Systems and methods for medical imaging using a rolling shutter imager
A system includes an illumination source and an imaging apparatus that includes an electronic rolling shutter imager and is configured for sequentially resetting rows of pixels of the rolling shutter imager from a first row to a last row, sequentially reading charge accumulated at the rows of pixels from the first row to the last row, wherein the first row is read after resetting the last row, controlling the illumination source to illuminate the tissue of the subject with illumination light for an illumination period that lasts longer than a vertical blanking period, wherein the vertical blanking period is the period from the resetting of the last row to the reading of the first row, and generating an image frame from the readings of charge accumulated at the rows of pixels, wherein at least one reading of charge accumulated at a row of pixels is removed or replaced.
1. A system for imaging tissue of a subject, the system comprising: an illumination source;
and an imaging apparatus that comprises an electronic rolling shutter imager, the imaging apparatus being configured for: sequentially resetting rows of pixels of the rolling shutter imager from a first row to a last row, sequentially reading charge accumulated at the rows of pixels from the first row to the last row, wherein the first row is read after resetting the last row, controlling the illumination source to illuminate the tissue of the subject for an illumination period that lasts longer than a vertical blanking period, wherein the vertical blanking period is the period from the resetting of the last row to the reading of the first row, and wherein the illumination period ends at or after an end of the vertical blanking period, and generating an image frame from the readings of charge accumulated at the rows of pixels, wherein at least one reading of charge accumulated at a row of pixels is removed or replaced to generate the image frame.
2. The system of claim 1 , wherein the imaging apparatus comprises a camera control unit connected to an imaging head that includes the rolling shutter imager.
3. The system of claim 1 , wherein the illumination source is configured for pulse width modulated illumination and the camera control unit generates a pulse width modulation waveform for controlling the illumination source.
4. The system of claim 1 , wherein the illumination period begins prior to the resetting of the last row.
5. The system of claim 1 , wherein the illumination period ends after the reading of the first row.
6. The system of claim 1 , wherein the illumination period begins at least when the vertical blanking period begins.
7. The system of claim 1 , wherein at least a reading of charge accumulated at the first row of pixels is removed or replaced to generate the image frame.
8. The system of claim 1 , wherein at least a reading of charge accumulated at the last row of pixels is removed or replaced to generate the image frame.
9. The system of claim 1 , wherein the at least one reading of charge accumulated at a row of pixels is replaced by at least one predetermined value to generate the image frame.
10. The system of claim 1 , wherein at least one reading of charge accumulated at a row of pixels is removed by cropping to generate the image frame.
11. The system of claim 1 , wherein the imaging apparatus is configured for controlling the illumination source to illuminate the tissue of the subject with fluorescence excitation light at least during a subsequent vertical blanking period and generating a fluorescence image frame based on light emitted from the tissue of the subject in response to the fluorescence excitation light.
12. The system of claim 11 , wherein the imaging apparatus is configured for imaging a fluorescence imaging agent present in the tissue of the subject.
13. The system of claim 11 , wherein the imaging apparatus is configured for controlling the illumination source to illuminate the tissue of the subject with fluorescence excitation light and visible illumination light simultaneously during the illumination period.
14. The system of claim 1 , wherein controlling the illumination source to illuminate the tissue of the subject with illumination light comprises controlling the illumination source to pulse the illumination light.
15. The system of claim 14 , wherein the imaging apparatus is configured for controlling a pulse width of the pulsed illumination light based on readings of charge accumulated at the rows of pixels during a previous frame.
16. The system of claim 1 , wherein the illumination light is generated by at least one LED.
17. The system of claim 1 , wherein the imaging apparatus is an endoscopic imager.
18. The system of claim 1 , wherein the rolling shutter imager comprises a mechanical shutter and the mechanical shutter remains at least partially open from before the illumination period begins until after the illumination period ends.
19. The system of claim 18 , wherein the imaging apparatus is configured for reducing an amount of light received at the rolling shutter imager by operating the mechanical shutter.
20. The system of claim 1 , wherein the imaging apparatus is configured for adjusting a gain of the rolling shutter imager based on readings of charge accumulated at the rows of pixels during a previous frame.