Medical imaging systems and methods
An illustrative system includes an image sensor comprising a first pixel, a second pixel, a third pixel, and a fourth pixel. The system further includes a pixel-level broadband infrared cutoff filter that covers the second pixel and that is configured to prevent the second pixel from collecting infrared light having wavelengths included in a first range of wavelengths. The first, third, and fourth pixels are not covered by pixel-level broadband infrared cutoff filters configured to prevent the first, third, and fourth pixels from collecting infrared light having wavelengths included in the first range of wavelengths.
1. A system comprising:
an image sensor comprising a first pixel, a second pixel, a third pixel, and a fourth pixel; and
a pixel-level broadband infrared cutoff filter that covers the second pixel and that is configured to prevent the second pixel from collecting infrared light having wavelengths included in a first range of wavelengths;
wherein the first, third, and fourth pixels are not covered by pixel-level broadband infrared cutoff filters configured to prevent the first, third, and fourth pixels from collecting infrared light having wavelengths included in the first range of wavelengths; and
wherein the system further comprises a narrowband infrared cutoff filter that covers the first, third, and fourth pixels and that is configured to prevent the first, third, and fourth pixels from collecting infrared light having a wavelength included in a second range of wavelengths, the second range of wavelengths included in and narrower than the first range of wavelengths.
2. The system of claim 1 , wherein the narrowband infrared cutoff filter comprises a glass filter that covers the first, second, third, and fourth pixels.
3. The system of claim 1 , wherein the narrowband infrared cutoff filter comprises:
a first pixel-level narrowband infrared cutoff filter that covers the first pixel;
a second pixel-level narrowband infrared cutoff filter that covers the third pixel; and
a third pixel-level narrowband infrared cutoff filter that covers the fourth pixel.
4. The system of claim 1 , further comprising:
a visible light illumination source configured to illuminate a scene with visible light, the first pixel collecting a first color component of the visible light after the visible light reflects from one or more surfaces in the scene, the second and third pixels each collecting a second color component of the visible light after the visible light reflects from the one or more surfaces in the scene, and the fourth pixel collecting a third color component of the visible light after the visible light reflects from the one or more surfaces in the scene; and
a fluorescence excitation illumination source configured to emit fluorescence excitation illumination that elicits fluorescence illumination by a fluorescence imaging agent.
5. The system of claim 4 , wherein:
the fluorescence excitation illumination has a wavelength included in the second range of wavelengths such that the pixel-level broadband infrared cutoff filter and the narrowband infrared cutoff filter prevent the first, second, third, and fourth pixels from collecting the fluorescence excitation illumination; and
the fluorescence illumination has a wavelength included in the first range of wavelengths but not included in the second range of wavelengths such that the pixel-level broadband infrared cutoff filter prevents the second pixel from collecting the fluorescence illumination while the narrowband infrared cutoff filter allows the first, third, and fourth pixels to collect the fluorescence illumination.
6. The system of claim 5 , further comprising an image processing system configured to:
activate the visible light illumination source and the fluorescence excitation illumination source to concurrently emit the visible light and the fluorescence excitation illumination, and
while the visible light and the fluorescence excitation illumination are concurrently being emitted,
receive a first signal representative of light collected by the first pixel, the first signal comprising data representative of a combination of the first color component and the fluorescence illumination,
receive a second signal representative of light collected by the second pixel, the second signal representative of the second color component,
receive a third signal representative of light collected by the third pixel, the third signal representative of a combination of the second color component and the fluorescence illumination, and
receive a fourth signal representative of light collected by the fourth pixel, the fourth signal representative of a combination of the third color component and the fluorescence illumination.
7. The system of claim 6 , wherein the image processing system is further configured to:
subtract the second signal from the third signal to identify a fluorescence illumination component of the third signal that is representative of the fluorescence illumination;
subtract the fluorescence illumination component from the first signal to generate a processed first signal representative of only the first color component; and
subtract the fluorescence illumination component from the fourth signal to generate a processed fourth signal representative of only the third color component.
8. The system of claim 7 , wherein the image processing system is further configured to:
receive a command to present a full-color image that does not include a fluorescence image, and
in response to the command, generate the full-color image based on the processed first signal, the second signal, and the processed fourth signal.
9. The system of claim 8 , wherein the image processing system is further configured to:
receive a command to present a full-color fluorescence image, and
in response to the command, generate the full-color fluorescence image based on the processed first signal, the second signal, the processed fourth signal, and the fluorescence illumination component.
10. The system of claim 1 , further comprising:
a first color filter that covers the first pixel and that is configured to allow the first pixel to collect a first color component of visible light and prevent the first pixel from collecting second and third color components of the visible light;
a second color filter that covers the second and third pixels, the second color filter configured to allow the second and third pixels to each collect the second color component of the visible light and prevent the second and third pixels from each collecting the first and third color components of the visible light; and
a third color filter that covers the fourth pixel and that is configured to allow the fourth pixel to collect the third color component of the visible light and prevent the fourth pixel from collecting the first and second color components of the visible light.
11. The system of claim 10 , wherein:
the first color filter comprises a red filter configured to prevent the first pixel from collecting blue and green components of the visible light;
the second color filter comprises a blue filter configured to prevent the second and third pixels from each collecting the red and green components of the visible light; and
the third color filter comprises a green filter configured to prevent the fourth pixel from collecting the red and blue components of the visible light.
12. The system of claim 10 , wherein:
the first color filter comprises a red filter configured to prevent the first pixel from collecting blue and green components of the visible light;
the second color filter comprises a green filter configured to prevent the second and third pixels from each collecting the blue and red components of the visible light; and
the third color filter comprises a blue filter configured to prevent the fourth pixel from collecting the green and red components of the visible light.
13. The system of claim 1 , wherein the pixel-level broadband infrared cutoff filter comprises a coating configured to adhere to a surface of the second pixel.
14. The system of claim 1 , wherein the first, second, third, and fourth pixels are arranged in a two-by-two array of pixels.