# US 2020/0404202 A1 · Fluorescence imaging with fixed pattern noise cancellation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0404202 A1 - Document ID: US20200404202A1 - Status: Published application - Kind: A1 - Application number: 16/735,932 - Filed: 2020-01-07 - Published: 2020-12-24 - Earliest claimed: 2019-06-20 - Assignees: Ethicon, Inc. - Applicants: Ethicon LLC - Inventors: Joshua D. Talbert; Donald M. Wichern - Web page: https://patentgrep.com/patent/US20200404202A1 ## CPC - A61B 1/043: {for fluorescence imaging} - A61B 1/00006: {of control signals} - A61B 1/045: Control thereof - A61B 1/0653: {with wavelength conversion} - A61B 5/0022: {Monitoring a patient using a global network, e.g. telephone networks, internet} - A61B 5/0071: {by measuring fluorescence emission} - A61B 5/1495: Calibrating or testing of in-vivo probes - A61B 5/7225: {Details of analogue processing, e.g. isolation amplifier, gain or sensitivity adjustment, filtering, baseline or drift compensation (input circuits for detecting, measuring, or recording bioelectric or biomagnetic signals A61B5/30; specific diagnostic methods using bioelectric or biomagnetic signals A61B5/316)} - H04N 5/04: Synchronising (for television systems using pulse code modulation H04N7/56) - H04N 25/617: for reducing electromagnetic interference, e.g. clocking noise - H04N 25/633: by using optical black pixels - H04N 25/671: for non-uniformity detection or correction - H04N 25/674: based on the scene itself, e.g. defocusing - A61B 1/000095: {for image enhancement} - A61B 5/0077: {Devices for viewing the surface of the body, e.g. camera, magnifying lens} - A61B 5/0261: {using optical means, e.g. infrared light} - A61B 5/20: for measuring urological functions {restricted to the evaluation of the urinary system (A61B5/4375 takes precedence)} - A61B 5/489: {Blood vessels} - A61B 5/4893: {Nerves} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract Fluorescence imaging with reduced fixed pattern noise is disclosed. A method includes actuating an emitter to emit a plurality of pulses of electromagnetic radiation and sensing reflected electromagnetic radiation resulting from the plurality of pulses of electromagnetic radiation with a pixel array of an image sensor. The method includes reducing fixed pattern noise in an exposure frame by subtracting a reference frame from the exposure frame. The method is such that at least a portion of the plurality of pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 795 nm to about 815 nm. ## Claims ### Claim 1 A method comprising: actuating an emitter to emit a plurality of pulses of electromagnetic radiation; sensing reflected electromagnetic radiation resulting from the plurality of pulses of electromagnetic radiation with a pixel array of an image sensor to generate a plurality of exposure frames; generating a reference frame for use in removing fixed pattern noise from the plurality of exposure frames, wherein the reference frame is based on dark frame data captured when the emitter is not emitting electromagnetic radiation; and reducing fixed pattern noise in an exposure frame of the plurality of exposure frames by subtracting the reference frame from the exposure frame; wherein at least a portion of the plurality of pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 795 nm to about 815 nm. ### Claim 2 (depends on 1) The method of claim 1, further comprising: stopping the emitter from pulsing electromagnetic radiation; and sensing the dark frame data with the pixel array when the emitter is not emitting electromagnetic radiation. ### Claim 3 (depends on 1) The method of claim 1, wherein the plurality of pulses of electromagnetic radiation are emitted in a pattern of varying wavelengths of electromagnetic radiation, and wherein the emitter repeats the pattern of varying wavelengths of electromagnetic radiation. ### Claim 4 (depends on 3) The method of claim 3, wherein the pattern of varying wavelengths of electromagnetic radiation comprises a zero-emission period wherein the emitter does not pulse electromagnetic radiation, and wherein the method further comprises sensing the dark frame data with the pixel array during the zero-emission period. ### Claim 5 (depends on 1) The method of claim 1, further comprising sensing a plurality of dark exposure frames with the pixel array when the emitter is not emitting electromagnetic radiation, wherein each of the plurality of dark exposure frames comprises dark frame data. ### Claim 6 (depends on 5) The method of claim 5, wherein the plurality of dark exposure frames are interspersed within the plurality of exposure frames. ### Claim 7 (depends on 5) The method of claim 5, wherein generating the reference frame comprises generating a plurality of reference frames based on the plurality of dark exposure frames, and wherein the method further comprises enhancing precision of at least one reference frame of the plurality of reference frames by sampling subsequent dark frame data from subsequent dark exposure frames. ### Claim 8 (depends on 7) The method of claim 7, wherein enhancing precision of the at least one reference frame comprises accounting for the subsequent dark frame data from the subsequent dark exposure frames using exponential smoothing. ### Claim 9 (depends on 1) The method of claim 1, wherein generating the reference frame comprises interpolating two or more instances of dark frame data from two or more dark exposure frames captured at different integration times. ### Claim 10 (depends on 1) The method of claim 1, wherein sensing the reflected electromagnetic radiation comprises sensing during a readout period of the pixel array, wherein the readout period is a duration of time when active pixels in the pixel array are read. ### Claim 11 (depends on 1) The method of claim 1, wherein actuating the emitter comprises actuating the emitter to emit, during a pulse duration, a plurality of sub-pulses of electromagnetic radiation having a sub-duration shorter than the pulse duration. ### Claim 12 (depends on 1) The method of claim 1, wherein actuating the emitter comprises actuating the emitter to emit two or more wavelengths simultaneously as a single pulse or a single sub-pulse. ### Claim 13 (depends on 1) The method of claim 1, wherein sensing the reflected electromagnetic radiation comprises generating a fluorescence exposure frame, and wherein the method further comprises providing the fluorescence exposure frame to a corresponding system that determines a location of a critical tissue structure within a scene based on the fluorescence exposure frame. ### Claim 14 (depends on 13) The method of claim 13, further comprising: receiving the location of the critical tissue structure from the corresponding system; generating an overlay frame comprising the location of the critical tissue structure; and combining the overlay frame with a color image frame depicting the scene to indicate the location of the critical tissue structure within the scene. ### Claim 15 (depends on 14) The method of claim 14, wherein the critical tissue structure comprises one or more of a nerve, a ureter, a blood vessel, an artery, a blood flow, or a tumor. ### Claim 16 (depends on 1) The method of claim 1, further comprising synchronizing timing of the plurality of pulses of electromagnetic radiation to be emitted during a blanking period of the image sensor, wherein the blanking period corresponds to a time between a readout of a last row of active pixels in the pixel array and a beginning of a next subsequent readout of active pixels in the pixel array. ### Claim 17 (depends on 1) The method of claim 1, wherein sensing the reflected electromagnetic radiation comprises sensing with a first pixel array and a second pixel array such that a three-dimensional image can be generated based on the sensed reflected electromagnetic radiation. ### Claim 18 (depends on 1) The method of claim 1, wherein actuating the emitter comprises actuating the emitter to emit a sequence of pulses of electromagnetic radiation repeatedly sufficient for generating a video stream comprising a plurality of image frames, wherein each image frame in the video stream comprises data from a plurality of exposure frames, and wherein each of the exposure frames corresponds to a pulse of electromagnetic radiation. ### Claim 19 (depends on 1) The method of claim 1, wherein at least a portion of the plurality of pulses of electromagnetic radiation emitted by the emitter is an excitation wavelength for fluorescing a reagent, and wherein at least a portion of the reflected electromagnetic radiation sensed by the pixel array is a relaxation wavelength of the reagent. ### Claim 20 A system comprising: an emitter for emitting a plurality of pulses of electromagnetic radiation; an image sensor comprising a pixel array for sensing reflected electromagnetic radiation to generate a plurality of exposure frames; and one or more processors configurable to execute instructions stored in non-transitory computer readable storage media, the instructions comprising: generating a reference frame for use in removing fixed pattern noise from the plurality of exposure frames, wherein the reference frame is based on dark frame data captured when the emitter is not emitting electromagnetic radiation; and reducing fixed pattern noise in an exposure frame of the plurality of exposure frames by subtracting the reference frame from the exposure frame; wherein at least a portion of the pulses of electromagnetic radiation emitted by the emitter comprises electromagnetic radiation having a wavelength from about 795 nm to about 815 nm. ### Claim 21 (depends on 20) The system of claim 20, wherein the instructions further comprise: stopping the emitter from pulsing electromagnetic radiation; and sensing the dark frame data with the pixel array when the emitter is not emitting electromagnetic radiation. ### Claim 22 (depends on 20) The system of claim 20, wherein the plurality of pulses of electromagnetic radiation are emitted in a pattern of varying wavelengths of electromagnetic radiation, and wherein the emitter repeats the pattern of varying wavelengths of electromagnetic radiation. ### Claim 23 (depends on 22) The system of claim 22, wherein the pattern of varying wavelengths of electromagnetic radiation comprises a zero-emission period wherein the emitter does not pulse electromagnetic radiation, and wherein the method further comprises sensing the dark frame data with the pixel array during the zero-emission period. ### Claim 24 (depends on 20) The system of claim 20, wherein the pixel array senses a plurality of dark exposure frames over a plurality of instances when the emitter is not emitting electromagnetic radiation, wherein each of the plurality of dark exposure frames comprises dark frame data. ### Claim 25 (depends on 24) The system of claim 24, wherein the instructions are such that generating the reference frame comprises generating a plurality of reference frames based on the plurality of dark exposure frames, and wherein the method further comprises enhancing precision of at least one reference frame of the plurality of reference frames by sampling subsequent dark frame data from subsequent dark exposure frames. ### Claim 26 (depends on 20) The system of claim 20, wherein at least a portion of the pulses of electromagnetic radiation emitted by the emitter results in a fluorescence exposure frame created by the image sensor, and wherein the instructions further comprise providing the fluorescence exposure frame to a corresponding system that determines a location of a critical tissue structure within a scene based on the fluorescence exposure frame. ### Claim 27 (depends on 26) The system of claim 26, wherein the instructions further comprise: receiving the location of the critical tissue structure from the corresponding system; generating an overlay frame comprising the location of the critical tissue structure; and combining the overlay frame with a color image frame depicting the scene to indicate the location of the critical tissue structure within the scene. ### Claim 28 (depends on 27) The system of claim 27, wherein the critical tissue structure comprises one or more of a nerve, a ureter, a blood vessel, an artery, a blood flow, or a tumor. ### Claim 29 (depends on 20) The system of claim 20, wherein the image sensor comprises a first image sensor and a second image sensor such that the image sensor can generate a three-dimensional image. ### Claim 30 (depends on 20) The system of claim 20, further comprising a filter that filters electromagnetic radiation having a wavelength from about 795 nm to about 815 nm.