Method and apparatus for adaptive leakage reduction of capsule endoscope processor

Abstract

The invention relates to a method and device for adaptive leakage reduction of a capsule endoscope processor. Methods and devices for imaging the gastrointestinal tract using a capsule endoscope are provided. According to the method, at least two operating states during a gastrointestinal tract examination using a capsule endoscope are determined, where the at least two operating states comprise a first operating state and a second operating state, and the capsule endoscope comprises one or more capsule processors equipped with reverse bias control. In response to the current operating state being the first operating state or the second operating state, a current body bias of the one or more capsule processors is set to a first body bias or a second body bias, respectively, where the first body bias is different from the second body bias. One or more images are captured using the current body bias of the one or more capsule processors.

Description

[0001] Cross - reference to related applications

[0002] This invention relates to U.S. Patent No. 7,495,993, issued on February 24, 2009. The entire disclosure of this U.S. patent is hereby incorporated by reference in its entirety. Technical field

[0003] This invention relates to a method and apparatus for obtaining images of the gastrointestinal tract within the body. Specifically, this invention relates to a technique for extending the lifespan of a capsule endoscope without compromising its performance. Background art

[0004] Devices for imaging body cavities or passageways within the body are known in the art, including endoscopes and self - contained encapsulated cameras. An endoscope is a flexible or rigid tube that enters the body through an orifice or surgical opening, typically through the mouth into the esophagus or through the rectum into the colon. An image is formed at the distal end using lenses and transmitted to the proximal end outside the body through a lens relay system or a coherent fiber optic bundle. Conceptually similar instruments may record images electronically at the distal end, for example, using a CCD or CMOS array, and transmit the image data as an electrical signal through a cable to the proximal end. Endoscopes allow a doctor to control the field of view and are widely accepted diagnostic tools. However, they do have many limitations, pose risks to patients, are invasive and uncomfortable for patients, and their cost limits their use as a routine health screening tool.

[0005] Due to the difficulty of passing through complex passageways, endoscopes cannot easily reach most of the small intestine and require special techniques and precautions to reach the entire colon, which increases costs. Endoscope risks include the possibility of perforating the body organs through which they pass and complications associated with anesthesia. In addition, a trade - off must be made between the pain of the patient during the procedure and the health risks associated with anesthesia and the post - operative downtime.

[0006] Another type of in - body image sensor that addresses these problems is the capsule endoscope. A camera is mounted in a swallowable capsule together with a radio transmitter for transmitting data (mainly including images recorded by a digital camera) to a base - station receiver or transceiver and data recorder outside the body. The capsule may also include a radio receiver for receiving instructions or other data from a base - station transmitter. Lower - frequency electromagnetic signals may be used instead of radio - frequency transmission. The capsule can be powered inductively from an external inductor to an internal inductor within the capsule or from a battery within the capsule.

[0007] U.S. Patent No. 7,983,458, issued on July 19, 2011, discloses an autonomous capsule camera system with on-board data storage, titled "In Vivo Autonomous Camera with On-Board Data Storage or Digital Wireless Transmission in Regulatory Approved Band". This patent describes a capsule system that uses on-board memory (such as a semiconductor non-volatile archival memory) to store captured images. After the capsule leaves the body, it is retrieved. The capsule housing is opened, and the stored images are transferred to a computer workstation for storage and analysis. For capsule images received via wireless transmission or retrieved from on-board memory, the images must be displayed and examined by a diagnostic physician to identify potential abnormalities.

[0008] Figure 1 An exemplary capsule system with on-board storage is shown. The capsule device 110 includes an illumination system 12 and a camera including an optical system 14 and an image sensor 16. A semiconductor non-volatile archival memory 20 can be provided to allow storage of images and retrieval of the images at a docking station outside the body after capsule recovery. The capsule device 110 includes a battery power source 24 and an output port 26. The capsule device 110 can be propelled through the gastrointestinal (GI) tract by peristalsis.

[0009] The illumination system 12 can be implemented by LEDs. In Figure 1 it, the LEDs are located near the camera aperture, but other configurations are possible. The light source can also be set behind the aperture. Other light sources, such as laser diodes, can also be used. Alternatively, a white light source or a combination of two or more narrow wavelength band light sources can be used. Available white light LEDs can include blue LEDs or violet LEDs, as well as phosphorescent materials that are excited by the LED light to emit light of longer wavelengths. The portion of the capsule housing 10 that allows light to pass through can be made of biocompatible glass or polymer.

[0010] The optical system 14 may include a plurality of refractive, diffractive, or reflective lens elements that provide an image of the cavity wall (100) on the image sensor 16. The image sensor 16 may be provided by a charge-coupled device (CCD) or a complementary metal-oxide semiconductor (CMOS)-type device that converts the received light intensity into a corresponding electrical signal. The image sensor 16 may have a monochromatic response or include a color filter array so that a color image (e.g., using RGB or CYM representation) can be captured. The analog signal from the image sensor 16 is preferably converted into digital form for processing in digital form. This conversion can be achieved using an analog-to-digital (A / D) converter, which can be provided inside the sensor (as is currently the case) or in another part within the capsule housing 10. The A / D unit can be provided between the image sensor 16 and the rest of the system. The LEDs in the illumination system 12 are synchronized with the operation of the image sensor 16. The processing module 22 can be used to provide the processing required by the system, such as image processing and video compression. The processing module can also provide the required system control, such as controlling the LEDs during an image capture operation. The processing module can also be responsible for other functions, such as managing image capture and coordinating image retrieval. Although Figure 1 a capsule endoscope having an archival memory to store the captured images is shown, the capsule endoscope can also be equipped with a wireless transmitter to transmit the captured images to an external receiver.

[0011] After the capsule camera passes through the gastrointestinal tract and exits the body, the capsule camera is retrieved, and the images stored in the archival memory are read out through an output port. The received images are typically transmitted to a base station for processing and examination by a diagnostician. The accuracy and efficiency of the diagnosis are of utmost importance. The diagnostician needs to examine the images and correctly identify any abnormalities.

[0012] The capsule device includes one or more processors for performing various tasks as needed, such as controlling illumination, capturing images, storing or transmitting images, etc. In sync with Moore's law, in each new generation of semiconductor processes, the device feature size becomes smaller and the operating voltage of the integrated circuit also becomes lower. With the miniaturization of transistors, lower voltages for the punch through effect, hot electrons, and oxide reliability of the processing device also emerge. Since CV = Q (C: capacitance, V: voltage, Q: charge), the charging and discharging of the capacitance require less current, so it also has a very significant advantage in reducing power consumption. Therefore, if V is lower, Q will be lower, and less current is required. On the other hand, the total energy, which is important in greenhouse effects (e.g., data centers, search engine operations, and the recent ChatGPT) or battery-powered systems, further depends on the operating voltage (energy = QV = CV 2 ). In addition, the heat generated will first affect the performance of the integrated circuit.

[0013] However, a competing factor is emerging quietly and needs to be seriously considered. Take the inverter as an example, and its transfer curve is as Figure 2 shown. To make it an effective switch, there must be a high-gain region in the transfer curve where both P-channel and N-channel transistors are turned on, which in turn means that the operating voltage must be higher than |VTN| + |VTP|, where VTN and VTP are the threshold voltages of the n-channel and p-channel transistors respectively. As the operating voltage decreases, the threshold voltage of the transistor will necessarily decrease. The transistor subthreshold current is an exponential function inversely proportional to the threshold voltage and is measured in decades per 100 mv. As the threshold voltage continues to decrease, the leakage current begins to become an important factor in current consumption compared to the operating current. Since the operating current continues to decrease according to Moore's law while the leakage current continues to increase as the size shrinks.

[0014] Therefore, methods need to be developed to reduce the leakage current without significantly affecting the performance of the device. SUMMARY OF THE INVENTION

[0015] Methods and devices for imaging the gastrointestinal tract using a capsule endoscope are disclosed herein. According to the method, at least two operating states during a gastrointestinal examination using a capsule endoscope are determined, where the at least two operating states include a first operating state and a second operating state, and the capsule endoscope includes one or more capsule processors equipped with back-bias control. In response to the current operating state being the first operating state or the second operating state, the current body bias of the one or more capsule processors is correspondingly set to a first body bias or a second body bias, where the first body bias is different from the second body bias. One or more images are captured using the current body bias of the one or more capsule processors.

[0016] In one example, the first operating state corresponds to the capsule endoscope being in or before reaching the esophagus, and the second operating state corresponds to the capsule endoscope being in a portion of the human gastrointestinal tract away from the esophagus. In one example, during an initial time period after the capsule endoscope is turned on, the capsule endoscope is set to the first operating state. In one example, the initial time period is less than 2 minutes. In one example, after the capsule endoscope is detected in the body, the capsule endoscope is set to the first operating state. In one example, the capsule endoscope is set to the first operating state within 2 minutes after it is detected in the body. In one example, the first body bias has more forward reverse bias or less reverse reverse bias than the second body bias. In another example, after the capsule endoscope is detected to enter the human body, the capsule endoscope enters the first state. There are many ways to detect the capsule endoscope entering the human body. For example, the detection can be based on image sensor pixel values, such as pixel values that become smaller. Before entering the first state, the reverse bias is set to be less forward or more reverse relative to the first state.

[0017] In one example, the first operating state corresponds to fast frame rate operation and the second operating state corresponds to normal frame rate operation. In one example, the first body bias has more forward reverse bias or less reverse reverse bias than the second body bias.

[0018] In one example, the first operating state corresponds to high definition operation, while the second operating state corresponds to normal definition operation. In one example, the first body bias has more forward reverse bias or less reverse reverse bias than the second body bias. Description of the Drawings

[0019] Figure 1 An example of a capsule endoscope having one or more capsule processors is shown.

[0020] Figure 2 An example of an inverter transfer curve is shown.

[0021] Figure 3 An example of a fully depleted silicon on insulator (FD - SOI) transistor is shown, where the device includes an ultra - thin buried oxide layer.

[0022] Figure 4A An example of the device structure of forward body bias (FBB) is shown

[0023] Figure 4B An example of the device structure of reverse body bias (RBB) is shown.

[0024] Figure 5An exemplary flowchart of capturing in-vivo images using a capsule endoscope with reverse bias control according to an embodiment of the present invention is shown. Detailed Description

[0025] It is readily understood that the components of the present invention, as generally described and illustrated herein, can be arranged and designed in a variety of different configurations. Accordingly, the following more detailed description of embodiments of the systems and methods of the present invention, as shown in the accompanying drawings, is not intended to limit the scope of the present invention (as claimed), but merely represents selected embodiments of the present invention. References in this specification to "one embodiment," "an embodiment," or similar language mean that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0026] Furthermore, the features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. However, those skilled in the relevant art will recognize that the present invention can be practiced without one or more of the specific details, or with other methods, components, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the present invention. The illustrated embodiments of the present invention will be best understood by reference to the drawings, wherein like parts are always designated by like numerals. The following description is only by way of example and only illustrates certain selected embodiments of the devices and methods consistent with the present invention as claimed herein.

[0027] In the field of semiconductor technology, various leakage current control schemes have been developed. An example of the device structure of transistors below 30 nm is the fully depleted silicon-on-insulator (FD-SOI) transistor. Figure 3 An example of an FD-SOI transistor is shown, where the device includes an ultra-thin buried oxide layer. The buried oxide layer reduces the parasitic capacitance between the source and the drain. It also effectively limits the electrons flowing from the source to the drain, greatly reducing the leakage current that causes performance degradation. A body bias contact 310 is provided to apply a bias voltage. Body bias is commonly referred to as back bias in the semiconductor field. Thus, in this disclosure, body bias and back bias can be used interchangeably.

[0028] Figure 4A An example of the device structure of forward body bias (FBB) is shown, Figure 4BAn example of a device structure with reverse body bias (RBB) is shown. Other device structures are also used below 20 - 30 nm. When the body effect biases more forward, the source-drain conduction current of the transistor will increase, which will increase the speed and performance bandwidth. For FBB, its leakage current will also increase, which is current dissipation, but it will not increase the speed or performance bandwidth. When the body effect biases in the opposite direction (i.e., RBB), the source-drain conduction current of the transistor will decrease, but the speed and performance bandwidth will also decrease, and at the same time its leakage current will decrease.

[0029] Therefore, using body bias control can provide dynamic leakage current reduction and performance control. Therefore, according to the performance requirements, an appropriate bias voltage can be applied to achieve the desired performance and leakage current reduction.

[0030] For capsule endoscopy surgery, since the transit time of the esophagus is faster than the rest of the gastrointestinal tract, the esophagus requires a higher bandwidth. To increase the speed and bandwidth, integrated circuits have the advantage of handling fast frame rates, which can be achieved by increasing the forward back bias (or reducing the reverse bias), but at the cost of increased leakage current. However, the transit time of the esophagus is usually less than 1 minute, while the transit time of the rest of the gastrointestinal tract takes several hours. The total energy (i.e., power × duration) dissipation caused by leakage current during the esophagus transit time can be negligible. During the remaining transit time of the gastrointestinal tract, we can use less forward (or more reverse) back bias to reduce the leakage current for the very long transit time with a much lower frame rate requirement.

[0031] Sometimes, it may be necessary to examine the stomach at a fast frame rate within a limited time. Therefore, more forward bias (or less reverse bias) can be applied during the stomach examination, and less forward back bias (or more reverse back bias) can be adopted afterwards. In another embodiment, when the capsule system detects fast movement in the rest of the gastrointestinal tract, more forward back bias can be applied until the detected fast movement ends, and then less forward back bias (or more reverse back bias) can be adopted.

[0032] In one embodiment, when the capsule transportation is at the substantial start stage of the in-vivo duration (e.g., the first 1 or 2 minutes), more forward reverse bias is applied, and after this time period, less reverse reverse bias or no reverse reverse bias is applied. In another embodiment, when the capsule transportation is at the substantial start stage of the in-vivo duration (e.g., the first 1 or 2 minutes), no or less reverse reverse bias is applied, and during the duration after this time period, more reverse reverse bias is applied.

[0033] In one embodiment, when fast frame rate or high-definition image capture is required (both of which require high bandwidth performance), more forward reverse bias is applied. When the bandwidth requirement is low, less forward reverse bias is applied or no forward reverse bias is applied. In another embodiment, when fast frame rate or high definition (both of which require high bandwidth performance) is required, no reverse bias is applied or less reverse reverse bias is applied, while when the bandwidth requirement is low, more reverse reverse bias is applied.

[0034] In one embodiment, when fast frame rate or high-definition image capture is required (both of which require high bandwidth performance), more forward reverse bias is applied. When the bandwidth requirement is low, less forward reverse bias is applied, or no forward reverse bias is applied, or even reverse reverse bias is applied. In another embodiment, when fast frame rate or high-definition image capture is required (both of which require high bandwidth performance), forward bias is applied, or no reverse bias is applied, or less reverse reverse bias is applied. When the bandwidth requirement is low, more reverse reverse bias is applied.

[0035] The capsule endoscope can also be configured to have a low frame rate. This state will be useful when it is not necessary to capture images at a normal or conventional frame rate (e.g., 2-5 frames per second). For example, occasionally the capsule endoscope may get stuck in the gastrointestinal tract and there is no or very little movement for a period of time. Therefore, a low frame rate may help to extend the battery life of the capsule endoscope. Compared with the state corresponding to the conventional frame rate, a low frame rate can be achieved by reducing the leakage current through more reverse reverse bias.

[0036] During the process of gastrointestinal imaging by the capsule endoscope, the capsule endoscope works at a conventional frame rate most of the time. The conventional state can be achieved by setting the reverse bias to the default level. If a faster frame rate is needed, the reverse bias can be set to more forward reverse bias or less reverse reverse bias (if reverse reverse bias has been used in the conventional state). If a slower frame rate is needed, the reverse bias can be set to more reverse reverse bias or less forward reverse bias (if forward reverse bias has been used in the conventional state).

[0037] In the above disclosure, the preferred embodiment depends on the one or more capsule processors within the capsule endoscope through a control scheme. Control decisions can be implemented based on the one or more processors. However, control decisions can also be made outside the capsule endoscope. For example, in the case where the capsule endoscope includes a wireless transmitter (e.g., a transmitter using RF (radio frequency) signals) to transmit the captured images to a wireless receiver outside the human body. In this case, control decisions can be made based on the images received using a computer, a workstation, or any device with sufficient computing power. The control decisions can be wirelessly sent to the capsule endoscope to adjust the reverse bias accordingly.

[0038] The above-described external control scheme can be implemented using various programmable devices, such as a microcontroller, a central processing unit (CPU), a field-programmable gate array (FPGA), a digital signal processor (DSP), or any programmable processor with or without firmware or software. The external scheme can have AI to detect different anatomical structures (such as the stomach) and wirelessly send commands to the capsule to adjust the reverse bias accordingly.

[0039] Figure 5 An exemplary flowchart of capturing in-vivo images using a capsule endoscope with reverse bias control according to an embodiment of the present invention is shown. According to the method, in step 510, at least two operating states during a gastrointestinal examination using the capsule endoscope are determined, where the at least two operating states include a first operating state and a second operating state, and the capsule endoscope includes one or more capsule processors equipped with reverse bias control. In response to the current operating state being the first operating state or the second operating state, in step 520, the current body bias of the one or more capsule processors is correspondingly set to a first body bias or a second body bias, where the first body bias is different from the second body bias. In step 530, one or more images are captured using the current body bias of the one or more capsule processors.

[0040] The above description is to enable a person of ordinary skill in the art to practice the present invention in the context of a particular application and its requirements. Those skilled in the art will clearly make various modifications to the embodiments, and the general principles defined herein can be applied to other embodiments. Therefore, the present invention is not limited to the specific embodiments shown and described, but should be given the widest scope consistent with the principles and novel features disclosed herein. In the above detailed description, various specific details are set forth in order to provide a thorough understanding of the present invention. However, those skilled in the art will understand that the present invention can be practiced.

[0041] The present invention can be implemented in other specific forms without departing from its spirit or essential characteristics. The examples should be considered illustrative in all respects and not restrictive. Therefore, the scope of the present invention is indicated by the appended claims rather than the foregoing description. All changes that come within the meaning and range of equivalence of the claims should be embraced within their scope.

Claims

1. A method for imaging the gastrointestinal tract using a capsule endoscope, characterized in that: include: determining at least two operating states during a gastrointestinal examination using the capsule endoscope, wherein the at least two operating states include a first operating state and a second operating state, the capsule endoscope comprising one or more capsule processors equipped with a reverse bias control; In response to the current operating state being the first operating state or the second operating state, correspondingly setting the current body bias of the one or more capsule processors to the first body bias or the second body bias, wherein the first body bias is different from the second body bias; and One or more images are captured using the current body bias of the one or more capsule processors.

2. The method according to claim 1, characterized in that The first operation state corresponds to the capsule endoscope being in the esophagus or before reaching the esophagus, and the second operation state corresponds to the capsule endoscope being in a portion of the human gastrointestinal tract far from the esophagus.

3. The method according to claim 2, characterized in that In an initial time period after the capsule endoscope is turned on, the capsule endoscope is set to the first operating state.

4. The method according to claim 3, characterized in that This initial time period is less than 2 minutes.

5. The method according to claim 2, characterized in that After the capsule endoscope is detected in the body, the capsule endoscope is set to the first operating state.

6. The method according to claim 5, characterized in that Within 2 minutes after the capsule endoscope is detected in the body, the capsule endoscope is set to the first operation state.

7. The method according to claim 1, characterized in that The first body bias is more forward reverse biased or less reverse reverse biased than the second body bias.

8. The method according to claim 1, characterized in that The first operating state corresponds to fast frame rate operation and the second operating state corresponds to normal frame rate operation.

9. The method according to claim 8, characterized in that The first body bias is more forward reverse biased or less reverse reverse biased than the second body bias.

10. The method according to claim 1, characterized in that The first operating state corresponds to high definition operation and the second operating state corresponds to normal definition operation.

11. The method according to claim 10, characterized in that The first body bias is more forward reverse biased or less reverse reverse biased than the second body bias.

12. A non-transitory computer-readable medium, characterized in that A computer readable code executable by a processor is stored thereon to cause the processor to perform the following operations: determining at least two operating states during a gastrointestinal examination using a capsule endoscope, wherein the at least two operating states include a first operating state and a second operating state, and the capsule endoscope includes one or more capsule processors equipped with a reverse bias control; In response to the current operating state being the first operating state or the second operating state, correspondingly setting the current body bias of the one or more capsule processors to the first body bias or the second body bias, wherein the first body bias is different from the second body bias; and One or more images are captured using the current body bias of the one or more capsule processors.

13. A capsule endoscope for capturing in vivo images, characterized in that: include: An image sensor for capturing images; A light source, used to provide illumination for the image sensor; one or more capsule processors equipped with back-bias control; a battery for providing power to the image sensor, the light source, and the one or more capsule processors; as well as a capsule housing suitable for swallowing, wherein the image sensor, the light source, the one or more capsule processors and the battery are encapsulated in the capsule housing; Wherein, the image sensor, the light source and the one or more capsule processors are configured as: Determining at least two operating states during a gastrointestinal examination using the capsule endoscope, wherein the at least two operating states include a first operating state and a second operating state; In response to the current operating state being the first operating state or the second operating state, correspondingly setting the current body bias of the one or more capsule processors to the first body bias or the second body bias, wherein the first body bias is different from the second body bias; and One or more images are captured using the current body bias of the one or more capsule processors.

Images