RELATED APPLICATIONS

The present application claims priority from US Provisional application number 63/287,117 filed on December 8, 2021, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to a system and method for controlling an X-ray imaging capsule for colon cancer screening and more specifically to controlling scanning and standby intervals of the capsule while traversing a user’s gastrointestinal tract.

BACKGROUND OF THE INVENTION

Radiation based imaging capsules can be used to perform Colorectal Cancer (CRC) screening within a user’s gastrointestinal tract. The imaging capsule typically uses X-ray radiation and/or Gama-ray radiation to detect polyps, lesions and cancer in the user’s colon or small intestine. The imaging capsule detects changes in morphology of the colon by measuring the distances from the capsule to the colon wall and reconstructing 2D or 3D images of the colon walls.

Typically, the imaging capsule records the measurements and transmits them (e.g. a count rate detected by a particle detector) to an external analysis device, for example a computer or other dedicated instruments for analysis and reconstruction of images of the inner wall of the colon and/or small intestine.

The imaging capsule may also incorporate a tracking system including various sensors to identify the location of the imaging capsule as it traverses the gastrointestinal tract and enable reconstruction of a 2D or 3D map with the images of the colon and/or small intestine. The sensors also may help to decide when to scan the surroundings of the imaging capsule and when to remain in standby mode. SUMMARY OF THE INVENTION

An aspect of an embodiment of the invention, relates to an imaging capsule for scanning with radiation within the gastrointestinal tract of the user, wherein the imaging capsule is controlled by a Scan Control program (SCP) that determines when to scan to optimally cover the inner walls of the gastrointestinal tract. The imaging capsule is used with an external receiver that is worn by the user (e.g., as a belt or patches attached to the user’s back) to track the imaging capsule and collect scan image data produced by the imaging capsule. The imaging capsule and external receiver include various sensors such as an accelerometer, a magnetometer and/or a low intensity coil to provide measurements that identify sample points representing the location of the imaging capsule. The sample points may not be so accurate since they are affected by user motion and position measurement errors. The tracking system analyzes a set of sample points and generates a virtual movement point, which is more accurate since it is based on multiple sample points (e.g., by averaging) to remove errors and noise. A sequence of movement points forms a path that exemplifies the 3D motion of the imaging capsule within the gastrointestinal tract of the user.

In an embodiment of the disclosure, the scan control program also uses measurements from various sensors to identify the organ in which the imaging capsule is located and/or an approximate location within the organ to enhance accuracy.

There is thus provided according to an embodiment of the disclosure, a system for scanning a gastrointestinal tract of a user, comprising:

An imaging capsule that is configured to scan with radiation within the gastrointestinal tract, comprising:

A radiation source that emits a radiation beam;

At least one detector configured to detect particles resulting from X-ray fluorescence and/or Compton backscattering responsive to the radiation beam; A controller configured to execute a scan control program that controls commencing a scan responsive to motion of the imaging capsule; an external receiver comprising:

A tracking system configured to track the motion of the imaging capsule and communicate with the controller of the imaging capsule;

Wherein the tracking system analyzes a set of sample points based on sensor measurements of the imaging capsule and the external receiver, and generates from them movement points that represent an accurate path of the imaging capsule within the gastrointestinal tract of the user; and

Wherein the number of sample points used to generate the movement points is adjusted based on a rate of motion of the imaging capsule.

In an embodiment of the disclosure, the system is configured to predict a fast mass movement in the colon and reduce the number of sample points used to form a movement point prior to the fast mass movement. Optionally, the system is configured to adjust the scan rate responsive to an amount of power remaining in the battery of the imaging capsule. In an embodiment of the disclosure, the system is configured to scan only within specific organs. Optionally, identifying that the imaging capsule is in the small intestine is based on a frequency of movement of the imaging capsule. In an embodiment of the disclosure, identifying that the imaging capsule is in the small intestine is based on results of a scan. Optionally, the movement points are based on an average of the set of sample points. In an embodiment of the disclosure, the movement points are generated by applying a Kalman filter to the sample points. Optionally, a low pass filter is used to form a moving average from the sample points and reduce noise in the values of the sampled points. In an embodiment of the disclosure, when reducing the number of sampling points for handling a fast mass movement the tracking system continues to generate movement points also for a larger number of sampling points to enhance mapping accuracy.

There is further provided according to an embodiment of the disclosure, a method, comprising: Swallowing an imaging capsule to scan with radiation within the gastrointestinal tract; wherein the imaging capsule includes a radiation source that emits a radiation beam, detectors to detect particles resulting from X-ray fluorescence and/or Compton backscattering responsive to the radiation beam, a controller configured to execute a scan control program that controls commencing a scan responsive to motion of the imaging capsule;

Placing an external receiver on the user to track the motion of the imaging capsule and communicate with the controller of the imaging capsule;

Analyzing a set of sample points based on sensor measurements of the imaging capsule and the external receiver;

Generating movement points that represent an accurate path of the imaging capsule within the gastrointestinal tract of the user, based on the set of sample points; and

Wherein the number of sample points used to generate the movement points is adjusted based on a rate of motion of the imaging capsule.

BRIEF DESCRIPTION OF THE DRAWINGS

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:

Fig. 1 is a schematic illustration of a system for examining within the gastrointestinal tract, according to an embodiment of the disclosure;

Fig. 2 is a schematic illustration of an imaging capsule in a user’s small intestine or colon, according to an embodiment of the disclosure;

Fig. 3 is a flow diagram of a method of examining a user’s small intestine or colon, according to an embodiment of the disclosure;

Fig. 4A is a schematic graph of the position of an imaging capsule moving in the small intestine, according to an embodiment of the disclosure;

Fig. 4B is a schematic graph of energy amplitudes of an imaging capsule in the small intestine, according to an embodiment of the disclosure;

Fig. 4C is a schematic graph of a zoom in on a segment of the above graphs, according to an embodiment of the disclosure;

Fig. 5 is a schematic illustration of a graph depicting current consumption versus battery consumption as a function of time, according to an embodiment of the disclosure; and

Fig. 6 is a schematic illustration of movement points forming a path, and a 3D graph of a mapping of the path taken by the imaging capsule through a user’s colon, according to an embodiment of the disclosure.

DETAILED DESCRIPTION

Fig. 1 is a schematic illustration of a system for examining within the gastrointestinal tract, and Fig. 2 is a schematic illustration of an imaging capsule 150 in a user’s colon 195, according to an embodiment of the disclosure. The imaging capsule 150 is configured to enable scanning a user’s gastrointestinal tract optionally including the small intestine 193, the cecum 194 and the colon 195 to detect abnormalities, such as polyps 162 or inflammation 164. Generally, it is desirable to scan the entire colon 195 and sometimes also to scan in the small intestine 193 and/or cecum 194.

The imaging capsule 150 includes a controller 168 that is programmed with a scan control program (SCP) 169, which decides when to scan and when to standby based on measurements from sensors within the imaging capsule 150 and from an external receiver 120. The imaging capsule 150 further includes a power source, for example a battery 155 for powering the imaging capsule 150. Optionally, the imaging capsule records measurements and transmits them to the external receiver 120 for analysis to conserve energy in the imaging capsule 150.

In an embodiment of the disclosure, the imaging capsule emits X-ray radiation to scan the inner walls of the small intestine and/or colon and uses at least one detector to detect particles resulting from X-ray fluorescence and/or Compton backscattering. Optionally, the scan control program 169 aims on one hand to continuously scan the entire inner wall of the colon 195 and transmit the measurements to the external receiver 120. On the other hand, the scan control program aims to reduce and conserve the power of the imaging capsule (e.g., the battery power), so that the power will last while traversing the entire gastrointestinal tract, typically between 24-72 hours or more. Accordingly, the scan control program 169 aims to instruct the imaging capsule 150 to scan and transmit only once at each new location to conserve energy. However, by limiting the scans there is the risk of skipping segments of the colon and missing important information. Additionally, although the exposure to X-ray radiation is minimal ideally it is desirable to only scan once at each location to limit unnecessary exposure.

In an embodiment of the disclosure, the user swallows a radio opaque contrast agent solution 160 (e.g., based on Barium or Iodine). The radio opaque contrast agent solution 160 is mixed with the content of the gastrointestinal tract to increase the accuracy of the measurements performed by imaging capsule 150. Typically, the user waits a few hours (e.g., between 2-48 hours) after swallowing the radio opaque contrast agent solution 160 before swallowing the imaging capsule 150 so that the contrast agent solution 160 will spread through the gastrointestinal tract.

In an embodiment of the disclosure, the imaging capsule 150 travels through the patient's mouth 190, esophagus 191, stomach 192, small intestine (bowel) 193 and then enters the cecum 194, which is the beginning of the colon 195. Then the imaging capsule 150 passes through the colon 195 and exits through the rectum and anus. In an embodiment of the disclosure, the imaging capsule 150 identifies its location (e.g., in which organ it is located and/or where it is located within the organ) based on measurements performed by various sensors in the imaging capsule 150. The imaging capsule 150 takes actions based on its location. Usually, to examine the colon 195 and sometimes scan a bit in the small intestine 193.

In an embodiment of the disclosure, the imaging capsule 150 is configured to scan an inner circumference of the surrounding walls of the colon 195 and transmit measurements (e.g. a count rate of particles having specific energies or range of energies) to the external receiver 120 that is typically positioned on the body of the user in the vicinity of the gastrointestinal tract. The external receiver 120 analyzes the information and may also record the information on a memory card (e.g., SD card) for later analysis. Alternatively or additionally, the receiver 120 may transmit the information to a computer 130 for analysis, for example with an analysis program 145. Optionally, the program 145 may reconstruct an image 180 of the surroundings of the imaging capsule 150. The computer 130 may display the reconstructed image 180 on a screen 135 and/or provide instructions in real time to the scan control program 169, for example to rescan its current position and provide additional images.

In an embodiment of the disclosure, imaging capsule 150 emits radiation (e.g. X-ray and/or Gamma radiation) from a radiation source 110 through collimators 115 to examine the surroundings of the imaging capsule 150. Optionally, the capsule includes one or more detectors 170 to detect particles scattered or emitted through x-ray fluoresce from the contrast agent in response to the radiation emitted from the radiation source 110. The scattered particles are generally due to Compton backscattering (CMT) from the tissue of the surrounding walls and/or X-ray fluorescence (XRF) from the contrast agent solution 160 mixed with the contents of the small intestine 193 or colon 195. For example, the contrast agent solution 160 travels through the small intestine 193 and adheres to the content and surrounding walls.

In an embodiment of the disclosure, the detectors 170 are configured to detect and count particles only from specific energy ranges. Optionally, a certain energy range is identified as CMT particles from human tissue and another energy range is identified as particles from XRF of the contrast agent.

In an embodiment of the disclosure, the imaging capsule 150 senses when it departs from the stomach 192 to the small intestine 193 by using a pH sensor 172 on an enclosure 185 of the imaging capsule 150. The pH sensor 172, senses the change in acidity, from a high acidity in the stomach 192 (pH 1-3 typically) to lower acidity in the small intestine 193 (typically pH 5-7). Optionally, the pH sensor 172 may also identify other organs (e.g., colon 195).

In an embodiment of the disclosure, the imaging capsule 150 may scan with radiation from time to time as it advances, to measure the diameter surrounding it and/or reconstruct images 180. In the stomach 192, the distance to the walls will be in the order of a few centimeters at least in some of the directions around the capsule. In contrast in the small intestine 193, it will be no more than a few millimeters at the most in all directions. Also, the amount of contrast agent solution 160 in the stomach 192 is expected to be much higher than in the small intestine 193, hence higher XRF measurements are expected. In an embodiment of the disclosure, the capsule may sense the rhythmic bowel movements of the small intestine 193 with an accelerometer 174, magnetometer 175 and/or pressure sensor 176 or from electromagnetic 3D position data to help detection of entrance into the small intestine 193 and exiting.

In an embodiment of the disclosure, hydrostatic pressure around the capsule provides an indication of the location of the imaging capsule 150, since for example the hydrostatic pressure inside the imaging capsule 150 increases when gasses in the colon 195 diffuse into the imaging capsule 150, creating a higher internal pressure in the imaging capsule 150 when it in the colon 195 than in the small intestine 193 or the stomach 192. Accordingly, based on the time from being swallowed and on the hydrostatic pressure within the imaging capsule 150, the imaging capsule can identify the organ in which it is located.

In an embodiment of the disclosure, the imaging capsule 150 may include an accelerometer 174, magnetometer 175 and a coil 178 or permanent magnet 179. These sensors cooperate with similar sensors (e.g., accelerometer 124, magnetometer 125 and coil 128) in external receiver 120 to feed a tracking system 122 that tracks the position and orientation of the imaging capsule 150. Optionally, the tracking system 122 may be implemented by a dedicated processor (e.g., an ASIC) or a general-purpose processor programmed to track the imaging capsule 150.

In an embodiment of the disclosure, as the imaging capsule 150 travels through the small intestine 193, it scans the inner walls and measures the number of CMT and XRF photons received from each radial sector surrounding the imaging capsule 150. Optionally, scanning is triggered by sensing a change in position as detected by the tracking system 122. The tracking system 122 may be based on coils 128, 178, which transmit low frequency electromagnetic signals, or permanent magnets 129, 179 located in the imaging capsule 150 or in the external receiver 120 worn by the user. Optionally, the tracking system 122 notifies the imaging capsule 150 via a transceiver 177 that the imaging capsule 150 moved to a new location. When the imaging capsule 150 moves the scan control program 169 initiates a scan of the surroundings of the imaging capsule and provides measurements to the external receiver 120, which also includes a transceiver 127. Alternatively, or additionally, the imaging capsule 150 may detect motion based on internal sensors, for example accelerometer 174 and/or a magnetometer 175.

In some embodiments of the disclosure, the imaging capsule 150 does not require a contrast agent solution 160 for analysis in the small intestine 193. Instead, in the small intestine 193 only Compton backscattering (CMT) particles are detected to identify the width of the surrounding tissue. Compton backscattering is proportional to the tissue density of the small intestine 193, and the density is influenced by the presence of an inflammation 164 or cancer growth (e.g. a malignant polyp 162).

In another embodiment of the disclosure, a thermal sensor 173 is placed on the enclosure 185 of imaging capsule 150. The thermal sensor 173 is used to detect changes in local temperature in the gastrointestinal tract. For example, while travelling through the small intestine 193 and/or the colon 195. The temperature changes can provide an indication relating to organ and/or inflamed areas 164.

In an embodiment of the disclosure, the sensors described above (e.g., pH sensor 172, thermal sensor 173, accelerometer 174, magnetometer 175, pressure sensor 176) are able to identify an approximate location of the imaging capsule 150, for example in which organ the imaging capsule 150 is located. Optionally, the sensors may identify when entering or exiting a specific organ. Likewise the imaging capsule 150 may include a timer 167 (e.g. in a controller 168) to estimate where the imaging capsule 150 is located within a specific organ, for example based on how much time has passed after identifying entry into the specific organ. In an embodiment of the disclosure, the imaging capsule 150 estimates approximately when the imaging capsule 150 is in the middle or end of a specific organ (e.g. the small intestine 193 or colon 195) based on typical flow rates of imaging capsules 150 through specific organs. Alternatively or additionally, the sensors may provide an indication of the location within a specific organ based on sensor measurements, for example based on a change in pressure, temperature, vibration frequency or other measurements.

The small intestine 193 is known to have a typical mobility of about 10-15 movements per minute (e.g., 12 movements per minute 0.2 Hz). In an embodiment of the disclosure, the mobility in the small intestine is sensed by accelerometer 174, magnetometer 175 and/or the tracking system 122. The mobility pattern enables to identify that the imaging capsule 150 is currently located in the small intestine 193.

Fig. 4A is a schematic graph of the position of an imaging capsule moving in the small intestine, according to an embodiment of the disclosure. The upper graph 400 shows independently the X, Y and Z (3 lines) position coordinates in mm of the imaging capsule 150 in the small intestine 193 as a function of time (seconds). The position is taken relative to the tail bone of the user, which is designated as 0, 0, 0. Fig. 4B is a schematic graph 430 of the energy amplitudes of the imaging capsule in the small intestine, over time of a 0.2 Hz spectral window. As shown in Fig. 4B the energy amplitude decreases upon transition into the cecum (entering the colon), since it is not pushed by the small intestine anymore, but rather flows freely through the colon 195. Fig. 4C is a schematic graph 460 of a zoom-in of a segment 410 of graph 400. Graph 460 shows the typical 0.2 Hz position oscillation due to the small intestine constant movement at this frequency. Optionally, the absence of the typical 0.2 Hz capsule position oscillations indicates that the capsule has moved from the small intestine 193 into the colon 195.

In an embodiment of the disclosure, the scan control program 169 takes into consideration that the cecum 194, is almost always on the bottom right side of the user. Thus when entering the cecum 194 the small intestine 193 movements cease and the location is at the bottom right side of the torso of the user (the general position may be verified by the tracking system 122).

In an embodiment of the disclosure, the scan control program 169 may initiate a short scan every number of minutes when the capsule is traveling in the small intestine 193 to verify that the imaging capsule 150 is still in the small intestine 193. These scans are expected to show very small amounts of X-Ray fluorescence, for example from the iodine in the contrast agent near the capsule, since the small intestine 193 is very narrow and very small amounts of contrast agent are present between the capsule and the walls of the small intestine 193. An indication that the capsule has reached the cecum 194 or colon 195 is given when the amount of X-Ray fluorescence increases substantially indicating that the volume of contrast agent near the capsule has increased, signifying that this may be the entrance into the cecum 194. The scan control program 169, thus combines the indications from all the above giving weights to each type of indication. Based on the weights the scan control program 169 determines if the imaging capsule 150 has left the small intestine 193 and entered the colon 195.

Another indication for reaching the cecum 194 is the length of small bowel which should be around 7 meters. The small intestine diameter does not allow to the capsule to rotate. Thus, the only motion of the capsule in the small intestine 193 should be the motion in the capsule long axis direction. The scan control program 169 calculates the current velocity projection to the capsule direction followed by integration. When the scan control program 169 determines that the imaging capsule 150 has covered about 7 meters it will expect to identify entrance into the cecum 194.

In an embodiment of the disclosure, the scan control program 169 continuously monitors the estimated real time battery capacity by keeping track of the time and the current consumption of the capsule. The scan control program 169 uses the real time battery capacity estimation, to optimize the scan regime increasing or decreasing the sensitivity of the scan control program 169 to new scan demands in order to make sure that sufficient battery capacity is available for the capsule to optimally scan through the entire colon. Additionally, the tracking system 122 continuously estimates how much of the colon 195 the capsule has passed, and hence correlate with an estimate of the battery capacity real time estimation to optimize scan spreading and battery usage. For example, the scan control program may scan whenever a small change in position is detected or only when significant movement is detected to conserve energy. Fig. 5 is a schematic illustration of graphs depicting current consumption versus battery consumption as a function of time, according to an embodiment of the disclosure. Graph 500 exemplifies current consumption peaks during capsule scans as a function of time, and graph 550 exemplifies battery consumption as a function of time.

In an embodiment of the disclosure, the imaging capsule 150 records measurements of various sensors periodically or on detecting changes, for example from accelerometer 174, magnetometer 175 and/or coil 178. The imaging capsule 150 transmits the measurements to external receiver 120, which also collects local measurements, for example from accelerometer 124, magnetometer 125 and/or coil 128. Imaging capsule 150 and/or tracking system 122 of external receiver 120 analyze measurements to identify real movements of imaging capsule 150 and rule out noise and measurements that are the result of user movements.

Fig. 6 is a schematic illustration of virtual movement points 610 forming a path 600, and a 3D graph of a mapping 650 of the path 600 taken by the imaging capsule 150 through a user’s colon 195, according to an embodiment of the disclosure. The movement points 610 are identified by averaging movement over a sequence of sample points 605 based on the measurements of the imaging capsule sensors and the external receiver sensors. Optionally, sampling a large set of sample points 605 enables generation of accurate movement points 610. In contrast averaging over a small set of sample points 605 generates less accurate movement points 610. When identifying significant movement, for example new movement points 610 that are more than 5-7 mm away from a previous movement point, imaging capsule 150 is instructed to scan the current location to form an image of a respective segment of the inner walls of the colon. When the imaging capsule 150 moves slowly through the colon 195 a large set of sample points 605 may be used to accurately identify movement points 610. However when the imaging capsule is swept by a fast mass movement, tracking system 122 must quickly identify movement points 610 based on a small number of sample points 605 and instruct the imaging capsule 150 to scan to prevent skipping segments of the internal walls of the colon 195.

Fig. 3 is a flow diagram of a method 300 of examining a user’s small intestine 193 and/or colon 195, according to an embodiment of the disclosure. In an embodiment of the disclosure, the user is generally required to swallow (310) contrast agent 160 to enhance the measurements of X-ray fluorescence in response to the molecules of the contrast agent. After waiting for between about 2-48 hours for the contrast agent to disperse throughout the user’s gastrointestinal tract the user swallows (320) the imaging capsule 150. While traversing the gastrointestinal tract the controller 168 of imaging capsule 150 uses scan control program 169 to identify (330) its location, for example, in which organ it is located and an approximate position within the organ. Optionally, the organ is detected based on the measurements of one or more sensors, for example pH sensor 172, thermal sensor 173, accelerometer 174, magnetometer 175 and/or pressure sensor 176, tracking system 122 or a combination thereof. Alternatively or additionally, the organ may be detected by measurements of the detectors 170, which enable for example to determine the distance to the surrounding walls or by identifying an increase or decrease in certain types of radiation (e.g. XRF, CMT). In an embodiment of the disclosure, the organ and position within the organ can be estimated by using timer 167 to keep track of the time from swallowing the imaging capsule 150 and/or from entry into each organ.

In an embodiment of the disclosure, scan control program 169 in controller 168 instructs the imaging capsule 150 to scan inside the user only in specific organs, for example only within the small intestine 193 and/or the colon 195. Optionally, in the specific organs the imaging capsule only scans when motion is detected (340) indicating that the imaging capsule moved to a new position. Optionally, while within the small intestine 193 or colon 195 the imaging capsule 150 waits until motion is detected (340) and then scans the surrounding area (350) as the imaging capsule 150 moves forward within the organ. In contrast when no motion is detected the imaging capsule 150 may remain in standby mode or scan periodically, for example every 10-30 minutes or every hour to verify that it has not advanced. Optionally, the imaging capsule 150 transmits (360) the measurements of the scans to the external controller 120 for processing.

In an embodiment of the disclosure, the external controller 120 analyzes the measurements and identifies (370) approximate sample points 605 based on the measurements. After collecting a set of sample points 605 the external controller generates (380) a virtual movement point 610, which represents a calculated accurate position of the imaging capsule 150 based on the set of not so accurate sample points 605. The generated movement points 610 are used to construct (390) a representation of the path 600 of the imaging capsule through the user’s colon 195 and/or small intestine 193.

In an embodiment of the disclosure, the scan control program 169 detects or is notified of the current position and/or movement of the imaging capsule 150 and determines if the imaging capsule 150 has moved to a new position, where the capsule has not been before (forward movement). If a new capsule position is reached, the scan control program 169 instructs the capsule to scan the new position. Optionally, the decision that the capsule is in a new position is reached by the scan control program 169 and/or the tracking system 122 if the capsule is more than about 0.5 - 0.7 cm from the last position that was scanned by the capsule. The position interval is referred to as the "capsule imaging footprint" and is the estimate of the imaging slice average width taking into account the average distance of the capsule from the inner walls of the colon 195, the collimator angular opening and the distance between the collimator opening center and the center of the detector 170. In an embodiment of the disclosure, tracking system 122 employs a low pass filter (LPF) 158 module that takes into account a number of sample points 605 and performs a moving average or alternatively calculates the median of these location points in order to filter position noise that may be due to small random movements of the capsule in the colon, small random movements of the colon in the body, position measurement noise, movements of the sensors of the tracking system 122 and other possible movements which are not net movements of the imaging capsule 150 in the colon.

In an embodiment of this invention, the length of the Low Pass Filter (LPF) 158, that is the number of points taken into the moving average, or median calculation is adaptively changed in response to an algorithm that is a part of the scan control program 169 which evaluates past movements and predicts the likelihood of an upcoming "mass movement", which is a fast movement along long segments of the colon 195. Once such fast movement is predicted, the no. of sampling points of the LPF 158 is shortened so that the scan control program 169 will respond rapidly to the commencement of the fast mass movement. Optionally, the number of sample points 605 used is reduced or increased according to the rate of motion of the imaging capsule 150 within the colon 195.

In an embodiment of the disclosure, a module in the scan control program 169 is designed to predict fast capsule movements based on parameters measured by the imaging capsule 150 and/or the external receiver 120. Such parameters may include an imaging capsule position vector from the tracking system 122, measurements from magnetometer 175 in the capsule, accelerometer 174 in the capsule, pressure sensor 176 measurements in the capsule and other information. The scan control program 169 and/or external receiver 120 use time series information from all or a subset of these signals to predict upcoming mass movements. For example, by identifying an increase in jitter/wobbling of the imaging capsule or an increase in internal pressure while moving in the colon 195. Optionally, prediction of an upcoming fast mass movements is possible due to the "preparation" of the colon for mass movements, which translates to changes in colon movement that translate to changes in some or all of the measured parameters.

A module of the scan control program 169 is designed to measure these parameters and send a signal to the scan control program 169 to change the LPF 158 sample length from long (a large set) which is adapted to slow capsule movements to a short sample length (small sample set) adapted to fast capsule movement (mass movements). Thus, the scan control program 169 is designed to switch between an LPF 158 using a long sampling set and an LPF 158 using a short sampling set in response to an estimation, that the colon is about to cause fast movement to the capsule.

In an embodiment of the disclosure, when using a short sampling set, LPF 158 may continue to calculate the movement points 610 also based on a long sampling set. The short sampling set may be used for immediate action (e.g., initiating scanning) so as not to miss segments of the colon. The long sampling set may be used to generate more accurate movement points 610 and compare them with the generated movement points 610 from the short sampling set, to improve path 600.

In an embodiment of the disclosure, a Kalman filter (also known as Linear Quadratic Estimation (LQE)) is implemented by LPF 158. The Kalman filter is used to generate the movement points 610 and also provide a prediction of future movement points 610. The prediction of the Kalman filter is used to enhance the position noise immunity of the system and to improve the response time of the system to “Mass movements” of the imaging capsule 150 in the colon 195.

In an embodiment of the disclosure, the LPF 158, continuously estimates the most probable direction of the future relevant capsule movement based on the premise that the capsule true movements along the colon are most likely to be in the long axis direction plus or minus 30 - 40 degrees off axis. The LPF 158 is designed to be more sensitive to the long axis direction of capsule movement plus or minus 30 - 40 degrees. In an embodiment of the disclosure, accelerometer 124 and/or magnetometer 125 in external receiver 120 on the back of the user are used to estimate the position change of the body of the user relative to the inertial frame of the world. This data is used by the LPF 158 to estimate movements in real time that are related to the body of the user, for example changing position in sleep, walking, turning and the like. The movement data of the external receiver 120 is used to reduce the number of capsule scans performed, by identifying movements that are the result of user movement and not imaging capsule 150 movements relative to the colon 195.

In an embodiment of the disclosure, real time map 650 of the colon is constructed out of consecutive movements of the imaging capsule 150 through the colon 195. Adjacent movement points 610 are recorded in time and a circle 615 is constructed around the movement points 610 enclosing a set of sample points 605. Sample points that are outside of a maximum radius are used to define new movement points 610. A series of movement points 610 with respective circles 615 define the real time map 650. Typically map 650 should represent a length of about 1.50 to 1.80 meters of a human colon 195. Optionally, the colon map 650 is used by the scan control program 169 to estimate capsule progress in the colon to calibrate battery power usage for optimal scan time. For example, the shape of the map is generally similar between users and a percentage of required power remaining in the battery at key positions is known. If the remaining power at the key positions is less than required the scan control program 169 can reduce scan frequency or increase scan frequency if more power is available.

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. 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.