JP5152795B2 - Fluorescence image acquisition device and method of operating fluorescence image acquisition device - Google Patents

Description

  The present invention relates to a fluorescence image acquisition method and a fluorescence image acquisition device, and more specifically, a fluorescence image acquisition method and a fluorescence image that captures an image including fluorescence emitted from an observed portion by irradiation of excitation light and generates a fluorescence image. The present invention relates to an acquisition device.

  Conventionally, endoscope apparatuses for observing tissue in a body cavity are widely known, and a normal image is obtained by imaging a portion to be observed in a body cavity illuminated by white light, and this normal image is displayed on a monitor screen. Electronic endoscopes are widely used.

  In recent years, in the field of electronic endoscope devices using solid-state imaging devices, devices that perform spectral imaging combined with a narrow-band bandpass filter based on spectral reflectance in the digestive tract such as the gastric mucosa, that is, narrow An electronic endoscope apparatus with a built-in band filter (Narrow Band Imaging-NBl) has attracted attention. This device is provided with a band pass filter of a narrow (wavelength) band instead of a frame sequential type R (red), G (green), and B (blue) rotary filter, and through these narrow band band pass filters. Illumination light is sequentially output, and a spectral image is formed by performing the same processing as in the case of R, G, B (RGB) signals while changing the respective weights for the signals obtained with these illumination lights. It is. According to such a spectral image, in the digestive organs such as the stomach and the large intestine, a fine structure or the like that has not been obtained conventionally is extracted.

  On the other hand, in Patent Document 1 and Patent Document 2, white light is irradiated in a simultaneous system in which a micro mosaic color filter is arranged on a solid-state imaging device, instead of the surface sequential type using the above-described narrowband bandpass filter. It has been proposed to form a spectral image by arithmetic processing based on an image signal obtained by imaging an observed part. This Patent Document 1 obtains estimated matrix data that takes into account the spectral characteristics of illumination light and the spectral characteristics of the entire imaging system, including the color sensitivity characteristics of the image sensor and the transmittance of the color filter, and is captured by the image sensor. A method is disclosed in which spectral data of the observed portion is obtained by calculating the RGB image signal and the estimated matrix data and not depending on the type of illumination light, the spectral characteristics unique to the imaging system, or the like.

  On the other hand, in addition to illuminating and observing the observed part with white light, the fluorescent light is picked up by receiving the autofluorescence emitted from the observed part by the excitation light irradiation, and the fluorescent image is combined with the normal image. A fluorescence image acquisition device used as a fluorescence endoscope device to be displayed on a monitor screen is known. Such autofluorescence is emitted from an endogenous fluorescent substance in living tissue. For example, if the observed part is the airway mucosa, most of the autofluorescence is considered to be emitted from the submucosa, and the endogenous fluorescent substances include riboflavin, tryptophan, tyrosine, NADH, NADPH, porphyrin, collagen, elastin, fibronectin. Or FAD etc. are considered.

  In addition, when excitation light of a predetermined wavelength band is irradiated to a part to be observed such as a living tissue, the light intensity / spectral shape of autofluorescence emitted from the self-fluorescent substance inherent in the part to be observed is normal as shown in It is known that autofluorescence emitted from a tissue differs from autofluorescence emitted from a diseased tissue. There is also known a fluorescence endoscope apparatus that uses this phenomenon to irradiate an observation part with excitation light having a predetermined wavelength, detect autofluorescence emitted from the observation part, and generate a fluorescence image. As described above, autofluorescence emitted from the diseased tissue is attenuated more than autofluorescence emitted from the normal tissue. Thickness of the mucosal epithelium of the diseased tissue, consumption of endogenous fluorescent substance in the diseased tissue, or fluorescent absorption material It is speculated that this is an increase.

  Further, as such a fluorescence image acquisition apparatus, for example, a photosensitizer (ATX-S10, 5-ALA, Npe6, HAT-D01, Photofrin-, which has tumor affinity and emits fluorescence when excited by light) 2) is administered to the subject in advance as a fluorescent drug and absorbed in a tumor part such as cancer, and the part is irradiated with excitation light in the excitation wavelength region of this fluorescent drug, and the fluorescence accumulated in the tumor part. There is also known a fluorescence image acquisition device that detects fluorescence of a drug emitted from a drug and generates a fluorescence image.

  Moreover, in these fluorescent image acquisition apparatuses, various comparative analysis methods have been proposed in order for an observer to acquire information on tissue properties more accurately based on fluorescent information. For example, when irradiating an observation part such as a living tissue with excitation light to capture the light intensity of autofluorescence emitted from the observation part as a fluorescent image, and displaying fluorescence information acquired based on the fluorescent image The fluorescence intensity emitted from a normal observed part is approximately proportional to the excitation light illuminance, but the excitation light illuminance decreases in inverse proportion to the square of the distance. For this reason, strong fluorescence may be received from a diseased tissue that is closer than a normal tissue that is far from the light source. For this reason, it is not possible to accurately determine the tissue properties of the observed portion only by the fluorescence intensity information.

In Patent Document 3, in order to reduce such inconvenience, light to be observed is irradiated as reference light with light in a wavelength band different from that of excitation light, and reflected by the part to be observed that has been irradiated with this reference light. By detecting the intensity of the reflected light, the diagnostic information indicating the lesioned part of the living tissue is obtained based on the fluorescence yield represented by the ratio between the intensity of the fluorescence and the intensity of the reflected light of the reference light. There has been proposed a fluorescence image acquisition apparatus for diagnosing the tissue properties of a living body by displaying the lesion area as a red color or the like on the fluorescent image display screen.
JP 2003-93336 A JP 2007-202621 A Japanese Patent Laid-Open No. 2004-000477

  Usually, in such a fluorescent image acquisition device, it is sometimes necessary to acquire only a excitation light to irradiate the observed part and acquire a fluorescent image and to irradiate only the illumination light to the observed part and acquire a normal image. Dividing is done.

  However, when a fluorescent image and a normal image are acquired in a time-sharing manner, the number of frames per unit time of the fluorescent image and the normal image is reduced, and a good display image cannot be obtained when displaying as a moving image. there were.

  The present invention has been made in view of the above circumstances, and provides a fluorescence image acquisition method and a fluorescence image acquisition device that can generate a good display image even when displayed as a moving image. With the goal.

The fluorescent image acquisition method of the present invention captures an image composed of the reflected light of the observed portion irradiated with illumination light and the fluorescence emitted from the observed portion irradiated with excitation light simultaneously with the illumination light,
For each pixel of the captured image signal, a specific fluorescence wavelength that is a wavelength band including at least the substantially central wavelength band of the fluorescence from the image signal value of the pixel and an estimation matrix for calculating estimated spectral data stored in advance Calculate estimated spectral data of the band, obtain information reflecting the emission intensity of the fluorescence emitted from the observed portion from the estimated spectral data of the specific fluorescence wavelength band, and based on the information reflecting the emission intensity of the fluorescence A fluorescent image is generated.

The fluorescent image acquisition method of the present invention comprises a light irradiation means for simultaneously irradiating an observation part with illumination light and excitation light,
An imaging unit that captures an image composed of the reflected light of the illumination light in the observed part and the fluorescence emitted from the observed part irradiated with the excitation light;
A storage unit for storing an estimation matrix for calculating estimated spectral data;
For each pixel of the image signal output from the imaging means, using the image signal value of the pixel and the estimation matrix, estimation spectroscopy of a specific fluorescence wavelength band that is a wavelength band including at least the substantially central wavelength band of the fluorescence Calculates data, obtains information reflecting the emission intensity of the fluorescence emitted from the observed portion from the estimated spectral data of the specific fluorescence wavelength band, and generates a fluorescence image based on the information reflecting the emission intensity of the fluorescence And an image processing means.

  Here, the “estimated matrix for calculating estimated spectral data” is a matrix that takes into account the spectral characteristics of the illumination light and the spectral characteristics of the imaging means, and by performing matrix calculation with the image signal, It is a matrix from which estimated spectral data including estimated spectral reflectance information can be calculated. In addition, “a specific fluorescence wavelength band that is a wavelength band including at least the approximately central wavelength band of the fluorescence” means a wavelength band including at least the center wavelength of the fluorescence or a wavelength near the center wavelength, and substantially the intensity of the fluorescence. As long as the wavelength band reflects the above. Further, the “information reflecting the fluorescence emission intensity emitted from the observed portion” may be information reflecting at least the magnitude of the fluorescence emission intensity emitted from the observed portion.

The light irradiating means irradiates the observed portion with reference light having a wavelength different from that of the excitation light simultaneously with the irradiation of the excitation light,
If the imaging means captures an image including the reflected light of the reference light in the observed portion,
The image processing means calculates a reference light intensity that is an intensity of reflected light of the reference light imaged by the imaging means, and is a light intensity of the specific fluorescence wavelength band from estimated spectral data of the specific fluorescence wavelength band. A pseudo fluorescence intensity may be calculated, and a pseudo fluorescence yield obtained by dividing the pseudo fluorescence intensity by the reference light intensity may be calculated as the emission intensity information of the fluorescence.

  Here, the “reference light” may be light having a wavelength band different from that of illumination light, such as IR light, or may be light having a wavelength included in the wavelength band of illumination light. When the wavelength band of the reference light is included in the wavelength band of the illumination light, light in the entire illumination light or a part of the wavelength band of the illumination light can be used as the reference light.

  The image processing means uses, for each pixel of the image signal output from the imaging means, a quasi-normal wavelength that is a wavelength band not including the specific fluorescence wavelength band, using the image signal value of the pixel and the estimation matrix The estimated spectral data of the band may be obtained, and the pseudo normal image may be generated based on the estimated spectral data of the quasi-normal wavelength band.

  Here, the “quasi-normal wavelength band” may be all of the wavelength band excluding the specific fluorescence wavelength band from the wavelength band of the illumination light, or may be a part of the wavelength band. . The “pseudo normal image” may be a color image or a black and white image.

  The fluorescence image acquisition apparatus may include a display processing unit that generates a fluorescence superimposed image in which the fluorescence image is superimposed on the pseudo normal image. Further, an input means for setting the specific fluorescence wavelength band by an input operation may be provided.

  In the fluorescence image acquisition method and the fluorescence image acquisition device according to the present invention, the light comprises reflected light of the observed portion irradiated with illumination light and fluorescence emitted from the observed portion irradiated with excitation light simultaneously with the illumination light. For each pixel of the captured image signal, a wavelength band including at least a substantially central wavelength band of the fluorescence from the image signal value of the pixel and an estimated matrix for calculating estimated spectral data stored in advance The estimated spectral data of the specific fluorescence wavelength band is calculated, the emission intensity information of the fluorescence emitted from the observed part is obtained from the estimated spectral data of the specific fluorescence wavelength band, and the fluorescence image is obtained based on the fluorescence intensity information. Since the number of frames of fluorescent images that can be acquired per unit time is not reduced by generating, a good display image can be obtained even when displaying fluorescent images as moving images. It is possible to generate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a schematic configuration diagram of a fluorescence endoscope apparatus which is an embodiment to which a fluorescence image acquisition apparatus of the present invention is applied. The present fluorescence endoscope apparatus 100 irradiates the observation unit 10 with the illumination light L1 and the excitation light L2 in the normal image mode in which the color normal image obtained by irradiating the observation unit 10 with the illumination light L1 is displayed as a moving image. The pseudo color normal image and the fluorescence superimposed image obtained by the arithmetic processing described later from the color image acquired in this manner are operated in the fluorescence image mode for displaying as a moving image. As shown in the figure, the fluorescence endoscope apparatus 100 is inserted into a body cavity of a subject, and a scope unit 110 for observing the observed portion 10 and a processor unit to which the scope unit 110 is electrically detachably connected. 170 and the scope unit 110 are optically and detachably connected, and the illumination light unit 150 that houses the xenon lamp 151 that emits the illumination light L1 and the illumination light unit 150 are electrically and optically detachably connected. And an excitation light unit 130 that houses a GaN-based semiconductor laser 131 that emits the excitation light L2. Note that the processor unit 170 and the illumination light unit 150 may be configured integrally or may be configured separately.

  An illumination optical system 111 is provided at the tip of the scope unit 110. One end of the light guide 112 through which the illumination light L1 is guided faces the illumination optical system 111. The light guide 112 extends to the outside of the scope unit 110, and an optical connector 113 is provided at the other end, and is detachably connected to an optical connector 153 of an illumination light unit 150 described later.

  In addition, an imaging lens 115, an excitation light cut filter 116, and a CCD (Charge Coupled Device) 117 that is a solid-state imaging device are coaxially provided in this order on the distal end portion of the scope unit 110. The imaging lens 115 forms an image of the observed portion 10 on the CCD 117. As the excitation light cut filter 116, for example, a notch filter that blocks only light in a very narrow band can be used so that only excitation light is blocked and light of other wavelengths is transmitted. For example, a primary color filter having RGB color filters is attached to the imaging surface of the CCD 117. The CCD 117 is connected to a CCD drive circuit 118 that forms a drive pulse based on a synchronization signal, and also CDS / AGC (correlated double sampling / automatic) that samples and amplifies an image (video) signal output from the CCD 115. Gain control) circuit 119 is connected. The CDS / AGC circuit 119 is connected to an A / D converter 120 that digitizes the analog output. Further, in the scope unit 110, a control unit 121 that controls various circuits provided therein and controls communication with the processor unit 170 is disposed. Further, near the base of the scope unit 110, a push-type switch 122 that is connected to the control unit 121 and switches the operation mode is provided. One end of a signal line 125 is connected to the A / D converter 120, and one end of a signal line 126 is connected to the control unit 121. The signal line 125 and the signal line 126 extend from the main body of the scope unit 110 to the outside, and a connector 127 is provided at the other end. This connector 127 is detachably connected to a connector 194 of a processor unit 170 described later.

  The illumination light unit 150 is detachably connected to a xenon lamp 151 that emits illumination light L1, a drive circuit 152 that drives the xenon lamp 151, and an optical connector 113 provided at the tip of the light guide 112 of the scope unit 110. The optical connector 153 is provided. The optical connector 153 is provided with a connection detection unit 154 that detects whether or not the optical connector 113 is connected. Between the xenon lamp 151 and the optical connector 153, a wavelength filter 155 that limits the wavelength band of the illumination light L1 to 410 nm or more and 700 nm or less, a diaphragm 156 that controls the light quantity of the illumination light L1, and a wavelength of 410 nm or more A dichroic mirror 157 that transmits light having a wavelength and reflects light having a wavelength shorter than 410 nm at right angles, a condensing lens 158, and a rotary shutter 159 are disposed. Further, the illumination light unit 150 is provided with an optical connector 161 that is detachably connected to an optical connector 136 that is provided at the tip of a light guide 133 of the excitation light unit 130 described later. The optical connector 161 is provided with a connection detection unit 162 that detects whether the optical connector 136 is connected. One end (incident end) of a light guide 163 that guides excitation light in the illumination light unit 150 is connected to the optical connector 161. The other end (outgoing end) of the light guide 163 is disposed at a position where the excitation light L <b> 2 emitted from the light guide 163 enters the dichroic mirror 157. A lens 164 is disposed between the light guide 163 and the dichroic mirror 157.

  Further, the illumination light unit 150 is provided with a connector 165 detachably connected to a connector 142 of the excitation light unit 130 described later. The connector 165 is provided with a connection detection unit 166 that detects whether or not it is connected to the connector 142. In addition, the illumination light unit 150 is connected to each part provided in the illumination light unit 150 such as the connector 165 and the connection detection unit 166, and controls each part, and between the processor unit 170 and the excitation light unit 130. A control unit 167 for performing communication control is arranged.

  The excitation light unit 130 includes a GaN-based semiconductor laser 131 that emits the excitation light L2, a drive circuit 132 that drives the semiconductor laser 131, and a light guide 133 that guides the excitation light L2 emitted from the semiconductor laser 131. I have. The light guide 133 extends from the casing of the excitation light unit 130 to the outside, and an optical connector 136 is provided at the other end. This optical connector 136 is detachably connected to the optical connector 161 of the illumination light unit 150. A switch 134 is provided between the semiconductor laser 131 and the drive circuit 132. A condensing optical system 135 is disposed between the semiconductor laser 131 and one end (incident end) of the light guide 133.

  Further, the pumping light unit 130 is connected to each part provided in the pumping light unit 130 such as the drive circuit 132 and the switch 134, and controls these parts and also controls communication with the illumination light unit 150. A control unit 140 that performs is arranged. One end of a signal line 141 is connected to the control unit 140. The signal line 141 extends from the casing of the excitation light unit 130 to the outside, and a connector 142 is provided at the other end. The connector 142 is detachably connected to the connector 165 of the illumination light unit 150.

  On the other hand, the processor unit 170 performs normal signal processing when the normal image mode is selected, the normal image processing unit 174 and the display processing unit 176, and estimated spectral data that performs signal processing when the fluorescent image mode is selected. A processor unit 172 provided with a calculation unit 180, an image processing unit 182 and a display processing unit 184, and a light amount control unit 186 for controlling the intensity of illumination light and excitation light is provided.

  The normal image processing unit 174 performs various types of signal processing on the three-color image signals of R, G, and B output from the A / D converter 120 of the scope unit 110 when the normal image mode is selected. In addition, a Y / C signal composed of a luminance (Y) signal and a color difference [C (R−Y, B−Y)] signal is generated and output to the display processing unit 176. The display processing unit 176 performs various types of signal processing on the Y / C signal, generates a color normal image signal for display, and outputs the color normal image signal to the monitor 11 including, for example, a liquid crystal display device or a CRT. .

  In the estimated spectral data calculation means 180, when the fluorescence image mode is selected, the R, G, B three-color image signals output from the A / D converter 120 of the scope unit 110 are stored in advance for each pixel. The estimated spectral data is calculated using the estimated matrix data for calculating the spectral data, and is output to the image processing unit 182.

  In the image processing unit 182, first, when the excitation light L2 is irradiated, estimated spectral data of a specific fluorescence wavelength band that is a wavelength band including 480 nm that is the central wavelength band of the fluorescence emitted from the observed unit 10, for example, 460 nm to 500 nm. And a fluorescence image is generated based on the estimated spectral data of the specific fluorescence wavelength band. Further, estimated spectral data in a quasi-normal wavelength band, for example, 410 nm to 460 nm and 500 to 700 nm, which is a wavelength band not including the specific fluorescence wavelength band, is obtained, and pseudo color normal image data is obtained based on the estimated spectral data in the quasi-normal wavelength band. And pseudo monochrome normal image data are generated. Further, fluorescence superimposed image data is generated by superimposing the fluorescence image data on the pseudo monochrome normal image data, and the pseudo color normal image data and the fluorescence superimposed image data are output to the display processing unit 184. The display processing unit 184 generates a display image in which the pseudo-color normal image data and the fluorescence superimposed image data are displayed side by side, or generates a display color image signal that is synthesized into one image and outputs the display color image signal to the monitor 11. .

  The light amount control unit 186 is connected to the normal image processing unit 174 and the image processing unit 182, and controls the light amount of the illumination light L1 based on the luminance of the color normal image when the illumination normal image mode is selected. . When the fluorescence image mode is selected, the light amounts of the illumination light L1 and the excitation light L2 are controlled based on the luminance of the pseudo color normal image.

  Further, a connector 194 that is detachably connected to the memory 190, the keyboard-type input unit 192, and the connector 127 of the scope unit 110 is connected to the processor unit 172. The connector 194 is provided with a connection detection unit 195 that detects whether or not it is connected to the connector 127. The processor unit 172 is connected to the control unit 140 in the control unit 121 of the scope unit 110, the control unit 167 of the illumination light unit 150, and the excitation light unit 130.

The memory 190 stores estimated matrix data for calculating estimated spectral data of the observed portion 10. The estimated matrix data is stored in advance in the memory 190 as a table. This estimated matrix data is matrix data that takes into account the spectral characteristics of the illumination light L1 and the spectral characteristics of the entire imaging system including the color sensitivity characteristics of the image sensor and the transmittance of the color filters. By calculating the image signal and the estimated matrix data, it is possible to obtain spectral data of the observed portion that does not depend on the type of illumination light, the spectral characteristics unique to the imaging system, or the like. The details of the estimation matrix data are disclosed in Japanese Patent Laid-Open No. 2003-93336 or Japanese Patent Laid-Open No. 2007-202621. In this embodiment, an example of estimated matrix data stored in the memory 190 is as shown in Table 1 below.

The matrix data in Table 1 is composed of 59 wavelength range parameters (coefficient sets) p1 to p59 obtained by dividing the wavelength range from 410 nm to 700 nm, for example, at 5 nm intervals. Each of the parameters p1 to p59 includes coefficients k _pr , k _pg , and k _pb (p = 1 to 59) for matrix calculation.

  Hereinafter, the operation of the fluorescence endoscope apparatus of the present embodiment having the above configuration will be described. First, an operation in the normal image mode in which a color normal image acquired by irradiating the observation part 10 with the illumination light L1 is displayed as a moving image will be described.

  Prior to use of the present fluorescence endoscope apparatus, the cleaned and sterilized scope unit 110 is attached to the processor unit 170 and the illumination light unit 150. The connector 127 provided at the tip of the signal line 125 and the signal line 126 of the scope unit 110 is connected to the connector 194 of the processor unit 170. The optical connector 113 provided at the tip of the light guide 112 is connected to the optical connector 153 of the illumination light unit 150. The connection detection unit 195 provided in the connector 194 outputs a connection signal to the processor unit 172 when the connector 127 is connected to the connector 194. The connection detection unit 154 provided to the optical connector 153 outputs a connection signal to the control unit 167 when the optical connector 113 is connected to the optical connector 153.

  When a connection signal is input from the connection light detection unit 195 and the connection detection unit 154, the processor unit 172 rotates the rotary shutter 159 of the illumination light unit 150 to enable operation in the normal image mode. A function form of a predetermined key is set, and a function form of the switch 122 is set via the control unit 121 of the scope unit 110. When the user presses a predetermined key or switch 122 of the input unit 192 under the control of the processor unit 172, the operation mode is switched between the stopped state and the normal image mode.

  When the user presses a predetermined key or switch 122 of the input unit 192 once, the operation in the normal image mode is started. In the illumination light unit 150, the xenon lamp 151 is turned on by the drive circuit 152, and the illumination light L1 is emitted. The illumination light L 1 passes through the wavelength filter 155, the stop 156, and the dichroic mirror 157, and is collected on the end face of the optical connector 113 by the condenser lens 158 and enters the light guide 112. The illumination light L1 propagated through the light guide 112 is emitted from the tip of the light guide 112, and is irradiated to the observed portion 10 through the illumination optical system 111.

  The wavelength band of the illumination light L1 is limited to 410 nm or more and 700 nm or less by the wavelength filter 155, and the light quantity of the illumination light L1 is controlled by the diaphragm 156. The light amount control operation of the illumination light L1 by the diaphragm 156 will be described later.

  The CCD 117 driven by the CCD driving circuit 118 takes an image of the observed portion 10 and outputs an image pickup signal. The imaging signal is amplified by correlated double sampling and automatic gain control by the CDS / AGC circuit 119, and then A / D converted by the A / D converter 18, and is processed as an RGB image signal by the processor unit 172 of the processor unit 170. Are input to the normal image processing unit 174. When the normal image mode is selected, the normal image processing unit 174 performs various types of signal processing on the R, G, and B three-color image signals output from the A / D converter 120 of the scope unit 110. Above, a Y / C signal (color normal image signal) composed of the luminance signal Y and the color difference signal C is generated and output to the display processing unit 176. The display processing unit 176 performs various signal processing such as I / P conversion and noise removal on the Y / C signal, and outputs it to the monitor 11.

  Further, the normal image processing unit 174 outputs the luminance signal Y for each pixel or the average luminance signal Y ′ of a plurality of adjacent pixels to the light amount control unit 186. The light amount control unit 186 calculates an average luminance value Ya of the designated area pixel for each frame, compares it with a reference luminance value Yr stored in advance in the memory 190, and selects an aperture control signal based on the comparison result. And output to the controller 167 of the illumination light unit 150. As the diaphragm control signal, a signal for decreasing the diaphragm amount of the diaphragm 156 is selected if the average luminance value Ya is larger than the reference luminance value Yr, and the diaphragm amount of the diaphragm 156 is selected if the average luminance value Ya is smaller than the reference luminance value Yr. When a signal to be increased is selected and the average luminance value Ya is substantially equal to the reference luminance value Yr, a signal for maintaining the aperture amount is selected.

  The control unit 167 of the illumination light unit 150 controls the aperture amount of the aperture 156 based on the aperture control signal.

  Next, the operation in the fluorescence image mode will be described. Before using the fluorescence image mode, first, the cleaned and sterilized scope unit 110 is attached to the processor unit 170 and the illumination light unit 150. The connector 127 provided at the tip of the signal line 125 and the signal line 126 of the scope unit 110 is connected to the connector 194 of the processor unit 170. The connection detection unit 195 provided in the connector 194 outputs a connection signal to the processor unit 172 when the connector 127 is connected to the connector 194. The optical connector 113 provided at the tip of the light guide 112 is connected to the optical connector 153 of the illumination light unit 150. The connection detection unit 154 provided to the optical connector 153 outputs a connection signal to the control unit 167 when the optical connector 113 is connected to the optical connector 153.

  Further, the excitation light unit 130 is connected to the illumination light unit 150. The connector 142 provided at the tip of the signal line 141 of the excitation light unit 130 is connected to the connector 165 of the illumination light unit 150. The connection detection unit 166 provided in the connector 165 outputs a connection signal to the control unit 167 when the connector 142 is connected to the connector 165. The optical connector 136 provided at the tip of the light guide 133 is connected to the optical connector 161 of the illumination light unit 150. The connection detection unit 162 provided in the optical connector 161 outputs a connection signal to the control unit 167 when the optical connector 136 is connected to the optical connector 162.

  The control unit 140 of the excitation light unit 130 communicates with the control unit 167 of the illumination light unit 150, and when a connection signal is input from the connection detection unit 166 and the connection detection unit 162, the switch 134 of the excitation light unit 130 is turned on. The semiconductor laser 131 and the drive circuit 132 are electrically connected to each other, the semiconductor laser 131 can be driven by the drive circuit 132, and a predetermined key of the input unit 192 is provided via the processor unit 172 of the processor unit 170. And the functional form of the switch 122 is set via the processor unit 172 and the control unit 121 of the scope unit 110. When the user presses a predetermined key or switch 122 of the input unit 192 under the control of the control unit 140, the operation mode is switched between the stopped state, the normal image mode, and the fluorescent image mode. In the case where no connection signal is input from both the connection detection unit 166 and the connection detection unit 162, that is, no connection signal is input from either of them, or no connection input signal is input from either of them. In the excitation light unit 130, the switch 134 is always open. For this reason, the semiconductor laser 131 is not driven in a state where the excitation light unit 130 is not connected to the illumination light unit 150.

  When operating in the normal image mode, when the user presses a predetermined key or switch 122 of the input unit 192 once, the operation in the fluorescent image mode is started.

  In addition to the illumination light unit 150, the excitation light unit 130 starts operating. The semiconductor laser 131 is driven by the drive circuit 132, and excitation light L2 having a wavelength of 405 nm is emitted. The excitation light L2 is condensed by the condensing optical system 135 and enters the end face of the light guide 133. The excitation light L 2 that has propagated through the light guide 133 enters the light guide 163 via the optical connector 136 and the optical connector 161. The excitation light L2 propagating through the light guide 163 and exiting from the end thereof is converted into parallel light by the collimator lens 164 and enters the dichroic mirror 157. Since the wavelength of the excitation light L <b> 2 is 405 nm, the excitation light L <b> 2 is reflected by the dichroic mirror 157 at a right angle, is condensed on the end face of the optical connector 113 by the condenser lens 158, and enters the light guide 112. The excitation light L <b> 2 propagated through the light guide 112 is emitted from the tip of the light guide 112 and is irradiated to the observed part 10 through the illumination optical system 111. At this time, the observation part 10 is also irradiated with the illumination light L1. The light amount of the excitation light L2 is controlled by the drive current of the drive circuit 132. The light amount control operation of the excitation light L2 by this drive current will be described later.

  The CCD 117 driven by the CCD driving circuit 118 irradiates the reflected light of the illumination light L1 reflected by the observed portion 10 and the excitation light L2, and thereby forms an image composed of fluorescence emitted from the observed portion 10. Take an image. Note that since the excitation light cut filter for cutting light having a wavelength of 410 nm or less is provided at the tip of the CCD 117, the reflected light of the excitation light L2 hardly enters the CCD 117. The CCD 117 outputs an imaging signal. This imaging signal is amplified by correlated double sampling and automatic gain control by the CDS / AGC circuit 119, and then A / D converted by the A / D converter 18 to obtain an RGB image. A signal is input to the estimated spectral data calculation means 180 of the processor unit 172 of the processor unit 170.

The estimated spectral data calculation means 180 uses a 3 × 59 matrix composed of all parameters of estimated matrix data stored in the memory 100 for the three-color image signals R, G, and B for each pixel. Then, matrix calculation represented by the following equation is performed to generate estimated spectral data (q1 to q59) and output to the image processing unit 182.

  2A and 2B show an example of the spectrum distribution of the estimated spectral data (q1 to q59) created for each pixel. FIG. 2A shows a spectral distribution in a pixel corresponding to the observed part 10 that is emitting fluorescence, and FIG. 2B shows a spectral distribution in a pixel corresponding to the observed part 10 that is not emitting fluorescence. The horizontal axis indicates the wavelength corresponding to each of the data values q1 to q59 of the estimated spectral data, and the vertical axis indicates the intensity of q1 to q59 of each data value.

  As shown in FIG. 2B, the spectral distribution acquired from the observed portion 10 that is not emitting fluorescence reflects the spectral reflectance in the observed portion 10. More specifically, the intensity of each data value q1 to q59 is a value reflecting the product of the spectral reflectance of the observed portion 10 and the intensity of light incident on each pixel of the CCD 17.

  As shown in FIG. 2A, the spectral distribution of the estimated spectral data (q1 to q59) acquired from the observed part 10 that is emitting fluorescence is in the vicinity of the wavelength 480 nm that is the central wavelength of the fluorescence. It reflects the spectral reflectance and the spectral emissivity of fluorescence. More specifically, the intensity of each data value q1 to q59 reflects the spectral reflectance of the observed portion 10, the spectral emissivity of the emitted fluorescence, and the intensity of light incident on each pixel of the CCD 17. Value. Note that the estimated matrix used to create the estimated spectral data (q1 to q59) is a matrix for calculating the spectral reflectance of the observed portion 10, so that each data value q1 to q59 is a fluorescence spectrum. It is not a value that accurately reflects the emissivity, but includes information about the magnitude of the spectral emissivity of fluorescence. For this reason, as will be described below, it is possible to calculate the pseudo-fluorescence yield, which is information reflecting the emission intensity of the fluorescence emitted from the observed portion, using the estimated spectral data.

  The image processing unit 182 performs the following signal processing for each pixel. First, when the excitation light L2 is irradiated, a specific fluorescence wavelength band that is a wavelength band including 480 nm that is a central wavelength band of fluorescence emitted from the observed portion 10, for example, a wavelength band of 460 nm to 500 nm as shown in FIG. From the estimated spectral data (q11 to q19), the pseudo fluorescence intensity which is the light intensity in the specific fluorescence wavelength band is calculated. The pseudo fluorescence intensity is not a value representing the fluorescence intensity itself, but is a value including information on the magnitude of the fluorescence spectral emissivity as described above.

  As the specific fluorescence wavelength band, a wavelength band set in advance in the image processing unit 183 may be used, or a wavelength band input by an input operation from the input unit 192 may be used.

  Further, pseudo three-color image signals Rs, Gs are obtained from estimated spectral data in a quasi-normal wavelength band that does not include the specific fluorescence wavelength band, for example, wavelength bands of 410 nm to 460 nm and 500 to 700 nm as shown in FIG. , Bs. In this case, for example, the light intensity is calculated from the estimated spectral data in the wavelength band of 410 nm to 460 nm, and the value is used as the Bs signal. Further, the light intensity is calculated from the estimated spectral data in the wavelength band of 500 nm to 600 nm, the value is used as the Gs signal, the light intensity is calculated from the estimated spectral data in the wavelength band of 600 nm to 700 nm, and the value is set as the Rs signal. To do.

  Using these pseudo three-color image signals Rs, Gs, and Bs, a Y / C signal (pseudo color normal image signal) composed of a luminance signal Y and a color difference signal C is generated, and a display processing unit is provided as a pseudo color normal image signal. Output to 184.

  The intensity (radiation intensity) of the fluorescence emitted from the fluorescent material is substantially proportional to the excitation light illuminance, but the excitation light illuminance decreases in inverse proportion to the square of the distance. For this reason, strong fluorescence may be received from a lesion tissue that is closer than normal tissue that is far from the light source, and the tissue properties of the observed part can be expressed only by information on the intensity of the received fluorescence. Can not. Therefore, conventionally, the intensity of the reflected light reflected by the observed portion irradiated with the reference light (hereinafter referred to as the reference light intensity) is irradiated as the reference light with light having a wavelength band different from that of the excitation light. ) Is detected, a fluorescence yield obtained by dividing the fluorescence intensity by the reference light intensity is obtained, and a fluorescence image is generated based on the fluorescence yield.

  In the image processing unit 182, by using the value of the luminance signal Y of the pseudo color normal image signal as the reference intensity, that is, by dividing the pseudo fluorescence intensity by the value of the luminance signal Y of the pseudo color normal image signal, Determine the pseudofluorescence yield. For example, as shown in FIG. 5, green is assigned to the pseudo-fluorescence yield if it is equal to or higher than a predetermined determination value, and red is assigned if it is smaller than the determination value to generate a fluorescent image. Alternatively, red and green may be mixed by an additive color mixing method to generate a fluorescent image in which the display color sequentially changes to red, yellow, and green according to the value of the pseudo fluorescence yield. If the pseudofluorescence yield is less than or equal to a predetermined lower limit, only red may be assigned, and if it is greater than or equal to the predetermined upper limit, green may be assigned. Normal tissue with a large pseudofluorescence yield is displayed in red and in green.

  Alternatively, as shown in FIG. 6, a fluorescence image can be generated by assigning red, green, and blue to the pseudo fluorescence yield by comparison with a determination value. Also, by mixing red, green, and blue by additive color mixing, a fluorescent image can be generated in which the display color changes sequentially to red, yellow, green, cyan, and blue depending on the value of the pseudo fluorescence yield. Good. Note that an achromatic color may be assigned when the pseudo fluorescence yield is equal to or lower than a predetermined lower limit value or equal to or higher than a predetermined upper limit value.

  In this embodiment, the value of the luminance signal Y of the pseudo color normal image signal is used as the reference light intensity. For example, instead of the value of the luminance signal Y of the pseudo color normal image signal, the value of the image signal Rs is changed. Light intensity, or light intensity obtained from estimated spectral data in a long wavelength band with a small difference between the fluorescence intensity emitted from normal tissue and the fluorescence intensity emitted from diseased tissue, for example, 620 nm may be used.

  In the image processing unit 182, an image that reflects only the luminance signal Y of the pseudo-color normal image signal, that is, the pseudo-monochrome normal image is displayed so that the observer can easily confirm the position of the lesion tissue in which the pseudo-fluorescence yield becomes small. Then, the fluorescence superimposed image data on which the above-described fluorescence image is superimposed is generated and output to the display processing unit 184. The display processing unit 184 generates a display image in which the pseudo color normal image data and the fluorescence superimposed image data output from the image processing unit 182 are displayed side by side, or generates the pseudo color normal image data and the fluorescence superimposed image data as one image. A color image signal for display that has been combined into the image is generated and output to the monitor 11 for display.

  Note that the processor unit 172 determines in advance whether or not the pseudo fluorescence yield in all pixels is equal to or higher than a predetermined determination value, and if it is equal to or higher than a predetermined value, that is, a lesion in the image. If there is no portion corresponding to the tissue, only the pseudo color normal image data may be displayed.

  In addition, the image processing unit 182 outputs the luminance signal Y of the pseudo color normal image signal for each pixel or the average luminance signal Y ′ of a plurality of adjacent pixels to the light amount control unit 186. The light amount control unit 186 calculates an average luminance value Ya of the designated area pixel for each frame, compares it with a reference luminance value Yr stored in advance in the memory 190, and selects an aperture control signal based on the comparison result. And output to the controller 167 of the illumination light unit 150. At the same time, the pumping light unit 130 obtains a driving current control signal for controlling the value of the driving current supplied from the driving circuit 132 to the semiconductor laser 131, and outputs this driving current control signal to the control unit 140 of the pumping light unit 130. .

  As the aperture control signal, a signal for decreasing the aperture amount of the aperture 156 is selected if the average luminance value Ya is larger than the reference luminance value Yr, and the aperture amount of the aperture 156 is increased if the average luminance value Ya is smaller than the reference luminance value Yr. If the average luminance value Ya is substantially equal to the reference luminance value Yr, a signal for maintaining the aperture amount is selected. Further, the drive current control signal corresponding to the aperture control signal is output so that the ratio between the light amount of the illumination light L1 and the light amount of the excitation light L2 becomes a predetermined value. Note that the ratio between the light amount of the illumination light L1 and the light amount of the excitation light L2 can be set in advance by an input operation from the input unit 192, and the light amount control unit 186 sets the set ratio and the aperture amount of the illumination light L1. Based on the above, the drive current amount is determined for the excitation light L2, and a drive current control signal is output.

  The control unit 167 of the illumination light unit 150 controls the aperture amount of the aperture 156 based on the aperture control signal. In addition, the control unit 140 of the excitation light unit 130 controls the current value supplied from the drive circuit 132 to the semiconductor laser 131 based on the drive current control signal.

  As is clear from the above description, in the fluorescence endoscope apparatus 100 according to the present invention, the number of frames per unit time of the pseudo normal color image and the fluorescence superimposed image is the same as the number of frames of the normal color image. Even when displaying as a moving image, a good display image can be generated.

  In this embodiment, the normal image processing unit 174 and the display processing unit 176 perform signal processing when the normal image mode is selected, and the signal processing is performed when the fluorescent image mode is selected. Although the spectral data calculation unit 180, the image processing unit 182 and the display processing unit 184 are provided with the processor unit 172, the form of the processor unit 172 is not limited to such a form. For example, the estimated spectral data calculation unit 180, an image processing unit that functions as a normal image processing unit 174 and an image processing unit 182, and a display processing unit that functions as a display processing unit 176 and a display processing unit 184. When the normal image mode is selected When the signal output from the scope 110 is directly input to the image processing unit and the fluorescence image mode is selected, the signal from the scope 110 is It may be configured so as to enter the force signal to the estimated spectral data calculation unit 180.

  In the present embodiment, a wavelength band having a predetermined width including 480 nm, which is the central wavelength band of fluorescence, is used as the specific fluorescence wavelength band. However, the specific fluorescence wavelength band is not limited to this. For example, only 480 nm, or only 470 nm or 490 nm. Or 475 nm-485 nm etc. may be sufficient. For example, if the specific fluorescence wavelength band is only 480 nm, the pseudo fluorescence intensity can be obtained by calculating only the estimated spectral data (q15), and if the specific fluorescence wavelength band is 475 nm to 485 nm, the estimated spectral data ( If q14, q15, and q16) are calculated, the pseudo fluorescence intensity can be obtained.

  Moreover, it is preferable that this specific fluorescence wavelength band has all the wavelength bands in the substantial fluorescence wavelength band, and it is not preferable that it is an unnecessarily wide wavelength band. Specifically, the wavelength bandwidth is preferably 100 nm or less. More preferably, it is 50 nm or less. Further, it may be 10 nm or less or a single wavelength as described above.

  Furthermore, in the present embodiment, the illumination light L1 and the excitation light L2 propagated in the scope unit 110 are simultaneously irradiated onto the observed part 10 and imaged by the CCD 117 and stored in the memory 190 in advance. The matrix spectroscopic data is used to calculate the estimated spectral data, the pseudo fluorescence intensity is calculated from the estimated spectral data, and the fluorescence endoscope apparatus that generates the fluorescence image based on the pseudo fluorescence intensity has been described. The form of the fluorescence image acquisition device of the present invention is not limited to the above-described embodiment, and any form may be used as long as it irradiates illumination light and excitation light to acquire a fluorescence image. Also good. The excitation light source may be an LED. Further, for example, an endoscope apparatus, a colposcope, or a capsule endoscope apparatus provided with a light source unit such as an LED at the distal end of the scope unit, or a microscope or the like having a fluorescence image acquisition function may be used. Good.

  Further, although the description has been given using the primary color type three-color filter as the mosaic filter of the CCD 117, the present invention is not limited to this, and a mosaic filter such as a four-color type or a complementary color type can also be used. In this case, the signal output from the CCD 117 may be converted into a primary color type signal by signal processing, or estimated matrix data matching the spectral characteristics of these mosaic filters may be stored in the memory in advance. Good.

The block diagram which shows the structure of the fluorescence endoscope apparatus which concerns on one Embodiment of this invention. Diagram showing the relationship between wavelength and pseudo spectral reflectance data Diagram showing the relationship between wavelength and spectral reflectance data The figure which shows the relationship between the wavelength in the specific fluorescence wavelength band and the pseudo spectral reflectance data The figure which shows the relationship between the wavelength and the quasi-spectral reflectance data in the quasi-normal wavelength band Illustration of how to assign colors to fluorescence yield Illustration of how to assign colors to other fluorescence yields Illustration of the spectrum of fluorescence emitted from normal and diseased tissues

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Observation part 11 Monitor 100 Fluorescence endoscope apparatus 110 Scope unit 111 Optical system for illumination 112 Light guide 113 Optical connector 115 Imaging lens 116 Excitation light cut filter 117 CCD
118 CCD Drive Circuit 121 Control Unit 122 Switch 125 Signal Line 126 Signal Line 127 Connector 130 Excitation Light Unit 131 Semiconductor Laser 132 Drive Circuit 133 Light Guide (Fiber)
134 Switch 136 Optical Connector 150 Illumination Light Unit 151 Xenon Lamp 152 Drive Circuit 153 Optical Connector 154 Connection Detection Unit 155 Wavelength Filter 156 Aperture 157 Dichroic Mirror 158 Condensing Lens 159 Rotary Shutter 161 Optical Connector 162 Connection Detection Unit 163 Light Guide (Fiber)
164 Lens 165 Connector 166 Connection detection unit 167 Control unit 170 Processor unit 172 Processor unit 174 Normal image processing unit 176 Display processing unit 180 Estimated spectral data calculation unit 182 Image processing unit 184 Display processing unit 186 Light quantity control unit 190 Memory 192 Input unit

Claims (9)

An operation method of a fluorescence image acquisition apparatus comprising light irradiation means, imaging means, and image processing means,
  The light irradiating means irradiates the observed part simultaneously with illumination light and excitation light,
  The imaging means captures an image composed of reflected light of the illumination light in the observed portion and fluorescence emitted from the observed portion irradiated with the excitation light;
  For each pixel of the image signal output from the imaging means, the image processing means at least from the image signal value of the pixel and an estimated matrix for calculating estimated spectral data stored in advance, at least approximately the central wavelength of the fluorescence Calculating estimated spectral data of a specific fluorescence wavelength band that is a wavelength band including the band, obtaining information reflecting a radiation intensity of the fluorescence emitted from the observed portion from the estimated spectral data of the specific fluorescence wavelength band, and calculating the fluorescence For each pixel of the image signal output from the imaging means, and using the image signal value of the pixel and the estimation matrix, the specific fluorescence wavelength is generated based on information reflecting the radiation intensity of A fluorescent light characterized by obtaining estimated spectral data of a quasi-normal wavelength band, which is a wavelength band not including a band, and generating a pseudo-normal image based on the estimated spectral data of the quasi-normal wavelength band. Operation method for an image acquisition device. A light irradiation means for simultaneously irradiating the observation part with illumination light and excitation light;
An imaging unit that captures an image composed of the reflected light of the illumination light in the observed part and the fluorescence emitted from the observed part irradiated with the excitation light;
A storage unit for storing an estimation matrix for calculating estimated spectral data;
For each pixel of the image signal output from the imaging means, using the image signal value of the pixel and the estimation matrix, estimation spectroscopy of a specific fluorescence wavelength band that is a wavelength band including at least the substantially central wavelength band of the fluorescence Calculates data, obtains information reflecting the emission intensity of the fluorescence emitted from the observed portion from the estimated spectral data of the specific fluorescence wavelength band, and generates a fluorescence image based on the information reflecting the emission intensity of the fluorescence And
And for each pixel of the image signal output from the imaging means, the estimated spectral data of the quasi-normal wavelength band that is a wavelength band not including the specific fluorescence wavelength band, using the image signal value of the pixel and the estimation matrix And an image processing means for generating a pseudo-normal image based on the estimated spectral data of the quasi-normal wavelength band . The light irradiating means irradiates the observed portion with reference light having a wavelength different from that of the excitation light simultaneously with the irradiation of the excitation light,
The imaging means captures an image including reflected light of the reference light in the observed portion;
The image processing means calculates a reference light intensity that is the intensity of the reflected light of the reference light imaged by the imaging means, and is the light intensity of the specific fluorescence wavelength band from the estimated spectral data of the specific fluorescence wavelength band The fluorescence image acquisition apparatus according to claim 2, wherein pseudo fluorescence intensity is calculated, and a pseudo fluorescence yield obtained by dividing the pseudo fluorescence intensity by the reference light intensity is calculated as radiation intensity information of the fluorescence. . 4. The fluorescence image acquisition apparatus according to claim 2, further comprising display processing means for generating a fluorescence superimposed image in which the fluorescence image is superimposed on the pseudo-normal image. The specific fluorescence fluorescence image obtaining apparatus of the wavelength band from claim 2, characterized in that it comprises an input means for setting the input operation 4 any one of claims.   The fluorescent image acquisition apparatus according to claim 2, wherein the image processing unit generates a pseudo-monochrome normal image based on the estimated spectral data of the quasi-normal wavelength band.   The fluorescence image acquisition apparatus according to claim 6, wherein the image processing unit generates a fluorescence multiple image in which the pseudo monochrome normal image and the fluorescence image are superimposed.   The image processing means generates a pseudo color normal image based on the estimated spectral data of the quasi-normal wavelength band;
  The fluorescence image acquisition apparatus according to claim 7, further comprising a display processing unit that generates a display image in which the pseudo color normal image and the fluorescence multiple image are arranged.   The fluorescence image acquisition apparatus according to any one of claims 2 to 8, wherein the quasi-normal wavelength band includes a wavelength band of 410 nm to 460 nm and 500 nm to 700 nm.

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