WO2010140126A2

WO2010140126A2 - Ultrasonic capsule with rotatable reflector

Info

Publication number: WO2010140126A2
Application number: PCT/IB2010/052459
Authority: WO
Inventors: Gavriel Iddan
Original assignee: Rdc Rafael Development Corporation
Priority date: 2009-06-02
Filing date: 2010-06-02
Publication date: 2010-12-09
Also published as: WO2010140126A3

Abstract

A system and method are described for the purpose of performing non invasive examination of the colon using ultrasound in an ingestible capsule. A rotatable reflector is used to reflect an ultrasound beam produced by an ultrasonic source. The rotatable reflector is designed to minimize drag. The capsule includes ultrasonic transducer elements, a control circuit and an external wireless power supply and data recorder. The recorded ultrasonic data is later processed and a virtual image of the lumen is generated for diagnostic purposes.

Description

ULTRASONIC CAPSULE WITH ROTATABLE REFLECTOR

FIELD OF THE INVENTION

[001] The present invention relates to an apparatus and method for the purpose of performing non- invasive examination of the gastrointestinal (GI) tract and more specifically the colon.

BACKGROUND OF THE INVENTION

[002] Devices and methods for performing in-vivo imaging of passages or cavities within a body are known in the art. Such devices may include, inter alia, various endoscopic imaging systems and devices for performing imaging in various internal body cavities.

[003] Typical current in-vivo imaging devices use light or other electromagnetic energy to form images. Images based on light or other electromagnetic energy may not provide information on, for example, features or structures obscured by the contents of the gastrointestinal (GI) tract or beyond or behind the surface of the lumen being imaged. A medical practitioner may desire to image such structures or features.

[004] Further, when imaging the GI tract, a thorough cleaning may be required beforehand. In particular, the colon may be filled with matter such as feces, while other parts of the GI tract may be filled with liquid which is more transparent. However, various parts of the GI tract may also be filled with more opaque matter. Uncomfortable cleaning may for example require a multi day liquid diet or low residue diet, or the use of special cleaning agents such as laxatives. [005] The use of an ultrasonic capsule for the purpose of colon diagnosis has been disclosed in, for example, US application 20030195415; entitled "Device, system and method for acoustic in-vivo measuring". This publication discloses a capsule incorporating a ring or rings of miniature ultrasonic elements performing an electronic circular scan as it moves through the colon. The gathered data is transmitted to an external recorder for offline processing. An advantage in using ultrasound is that it eliminates or greatly reduces the need for cleaning of the GI tract, since unlike in optical imaging, the presence of matter in the GI tract enhances, rather than detracts from, the image. [006] Although ultrasound scanning has been used for endoscopic devices, this methodology has not been used for ingestible capsules. One reason for this is that batteries that are successfully used within a video capsule are not able to supply the power required by a high density ultrasonic array. The residence time of a capsule inside the colon may be as long as two days or more if accelerating medication is not used. Moreover, miniaturization of components would be required.

[007] It would therefore be beneficial to have a system and method for colon screening using a capsule that does not require preparation, and wherein the power requirements are met.

SUMMARY OF THE INVENTION

[008] There is provided, in accordance with embodiments of the present invention, an ingestible capsule for non-invasive ultrasound imaging. The capsule includes a receiving antenna capable of receiving RF power, an ultrasonic source for generating an ultrasonic signal in response to an RF electric signal received from the receiving antenna, a rotatable reflector for reflecting the generated ultrasonic signal and projecting the ultrasonic signal out of the capsule, the projected signal reflected back to the ultrasonic source, to generate an imaging signal, the rotatable reflector having a structure such that drag forces during rotation of the rotatable reflector are minimized, thereby minimizing power requirements, a motor for rotating said rotatable reflector; a motor controller for driving said motor and controlling rotation of the rotatable reflector, and a controller for controlling parameters of the RF electric signal received from the receiving antenna and parameters of the reflected ultrasonic signal. [009] In accordance with further embodiments of the present invention, the capsule may further include a power supply in electrical communication with the receiving antenna for supplying electrical power to operate the motor, the motor controller, and the controller within the capsule. The capsule may further include a memory module for storing received data and a conditioned reflected signal. The capsule may further include a transmitting antenna and a transceiver, for transferring data to and from an external unit. In accordance with further embodiments of the present invention, the rotatable reflector may have a sharp edge for minimization of drag. In accordance with yet additional embodiments of the present invention, the rotatable reflector may be rotatable due to its being fixed within a rotatable cylindrical housing transparent to ultrasound waves. In accordance with additional embodiments, the receiving antenna is a tuned RF resonance coil. The receiving antenna may have a cross-section spanning a majority of a diameter of the capsule. In accordance with additional embodiments, the power supply may include electrical rectification and power conditioning circuits for generation of DC electrical power from the received RF power. The power supply may include a regular and/or a rechargeable battery. In accordance with additional embodiments, the controller may include RF switches and phase shifting devices for controlling the RF signal delivered to the ultrasonic source. The capsule may further include a data receiver/transmitter, a central controller, a data logging device, or an additional sensor or sensors.

[0010] There is provided, in accordance with embodiments of the present invention, a system for imaging an internal tract in a body. The system includes an ingestible capsule including a receiving antenna capable of receiving RF power, an ultrasonic source generating an ultrasonic signal in response to an RF electric signal received from the power receiving antenna, a rotatable reflector for reflecting the ultrasonic signal and projecting the ultrasonic signal out of the capsule and into the internal tract of the body, the projected signal reflected back to the ultrasonic source to generate an imaging signal, the rotatable reflector having a structure such that drag forces during rotation of the rotatable reflector are minimized, thereby minimizing power requirements, a motor for rotation of the rotatable reflector, a motor controller for driving said motor and controlling rotation of said rotatable reflector, a controller for controlling parameters of the RF electric signal received from the receiving antenna to the ultrasonic source parameters of the ultrasonic signal, and a power supply housed within the capsule, and in electrical communication with the power receiving antenna and with the controller and the data receiver, wherein the power supply supplies electrical power to operate electronic circuits within the capsule, and an external unit including an RF transmitter for transmitting RF power to the receiving antenna of the capsule, and a data receiver for receiving data from the ultrasonic signal, and a storage module for storing said received data. [0011] In accordance with further embodiments of the present invention, the system may further include a workstation for processing the received data. The system may further include a viewing module for viewing the processed data. In some embodiments, the external unit may include sensors capable of sensing a location and orientation of the capsule. In some embodiments, the workstation may further include a processor capable of receiving data from the external unit and processing the data to render 3D images based on the data, and a display for displaying the rendered 3D images.

[0012] There is provided, in accordance with embodiments of the present invention, a method for imaging an internal tract in a body. The method includes providing an ingestible capsule having at least one ultrasound transducer and a rotatable reflector for reflecting a signal produced by the ultrasound transducer, introducing the ingestible capsule into the internal tract, transmitting RF power from an external unit to the ingestible capsule, converting the transmitted RF power into an ultrasonic beam via the ultrasound transducer, reflecting a portion of the ultrasonic beam from the internal tract, converting the reflected portion of the ultrasonic beam into an electronic signal, and transmitting the electronic signal to the external unit.

[0013] In accordance with further embodiments of the present invention, the transmitting of RF power may include transmitting a signal at a frequency equal to a frequency of the RF power. The method may further include detecting a position and orientation of the capsule with respect to the external unit. The method may further include calculating a 3D image of boundaries of the internal tract through which the capsule is traversing based on a signal indicative of the converted electric signal and the detected position and orientation of the capsule with respect to the external unit. The method may further include displaying the calculated 3D image.

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The above and further advantages of the present invention may be better understood by referring to the following description in conjunction with the accompanying drawings in which: FIG. 1 is a schematic illustration of a system for non-invasive ultrasonic examination of the gastrointestinal tract in accordance with an embodiment of the present invention;

FIG. 2 is a schematic illustration of a capsule used in the system of FIG. 1, in accordance with embodiments of the present invention; FIG. 3 is a schematic illustration of the capsule of FIG. 2, showing electronic components in accordance with one embodiment of the present invention;

FIG. 4A is a schematic illustration showing the operation of a rotatable reflector positioned within the capsule of FIG. 2;

FIG. 4B is a schematic illustration of the rotatable reflector of FIG. 4 A, in accordance with an embodiment of the present invention;

FIGS. 5A and 5B are schematic illustrations of an ultrasonic source within the capsule of

FIG. 2, in accordance with embodiments of the present invention;

FIG. 6 is a schematic illustration of a setup of the system of FIG. 1, according to an exemplary embodiment of the present invention; FIG. 7A is a graphical illustration of reflected echoes indicating the colon wall;

FIG. 7B is a schematic illustration of the reflections of FIG. 7A from the colon wall;

FIG. 7C is a schematic illustration of a completed slice image based on the reflections of

FIGS. 7A and 7B;

FIG. 8 is a schematic illustration of a plurality of 2D images taken at different capsule locations and inclination angles; and

FIG. 9 is a perspective illustration of a vessel based on the plurality of images of FIG.8.

[0016] It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. Moreover, some of the blocks depicted in the drawings may be combined into a single function. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention relates to an apparatus and method for the purpose of performing non invasive examination of in vivo body cavities, for example the GI tract and more specifically the colon. [0018] Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

[0019] In discussion of the various figures described herein below, like numbers refer to like parts. The drawings are generally not to scale. As used herein, an element or step recited in the singular and preceded with the word "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited.

[0020] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be understood by those of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and structures may not have been described in detail so as not to obscure the present invention.

[0021] The principles and operation of systems and methods according to the present invention may be better understood with reference to the drawings and accompanying descriptions. [0022] An advantage in using an ultrasonic imaging capsule rather than an optical imaging capsule, is that ultrasound does not require the same level of cleanliness in the body as optical imaging does. In fact, the presence of matter within the vessel to be viewed enables and enhances the ultrasound imaging. Thus, the use of ultrasound imaging within a capsule would be advantageous in that the patient would not be required to endure the systematic cleaning out of the GI tract, as is currently the case for other methods used to view the GI tract. This could result in an increase in the number of people willing to follow recommended screening guidelines for GI health. While ultrasonic arrays are used for imaging of body lumens, including the GI tract, blood vessels, vagina and the urinary vessels, this is commonly done using endoscopes, wherein the operating power is drawn from the outside via a cable. The use of a capsule presents a difficulty in that the use of a cable is not possible, while the use of batteries for the operation of the ultrasonic imaging limits the duration of operation. Thus, it is critical to both find a way of powering such a capsule via a wireless method, and to minimize the power requirements as much as possible. Embodiments of the present invention provide an ultrasound imaging capsule which operates via a rotatable reflector so as to produce a uniform image with high resolution. The rotatable reflector is designed in such a way so as to minimize drag, thus minimizing power requirements, and enabling its use in an ingestible capsule.

[0023] Reference is now made to FIG. 1, which is a schematic illustration of a system 400 for non-invasive ultrasonic examination of the GI tract and more specifically the colon according to an embodiment of the current invention. System 400 includes an ingestible capsule 10, an external unit 200, and a workstation 410. Capsule 10 is configured and sized to be ingested by a human or animal patient and to pass through the gastrointestinal tract. Examples of ingestible capsules are, for example, those available from Given Imaging (Pillcam). Capsule 10 is configured to receive RF power from external unit 200, convert the received power into ultrasound energy, transmit the ultrasound energy into the patient's body, receive reflected ultrasound backscatter data, and transmit the received data to external unit 200. In some embodiments, capsule 10 also includes an internal battery and memory storage for autonomous operation, for example, when external unit 200 is temporarily or completely removed. External unit 200 includes an RF transmitter/receiver 202 and a data recorder 204. As depicted by arrow 14, capsule 10 is in RF two-way communication with external unit 200 via RF transmitter/receiver 202. External unit 200 may be positioned in proximity to or in contact with the patient's body, for example, on a belt or garment to be worn by the patient. External unit 200 may also include a data processor and a mobile power source such as a battery to allow the patient to move about while the imaging takes place. Workstation 410 is configured to receive the data from external unit 200 and to process the received data so as to form images of the internal tract being viewed. Workstation 410 may also include a viewing module for viewing resulting images. Workstation 410 may be a computer such as a PC, a laptop, or a dedicated computing and viewing unit. [0024] External unit 200 may establish a link 420 to workstation 410. In some embodiments, link 420 is a wireless link such as RF link, Bluetooth, Wi-Fi, cellular, fiber optics channel, or others. In other embodiments, link 420 is established via a cable (e.g. LAN or USB cable, etc.). In yet additional embodiments, data is stored in external unit 200, for example on a memory card or a removable data storage device such as disk-on- key and retrieved and physically removed from external unit 200 and inserted into workstation 410. It should be readily apparent that any combination of these embodiments may be used as well. [0025] In some embodiments, workstation 410 is connected through a communication link 960 such as LAN, phone modem, cellular modem, etc. to a remote a site such as a central server, a hospital PACS (Picture Archiving and Communication System) or a hospital billing system.

[0026] Reference is now made to FIG. 2, which is a schematic illustration of capsule 10, in accordance with embodiments of the present invention. Capsule 10 is encapsulated in a bio-compatible and ultrasound-compatible shell 297. Materials for bio-compatibility and ultrasound-compatibilty are well-known in the art. Capsule 10 is sized to be ingested or inserted into a subject, and more particularly, into the subject's GI tract. In some embodiments, capsule 10 is elongated and has a long axis 101. When moving in the GI tract, capsule 10 may advance such that long axis 101 is at least approximately oriented towards the direction of motion and thus long axis 101 is approximately parallel to the axis of the GI cavity in which capsule 10 is advancing. Alternatively, other shapes of a capsule may be used, for example a sphere or a pill having three different axis lengths or a round pill having one short axis. [0027] Capsule 10 includes an ultrasonic source 20, a rotatable reflector 22 positioned to reflect a beam from ultrasonic source 20, and a scan motor 24 for controlling rotation of rotatable reflector 22. Capsule 10 further includes a power source 26 and a receiving antenna 28. Ultrasonic source 20 and rotatable reflector 22 are housed within a sealed fluid chamber 30. Ultrasonic source 20 is configured to send a focused ultrasound beam 50 towards rotatable reflector 22. Rotatable reflector 22 is then configured to reflect ultrasound beam 50 at an angle to produce a scanning beam 51 , wherein scanning beam 51 is directed towards a wall of capsule 10, and out of capsule 10 into the body lumen. The angle of reflection may be approximately 90 degrees or any other desired angle. Scanning beam 51 is used to scan the interior of the body lumen wall, as will be described in greater detail hereinbelow. Various electronic components 32 involved with the operation of the system but not needed to be described to understand the present invention, are positioned on circuit boards in different locations within capsule 10. [0028] A scanning portion 299 of bio-compatible shell 297 is comprised of a material which is transparent to ultrasound beam 50, allowing ultrasound beam 50 to exit from capsule 10 to reach the interior of the body lumen being scanned. In some embodiments, scanning portion 299 is comprised of a different material than the rest of bio-compatible shell 297. In other embodiments, scanning portion 299 is comprised of the same material as the rest of bio-compatible shell 297.

[0029] Ultrasonic source 20 may be comprised of any suitable ultrasound transducer element or array of elements, such as a crystal, ceramic, polymer, piezoelectric, or MEMS transducer element. Sealed fluid chamber 30 is filled with a fluid such as water, oil or other fluids which are ultrasonically well-matched to shell 297 of capsule 10. By matching impedances of liquid within fluid chamber 30 with shell 297, a relatively transparent passage can be created with reduced reflection from shell 297, which can improve performance and reduce reflected energy from shell 297. Materials and fluids which can be matched in this way are known in the art. [0030] Reference is now made to FIG. 3, which is a schematic illustration of capsule 10 showing electronic components 32 in accordance with one embodiment of the present invention. It is an aspect of the current invention to deliver the energy required for the operation of the ultrasonic elements via an RF link. Receiving antenna 28 is configured to receive RF signals 35 from external unit 200. Receiving antenna 28 is preferably a tuned coil, tuned to the RF frequency, however other types of antennae may be used, for example a whip antenna extending outside of capsule 10, a printed antenna formed on a PCB or on the shell of capsule 10, or any other suitable antenna. In some embodiments, receiving antenna 28 has a large cross section, occupying a substantial space within capsule 10 so as to effectively receive RF radiation. [0031] In some embodiments, the RF power delivered to capsule 10 is already at the frequency of the ultrasonic signal used for ultrasound transmission. Thus, the RF power is in tune with the ultrasonic source (for example, a piezoelectric element) so as to maximize resonance between them. Penetration depth and resolution of ultrasound imaging depends on the frequency used, wherein lower frequency is used for deep tissue imaging and high frequency is used for high resolution shallow imaging. Axial resolution is achieved using short ultrasonic pulses to avoid ambiguity. Generation of short pulses necessitates high frequency and large bandwidth. Transverse (angular) resolution necessitates an imaging system of a large F number, which necessitates the use of a wide transducer array and short ultrasonic wavelength (that is - high frequency).

[0032] Due to the relatively small dimension of the pill, it may be useful to employ high frequency in order to achieve high radial and tangential resolution. Additionally, shallow imaging is possible as the main information required is imaging of the body cavity boundary which is optionally close to capsule 10 and may appear as a large ultrasonic reflection due to the large difference in mechanical properties between the cavity content and the cavity wall.

[0033] Power generated by RF signals 35 is mostly converted into ultrasonic signals. However, some of the power generated by RF signals 35 may be diverted to activate motor 24, and some of the power generated by RF signals 35 may be used to replenish power source 26, which supplies electrical power to operate electronic circuits within capsule 10 and to provide backup power in case of removal of external unit 200. Power source 26 may comprise electrical rectification and power conditioning circuits for generation of DC electrical power from the received RF power. In some embodiments, a power storage device such as capacitor, a battery, or a rechargeable battery within power source 26 is used for smoothing the rectified signal and to maintain power supply between RF pulses. Optionally, a battery within power source 26 is capable of maintaining operation of capsule 10 for a specified duration of time in the absence of received RF power. [0034] Signals received by antenna 28 are sent to ultrasonic source 20 and are converted by a piezoelectric element, for example, into ultrasonic energy. Ultrasonic transducer 20 is configured to send ultrasound beam 50 to scan the vessel via rotating reflector 22, and also to receive an ultrasonic signal reflected from the scanning of the vessel. This reflected ultrasound energy is received by ultrasonic source 20, converted into electrical signals, and sent to a controller 36 positioned within capsule 10. In addition, some of the RF energy received by antenna 28 may be diverted to controller 36 within capsule 10. Controller 36 controls transmission of received electrical signals from ultrasonic source 20 through a transmission antenna 29 to external unit 200. Within external unit 200, a data decoder receives the data from capsule 10, and a data recorder records the received data and transmits the data to workstation 410. In some embodiments, controller 36 also controls parameters of motor 24, and further controls parameters of a memory module 38 which may be included within capsule 10 for storing data during periods of time when external unit 200 is removed. Controller 36 may control switches and phase shifters such that ultrasonic beam 50 is properly formed, aimed and optionally focused. Phase shifters may include, for example, controlled delay lines or voltage controlled capacitors in an RF resonance circuit. Controller 36 is further configured to receive digital data, which can help determine parameters for activation of motor 24 and for memory module 38. Thus, controller 36 manages components within capsule 10.

[0035] An RF resonance circuit is shown in FIG. 3. The circuit shown in FIG. 3 is a gated ultrasound receive circuit, comprising gating switches 42, an amplifier 44, a detector 46 and an ADC 48. However, it should be readily apparent that any suitable circuit may be used. A digital transceiver 40 receives data from memory module 38, and converts the data into a data stream for later processing at workstation 410. The data stream may be analog or digital. The data stream is then sent via a transmitting antenna 29 to external module 200. In some embodiments, a hand-held receiving/viewing device may be used, wherein the data stream is sent to the receiving/viewing device, and is converted into images for real-time viewing. Transmitting antenna 29 may be the same antenna as receiving antenna 28 used to receive RF signals, or transmitting antenna 29 may be a specially designated data communication antenna. Digital transceiver 40 transmits RF signals indicative of reflected ultrasonic signals from capsule 10 to external unit 200 through an RF link. Optionally, digital transceiver 40 performs additional data conditioning such as one or more of: decoding a signal indicative of reflected ultrasonic beam from tissue; converting the signal to digital form; signal conditioning and averaging; data reduction and compressing; or any other relevant operation. Optionally, digital transceiver 40 further comprises data storage such as volatile or non- volatile memory for storing data while the RF link is not functioning or unavailable. For example, data may be transferred from capsule 10 in bursts, for example using the same power RF frequency while RF power is not transmitted or its transmission is halted. In this case, receiving antenna 28 may be used as transmission antenna 29. [0036] Control signals transmitted by external unit 200 and received by capsule 10 may be used for turning on or off the ultrasonic beam 50, to alter the scanning pattern or sequence of ultrasonic beam 50, to initiate data transfer from capsule 10 to external unit 200, and to control any other parameters. Additionally, data transferred from capsule 10 to external unit 200 may be a raw RF signal as received by ultrasonic source 20, partially processed data, for example time evolution of the ultrasonic signal reflected from the tissue, as well as sensor reading and status indicating signals.

[0037] External unit 200 may include an RF generator, which generates trains of RF pulses. The RF pulses may have pulse durations compatible with the ultrasonic pulse of ultrasound beam 50. The pulses are generally amplified, and possibly mixed via an RF mixer to allow transmission of RF power from the amplifier to receiving antenna 28, and to allow directing of an RF signal indicative of the reflected ultrasonic signal from transmitting antenna 29 to the amplifier. The RF mixer may be a voltage controlled mixer or a switch, and may also serve to isolate the amplifier from the high power transmitted from the RF generator. External unit 200 is externally powered using a main power line or powered by a battery pack. External unit 200 may comprise a plurality of elements working together or one or a few at a time using a multiplexer.

[0038] In some embodiments, operation of capsule 10 is configured to commence only at certain times, such as at arrival into the colon. Additional sensor(s) may be housed in capsule 10 and/or in external unit 200, which may be used for measuring bio-parameters such as pressure or pH to indicate the arrival at a particular location, such as the colon. Alternately, optical sensors may be used to detect arrival at a particular location, such as the colon. Sensors may also be used to trigger the operation of capsule 10 and external unit 200. [0039] Reference is now made to FIGS. 4A and 4B, which are respectively a schematic illustration showing the operation of rotatable reflector 22, and a schematic illustration of a rotatable reflector 22 in accordance with an embodiment of the present invention. As shown in FIG. 4A, ultrasonic source 20 is a transducer configured to send an ultrasound beam 50 to rotatable reflector 22. As ultrasound beam 50 bounces off of rotatable reflector 22, scanning beam 51 is a radial beam formed in a direction external to the capsule, generally at an angle of approximately 90 degrees with respect to ultrasound beam 50 and the long axis of the capsule. Since rotatable reflector 22 continues to rotate, a scanning trajectory 52 is formed in a circular path, allowing for scanning of the internal lumen to occur rotatably as capsule 10 advances down the lumen. In order to conserve on power requirements, rotatable reflector 22 is configured so as to minimize drag caused by rotation of rotatable reflector 22 within the liquid medium necessary for ultrasound transducing. This can be done by constructing the edges of rotatable reflector 22 as thin as possible - as a blade of a knife, for example. In another embodiment, as shown in FIG. 4B, rotatable reflector 22 is attached at one end to motor 24, and is positioned within and fixed to a housing 23. Housing 23 is transparent to ultrasound waves, and is fixed to rotatable reflector 22 so that it also rotates when rotatable reflector 22 rotates. Housing 23 has a relatively smooth shape, such as a cylinder, so that irregularities are minimized, thus minimizing drag during rotation of housing 23 and reflector 22 through the liquid medium. Due to its transparent quality, rotatable reflector 22 is still able to reflect ultrasound waves through housing 23, while minimizing drag due to the shape of housing 23. In some embodiments, a counter-rotation device may be included to prevent rotation of capsule 10 upon activation of motor 24. Transparent housing 23 is may be constructed of, for example, a polymeric material or any other suitable material which is transparent to ultrasound waves. In one embodiment, rotatable reflector 22 is designed such that power requirements are less than ImW. [0040] Reference is now made to FIGS. 5 A and 5B, which are schematic illustrations of ultrasonic source 20, in accordance with embodiments of the present invention. Ultrasonic source 20 forms a focused ultrasound beam 50 which can hit rotatable reflector 22. The focused beam can be generated either by using a shaped transducer, as shown in FIG. 5A, or by using a phased array, as shown in FIG. 5B. [0041] Reference is now made to FIG. 6, which is a schematic illustration of a setup according to an exemplary embodiment of the present invention. A transceiver jacket 520 or belt is attached to a patient body 510 or worn by a patient. Transceiver jacket 520 incorporates an array of individual RF antenna elements 525 as is known in the art of video capsules. In some embodiments, additional ultrasound sensors 515 are added to detect the capsule-emitted ultrasound data stream. These pulses enable the detection of the positioning and orientation of capsule 10 while ultrasonic data is acquired. By knowing the capsule's position and orientation, for example as it traverses the colon 505 of patient 510, each of the ultrasonic slices that are acquired may later be used for the lumen reconstruction. RF power is supplied from external unit 200 to RF antenna elements 525. Ultrasonic data from ultrasound sensors 515 and RF antenna elements 525 as well as RF data from RF antenna elements 525 are supplied to external unit 200. [0042] Positioning of the ultrasonic sensors mounted on transceiver jacket 520 or belt is known with respect to the patient's coordinate system (depicted in two dimensions using x and y axes). Signals detected by sensors are used to triangulate the capsule position and orientation, thus identifying the ultrasound imaging plane 610 by locating the capsule position {x, y, z}, the tilt of capsule's long axis 101 and the rotation of the ultrasound acquired slice. [0043] According to some embodiments of the invention, the individual sensors are each connected to the recording device via proper cable, RF or IR link such as Bluetooth. At the recorder the data is optionally mixed and recorded on solid state or magnetic media. A timing clock signal may also be incorporated to help in the reconstruction. A recording device may be housed away from the body as a separate unit. [0044] Reference is now made to FIG. 7A, which is a graphical illustration of reflected echoes indicating the colon wall, including as much information as is available for separating between artifacts and polyps, FIG. 7B, which is a schematic illustration of the reflections from the colon wall, and FIG. 7C, which is a schematic illustration of a completed slice image. As shown in FIG. 7A, the pulse reflections and timing are depicted in graphical form. These pulses and reflections reflect a detailed topography from the colon wall, as shown in FIG. 7B. While capsule 10 is traversing the body cavity, a two- dimensional ultrasonic image is acquired of the plane 610, defined by the array 17 and preferably perpendicular to capsule axis 101. In FIG. 7B, plane 610 is viewed from the side and thus appears as a line. The 2D slice image 620 is centered at body coordinates {x,y,z} . It should be noted that plane 610 is generally inclined with respect to patient body coordinates, by tilt angles α and β and a rotation angle Φ about axis 101. [0045] Plane 610 intersects with the colon wall 612. In the 2D slice image, the colon wall may be identified by its characteristic ultrasonic properties and ultrasonic reflection and the lumen boundaries. This information is used to reconstruct an image, as shown in FIG. 7C.

[0046] Using trigonometry, each image point in image 620, and specifically each image point in colon wall 612 can be matched with a specific coordinate in the 3D patient coordinate system. Thus, a plurality of 2D images taken at different capsule locations and inclination angles is obtained, as shown in FIG. 8.

[0047] As capsule 10 advances through the colon or other body cavity such as the intestine, a 3D image of sections of the cavity or the entire cavity may be reconstructed at workstation 410 formed, as shown in FIG. 9, by data extracted from the plurality of 2D images as shown in FIG. 8. The captured data should have a bandwidth that is sufficient to be processed at workstation 410 and yield amplitude as well as Doppler data. [0048] It should be noted that in one embodiment slices are sequentially numbered in chronological order, but slices may be overlapping partially and intersect with each other giving rise to duplication in the data set. In this case, data averaging and other statistical data analysis methods, such as majority rules, may be used to reconstruct the 3D image of the lumen.

[0049] Optionally, proper localization and orientation of each and every one of the images previously obtained is performed using data obtained from the information gathered by the ultrasound sensors and by data gathered by RF antenna array by known techniques.

[0050] Edge detection type algorithms may be applied on each of the cross section images to enhance the lumen wall 612 and eliminate the lumen contents. Data from processed slices are registered with patient coordinates. A polyp may be noticed in this image as an inwards protrusion of the lumen wall. Perspective views of the inner lumen may be generated, for example oriented along the local lumen axis.

[0051] A physician may view the perspective views of the inner lumen sequentially. The physician may identify polyps or other suspected structures and locations, such as for example, irregularities of the lumen wall. The physician then can use navigation and processing tools to enhance his or her ability to diagnose the irregularity by performing one or more of: stopping the progress of the "fly through"; pausing, reversing or forwarding movement along the lumen axis; changing magnification and image contrast; viewing raw and differently processed data associated with the locality of the suspected area; changing perspective, or any other manipulation. [0052] The workstation may include a PC, a workstation, laptop computer, and optionally a viewing module. The display may be a dual screen or multi-window display, and may include textual information such as physiological details, imaging time and date, input zones for inputting a physician's report and diagnosis, or other relevant text. The display may also include an image window showing for example, a single cross section image indicating a polyp, fly-through images of the body, or other displays. The display may also include a navigation and orientation window, which may be a different size than the image window. A navigation and orientation window may show a schematic view or actual projection of the body lumen, or a presentation of the present view, or a vector showing direction of current view, as well as navigation, zoom and orientation tools. Capability for adding markings or comments on the images may be included as well. In some embodiments, capsule 10 may include a magnet which can be used to control orientation of capsule 10 via external magnetic fields.

[0053] The reconstructed lumen may be displayed on a monitor side by side with the colon schematic shape, so that the physician using the system can easily maneuver virtually in and out of the lumen. If the capsule has in addition a video camera capable of sensing any portion of the spectrum the captured video image may also be presented to the physician.

[0054] Lumen contents may have complex appearance and structure depending on their compositions. However, using image processing software it is possible to identify the lumen boundaries in an image due, for example, to the contrast between elastic properties of the rectal/colon wall and the rectal/colon content, which may cause a strong ultrasound reflection from the lumen boundary. In some embodiments, a Doppler system may be incorporated within workstation 410 to further differentiate between images by identifying blood flow. This can be done, for example, by adding an additional filter layer within the circuitry. In some embodiments, color gradations are used to indicate levels of Doppler shift. For example, an overlay of color - such as red to indicate blood flow - may be included on the image so as to indicate to the physician or user areas of concern. Generally, detection of significant Doppler shift is an indication of a potential polyp, as opposed to feces artifacts which do not have blood circulation and therefore have no Doppler signature. [0055] It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub combination.

[0056] Although the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention.

Claims

1. An ingestible capsule for non- invasive ultrasound imaging comprising: a receiving antenna capable of receiving RF power; an ultrasonic source for generating an ultrasonic signal in response to an RF electric signal received from said receiving antenna; a rotatable reflector for reflecting said generated ultrasonic signal and projecting said ultrasonic signal out of the capsule, said projected signal reflected back to said ultrasonic source to generate an imaging signal, said rotatable reflector having a structure such that drag forces during rotation of said rotatable reflector are minimized; a motor for rotation of said rotatable reflector; a motor controller for driving said motor and controlling rotation of said rotatable reflector; and a controller for controlling parameters of said RF electric signal received from said receiving antenna, and parameters of the reflected ultrasonic signal.

2. The capsule of claim 1, further comprising a power supply in electrical communication with said receiving antenna, said power supply for supplying electrical power to operate said motor, said motor controller, and said controller.

3. The capsule of claim 1, further comprising a memory module for storing received data and a conditioned reflected signal.

4. The capsule of claim 1, further comprising a transmitting antenna and a transceiver, for transferring data to and from an external unit.

5. The capsule of claim 1, wherein said rotatable reflector has a sharp edge for minimization of drag.

6. The capsule of claim 1, wherein said rotatable reflector is rotatable due to its being fixed within a rotatable cylindrical housing, said housing transparent to ultrasound waves.

7. The capsule of claim 1, wherein said receiving antenna is a tuned RF resonance coil.

8. The capsule of claim 1, wherein said receiving antenna has a cross-section spanning a majority of a diameter of the capsule.

9. The capsule of claim 2, wherein said power supply comprises electrical rectification and power conditioning circuits for generation of DC electrical power from the received RF power.

10. The capsule of claim 2, wherein said power supply comprises a battery.

11. The capsule of claim 1, wherein said controller comprises RF switches and phase shifting devices for controlling the RF signal delivered to said ultrasonic source.

12. The capsule of claim 1, further comprising at least one of: a data receiver, a data transmitter, a central controller, a data logging device, and a sensor.

13. The capsule of claim 1, wherein said structure said rotatable reflector is configured such that power requirements are less than ImW.

14. A system for imaging an internal tract in a body, the system comprising: an ingestible capsule comprising: a receiving antenna capable of receiving RF power; an ultrasonic source generating an ultrasonic signal in response to an RF electric signal received from said power receiving antenna; a rotatable reflector for reflecting said ultrasonic signal and projecting said ultrasonic signal out of the capsule and into the internal tract of the body, said projected signal reflected back to said ultrasonic source to generate an imaging signal, said rotatable reflector having a structure such that drag forces during rotation of said rotatable reflector are minimized, thereby minimizing power requirements; a motor for rotation of said rotating reflector; a motor controller for driving said motor and controlling rotation of said rotatable reflector; a controller for controlling parameters of said RF electric signal received from said receiving antenna, and parameters of the reflected ultrasonic signal; and a power supply housed within the capsule, and in electrical communication with said power receiving antenna and with said controller and said data receiver, said power supply for supplying electrical power to operate electronic circuits within the capsule; and an external unit comprising: an RF transmitter for transmitting RF power to said receiving antenna of said capsule; a data receiver for receiving data from said imaging signal; and a storage module for storing said received data.

15. The system of claim 14, further comprising a workstation for processing said received data.

16. The system of claim 15, further comprising a viewing module for viewing said processed data.

17. The system of claim 14, said ingestible capsule further comprising a transmitting antenna, for transferring data from said data receiver to said external unit.

18. The system of claim 14, wherein said rotating reflector has a sharp edge.

19. The capsule of claim 14, wherein said rotating reflector is positioned within a housing, so as to minimize protruding parts.

20. The system of claim 14, wherein said receiving antenna is a tuned RF resonance coil.

21. The system of claim 14, wherein said receiving antenna has a cross-section spanning a majority of a diameter of the capsule.

22. The system of claim 14, wherein said power supply comprises electrical rectification and power conditioning circuits for generation of DC electrical power from the received RF power.

23. The system of claim 14, wherein said power supply comprises a battery.

24. The system of claim 14, wherein said controller comprises RF switches and phase shifting devices for controlling the RF signal delivered to said ultrasonic source

25. The system of claim 14, further comprising at least one of: a data receiver, data transmitter, a central controller, a data logging device, and a sensor.

26. The system of claim 14 wherein said external unit comprises sensors capable of sensing a location and orientation of said capsule.

27. The system of claim 15, said workstation further comprising: a processor capable of receiving data from said external unit and processing said data to render 3D images based on said data; and a display for displaying said rendered 3D images.

28. A method of viewing an internal tract in a body, the method comprising: providing an ingestible capsule having at least one ultrasound transducer and a rotatable reflector for reflecting a signal produced by said ultrasound transducer; introducing said ingestible capsule into the internal tract; transmitting RF power from an external unit to said ingestible capsule; converting said transmitted RF power into an ultrasonic beam via said ultrasound transducer; reflecting a portion of said ultrasonic beam from said internal tract; converting said reflected portion of said ultrasonic beam into an electronic signal; and transmitting said electronic signal to the external unit.

29. The method of claim 28, wherein said transmitting RF power comprises transmitting a signal at a frequency equal to a frequency of said RF power.

30. The method of claim 28 further comprising detecting a position and orientation of the capsule with respect to said external unit.

31. The method of claim 30, further comprising calculating a 3D image of boundaries of the internal tract through which the capsule is traversing based on a signal indicative of said converted electric signal and said detected position and orientation of the capsule with respect to said external unit.

32. The method of claim 31, further comprising displaying said calculated 3D image.