Endoscopes have attained great acceptance within the medical community since they provide a means for performing procedures with minimal patient trauma while enabling the physician to view the internal anatomy of the patient. Over the years, numerous endoscopes have been developed and categorized according to specific applications, such as, cystoscopy, colonoscopy, laparoscopy, and upper gastrointestinal endoscopy, among others. Endoscopes may be inserted into the body's natural orifices or through an incision in the skin.
An endoscope typically comprises an elongated tubular shaft, rigid or flexible, having a video camera or a fiber optic lens assembly at its distal end. The shaft is connected to a handle which sometimes includes an ocular for direct viewing. Viewing is also usually possible via an external screen. Various surgical tools may be inserted through a working channel in the endoscope for performing different surgical procedures.
Endoscopes, such as colonoscopes and gastroscopes, that are currently being used, typically have at least a front camera for viewing an internal organ, such as, the colon, an illuminator for illuminating the field of view of the camera, a fluid injector for cleaning the camera lens, and a working channel for insertion of surgical tools, for example, tools for removing polyps found in the colon. Commonly used illuminators comprise optical fibers which transmit light, generated remotely, to the endoscope tip section. In more currently developed endoscopes, discrete illuminators such as light-emitting diodes (LEDs) have been incorporated for providing illumination.
Multiple viewing elements endoscopes comprise two or more sets of optical assemblies, each having an optical lens associated with an image sensor and two or more illuminators. Other than flexible electronic boards, separate circuit boards are employed to hold and support the illuminators in a desired position with reference to the associated optical assemblies. The use of additional circuit boards increases the number of components that are required to be fitted into the limited space available in the tip of the endoscope. Since most of the components dissipate some power in the form of heat, use of multiple sets of illuminators, sensors and viewing elements produces a significant amount of heat in the distal tip during an endoscopic procedure. Tip heating not only causes discomfort to the patient, but may also affect performance of some of the electronic components inside the tip. Failure of a component to operate due to too high a temperature is also known. In some cases, the failure is reversible and vanishes as temperature drops again to normal levels, while in others it is irreversible. In particular, under high temperature conditions, LEDs exhibit reduced brightness and a shift in chromaticity towards blue. In general, imagers experience higher noise and a change in image characteristics such as hue, saturation, brightness and contrast at higher temperatures. Hence, there is a need for a method and system to measure and regulate the temperature of the distal tip. Existing methods of measuring the temperature at the distal tip involve the use of a dedicated sensor and wiring, which occupy valuable space and add to the crowding of components inside the tip.
Therefore, there is a need for methods and devices for measuring the temperature of a distal tip which can advantageously use existing components located within the tip of a multiple viewing elements endoscope. Such a method should provide for dynamic measurement of temperature, so that the temperature may be adjusted by reducing the power of suitable components, thus avoiding overheating.
Conventional multiple viewing elements endoscopes typically comprise multiple sets of illuminators that are operated in a very sub-optimal manner. A multiple sensor or multiple viewing elements endoscope tip section comprising a front-pointing camera and two or more side-pointing cameras positioned at or in proximity to a distal end of the tip section and a working channel configured for insertion of a surgical tool is disclosed in U.S. patent application Ser. No. 13/655,120, entitled “Multi-Camera Endoscope” and filed on Oct. 18, 2012, assigned to the Applicant of the present specification and herein incorporated by reference in its entirety. As described in the '120 application, the field of view (FOV) of each camera sensor in a multiple sensor endoscope is illuminated by two or more illuminators that are light emitting diodes (LEDs). Thus, multiple sensor endoscopes' tips that include a right pointing camera or viewing element, a front pointing camera or viewing element and a left pointing camera or viewing element may include a minimum of six or more LEDs. In some embodiments, each viewing element comprises three illuminators, totaling nine LEDs. Similarly, multiple sensor endoscope tip sections that include a front pointing camera or viewing element and a side pointing camera or viewing element may include four, five or more LEDs.
Since the depth corresponding to the field of view of a camera can vary significantly depending on the orientation of distal tip during a colonoscopy procedure (for example, when navigated through a patient's colon), illuminating all LEDs with a fixed illumination intensity is sub-optimal. Fixed illumination intensity may prove to be too weak in some orientations for example and may drive the camera sensor arrays beyond their dazzle limits due to light reflection from a nearby wall in other orientations. In some cases, when driven beyond their dazzle limits, camera sensor arrays such as Charge-Coupled Devices (CCDs) may create saturation and blooming that may appear as a white streak or blob in the generated images.
Further, keeping all LEDs illuminated at a constant intensity for long periods of time may result in production of excessive heat at the tip section of the endoscope. High temperature may adversely affect tissues during an endoscopic procedure. FIG. 1 shows a table 100 illustrating a quantitative relationship between temperature and thermal impact on porcine skin as published in “Studies of Thermal Injury: II. The Relative Importance of Time and Surface Temperature in the Causation of Cutaneous Burns”, The American Journal of Pathology 23.5 (1947): 695 by Moritz, A. Re, and F. C. Henriques Jr. The table 100 provides sub-threshold exposures 105 as well as threshold and supra-threshold exposures 110 related to an increasing temperature 115 and time of exposure 120. It is evident that severity of thermal injury to tissues increases with an increase in temperature and time of exposure.
One approach for controlling the illumination of a multiple illuminator endoscope system may be provided by dynamically controlling the emitted light or luminance intensities. It is further desirable to regulate the illumination of the multiple illuminators automatically in response to the usage of the endoscope tip section.
Therefore, there is a need for systems and methods for automatically detecting the activity level corresponding to the tip section of an endoscope and responsively regulating the luminance intensity level of each illuminator associated with the tip section.
As such, it would also be highly advantageous to provide a method of automatically detecting if the endoscope tip section is stationary or in motion and responsively regulating the luminance intensity level of each illuminator independently.