral channel corresponding to a second wavelength band, generating at least one image of the target area including a plurality of pixels based on the received light, determining a first intensity for each pixel based on the first spectral channel and a second intensity for each pixel based on the second spectral channel, determining at least one first image area based on the first intensity and the second intensity, the first image area corresponding to an area of the target area that exhibits fluorescence caused by the excited phosphor, and determining at least one second image area based on the first intensity and the second intensity, the second image area corresponding to an area of the target area that exhibits fluorescence caused by a fluorescent source other than the excited phosphor.

[0031] This method has the same advantages as the above-described control device, and the features of the dependent claims related to the control device can be used to complement this method.

[0032] Hereinafter, specific embodiments will be described with reference to the drawings.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0034] FIG. 1 is a schematic diagram of an operating microscope 100 according to an embodiment.

[0035] The operating microscope 100 is adapted to provide a magnified image of a target area 102 in a patient's body to a surgeon, for example, during microscopic surgery. In particular, the operating microscope 100 is adapted to acquire a fluorescence image of the target area 102. This fluorescence image is an image generated from the fluorescence light emitted by a phosphor located within the target area 102.

[0036] The illumination unit 104 of the surgical microscope 100 is configured to be directed towards the target area 102 and illuminate the target area 102 using white light. The excitation unit 106 of the surgical microscope 100 is configured to emit excitation light towards the target area 102 to excite the phosphor. The excitation unit 106 can include, in particular, a coherent light source, such as a white light laser, a continuous wave laser, or a pulsed laser having a single emission wavelength.

[0037] The optical detection unit 108 of the surgical microscope 100 has at least one microscope objective lens 110, and this at least one microscope objective lens 110 is configured to be directed towards the target area 102 and receive detection light 112 from the target area 102. The detection light 112 includes a plurality of components. Among the plurality of components of the detection light 112, there are fluorescence light emitted by the excited phosphor, fluorescence light emitted by other light sources other than the excited phosphor, and reflected light caused by white light illumination. The fluorescence light emitted by the excited phosphor is a desired fluorescence signal or a diagnostic fluorescence signal, while on the other hand, the fluorescence light emitted by other light sources is an undesired fluorescence signal.

[0038] The optical detection unit 108 is configured to generate, by way of example, three spectral channels, that is, to separately detect the detection light 112 in a first wavelength band, a second wavelength band, and a third wavelength band. These three wavelength bands will be described in more detail below with reference to FIG. 3. To generate the three spectral channels, the optical detection unit 108 includes, by way of example, an array of beam splitting elements 114a, 114b, such as dichroic elements or acousto-optic tunable filters (AOTF), and detector elements 116a, 116b, 116c. Alternatively, the three spectral channels may be generated by other means, such as a multispectral camera or a hyperspectral camera.

[0039] The first beam splitting element 114a is arranged subsequent to the microscope objective lens 110 in the beam path of the detection light 112. The first beam splitting element 114a is configured to direct the detection light 112 in the first wavelength band towards the first detector element 116a. The remaining detection light 112 is directed towards the second beam splitting element 114b. The second beam splitting element 114b is configured to direct the detection light 112 in the second wavelength band towards the second detector element 116b. Then, the remaining detection light 112 is directed towards the third detector element 116c.

[0040] The surgical microscope 100 further includes a control device 118. The control device 118 is connected to the illumination unit 104, the excitation unit 106, the optical detection unit 108, and the output unit 120. The control device 118 is configured to control the aforementioned elements of the surgical microscope 100. In particular, the control device 118 is configured to implement a method for acquiring an image of the target area 102, which will be described below with reference to FIG. 2.

[0041] One or more images of the target area 102 generated by the control device 118 are displayed to the surgeon by the output unit 120 of the surgical microscope 100. In this embodiment, the output unit 120 is exemplarily shown as a monitor. In FIG. 1, the output unit 120 displays a composite image of the target area 102 that exemplarily includes a reflectance image or a white light image of the target area 102, a first image area 122, and a second image area 124. The first image area 122 corresponds to a diagnostic fluorescence signal, in this example, a tumor labeled with 5-ALA. The second area corresponds to an undesired fluorescence signal, in this example, the autofluorescence of bone. In FIG. 1, the first image area 122 and the second image area 124 are distinguished by different hatchings. In an actual embodiment, the first image area 122 and the second image area 124 may be distinguished by different colors. Alternatively, the first image area 122 or the second image area 124 may be displayed as a blinking overlay covering the reflectance image.

[0042] FIG. 2 is a flowchart of a method for acquiring an image of the target region 102 by the surgical microscope 100 described above.

[0043] In step S200, the process starts. In step S202, the control device 118 controls the excitation unit 106 to emit excitation light toward the target region 102 to excite the phosphor located within the target region 102. In step 204, the control device 118 controls the optical detection unit 108 to receive light from the target region 102. The received light is split into at least two, in this embodiment three, spectral channels. In this embodiment, the first spectral channel is generated by the first detector element and corresponds to the first wavelength band, the second spectral channel is generated by the second detector element and corresponds to the second wavelength band, and the third spectral channel is generated by the third detector element and corresponds to the third wavelength band.

[0044] In step S206, the control device 118 generates at least one image of the target region 102 including a plurality of pixels based on the received light, that is, the detection light. In step S208, the control device 118 determines a first intensity for each pixel based on the first spectral channel, and determines a second intensity for each pixel based on the second spectral channel. In the present embodiment, the control device 118 generates a first image corresponding to the detection light 112 received by the first detector element and a second image corresponding to the detection light 112 received by the second detector element. The first image and the second image are monochrome images corresponding to the intensities of the detection light 112 received in the first wavelength band and the second wavelength band, respectively. That is, each pixel of the first image and the second image stores information regarding the intensities of the light received in the first wavelength band and the second wavelength band, respectively. In the present embodiment, further, the control device 118 generates a third image of the target region 102 based on the light received in the third wavelength band. The third image may particularly be a color image of the target region 102. That is, the third image is a reflectance image. Alternatively, the control device 118 may generate a single image of the target region 102. In this alternative embodiment, each pixel of the single image includes information regarding the intensities of the light received in the three detection channels.

[0045] In step S210, the control device 118 determines a first image area 122 based on the first intensity and the second intensity, and in step S212, the control device 118 determines a second image area 124 based on the first intensity and the second intensity. The determination of the first image area 122 and the second image area 124 will be described in more detail below with reference to FIG. 3.

[0046] In step S214, the control device 118 generates an image of the target area 102 based on the first image area 122 and the second image area 124, and controls the output unit 120 to output the image of the target area 102 to the surgeon. When the output unit 120 is a monitor or a digital eyepiece or the like, the control device 118 can generate a composite image including the reflectance image of the target area 102 and the first image area 122 and the second image area 124. When the output unit 120 is an AR set or the like, the control device 118 can generate a composite image including the first image area 122 and the second image area 124, which can be displayed to the surgeon as an AR overlay. In step S216, the process ends.

[0047] FIG. 3 shows three schematic diagrams 300, 302, 304, which respectively show the spectra of a plurality of different components of the detection light 112.

[0048] The horizontal axis of each of the diagrams 300, 302, 304 represents wavelength. The vertical axis of each of the diagrams 300, 302, 304 represents intensity. The first wavelength band and the second wavelength band are indicated by the dashed rectangles 306a, 306b in the diagrams 300, 302, 304.

[0049] The first diagram 300 shows the spectrum 308 of the fluorescent light emitted by the phosphor, that is, the spectrum of the diagnostic fluorescent signal. The diagnostic fluorescent signal has its maximum value 310 in the first wavelength band. The intensity of the diagnostic fluorescent signal in the second wavelength band is about one-fifth of the diagnostic fluorescent signal at the maximum intensity of the diagnostic fluorescent signal.

[0050] The second diagram 302 shows the spectrum 312 of the autofluorescent light emitted by the first tissue, that is, the spectrum of the first unwanted fluorescent signal. The first unwanted fluorescent signal has its maximum value 314 in the first wavelength band. The intensity of the first unwanted fluorescent signal in the second wavelength band is almost zero.

[0051] The third diagram 304 shows the spectrum 316 of the autofluorescence light emitted by the second tissue, i.e., the spectrum of the second unwanted fluorescence signal. The second unwanted fluorescence signal has its maximum value 318 between the first wavelength band and the second wavelength band. The intensity of the second unwanted fluorescence signal in the first wavelength band is approximately equal to the intensity of the second unwanted fluorescence signal in the second wavelength band.

[0052] As can be seen from the three diagrams 300, 302, 304, each light source of the fluorescence light has its respective characteristic spectrum 308, 312, 316, and these characteristic spectra 308, 312, 316 can be specified by the intensities detected in the first wavelength band and the second wavelength band, i.e., the first detection channel and the second detection channel. Therefore, for each pixel, it is possible to identify the light source of the fluorescence light received based on the first detection channel and the second detection channel.

[0053] Figure 4 is a schematic diagram of the spectra of a plurality of different components of the detection light 112.

[0054] Figure 4 shows the prior art in which only a single narrow wavelength band is used to capture the diagnostic fluorescence signal. The horizontal axis of the diagram 400 represents the wavelength. The vertical axis of the diagram 400 represents the intensity. In the diagram 400, a single narrow wavelength band is indicated by the dashed rectangle 402.

[0055] In Figure 4, the spectrum 308 of the diagnostic fluorescence signal is shown as a solid line. The spectra 312, 316 of the two unwanted fluorescence signals are shown as dashed lines. As can be seen, the three light sources of the fluorescence light are distinguished by their respective intensities in a single narrow wavelength band. However, since it is not easily possible to normalize the three signals, it is not possible to distinguish these signals only by their respective intensities in a single narrow wavelength band.

[0056] Elements having the same or similar functions are denoted by the same reference signs in all the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items and may be abbreviated as " / ". All combinations, among the individual features of each embodiment and between the individual features of each embodiment, as well as in combination with the individual features or groups of features of the foregoing description and / or the claims, are considered to be disclosed.

[0057] Although some aspects have been described in the context of an apparatus, it is clear that these aspects also represent a description of the corresponding method, where a block or apparatus corresponds to a step or a feature of a step. Similarly, aspects described in the context of a step also represent a description of the corresponding block or item or feature of the corresponding apparatus.

Description of Reference Signs

[0058] 100 Surgical microscope 102 Target area 104 Lighting unit 106 Excitation unit 108 Optical detection unit 110 Objective lens 112 Detection light 114a, 114b Beam splitting element 116a, 116b, 116c Detector element 118 Control device 120 Output unit 122, 124 Image area 300, 302, 304 Diagram 306a, 306b Rectangle 308 Spectrum 310 Maximum value 312 Spectrum 314 Maximum value 316 Spectrum 318 Maximum value 400 Diagram 402 Rectangle

Claims

1. A control device (118) for a surgical microscope (100), wherein the control device (118) is configured to control an excitation unit (106) of the surgical microscope (100) to emit excitation light so as to excite a phosphor located within a target region (102) of a patient; wherein the control device (118) is configured to control an optical detection unit (108) of the surgical microscope (100) to receive light from the target region (102) and separate the received light into at least two spectral channels, namely a first spectral channel corresponding to a first wavelength band and a second spectral channel corresponding to a second wavelength band; wherein the control device (118) is configured to generate at least one image of the target region (102) including a plurality of pixels based on the received light; wherein the control device (118) is configured to determine a first intensity for each pixel based on the first spectral channel and determine a second intensity for each pixel based on the second spectral channel; wherein the control device (118) is configured to determine at least one first image area (122) based on the first intensity and the second intensity, and the first image area (122) corresponds to an area in the target region (102) that exhibits fluorescence caused by the excited phosphor; wherein the control device (118) is configured to determine at least one second image area (124) based on the first intensity and the second intensity, and the second image area (124) corresponds to an area in the target region (102) that exhibits fluorescence caused by a fluorescent source other than the excited phosphor; A control device (118).

2. wherein the control device (118) is configured to determine the first image area (122) and the second image area (124) in real time; The control device (118) according to Claim 1.

3. wherein the control device (118) is configured to determine the first image area (122) and the second image area (124) by spectral decomposition; The control device (118) according to Claim 1 or 2.

4. The control device (118) is configured to control the illumination unit (104) of the surgical microscope (100) to emit illumination light for illuminating the target area (102) and to generate at least one reflectance image based on the received light. The control device (118) according to any one of claims 1 to 3.

5. The control device (118) is configured to control the optical detection unit (108) to separate the received light into at least three spectral channels. The third spectral channel corresponds to a third wavelength band. The third wavelength band is complementary to the first wavelength band and the second wavelength band. The control device (118) is configured to generate the reflectance image based on at least the third spectral channel. The control device (118) according to claim 4.

6. The control device (118) is configured to determine the first image area (122) and the second image area (124) based on the reflectance image. The control device (118) according to claim 4 or 5.

7. The control device (118) is configured to use machine learning to determine the first image area (122) and the second image area (124). The control device (118) according to any one of claims 1 to 6.

8. The control device (118) is configured to generate a composite image from the first image area (122) and the image of the target area (102). The control device (118) is configured to control the output unit (120) of the surgical microscope (100) to display the image of the target area (102) and / or the composite image. The control device (118) according to any one of claims 1 to 7.

9. The control device (118) is configured to generate the composite image from the first image area (122), the second image area (124), and the image of the target area (102). The first image area (122) has a first color, the second image area (124) has a second color, and the second color is different from the first color. The control device (118) according to claim 8.

10. The control device (118) is configured to generate the composite image from the first image area (122), the second image area (124), and the image of the target area (102). The first image area (122) or the second image area (124) is a flickering overlay that covers the image of the target area (102). The control device (118) according to claim 8 or 9.

11. The first wavelength band and the second wavelength band do not overlap. The control device (118) according to any one of claims 1 to 10.

12. A surgical microscope (100), wherein the surgical microscope (100) The control device (118) according to any one of claims 1 to 11, An excitation unit (106) configured to emit excitation light for exciting a phosphor located within a target area (102) of a patient, An optical detection unit (108) configured to receive light from the target area (102) and separate the received light into at least two spectral channels, namely a first spectral channel corresponding to a first wavelength band and a second spectral channel corresponding to a second wavelength band. A surgical microscope (100) including the above.

13. The surgical microscope (100) includes an output unit (120). The output unit (120) is in particular one of a screen, an eyepiece, an augmented reality set, and a virtual reality set. The surgical microscope (100) according to claim 12.

14. The optical detection unit (108) includes at least one microscope objective lens (110). The at least one microscope objective lens (110) is directed towards the target area (102) and is configured to receive the light from the target area (102). The surgical microscope (100) according to claim 12 or 13.

15. The optical detection unit (108) includes at least two detector elements and beam splitting means. The beam splitting means is configured to direct the received light having a wavelength in the first wavelength band towards the first detector element and the received light having a wavelength in the second wavelength band towards the second detector element. The surgical microscope (100) according to any one of claims 12 to 14.

16. The optical detection unit (108) includes a multispectral camera or a hyperspectral camera configured to generate the first spectral channel and the second spectral channel. The surgical microscope (100) according to any one of claims 12 to 15.

17. A method for acquiring an image by a surgical microscope (100), the method comprising: a) exciting a phosphor within a target region (102) of a patient; b) receiving light from the target region (102); c) separating the received light into at least two spectral channels, namely a first spectral channel corresponding to a first wavelength band and a second spectral channel corresponding to a second wavelength band; d) generating at least one image of the target region (102) including a plurality of pixels based on the received light; e) determining a first intensity for each pixel based on the first spectral channel and determining a second intensity for each pixel based on the second spectral channel; f) determining at least one first image region (122) based on the first intensity and the second intensity, the first image region (122) corresponding to a region of the target region (102) that exhibits fluorescence caused by the excited phosphor; g) determining at least one second image region (124) based on the first intensity and the second intensity, the second image region (124) corresponding to a region of the target region (102) that exhibits fluorescence caused by a fluorescent source other than the excited phosphor; A method comprising.

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