AU2008202329B2 - A Device and System for In Vivo Imaging - Google Patents

Description

Pool Section 29 Reguladon 3.2(2) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: A Device and System for In Vivo Imaging The following statement is a full description of this invention, including the best method of performing it known to us: P111AHAU/1107 A DEVICE AND SYSTEM FOR [N VIVO IMAGING FIELD OF THE INVENTION The present invention relates to an in vivo imaging device and system such as for imaging the digestive tract. BACKGROUND OF THE INVENTION Among known in vivo measuring systems are endoscopes, which are often utilized to provide images of the upper or lower gastro-intestinal tract. However, endoscopes do not provide views of the entire length of the small intestines. Additionally: they are uncomfortable, may cause damage to the patient and are complex to operate. Swallowable electronic capsules which are moved through the digestive traci through the action of digestion and which collect data and transmit the data to a receive system are known, one such example is the "Heidelberg" capsule. Yet another example is a capsule disclosed in US 5,604,531. These capsules may be utilized to measure pH. temperature and pressure throughout the intestines.

2 SUMMARY OF THE INVENTION The device and system embodying the present invention enable obtaining in-vivo images from within body lumens or cavities, such as images of the entire length of the gastrointestinal (GI) tract. The device and system contain an 5 imaging system that includes a complementary metal oxide semiconductor (CMOS) imaging camera. The device preferably also contains an ultra low power radio frequency (RF) transmitter for transmitting signals from the CMOS imaging camera to a receiving system. The CMOS imaging camera is preferably an ultra low power imager, may 10 have low sensitivity to the red spectrum and may be provided in chip scale packaging (CSP). The transmitter is preferably an ultra low power RF transmitter with high bandwidth input, possibly provided in chip scale packaging. The high integration and low power consumption achieved by the imaging system of the device and system embodying the invention were unobtainable 15 prior to the advances in CMOS technology. Further, the imaging system may advantageously utilize a white light emitting diode (LED) as a light source rather than a reddish incandescence miniature bulb or an RGB LED. The white LED enables to produce a higher quality and more pleasant to the eye image. 20 In one aspect, the present invention provides an optical unit for use in a swallowable capsule for imaging the gastrointestinal tract, the optical unit including: a dome shaped optical window; an optical system located behind the optical window; 25 a CMOS imaging camera located behind the optical system; and a plurality of light emitting diodes configured in a ring around the optical system to provide illumination. Preferably the optical system and the light emitting diodes are on substantially the same plane. In preferred embodiments the CMOS imaging 30 camera is located behind the optical system relative to the optical window. Advantageously, the optical system is arranged to focus an image on the CMOS imaging camera.

3 In preferred embodiments, the optical system includes a lens, and the light emitting diodes may be white LEDs. In another aspect, the invention provides a swallowable capsule for imaging the gastrointestinal tract, the capsule including: 5 a housing, the housing including a dome shaped optical window, the housing enclosing at least: an optical system located behind said optical window for focusing images onto a CMOS imaging camera; said CMOS imaging camera located behind the optical system; and 10 a plurality of light emitting diodes arranged around the CMOS imaging camera. In yet another aspect, the invention provides a swallowable capsule for in-vivo imaging of the gastrointestinal tract, said capsule including: a housing, said housing including at least a dome shaped optical window 15 portion disposed along a longitudinal axis of said capsule, said dome shaped optical window portion being part of the external surface of said housing, said housing enclosing at least: at least one CMOS imaging camera; at least two white LEDs for illuminating said gastrointestinal tract site only 20 through said optical window; an optical system including at least one lens for collecting light from said gastrointestinal tract site through said optical window onto said CMOS imaging camera for imaging said gastrointestinal tract site onto said CMOS imaging camera, said optical system being separated from said dome shaped optical 25 window portion, which is not part of said optical system, by a gap, the at least two white LEDs positioned in the vicinity of said optical system and not on the longitudinal axis of said optical system so that the at least two white LEDs illuminate said gastrointestinal tract site directly through said optical window and not through said optical system, and said CMOS imaging camera imaging said 30 gastrointestinal tract site via said optical window and via said optical system; and a transmitter for transmitting the signal of the CMOS imaging camera to a receiving system.

4 "Comprises/comprising" when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof. 5 5 This page has been intentionally left blank BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description taken in conjunction with the drawings in which: Figure 1 is a schematic longitudinal cross section illustration of an in vivo imaging device according to an embodiment of the invention; Figure 2 is a schematic presentation of the CMOS imaging camera according to an embodiment of the invention; Figure 3 is a cross section schematic illustration of a device, in accordance with an embodiment of the invention, including a-specific integrated illumination source; Figure 4 is a block diagram of the transmitter in accordance with an embodiment of the invention; and Figure 5 is a block diagram presentation of the method according to an embodiment of the invention. DETAILED DESCRIPTION OF THE INVENTION The device and system of the invention are utilized for viewing inside body lumens and cavities and for transmitting at least video data. Reference is now made to Fig.1which illustrates the device and its components. according to an embodiment of the invention. The device 10 typically comprises an optica window 21 and an imaging system for obtaining images from inside a body lumen, such a the GI tract. The imaging system includes an illumination source 23, such as a white LED a CMOS imaging camera 24, which detects the images and an optical system 22 whicl focuses the images onto the CMOS imaging camera 24. The illumination source 2 illuminates the inner portions of the body lumen through optical window 21. Device 1 6 further includes a transmitter 26 and an antenna 27 for transmitting the video signal of the CMOS imaging camera 24, and a power source 25, such as a silver oxide battery, that provides power to the electrical elements of the device 10. It will be appreciated that a plurality of CMOS imaging cameras may be used in the device and system of the invention. Each CMOS imaging camera may include its own optical system and either one or more illumination sources, in accordance with specific requirements of the device or system. Images obtained by the CMOS camera 24 are transmitted to a receiving system (not shown), which may also include a data processing unit. The receiving system and data processing unit are typically located outside a patient. The device 10 is capsule shaped, can be easily swallowed and may passively pass through the entire GI tract, pushed along by natural peristalsis. Nonetheless, it should be appreciated that the device may be of any shape suitable for being inserted into and passing through a body lumen or cavity. Furthermore, the device of the invention may be attached or affixed on to an instrument that is inserted into bod3 lumens and cavities, such as on an endoscope, laparoscope, stent, needle, catheter etc. Thus, the device may be introduced into a body lumen or cavity by swallowing by using an endoscopic device, by surgery and so on. A suitable CMOS imaging camera 24 is, for example, a "camera on a chip" typt CMOS imager specified by Given Imaging Ltd. of Yokneam, Israel and designed b: Photobit Corporation of California, USA, with integrated active pixel and post processing circuitry (as will be further described with reference to Fig. 2). The single chip camera cai provide either black and white or color signals. 7 The CMOS imaging camera 24 is designed such that it is less sensitive to light in the red spectrum than known CMOS cameras. The optical system 22 comprises at least one lens and optionally mirrors and/or prisms for collecting and collimating remitted light on to the pixels of the CMOS imaging camera 24. Typically, the optical system comprises an aspherical focussing lens. A suitable lens is, for example, the lens designed by Given Imaging Ltd. of Yokneam, Israel, in accordance with specific object plane, distortion and resolution parameters. Illumination source 23, transmits illumination to the walls of the body lumen via the optical window 21. The lens of the optical system 22 then focuses remittent light onto the pixels of the CMOS imaging c-mefa 24. A single or plurality of light sources or a specific integrated light source may be used and positioned in accordance with specific imaging requirements, such as to avoid stray light etc. Also, the optical window 21 may be positioned and shaped according to the device shape and according to specific imaging requirements. For example, optimized imaging conditions can be obtained when optical window 21 is formed to define ar ellipsoid shaped dome and the CMOS imaging chip camera system 24 and illuminatior sources 23 are positioned in the proximity of the focal plane of the shape defined by the optical dome. Obtaining the above imaging conditions is described in WO 00/76391, whicl is assigned to the common assignees of the present invention and which is hereb3 incorporated in its entirety by reference. The in vivo sites imaged in the present invention are usually very close to th< imager. For example, an II x 30mm capsule passing through and imaging the smal intestine, images the intestine walls from a very short distance. It is therefore possible t( 8 satisfy the illumination requirements of the imaging process utilizing solid state illumination sources, such as LEDs. In an embodiment of the invention the illumination source is a white LED. The white light emitted from the white LED has a small fraction of red light and even smaller fraction of IR light. Hence, a white LED is beneficial for use with silicone based image sensors (such as CMOS imaging cameras) because of the silicone sensitivity to red and IR light. In a system which includes the CMOS imaging camera of the invention with its reduced sensitivity to light in the red spectrum and a white LED illumination source, no IR reject filters (photopic filters) are needed. A suitable transmitter may comprise a modulator which receives the video signal (either digital or analog) from the CMOS imaging camera, a radio frequency (RF) amplifier, an impedance matcher and an antenna. The transmitter will be further illustrated in Fig. 4. Other optional parts of the system as well as the method for localization of a capsule containing the system within the digestive system may be similar to those described in US 5,604,531 (which is assigned to the common assignees of the present invention and which is hereby incorporated in its entirety by reference). Device 10 can additionally include sensor elements for measuring pH, temperature, pressure, etc. These sensor elements, some of which are described in the prior art, may be any element suitable for measuring conditions prevailing in the body lumen (for example, the digestive system) and that are capable of being appended to or included in the device. 9 Reference is now made to Fig. 2, in which a schematic layout of the CMOS imaging camera is presented. The CMOS imaging camera 200 comprises active pixel and post processing circuitry on a single chip. The CMOS imaging camera 200 includes photo cell 202 (the pixels of the CMOS imaging camera), correlated double sampler (CDS) 204, analog to digital (A/D) converter 206, encoding and randomizing unit 208 and timing generator 210 for control and synchronization of the circuitry elements. Light collected by an optical system is directed onto CMOS imaging camera 200 and photons are converted to electrons as the light is absorbed by photo cell 202. Electrons are converted to electrical current and an analog signal is produced by the active pixel circuitry. The analog signal is conivetd for further processing by on-chip post processing circuitry. The signal is further processed by CDS 204. CDS 204 performs correlated double sampling, for canceling noise and signal shaping before conveying the signal to the A/B converter 206. The A/D converter 206 is a serial output A/D converted which enable. serial, low power transmission of signals. The signal is converted into a digital signal and i, further conveyed to encoding and randomizing unit 208 for defining frame and rov parameters (encoding) and for priming the signals for transmission (randomizing). The encoding and randomizing unit 208 randomizes the occurrence of the digital "0" and "1' signals such that transmission is not impeded by a reoccurring signal of one type. The CMOS imaging camera 200 is specified by Given Imaging Ltd. of Yokneam Israel and designed by Photobit Corporation of California, USA, according to ; specification adjusted to in vivo imaging. The CMOS imaging chip has ultra low powe requirements (less than 3 milliwatts). The dynamics of the increase of dark curren generated by the imaging camera, as a function of temperature, is less than that of solii state devices known in the art, such that at 37 0 C a low fraction of the out put video signal i 10 dark current. Further, as discussed above, the imaging camera has reduced sensitivity to light in the red spectrum, abating the need for photopic filters. Reference is now made to Fig. 3 in which a device for in vivo imaging comprising a specific integrated light source is illustrated. Device 300 comprises CMOS imaging camera 302, an optical system (not shown) for imaging in vivo images onto the CMOS imaging camera 302 and an integrated light source 304 for illuminating a site in vivo. The device 300 further includes a transmitter 305 for transmitting video data from the imaging camera 302 to a receiver (not shown). The transmitter 305 generates a high voltage and current source for the light source 304. The integrated light source 304 is connected to the transmitter 305 through connective wires 301. The electrical components of the device are powered by a battery contained within the device (not shown). The integrated light source 304 comprises a strip 306 of a refracting crystal matri, encircling the CMOS imaging camera 302. Blue LED chips 308, encapsulated within the refracting crystal matrix of strip 306, are positioned along the strip 306 such tha illumination is provided in a ring around the CMOS imaging camera 302. Blue LED chips 308 can also be sprinkled throughout the strip 306 such that tht whole strip 306 emits light. Reference is now made to Fig. 4 in which a block diagram of the transmitter i: illustrated. The transmitter 400, an ASIC (application specific integrated circuit) designe< to fulfill international communication standards (such as the FCC) standards, operates on; minimum shift keying (MSK) modulation system to effect transmitting of digital signal through antenna 426 and 427 on radio frequencies to a receiving system. The transmitte 400 also controls the illumination and imager of the device of the invention and the logica conversion of the switch (as described above). The transmitter 400 includes a one tim 11 programming unit 408 in communication with external programming input 428, a control logic block 401 for communicating with the imager, a phase lock loop (PLL) 402 in communication with modulator 425, optionally, a LED power and control block 403 foi controlling the illumination, a main oscillator 404 and a switch 405 which controls an intemal electronic switch 406. The control logic block 401 communicates with the imager, reads preprogrammed parameters and performs the interface to the "outside" world in the programming mode Control logic block 401 maintains a master clock, is synchronized by bit rate data 412 anc frame rate 413, and through control 411, which is generated by the imager, triggers LEE power and control block 403. Coiitrol logic block 401 further controls the master clock 41z and the imager shutdown 415. During shutdown the transmitter sends out beacon signals only. The shutdown enables economic use of the device's power supply. For example, in a device designed fo imaging the small intestine, the transmitter 400 may be programmed to include a two hou delay, during which period shutdown of the imager and other device electronics is effected Two hours is approximately the time it takes a swallowable device to pass the stomach an( enter the small intestine, in particular patients. Thus, in those patients, the device will utiliz< power from the battery, for collecting images, only when the device has reached the smal intestine. The PLL 402 is a feedback system intended to automatically correct drifts in th. transmitted frequency. PLL 402 includes a pre-scaler 424 for fast frequency dividing that i not dependant on the channel frequency. The pre-scaler 424 is in communication with; divider 421 that divides the frequency of the oscillator 404 to perform the referenc frequency for the PLL. The division value is channel dependant. The PLL 402 also include 12 a phase frequency detector (PFD) 422 for performing the frequency comparison and the phase comparison of the PLL, and a charge pump 423 for performing the shape of the loop transmission of the whole loop. LED power and control block 403 includes a high voltage source 432 that is controlled by the external capacitor 431. LED power and control block 403 also includes a high current source 433 and the peak current value of the LEDs is controlled by the resistor which is connected to LedRes 435. The transmitter 400 is controlled by an external magnetic switch 405. The switch 405 is a normally opened (NO) switch that is kept closed by an external magnet, as described above. Switch 405 controls an internal electronic switch 406 that controls all the device electronics. Electronic switch 406 includes a low leakage circuitry to convert the logic of the NO switch 405 to "normally closed" (NC) logic, such that although switch 405 is a NO switch it will keep the transmitter inactive while it is closed. The low leakage circuit only uses 1% - 3% of the battery power per year, so tha the internal electronic switch 406 is not a significant factor in the power regimen of the device. In an embodiment of the invention the device is a swallowable capsule having at optical window and comprising a CMOS imaging camera, white LEDs, an optical system a transmitter and battery. The swallowable capsule is kept inactive while contained in i package having a magnet, such as the magnetic packaging described in PCT applicatior ILOO/00752 (which is assigned to the common assignee of the present invention and whici is hereby incorporated in its entirety by reference). Just prior to use the package having th< magnet is removed enabling the switch 405 to be opened, thereby activating the transmitte: and with it, initiating imager and illumination operation. 13 The input bandwidth of the information in the transmitter 400 is over 1.35Megabil per second. Such a low powered high input bandwidth transmitter for transmitting videc data, has not yet been shown in the art. Reference is now made to Fig. 5 in which a block diagram of the method of the invention is illustrated. The method for in vivo imaging includes the following steps illuminating a site in vivo (502); collecting remitted light onto pixels of a CMOS imaging camera, thereby generating an analog signal (504); converting the analog signal to a digita signal (506); randomizing the digital signal (508); transmitting the digital signal to receiving system (510) and processing the transmitted signals to obtain images of the ii vivo site (512). The step of illumination (502) is preferably carried out by employing white LED: to illuminate the site in vivo. Illumination may be continuous or alternating in accordance< with specific requirements of the system. Collecting light remitted from the site in vivo (504) and directing it on to th< pixels of a CMOS imaging chip is achieved by employing an optical system whic] comprises a lens and which may further comprise any suitable collimator. Conversion of the analog signal to a digital signal (506) is preferably effected ini serial manner. Randomizing the digital signal (508), namely randomizing the occurrence of th digital signals ("0" and "1"), is performed so that transmission is not impeded by reoccurring signal of one type. Transmission of the signal (510) is accomplished using radio frequencie (approximately 432 - 434 Mhz) at a rate of two to eight frames per second to an array c antennas attached to a patient's body. The antennas allow image capture and are also use 14 to calculate and indicate the position of the imager in the patient's body. An example of the calculation and indication the position of the imager in the patient's body is provided in the above mentioned US 5,604,531. Processing of signals (512) can be carried out by employing suitable processors and software. For example, the RAPID software (propriety software developed and owned by Given Imaging Ltd. of Yokneam, Israel) is used to obtain a video clip of images captured from within the GI tract. The video clip can be synchronized with the trajectory of the imaging device as it passes through the GI tract to enable localization of the device in the GI tract. Additionally, a plurality of receiving antennas can be used which can be moved tc the location enabling best receiving conditions. The images can be stored on a small portable recorder carried on a belt anc subsequently downloaded for analysis and retrieval. Additionally, the receiver can be connected directly to a stationary data recorder. Experiments were carried out with an 11 x 30 mm capsule comprising a CMOS imaging chip and miniature processor, white LED light sources, a short focal length len and a miniature transmitter and antenna. The capsule, powered by silver oxide batteries was swallowed and more than 5 hours of continuous recording of images from th< gastrointestinal tract were achieved. Live transmission of good quality video images were obtained for up to 6 hou periods in ambulatory dogs. With .ethical committee approval a human volunteer study was performed. Th capsule was easily swallowed. Moving images were obtained from the stomach and small 15 intestine. No discomfort was experienced. The optical window remained clear ttirougtiout the whole transmission. Trigonometric analysis of signal strength allowed continuous monitoring of the capsule position. Imaging of the small bowl was successfully completed in 2 hours. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the present invention is defined only by the claims which follow: 16

Claims (12)

1. An optical unit for use in a swallowable capsule for imaging the gastrointestinal tract, the optical unit including: a dome shaped optical window; 5 an optical system located behind the optical window; a CMOS imaging camera located behind the optical system; and a plurality of light emitting diodes configured in a ring around the optical system to provide illumination.

2. The optical unit of claim 1 wherein the optical system and the light emitting 10 diodes are on substantially the same plane, and the CMOS imaging camera is located behind the optical system relative to said optical window.

3. The optical unit of either of claim 1 or 2 wherein the optical system is arranged to focus an image on the CMOS imaging camera.

4. The optical unit of any one of claims 1 to 3 wherein the optical system 15 includes a lens.

5. The optical unit of any one of claims 1 to 4 wherein the light emitting diodes are white LEDs.

6. A swallowable capsule for imaging the gastrointestinal tract, the capsule including: 20 a housing, the housing including a dome shaped optical window, the housing enclosing at least: an optical system located behind said optical window for focusing images onto a CMOS imaging camera; said CMOS imaging camera located behind the optical system; and 25 a plurality of light emitting diodes arranged around the CMOS imaging camera.

7. The capsule of claim 6 wherein the optical system includes a lens. 18

8. The capsule of claim 6 or 7 wherein the optical system and light emitting diodes are on substantially the same plane, and the CMOS imaging camera is located behind the optical system relative to said optical window.

9. The capsule of any one of claims 6 to 8 wherein the light emitting diodes 5 are white LEDs.

10. A swallowable capsule for in-vivo imaging of the gastrointestinal tract, said capsule including: a housing, said housing including at least a dome shaped optical window portion disposed along a longitudinal axis of said capsule, said dome shaped 10 optical window portion being part of the external surface of said housing, said housing enclosing at least: at least one CMOS imaging camera; at least two white LEDs for illuminating said gastrointestinal tract site only through said optical window; 15 an optical system including at least one lens for collecting light from said gastrointestinal tract site through said optical window onto said CMOS imaging camera for imaging said gastrointestinal tract site onto said CMOS imaging camera, said optical system being separated from said dome shaped optical window portion, which is not part of said optical system, by a gap, the at least two 20 white LEDs positioned in the vicinity of said optical system and not on the longitudinal axis of said optical system so that the at least two white LEDs illuminate said gastrointestinal tract site directly through said optical window and not through said optical system, and said CMOS imaging camera imaging said gastrointestinal tract site via said optical window and via said optical system; and 25 a transmitter for transmitting the signal of the CMOS imaging camera to a receiving system.

11. An optical unit according to claim 1 and substantially as herein described with reference to the accompanying drawings. 19

12. A swallowable capsule according to claim 6 or claim 10 and substantially as herein described with reference to the accompanying drawings. GIVEN IMAGING LTD WATERMARK PATENT & TRADE MARK ATTORNEYS P21889AU02