Array system and method for detecting position of in vivo signal source

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention generally relates to in-vivo camera systems and, in particular, to systems and methods for locating such in-vivo camera systems.

【0002】

[Conventional technology]

Various in-vivo measurement systems have been conventionally known. These systems have ingestible electronic capsules that collect data and send that data to a receiving system. These capsules, which move through the digestive system by peristalsis, are the "Heidelberg" capsules that measure pH, the "Core Temp" capsules that measure temperature, and others that measure pressure in the intestine. Contains capsules. In addition, these capsules have been used to measure the gastric residence time and the intestinal transit time, which are the times required for food to pass through the stomach and intestines.

【0003】

In general, an intestinal capsule has a measuring system and a transmitting system, which transmits data measured at a radio frequency to a receiving system. In other systems, all data can be stored in a storage device inside the capsule. The data can then be read after the capsule exits the gastro-intestinal (GI) system.

【0004】

In vivo camera systems are known, and one such known camera system is carried by a swallowable capsule. The in-vivo camera system captures and transmits GI-based images as the capsule passes through the gastric-intestinal lumen. The system has a capsule that can pass through the entire digestive system and act as an autonomous video endoscope.

【0005】

Conventional attempts to locate transmit capsules in the stomach and uterus spatially scan a non-moving patient with a receiver. The receiver and scanning system will detect the location with the highest reception rate and plot the path of the capsule, in this case assuming the capsule is where the strongest signal is received. These attempts use laboratory equipment that is not portable and is not commercially available.

【0006】

Other attempts to locate the in vivo capsule analyze statistics of signal changes as the capsule passes through the GI system. Large signal level changes can be observed as the capsule passes through certain important locations in the lumen, and these changes are associated with specific anatomical features. This method is inherently inaccurate because the anatomically important locations of the GI system are not strongly positioned relative to the reference fixed frame.

【0007】

[Problems to be Solved by the Invention]

As a part of the present invention, there is an antenna array having a plurality of antenna elements. The antenna array can be fixed to the body and two or more antenna elements can receive signals from in vivo signal sources. The signal strength of the received signal can be measured, and the estimated position of the signal source can be obtained from the measured value of the signal strength.

【0008】

The subject matter of the present invention is specifically pointed out and explicitly asserted in the first part of the specification. However, the present invention, its features and advantages relating to a configuration and method of operation involving a container can best be understood by reading the following detailed description with reference to the accompanying drawings.

【0009】

It will be appreciated that the elements shown in the drawings are not necessarily drawn in constant dimensions for the sake of simplicity and clarity. For example, for clarity, the dimensions of some elements may be exaggerated relative to other elements. Also, reference numerals may be repeated between drawings to indicate corresponding or similar elements, where appropriate.

【0010】

[Means for solving problems]

In the following detailed description, a number of specific details are provided to fully understand the invention. However, as will be appreciated by those skilled in the art, the present invention can be practiced without these particular details. Other examples do not detail well-known methods, procedures, components and circuits so as not to obscure the invention.

【0011】

Unless otherwise specified, descriptions using terms such as "processing," "calculation," "calculation," and "decision" throughout the specification are calculated, as will be apparent from the following description. Manipulate and / or compute data represented as electronic physical quantities in system registers and / or memory System memory, registers or such other information storage, transmission and display devices. It is believed to indicate the operation and / or processing of a computer, computing system, or similar electronic computing device that transforms into other similar data expressed as the physical quantity of.

【0012】

Embodiments of the present invention can include devices that perform various operations. The device may specifically be configured for a desired purpose, or may include a general purpose computer that is selectively operated or reconfigured by a computer program stored in the computer. Such computer programs are, but are not limited to, floppy (registered trademark) disks, optical disks, CD-ROMs, any type of disk including optical magnetic disks, read-only memory (ROM), random access memory (RAM). , An electrically programmable read-only memory (EPROM), an electrically erasable and programmable read-only memory (EEPROM), a magnetic or optical card, or a computer system bus suitable for storing electronic instructions. It is stored in a computer-readable storage medium, such as any other type of medium that can be connected to.

【0013】

The processes and indications presented herein are not essentially related to any particular computer or other device. A variety of general purpose systems may be used with programs that follow the teachings herein, or it may be convenient to configure specific devices that perform the desired method. The desired structure of these various systems will become apparent from the description below. Also, embodiments of the present invention are not described for any particular programming language. It will be appreciated that the teachings of the invention described herein may be practiced using a variety of programming languages.

【0014】

BEST MODE FOR CARRYING OUT THE INVENTION

See Figures 1A and 1B. As shown in FIGS. 1A and 1B, as part of the present invention, a wearable antenna array or antenna array belt 10 can be used to locate in vivo signal sources. The antenna array belt 10 is wrapped around the patient and attached to the signal recorder 20. Another embodiment includes an antenna element having an adhesive, which can be adhered to a part of the living body. Each antenna element 10a to 10z of the array can be connected to a connector connected to the recorder 20 via a coaxial cable. Each antenna element 10a to 10z may be a loop antenna, or may have any other configuration known in the art.

【0015】

In one embodiment, the antenna array belt generally has eight antenna elements located in the central portion of the subject. For example, the antenna element can be positioned as follows. The first antenna element is located on the intersection of the right 7th intercostal muscle and the right central clavicle line, the second antenna element is located on the sword-shaped protrusion, and the third antenna element is on the left second. 7 Located on the intersection of the intercostal muscles and the left central clavicle line, the 4th antenna element is located on the right lumbar region at the height of the navel, and the 5th antenna element is located above the navel. However, the sixth antenna element is located on the left waist region at the height of the navel, the seventh antenna element is located on the right center region, and the eighth antenna element is located on the left center region. To position. The antennas may be arranged at other positions, or different numbers of antennas may be used. For example, the antenna array may be placed on the back of the subject.

【0016】

Further, as shown in FIG. 2, the data recorder 20 may have a receiver 21, a signal strength measuring device 24, a processing device 26, and an antenna selector 25 in addition to the data storage device 22. In another embodiment, the data recorder 20 may have a combination of other components, and the components described above may be divided among other devices. The signal strength measuring device 24 can measure the signal strength of the signal received by the receiver 21 from each antenna element from 10a to 10z, and the processing device 26 associates the received signal with the estimated location of the signal source. Can perform operations. The antenna selector 25 can open a signal path to a single antenna element on which the receiver 21 receives the signal. The antenna selector 25 can be adjusted to scan all or part of the antenna members 10a to 10z. The scan speed and scan pattern can be adjusted to maximize the signal-to-noise ratio of the received signal.

【0017】

FIG. 3 shows an example of the in-vivo signal source 100 according to the embodiment of the present invention. The signal source 100 is a capsule that can be taken. The capsule 100 can have a plurality of sensors such as a temperature sensor 110a, a pH sensor 110b, and an optical sensor 110c. Other sensors or sets of sensors may be used. The sensor 110 can supply data to, for example, the data transmitter 120. The beacon 130 can transmit an intermittent beacon signal and can also instruct the beacon 130 to transmit the data signal at the same time or substantially at the same time as the data transmitter 120 transmits the data signal. Generally, the data transmitter 120 transmits at a higher frequency than the beacon 130, but it does not have to. In one embodiment of the invention, the data transmitter 120 can transmit an unmodulated signal as a beacon signal. In one embodiment, the capsule may include components that are similar to or similar to those described in the art.

【0018】

FIG. 4 shows an enlarged view of a human torso wearing a belt 10, i.e., an adhesive antenna array according to an embodiment of the present invention. In addition, the estimated location of the in-vivo signal source 100 has appeared. This location is shown as the intersection of three circles with radii R1, R2, and R3. The value of each radius is the value of the estimated distance of the signal source 100 from each of the antenna elements 10k, 10f, and 10g, respectively. The distance value can be calculated by the processing device 26 based on the signal strength measurement performed by the signal strength measuring device 24. For example, as a propagation condition used for processing localization signal data, it is assumed that the radiation attenuation is linear in the body. This is equal to the following equation.

[Number 1]

<img file="JP2003019111A_D0001.tif" />【0019】

Where r is the distance (cm) between the capsule and the antenna, I₀Is the signal level in the capsule (dBm), Ir is the signal level in r (dBm), and α is the absorption coefficient (dB / cm). It is reasonable to assume linear attenuation in the operating frequency range (200 to 500 MHz) and in the intermediate distance between the transmitter and receiver, that is, at half the wavelength distance of 2 to 2.5 wavelengths. is there. If the signal level at the signal source and the signal level measured at each antenna are known, the distance between the signal source and the antenna can be obtained.

【0020】

The general signal source triangulation technique shown in Figure 4 is well known. However, for the sake of perfection, further examples of methods for estimating the position of the in vivo signal source according to the present invention are shown below.

【0021】

FIG. 5 shows three signal vectors for the signals received by the three antenna elements 10d, 10p, and 10q. Starting from the origin of the three coordinate systems centered on the navel, each signal vector indicates the direction of each antenna element and has a magnitude related to the received signal strength. Each signal vector can be calculated as the product of the directional vector from the origin to the point where each antenna element is located and the normalized received signal value. The normalized signal strength value can be calculated by dividing each measured signal strength value by the strongest measured value. This normalizes the strongest measurements to 1 and the rest to less than 1. Therefore, the signal vector pointing to the antenna element that receives the strongest signal level appears to be the same as the directional vector. Other signal vectors are shorter than the directional vector.

【0022】

The estimated point, that is, the location of the signal source 100 can be measured as the vector sum of all signal strength vectors and position vectors. The signal vector can be calculated for two or more antenna elements 10a to 10z. The signal vector can be calculated only for the antenna elements located in front of the fuselage, as shown in FIG. The signal vector can also be calculated for the antenna element located on the back of the body (Fig. 1B). In FIG. 6, the estimated point, which is the position of the signal source 100, is in the body. In general, a position vector starts at the origin of a three-dimensional system and ends at a point in the body.

【0023】

As part of the present invention, a set of absolute coordinates may be used to measure points in the body in standard units such as centimeters and inches. Alternatively, values can be assigned to anatomical points in the body and then the results can be normalized. For example, coordinate sets 0 and 0 may be given to the antenna element arranged on the navel, and coordinate sets 5 and 0 may be given to the antenna element arranged on the right end of the body at the height of the navel. It may be -5 or 0 for the antenna element arranged at the left end. The value of the distance, or the magnitude of the vector, can be calculated using these coordinate sets. The value can then be adjusted proportionally to fit the actual dimensions of the body. For example, if you calculate a 2.5 inch distance value based on the coordinates mentioned above, but later measure that your body is actually 7 units from the navel to the right edge, the 2.5 distance value will be the same percentage 7/5. Can be adjusted to.

【0024】

Only the strongest two or three sources can be used to reject weaker signal strength values and calculate signal vectors, or distance values that are the basis for position estimation. Once the strongest signal group has been identified, a second signal strength measurement may be performed. The processing apparatus may perform a conventional vector sum operation on a part of the largest vector and a weighted sum operation on a relatively small signal vector. Other operations may be used to perform other operations on the collected signal.

【0025】

The antenna selector 25 may be adjusted to scan only the antenna element that receives the strongest signal and exclude all other antennas. Eliminating or rejecting signal information from antennas that supply weak signals generally increases the signal-to-noise ratio.

【0026】

However, in other embodiments, position vectors, or distance values, can be calculated for many antenna elements, and signal vectors of relatively small magnitude may be multiplied by a reduction / weighting factor, as shown in FIG.

【0027】

The estimated position of the in-vivo signal source can be detected continuously or semi-continuously. The instantaneous velocity vector for the signal source can be calculated using position information. For example, the velocity vector is a vector that starts at the tip of the first position vector and ends at the tip of a continuous position vector. Alternatively, the velocity of the signal source can be calculated as a derivative of position and the direction can be plotted on a display or graph functionally associated with the data recorder 20.

【0028】

In embodiments of the present invention, additional procedures for detecting defective antenna elements can be performed. If it is determined that the antenna element is defective, the entire path may be invalidated. In an example of such a procedure, for each antenna, reads for all frames (if not discarded) are collected in two bins, eg, reads in the range bin 1 = 0-40, bin 2 = The number of readings in the range of 41 to 255, the number of readings in the range of bin 1 = 0 to 107, and the number of readings in the range of bin 2 = 108 to 255. The result is an 8-histogram of two bins, one for each antenna. If bin 1 / (bin 1 + bin 2)&gt; 0.75, the antenna is bad. Other than that, the antenna is good. If all antennas are good, the route is judged to be valid. Further, when thReception (n) &lt;60 (in the case of the first example) or thReception (n) &lt;117 (in the case of the second example), the reading of the sensor can be discarded.

【0029】

Although the specific features of the present invention have been illustrated and described herein, those skilled in the art can recall many modifications, substitutions, modifications, and equivalents. Therefore, it should be considered that the claims of the heading are intended to include all such modifications and alterations as being within the spirit of the present invention.

[Simple explanation of drawings]

[Fig. 1A]

A person wearing an antenna array according to an embodiment of the present invention is shown.

[Fig. 1B]

A person wearing an antenna array according to an embodiment of the present invention is shown.

[Figure 2]

A data recorder according to an embodiment of the present invention is shown.

[Fig. 3]

An in vivo signal source according to an embodiment of the present invention is shown.

[Fig. 4]

The estimated points of the fuselage and the signal source equipped with the antenna array according to the embodiment of the present invention are shown.

[Fig. 5]

It shows three signal vectors in a two-dimensional plane.

[Fig. 6]

It shows three signal vectors in three-dimensional space.

[Fig. 7]

The graph of the weighting function for the signal vector is shown.

[Explanation of symbols]

10 Antenna array belt 10a, 10b, 10c, 10d, 10e, 10f, 10g, 10h, 10i, 10j, 10k, 10l, 10m, 10n, 10o, 10p, 10q, 10r, 10s, 10t, 10u, 10v, 10w, 10x, 10y, 10z antenna element 20 signal recorder 21 receiver 22 Data storage device 24 Signal strength measuring device 25 antenna selector 26 Processing equipment 100 In vivo signal source 110a, 110b, 110c sensors 120 data transmitter 130 Beacon