Abstract:
An aspect of an embodiment of the invention, relates to an imaging capsule for scanning inside a living body with a fail-safe radiation mechanism that prevents the emission of radiation from the imaging capsule until the imaging capsule is instructed to emit radiation and power is available to activate a motor to unblock the emission of radiation. Optionally, when power is not available the imaging capsule automatically, blocks the emission of radiation.

Description:
RELATED APPLICATIONS 
       [0001]    The present application claims priority from U.S. Provisional application No. 61/344,693 filed on Sep. 15, 2010, the disclosure of which is incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates generally to limiting exposure of a patient to radiation and more specifically to a fail safe radiation concealment mechanism in an imaging capsule that is swallowed by a patient to examine the patient&#39;s gastrointestinal tract. 
       BACKGROUND OF THE INVENTION 
       [0003]    One method for examining the gastrointestinal tract for the existence of polyps and other clinically relevant features that may indicate regarding the potential of cancer is performed by swallowing an imaging capsule that will travel through the tract and view the patient&#39;s situation. In a typical case the trip can take between 24-48 hours after, which the imaging capsule exits in the patient&#39;s feces. Typically the patient swallows a contrast agent to enhance the imaging ability of the imaging capsule. Then the patient swallows the imaging capsule to examine the gastrointestinal tract while flowing through the contrast agent. The imaging capsule typically includes a radiation source, for example including a radioisotope that emits Xrays or Gamma rays. The radiation is typically collimated to allow it to be controllably directed toward a specific area during the imaging process. In an exemplary case the imaging capsule is designed to measure Compton back-scattering and transmits the measurements (e.g. count rate) to an external analysis device, for example a computer or other dedicated instruments. 
         [0004]    In a typical implementation a radio-opaque contrast agent is used so that a position with a polyp will have less contrast agent and will measure a larger back-scattering count. Alternatively, other methods may be used to image the gastrointestinal tract. 
         [0005]    U.S. Pat. No. 7,787,926 to Kimchy the disclosure of which is incorporated herein by reference, describes details related to the manufacture and use of such an imaging capsule. 
         [0006]    Use of an imaging capsule exposes the user to radiation, which may be potentially harmful. Accordingly, it is of interest to limit the user&#39;s exposure to radiation when not necessary, for example while the imaging capsule is located in positions that do not need to be measured. Typically, the imaging capsule may be designed with shutters that can be instructed to block the exit of radiation when not needed. However, there still exists the hazard that in case of malfunction of the imaging capsule, for example in case of a power failure radiation may be emitted without constraint. 
         [0007]    It is thus desirable to design a fail safe radiation blocking mechanism that automatically blocks the emission of radiation and only allows radiation to be emitted if power is available and the device provides an instruction to allow radiation to be emitted. 
       SUMMARY OF THE INVENTION 
       [0008]    An aspect of an embodiment of the invention, relates to an imaging capsule for scanning inside a living body, with a fail-safe radiation mechanism that prevents the emission of radiation from the imaging capsule until the imaging capsule is instructed to emit radiation and power is available to activate a motor to unblock the emission of radiation. Optionally, when power is not available the imaging capsule automatically, blocks the emission of radiation. 
         [0009]    In an exemplary embodiment of the invention, a rotatable disk with a collimated radiation source is attached to a motor by its rotation axis. The disk is configured to rotate 360° and emit radiation from the collimated radiation source on the disk. An outer ring which also rotates around the same rotation axis as the rotatable disk surrounds the circumference of the rotatable disk. The outer ring includes areas which block radiation and areas which don&#39;t block radiation. 
         [0010]    In an initial rest position the outer ring is situated relative to the rotatable disk such that the radiation emitted through the collimators is blocked. In an exemplary embodiment of the invention, responsive to commands from the imaging capsule the motor rotates the rotatable disk to a position that allows radiation to be emitted. Optionally, the rotatable disk continues to rotate in the same direction and drags the outer ring along while the outlets of the collimators are unblocked, so that the entire circumference of the imaging capsule is scanned for as many rotations as desired. 
         [0011]    In an exemplary embodiment of the invention, the rotatable disk and outer ring are connected together with a spring so that the emission of radiation from the collimators will be blocked automatically when the motor stops turning the rotatable disk. 
         [0012]    There is thus provided according to an exemplary embodiment of the invention, an imaging capsule for scanning inside a living body with a fail-safe radiation mechanism, including: 
         [0013]    a radiation source; 
         [0014]    a rotatable disk with the radiation source mounted on the disk and wherein the rotatable disk has a collimator structure allowing the emission of radiation from the radiation source substantially only from a few locations on the circumference of the disk; 
         [0015]    an outer ring surrounding the circumference of the disk and configured to rotate relative to the disk; wherein the outer ring includes areas that block radiation and areas that are transparent to the emission of radiation; and wherein in a rest position the outer ring is situated relative to the rotatable disk such that the areas that block radiation are blocking the emission of radiation from the few locations on the circumference of the disk that allow the emission of radiation; 
         [0016]    a motor for rotating the rotatable disk relative to the outer ring; and 
         [0017]    wherein the rotatable disk and outer ring are initially in the rest position blocking the emission of radiation until the motor is activated to rotate the rotatable disk and allow the emission of radiation. 
         [0018]    In an exemplary embodiment of the invention, the imaging capsule further includes a spring coupling the rotatable disk to the outer ring, and wherein the spring is configured to automatically return the rotatable disk and outer ring to the rest position when the motor is deactivated. Optionally, the imaging capsule further includes flaps extending from the outer ring and an encasement with an inner lining enclosing the imaging capsule, wherein the flaps are in contact with the inner lining of the encasement and are held by a force that prevents the outer ring from rotating responsive to the torque of the spring and the rotation of the rotatable disk. In an exemplary embodiment of the invention, the force between the flaps and the inner lining is a friction force. Alternatively, the force between the flaps and the inner lining is an electromagnetic force. In an exemplary embodiment of the invention, the force between the flaps and the inner lining is controllable. Optionally, if the motor is deactivated and the force between the flaps and the inner lining is turned off, the outer ring will rotate to return the rotatable disk and outer ring to the rest position. In an exemplary embodiment of the invention, if the motor is deactivated and the force between the flaps and the inner lining is turned on, the rotatable disk will rotate to return the rotatable disk and outer ring to the rest position. 
         [0019]    In an exemplary embodiment of the invention, the motor is connected to the rotatable disk with a clutch that allows the motor to rotate the rotatable disk in a specific direction and the rotatable disk can rotate back freely when the motor is deactivated. Optionally, the imaging capsule further includes an encasement with an inner lining enclosing the imaging capsule, wherein the inner lining applies an electromagnetic force on the outer ring, and wherein the electromagnetic force controllably prevents the outer ring from rotating responsive to the torque of the spring and the rotation of the rotatable disk. In an exemplary embodiment of the invention, the imaging capsule, further includes a first limiter attached to the rotatable disk and a second limiter attached to the outer ring, wherein the limiters prevent the rotatable disk and outer ring from leaving the rest position under the influence of the spring and the limiters force the outer ring to rotate with the rotatable disk under the force of the motor. Optionally, the rotatable disk and the outer ring are configured to controllably emit radiation 360 degrees around the rotatable disk. In an exemplary embodiment of the invention, the rotatable disk and the outer ring are configured to controllably emit radiation for a pre-selected amount of time or a pre-selected number of rotations. Optionally, the imaging capsule further includes a transceiver to receive instructions to activate or deactivate the motor. In an exemplary embodiment of the invention, the imaging capsule is pre-programmed to activate or deactivate the motor at specific times. 
         [0020]    There is further provided according to an exemplary embodiment of the invention, a method of providing fail-safe radiation while scanning inside a living body, including: 
         [0021]    mounting a radiation source on a rotatable disk; 
         [0022]    positioning collimators on the disk so that the radiation is substantially allowed to be emitted only from a few locations on the circumference of the disk; 
         [0023]    placing an outer ring to surround the circumference of the disk and configured to rotate relative to the disk; wherein the outer ring includes areas that block radiation and areas that are transparent to the emission of radiation; 
         [0024]    situating the outer ring and rotatable disk initially in a rest position wherein the outer ring is situated relative to the rotatable disk such that the areas that block radiation are blocking the emission of radiation from the few locations on the circumference of the disk that allow the emission of radiation; 
         [0025]    receiving instructions to begin emitting radiation; 
         [0026]    activating the motor to rotate the rotatable disk relative to the outer ring to a position that allows the emission of radiation. 
         [0027]    In an exemplary embodiment of the invention, the method further includes connecting between the rotatable disk and outer ring with a spring so that they will return to the rest position automatically when the motor is deactivated. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The present invention will be understood and better appreciated from the following detailed description taken in conjunction with the drawings. Identical structures, elements or parts, which appear in more than one figure, are generally labeled with the same or similar number in all the figures in which they appear, wherein: 
           [0029]      FIG. 1  is a schematic illustration of a perspective view of a failsafe imaging capsule, according to an exemplary embodiment of the invention; 
           [0030]      FIG. 2  is a schematic illustration of a perspective view of a radiation control mechanism, according to an exemplary embodiment of the invention; 
           [0031]      FIG. 3  is a schematic illustration of a top view of a radiation control mechanism, according to an exemplary embodiment of the invention; 
           [0032]      FIG. 4  is a schematic illustration of a top view of a radiation control mechanism in a rotated position, according to an exemplary embodiment of the invention; and 
           [0033]      FIG. 5  is a schematic illustration of a top view of a radiation control mechanism in a rotated position without a spring, according to an exemplary embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIG. 1  is a schematic illustration of a perspective view of a failsafe imaging capsule  100 , according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, a patient first swallows a contrast agent which mixes with the content of their gastrointestinal tract to increase the accuracy of the measurements. Then the patient swallows imaging capsule  100  to examine the gastrointestinal tract as imaging capsule  100  proceeds through the gastrointestinal tract. In an exemplary embodiment of the invention, imaging capsule  100  is designed to automatically block radiation from being emitted from it until receiving instructions to release radiation and image its surroundings. In an exemplary embodiment of the invention, power is required to prevent blocking emission of radiation. Optionally, if imaging capsule  100  lacks power the radiation will be blocked. 
         [0035]    In an exemplary embodiment of the invention, imaging capsule  100  includes an encasement  105  for holding and protecting the elements of the device from acids and other liquids or gases along its path of motion. Optionally, the encasement should be able to withstand external pressures for at least 50-100 hours to allow for imaging capsule  100  to traverse the gastrointestinal tract and exit while still intact. Inside encasement  105  imaging device  100  includes a power source  180  (e.g. one or more batteries), a motor  185 , a radiation source  110 , a detector  195  and a transceiver  135 . In an exemplary embodiment of the invention, radiation source  110  is located on a rotatable disk  145  and provides radiation that is blocked by a filling material  130  that forms the disk (e.g. made of lead or tungsten or other dense materials). Optionally, the radiation is only free to travel in a few specific directions through collimators  120 . 
         [0036]    In an exemplary embodiment of the invention, power source  180  provides power to motor  185 , motor  185  is configured to rotate disk  145  around a rotation axis  125  with radiation source  110  and collimators  120  mounted on disk  145 . Optionally, one or more directed radiation beams are emitted from collimators  120  controllably scanning the surroundings through imaging capsule  100 . Optionally, detector  195  detects backscattered particles resulting from the directed radiation beam. In an exemplary embodiment of the invention, detector  195  counts the detected particles and provides the information to transceiver  135  for transmission to an external device (e.g. a computer) for processing and optionally constructing a visual representation of the information. In some embodiments of the invention, transceiver  135  uses radio frequency (RF) transmissions to receive instructions from an external device and to provide information to the external device. Optionally, the external device may instruct imaging capsule  100  to start scanning, to stop scanning, to scan in a specific motion pattern or at specific times. 
         [0037]      FIG. 2  is a schematic illustration of a perspective view of a radiation control mechanism  200 , and  FIG. 3  is a schematic illustration of a top view of radiation control mechanism  200 , according to an exemplary embodiment of the invention. In an exemplary embodiment of the invention, radiation control mechanism  200  includes disk  145  and an outer ring  140  that shares the same rotation axis  125  as disk  145  and is free to rotate surrounding the circumference of disk  145 , for example by being connected to axis  125  from below disk  145 . Optionally, outer ring  140  includes shutters  150 , which are made up from a material that blocks radiation and the rest of outer ring  140  (transparent area  155 ) does not block radiation. In an initial rest position outer ring  140  is positioned so that shutters  150  coincide with the outlets of collimators  120 , so that the emission of radiation from the collimators  120  is blocked. 
         [0038]    In an exemplary embodiment of the invention, disk  145  and outer ring  140  are connected together with a spring  190 , for example in the shape of a spiral. Optionally, if disk  145  is rotated (e.g. clockwise) the spring will tighten and exert a force on outer ring  140 , so that it will aspire to follow suit. In an exemplary embodiment of the invention, outer ring  140  includes flaps  160  that extend from the sides of outer ring  140 . Optionally, outer ring  140  includes a hinge  175 , for example with an internal spring causing flaps  160  to extend outward from the side of outer ring  140  and causing them to be placed in contact with encasement  105  or a friction lining  115 . In an exemplary embodiment of the invention, the friction between the flaps  160  and the friction lining  115  prevent outer ring  140  from initially rotating while disk  145  is rotating and the spring  190  is getting tighter. 
         [0039]      FIG. 4  is a schematic illustration of a top view of radiation control mechanism  200  in a rotated position, according to an exemplary embodiment of the invention. As disk  145  rotates relative to outer ring  140 , in some positions, shutters  150  stop blocking the outlets of collimators  120  and the radiation is freely emitted to scan the patient. 
         [0040]    In some embodiments of the invention, a motion limiter  170  is attached to disk  170  and another motion limiter  170  is attached to outer ring  140 . Optionally, in the rest position of radiation control mechanism  200 , spring  190  is unwound, collimators  120  are blocked and the limiters prevent disk  145  from slipping and accidentally uncovering the outlets of collimators  120 . Optionally, after rotating 360° as shown in  FIG. 4  the collimators are open, and spring  190  is in a tightened position. Then motion limiters  170  meet on their opposite sides and the rotation of disk  145  by motor  185  forces outer ring  140  to rotate together with disk  145  and scan the patient even though flaps  160  are rubbing against friction lining  115 . Optionally, scanning may be performed over 360° (the entire circumference of imaging capsule  100 ) for a pre-selected amount of time or a pre-selected number of rotations. 
         [0041]    In an exemplary embodiment of the invention, when motor  185  is turned off, spring  190  exerts torque on disk  145  causing it to rotate in the opposite direction (e.g. counter clockwise) and to return to the rest position relative to outer ring  140  blocking the emission of radiation. 
         [0042]    In some embodiments of the invention, limiters  170  may be placed in various positions to initiate or prevent motion from various positions as explained above and not necessarily in the positions shown in the attached figures. 
         [0043]    In an exemplary embodiment of the invention, motor  185  is coupled to a clutch  187  for delivering rotational motion to disk  145 . Optionally, clutch  187  allows disk  145  to move freely in the opposite direction when motor  185  is turned off so that the entire motor assembly does not need to rotate in the reverse direction under the torque of spring  190 . Optionally, the clutch may be controlled electrically or mechanically to allow free motion in one state and motor controlled motion in the other state. 
         [0044]    In some embodiments of the invention, other mechanisms instead of flaps  160  may be used for causing friction between outer ring  140  and encasement  105 . Additionally, the roles of disk  145  and outer ring  140  may be reversed so that the motor will drive outer ring  140  and disk  145  will be held by friction with a non moving part of imaging capsule  100 . 
         [0045]      FIG. 5  is a schematic illustration of a top view of a radiation control mechanism  200  in a rotated position without a spring, according to an exemplary embodiment of the invention. In some embodiments of the invention, disk  45  and outer ring  140  are not connected with a spring  190  as described above. Accordingly, power is required to turn the motor and unblock the outlets of collimators  120  as described above. However the outlets are not automatically closed when the motor stops turning because of spring  190 . Instead motor  185  is required to change the direction of rotation to restore disk  145  to the rest position relative to outer ring  140  so that the outlets of collimators  120  are blocked by shutters  150 . 
         [0046]    In an exemplary embodiment of the invention, the friction between flaps  160  and lining  115  is controllable. Optionally, when motor  185  stops turning instead of releasing motor  185  and allowing disk  145  to rotate back to its rest position under the influence of the torque of spring  190 , the friction between flaps  160  and lining  115  is canceled and outer ring  140  moves under the influence of the torque of spring  190 , so that spring  190  unwinds and disk  145  returns to the rest position relative to outer ring  140  while disk  145  remains stationary. 
         [0047]    In an exemplary embodiment of the invention, the friction between flaps  160  and lining  115  is released by instructing hinge  175  to relax its hold on flaps  160  allowing them to move closer to outer ring  140  and thus releasing the friction between them and lining  115 . Alternatively, lining  115  may include an electromagnet that is turned on when motor  185  starts turning. The electromagnet exerts a force on flaps  160  inhibiting motion of outer ring  140 . Optionally, when motor  185  stops the flaps are released and the torque of spring  190  causes outer ring  140  to rotate such that disk  145  will return to the rest position relative to outer ring  140  thus blocking the emission of radiation. 
         [0048]    In some embodiments of the invention, the electromagnetic force acts directly on outer ring  140  and does not require the use of flaps  160 . When the electromagnetic force is activated the outer ring will be subject to a friction force that inhibits motion of outer ring  140 . 
         [0049]    In some embodiments of the invention, lining  115  may be made from a material that expands or contracts causing the flaps to rub against the lining or be released, for example the lining may be a Nitonol spring or wire that changes shape when current passes through it causing it to heat up and expand or contract. Optionally, a Nitinol alloy may have 2 positions: one when current passes through it and friction is required and the other when no current passes through it. 
         [0050]    In some embodiments of the invention, lining  115  may include a piezoelectric device that changes size responsive to an electric voltage being applied to it. Optionally, the piezoelectric device can form contact with flaps  160  or outer ring  140  to inhibit motion or the piezoelectric device can release them. 
         [0051]    It should be appreciated that the above described methods and apparatus may be varied in many ways, including omitting or adding steps, changing the order of steps and the type of devices used. It should be appreciated that different features may be combined in different ways. In particular, not all the features shown above in a particular embodiment are necessary in every embodiment of the invention. Further combinations of the above features are also considered to be within the scope of some embodiments of the invention. 
         [0052]    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.