Patent Application
20070238988
The present invention relates to a body insertable apparatus which is introduced inside a subject, acquires intra-subject information as information concerning the subject, and transmits radio signals including the acquired intra-subject information, a receiving apparatus which performs reception processing of the radio signals transmitted by the body-insertable apparatus, and a body-insertable system configured with the body-insertable apparatus and the receiving apparatus.
In recent years, in a field of endoscope, a swallowable capsule endoscope is proposed. The capsule endoscope is provided with an imaging function and a radio communication function. After being swallowed from a mouth of a subject (human body) for an observation (examination) until naturally discharged, the capsule endoscope travels inside body cavities, for example, internal organs such as a stomach and a small intestine following peristaltic movements, and has a function of sequentially capturing images.
While the capsule endoscope travels inside the body cavities, image data acquired through image capturing by the capsule endoscope inside the body is sequentially transmitted to an outside by radio communication and accumulated in a memory provided outside. By carrying a receiving apparatus provided with a radio communication function and a memory function, the subject can move freely after swallowing the capsule endoscope until discharging the same. After the capsule endoscope is discharged, a doctor or a nurse can make diagnosis by displaying images of the internal organs on a display based on the image data accumulated in the memory (see Patent Document 1, for example).
Further, among conventional capsule endoscope systems, some proposed systems include a mechanism to detect a position of the capsule endoscope in a body cavity. For example, it is possible to generate a magnetic field whose strength has a positional dependency inside the subject to which the capsule endoscope is introduced, and to detect the position of the capsule endoscope in the subject based on the strength of the magnetic field detected by a magnetic field sensor incorporated in the capsule endoscope. Such a capsule endoscope system adopts a structure in which a predetermined coil is arranged outside the subject for generation of a magnetic field, and generates the magnetic field inside the subject by letting a predetermined electric current flow through the coil.
When the position detection mechanism is further provided in the receiving apparatus as described above, various contrivances can be made in the conventional capsule endoscope system, for example, an imaging operation by an imaging mechanism can be started from a time point when the capsule endoscope reaches the small intestine of the subject. Accordingly, there can be advantages, for example, that the image data can be acquired only with respect to a necessary area for the doctor.
Patent Document 1: Japanese Patent Application Laid-Open No. 2003-19111
However, the conventional capsule endoscope system, having a position detection mechanism with a predetermined size, increases a burden placed on a patient unnecessarily when the position detection is not performed. Such inconveniences will be described in detail below.
In an examination with a capsule endoscope, there is not always a necessity to perform the position detection. For example, in an examination in which images are acquired constantly from an oral cavity to a large intestine of a subject, the examination is carried out without the position detection. In such an examination, the position detection mechanism provided in the receiving apparatus is not necessary, and the subject carries the receiving apparatus provided with the unnecessary position detection mechanism until the examination ends, whereby the burden on the subject increases unnecessarily, which is not desirable.
To alleviate the above inconvenience, it may be possible to prepare the receiving apparatus provided with the position detection mechanism and the receiving apparatus not provided with the position detection mechanism, and to selectively use each of the receiving apparatuses depending on a purpose of an examination. However, when such a structure is adopted, various types of receiving apparatuses become necessary, and costs required for the examination with the capsule endoscope increase, leading to another inconvenience.
The present invention is made in view of the above, and an object is to realize a subject insertable system provided with a body-insertable apparatus such as a capsule endoscope to allow to restrict a burden on the subject at a use of the body insertable system to a minimum degree depending on a purpose of use while suppressing an increase in operational cost.
A body insertable system includes a body insertable apparatus that is introduced inside a subject, acquires intra-subject information as information concerning the subject, and transmits radio signals including the acquired intra-subject information, and a receiving apparatus that performs reception processing of the radio signals transmitted by the body insertable apparatus. The body insertable apparatus includes an intra-subject information acquiring unit that acquires the intra-subject information; a magnetic field sensor that detects a magnetic field in a region where the body insertable apparatus is located; and a radio transmitting unit that transmits radio signals including at least the intra-subject information. The receiving apparatus includes a receiving unit that includes at least a receiving antenna which receives the radio signals transmitted by the body insertable apparatus and a receiving circuit which performs reception processing on the radio signals received by the receiving antenna; and a position detecting unit that includes a magnetic field generator which generates a predetermined magnetic field for position detection in a region where the body insertable apparatus can be present, and a position calculator that calculates a position of the body insertable apparatus based on a result of detection of the magnetic field for position detection acquired by the magnetic field sensor, the position detecting unit being formed separately and independently of the receiving unit.
According to the present invention, since the receiving unit and the position detecting unit are formed separately and independently of each other, the burden on the subject can be minimized according to the purpose of use. Specifically, when the acquisition of the intra-subject information alone is the purpose of use, the position detecting unit can be removed from the receiving apparatus and the receiving unit alone can be used, whereby the burden on the subject can be reduced.
Further, in the body insertable system according to the present invention, the radio transmitting unit may transmit radio signals including a result of detection acquired by the magnetic field sensor in addition to the intra-subject information, and the position detecting unit may acquire the result of detection acquired by the magnetic field sensor via the receiving unit.
Still further, in the body insertable system according to the present invention, the position detecting unit may be arranged in a fixed state relative to the subject at a time of use, and the receiving unit may be arranged in a movable state relative to the subject at a time of use.
Still further, a receiving apparatus performs reception processing of a radio signal transmitted from a predetermined detection target, and includes a receiving unit that includes at least a receiving antenna which receives the radio signal transmitted from the detection target, and a receiving circuit which performs reception processing on the radio signal received by the receiving antenna; and a position detecting unit that includes a magnetic field generator which generates a predetermined magnetic field for position detection in a region where the detection target can be present, and a position calculator which calculates a position of the detection target based on a result of detection of the magnetic field for position detection in the region where the detection target can be present, the position detecting unit being formed separately and independently of the receiving unit.
Still further, a body insertable apparatus is introduced inside a subject and acquires intra-subject information as information concerning the subject, and includes an intra-subject information acquiring unit that acquires the intra-subject information; a magnetic field sensor that detects a magnetic field in a region where the body insertable apparatus is located; a radio transmitting unit that transmits radio signals including at least the intra-subject information; and a magnetic field detection controller that controls a driven state of the magnetic field sensor.
According to the present invention, the body insertable apparatus can be employed only for an acquisition of the intra-subject information and for both the acquisition of the intra-subject information and position detection utilizing the magnetic field for position detection.
Still further, the body insertable apparatus according to the present invention may further include a radio receiving unit that receives a radio signal transmitted from an outside, and the magnetic field detection controller may control the driven state of the magnetic field sensor based on a control signal received by the radio receiving unit.
Still further, in the body insertable apparatus according to the present invention, the magnetic field sensor may perform a magnetic field detection in a stand-by mode in which a detection interval is longer than in a normal mode when the magnetic field for position detection is not generated in the region where the body insertable apparatus is located, and may transmit from the stand-by mode to the normal mode when the magnetic field for position detection is detected during the stand-by mode.
The body insertable system and the receiving apparatus according to the present invention are advantageous in that the burden on the subject can be minimized depending on the purpose of use since the receiving unit and the position detecting unit are formed separately and independently of each other. When the purpose is only to acquire the intra-subject information, the position detecting unit can be removed with respect to the receiving apparatus and the receiving unit alone can be used, whereby there is an advantage that the burden on the subject can be reduced.
Further, the body insertable apparatus according to the present invention is advantageous in that the body insertable apparatus can be used both for the purpose of only acquiring the intra-subject information, and for the purpose of position detection utilizing the intra-subject information and the magnetic field for position detection.
Exemplary embodiments of the present invention hereinafter simply referred to as “embodiments”), i.e., a body insertable apparatus, a receiving apparatus, and a body insertable system will be described below. The present invention is not limited to the embodiments. The drawings are merely schematic; it should be noted that relations between thickness and width of each portion and a ratio of thickness of one portion to thickness of another portion may be different from actual ones; and each drawing may include portions with different dimensional relation and different ratio.
First, a body insertable system according to a first embodiment will be described.
The display device 4 serves to display intra-subject images or the like acquired through image capturing by the capsule endoscope 2 and received by the receiving apparatus 3, and is configured like a workstation or the like that displays images based on data acquired from the portable recording medium 5. Specifically, the display device 4 may be configured so as to directly display images or the like as in a CRT display and a liquid crystal display, or alternatively, may be configured so as to output images or the like to other media as in a printer.
The portable recording medium 5 is attachable/detachable to/from a reception processing device 9 described later and the display device 4, and is configured so as to allow for output and recording of information when attached to the above two devices. Specifically, the portable recording medium 5, while the capsule endoscope 2 travels through body cavities of the subject 1, is attached to the reception processing device 9 and stores intra-subject images and positional relations of the target coordinate axes relative to the reference coordinate axes. The portable recording medium 5 is configured so as to be taken out from the reception processing device 9 and attached to the display device 4, after the capsule endoscope 2 is discharged from the subject 1, so that the recorded data is read out by the display device 4. When the data delivery between the reception processing device 9 and the display device 4 is performed with the portable recording medium 5 such as a Compact Flash (registered trademark) memory or the like, dissimilar to a system in which the reception processing device 9 and the display device 4 are connected with a cable, the subject 1 can move freely even while the capsule endoscope 2 travels inside the subject 1.
Next, the capsule endoscope 2 will be described. The capsule endoscope 2 functions as an example of a detection target and a body insertable apparatus according to the present invention. Specifically, the capsule endoscope 2 has functions of being introduced inside the subject 1, acquiring intra-subject information while traveling inside the subject 1, and transmitting radio signals including the acquired intra-subject information to an outside. Further, the capsule endoscope 2 has a magnetic field detection function for detecting positional relation described later and at the same time is configured so as to receive driving power from the outside, and specifically, the capsule endoscope 2 has functions of receiving radio signals transmitted from the outside and reproducing the driving power from the received radio signals.
The intra-subject information acquiring unit 14 serves to acquire intra-subject information, which is, in the first embodiment, an intra-subject image that is image data of the inside of the subject 1. Specifically, the intra-subject information acquiring unit 14 includes an LED 22 which functions as an illuminating unit, an LED driving circuit 23 which controls driving of the LED 22, a CCD 24 which functions as an imaging unit that captures images of at least a portion of an area illuminated by the LED 22, and a CCD driving circuit 25 which controls a driven state of the CCD 24. Here, as specific structures of the illuminating unit and the imaging unit, the use of the LED and the CCD is not essential, and a CMOS or the like can be employed as the imaging unit.
The magnetic field sensor 16 serves to detect an orientation and a strength of a magnetic field generated in a region where the capsule endoscope 2 is present. Specifically, the magnetic field sensor 16 is formed with an MI (Magneto Impedance) sensor, for example. The MI sensor is configured, for example, with a FeCoSiB amorphous wire as a magneto-sensitive medium, and detects the strength of the magnetic field by utilizing MI effect, i.e., the effect that magnetic impedance of the magneto-sensitive medium exhibits significant fluctuation attributable to an external magnetic field when a high-frequency electric current is conducted to the magneto-sensitive medium. The magnetic field sensor 16 may be configured with an element other than the MI sensor, for example, with an MRE (Magneto Resistive Effect) element, and a GMR (Giant Magneto Resistive Effect) magnetic sensor.
As shown also in
Further, the capsule endoscope 2 includes a radio transmitting unit 19 which includes a transmitting circuit 26 and a transmitting antenna 27 and serves to perform radio transmission to the outside, and a switching unit 20 which appropriately switches a signal output to the radio transmitting unit 19 between a signal output from the signal processing unit 15 and a signal output from the A/D converter 18. Further, the capsule endoscope 2 includes a timing generator 21 which serves to synchronize driving timings of the intra-subject information acquiring unit 14, the signal processing unit 15, and the switching unit 20.
Further, the capsule endoscope 2 has a function of controlling a driven state of the magnetic field sensor 16 and the like based on radio signals transmitted from the outside. Specifically, the capsule endoscope 2 includes a radio receiving unit 33 which receives radio signals transmitted from the position detecting unit 7 described later, a signal processing unit 30 which extracts predetermined control signals by performing predetermined processing on the received radio signals, and a magnetic field detection controller 31 which controls driven states of the magnetic field sensor 16 and the switching unit 20 based on the control signals.
The radio receiving unit 33 includes a receiving antenna 28, and a receiving circuit 29 which performs predetermined processing such as demodulation processing on the radio signals received via the receiving antenna 28. Further, the magnetic field detection controller 31 has a function of controlling a driven state of the magnetic field sensor 16 and the like according to contents of the control signals, and in a most simple structure, the magnetic field detection controller 31 controls so as to stop driving of the magnetic field sensor 16 and the like in a state in which no control signals are input, and to drive the magnetic field sensor 16 and the like in response to the input of the control signal.
Next, the receiving apparatus 3 will be described. As shown in
The receiving unit 6 includes, as shown in
The receiving antennas 8a to 8d serve to receive radio signals transmitted from the radio transmitting unit 19 provided in the capsule endoscope 2. Specifically, the receiving antennas 8a to 8d are formed with a loop antenna or the like, and used while being arranged on an outer surface of the subject 1.
The reception processing device 9 serves to perform reception processing and the like on the radio signals received via one of the receiving antennas 8a to 8d. Specifically, the reception processing device 9 includes a receiving antenna selector 35 which selects one of the receiving antennas 8a to 8d, a receiving circuit 36 which extracts an original signal included in the radio signal by performing demodulation processing and the like on the radio signal received via the selected receiving antenna, and a signal processing unit 37 which reconfigures an image signal and the like by processing the extracted original signal.
Specifically, the signal processing unit 37 has functions of reconfiguring magnetic field signals S1 to S3 and an image signal S4 based on the extracted original signal, and outputting the reconfigured signals to suitable elements, respectively. Here, the magnetic field signals S1 to S3 are magnetic field signals corresponding to a first linear magnetic field, a second linear magnetic field, and a diffuse magnetic field, respectively, detected by the magnetic field sensor 16, and are reconfigured when the receiving unit 6 and the position detecting unit 7 are used in a combined state as described later. Further, the image signal S4 corresponds to an intra-subject image acquired by the intra-subject information acquiring unit 14. As to specific forms of the magnetic field signals S1 to S3, the magnetic field signals S1 to S3 are represented by direction vectors corresponding to the detected magnetic field strength in the target coordinate axes fixed relative to the capsule endoscope 2, and include information related with an advance direction of the magnetic field in the target coordinate axes and the magnetic field strength.
Further, the reception processing device 9 includes a recording unit 38 which has a function of recording the image signals S4 and the like reconfigured by the signal processing unit 37 into the portable recording medium 5, a selection controller 39 which controls a manner of antenna selection by the receiving antenna selector 35 based on the magnetic field strength signal and the like output from the receiving circuit 36, an input/output interface 41 which serves for input/output of information into/from the position detecting unit 7, and a power supply unit 42 which supplies driving power to elements provided in the reception processing device 9.
The recording unit 38 has a function of recording input data into the portable recording medium 5. The recording unit 38 is configured so as to receive inputs of position information of the capsule endoscope 2 as calculated by the position detecting unit 7 and input via the input/output interface 41, in addition to the aforementioned image signals S4.
The selective controller 39 serves to select a receiving antenna which is appropriate for the reception from the receiving antennas 8a to 8d. Specifically, the selection controller 39 has a function of determining the receiving antenna 8 with a highest received signal strength based on information (RSSI (Received Signal Strength Indicator), for example) related to received signal strength and generated by the receiving circuit 36, and controlling the receiving antenna selector 35 so as to select the determined receiving antenna 8.
The input/output interface 41 serves for information delivery to/from the position detecting unit 7. Specifically, in the first embodiment, the input/output interface 41 at least outputs the magnetic field signals S1 to S3 to the position detecting unit 7, and inputs information concerning the position of the capsule endoscope 2 from the position detecting unit 7 side. As a specific structure of the input/output interface 41, any structure can be adopted as far as the structure allows for the input/output of information. For example, the input/output interface 41 may be configured so as to be connected by a cable with an input/output interface 44 (described later) provided in the position detecting unit 7, or alternatively, may be configured for a wireless connection.
Next, the position detecting unit 7 will be described. As shown in
The processing device 13 includes, as shown in
Further, the processing device 13 has functions of radio transmitting the control signals to the capsule endoscope 2 and controlling driving of the first linear magnetic field generator 11a and the like. Specifically, the processing device 13 includes a control signal generator 48 which generates the control signals, a transmitting circuit 49 which generates predetermined radio signals based on radio signals including the generated control signals, a transmitting antenna selector 50 which selects an antenna to transmit the generated radio signals from the transmitting antennas 10a to 10d, and a selection controller 51 which controls a manner of selection of the transmitting antenna. Further, the processing device 13 includes a magnetic field generation controller 52 which controls driven states of the first linear magnetic field generator 11a, the second linear magnetic field generator 11b, the diffuse magnetic field generator 12, and the control signal generator 48.
The control signal generator 48 has a function of generating control signals to be supplied to the magnetic field detection controller 31 provided in the capsule endoscope 2. As a content of the control signal any content can be employed, for example, if the magnetic field detection controller 31 has a function of driving the magnetic field sensor 16 and the like on receiving some signals, the control signal may consists of a single pulse, for example.
The selection controller 51 serves to determine a manner of selection of the transmitting antenna 10 to be used for transmission of the radio signal including the control signal. Specifically, the selection controller 51 has a function of determining the transmitting antenna 10, which can most efficiently transmit the radio signal to the capsule endoscope 2, based on the results of calculation by the orientation calculator 45 and the position calculator 46. In particular, the selection controller 51 grasps a position of the receiving antenna 28 provided in the capsule endoscope 2 on the target coordinate axes in advance, and acquires the positional relations between the target coordinate axes and the reference coordinate axes according to the results of calculation by the orientation calculator 45 and the position calculator 46. The selection controller 51 has functions of grasping positional relations between the transmitting antennas 10a to 10d and the receiving antenna 28 provided in the capsule endoscope 2 based on the acquired positional relations, determining the transmitting antenna 10 which is most appropriate for the transmission, and controlling the transmitting antenna selector 50 so as to select the determined antenna.
The magnetic field generation controller 52 serves to control a driven state of the magnetic field generators such as the first linear magnetic field generator 11a, as well as a driven state of the control signal generator 48. Specifically, the magnetic field generation controller 52 has functions of controlling to stop the driving of the first linear magnetic field generator 11a and the like when the position detecting unit 7 is not used in combination with the receiving unit 6, and to start the driving of the first linear magnetic field generator 11a and the like when the position detecting unit 7 is used in combination with the receiving unit 6. Specifically, in the first embodiment, the magnetic field generation controller 52 has a function of detecting that the input/output of the information to/from the input/output interface 44 from/to the input/output interface 41 provided in the receiving unit 6 becomes possible. The magnetic field generation controller 52 has functions of determining that the position detecting unit 7 is combined with the receiving unit 6 when the information input/output is allowed, and starting the driving of the first linear magnetic field generator 11a and the like.
Further, the processing device 13 has a mechanism for supplying the driving power to the elements described above. Specifically, the processing device 13 has a power supply unit 53 and is configured so as to supply power stored in the power supply unit 53 to each element.
Next, the first linear magnetic field generator 11a, the second linear magnetic field generator 11b, and the diffuse magnetic field generator 12, that are further elements in the position detecting unit 7 will be described. The first linear magnetic field generator 11a, the second linear magnetic field generator 11b, and the diffuse magnetic field generator 12 function as an example of the magnetic field generator recited in the appended claims, and the first linear magnetic field, the second linear magnetic field, and the diffuse magnetic field generated by the respective magnetic field generators function as examples of the magnetic field for position detection recited in the appended claims.
The first linear magnetic field generator 11a serves to generate a linear magnetic field in a predetermined direction inside the subject 1. Here, “linear magnetic field” means a magnetic field consisting of magnetic field components of substantially only one direction within at least a predetermined space region, i.e., a space region in which the capsule endoscope 2 inside the subject 1 can be present in the first embodiment. Specifically, the first linear magnetic field generator 11a includes, as shown in
Next, the second linear magnetic field generator 11b and the diffuse magnetic field generator 12 will be described. The second linear magnetic field generator 11b and the diffuse magnetic field generator 12 function as examples of the magnetic field generator as recited in the appended claims, and the second linear magnetic field and the diffuse magnetic field generated by the respective magnetic field generators function as examples of the magnetic field for position detection as recited in the appended claims. In the following description, the second linear magnetic field generator 11b will be specifically described as an example of the magnetic field generator, although as is apparent from the description, the description applies similarly to the diffuse magnetic field generator 12 as an example of the magnetic field generator.
The second linear magnetic field generator 11b serves to generate the second linear magnetic field which is a linear magnetic field advances in a different direction from the advance direction of the first linear magnetic field. Further, the diffuse magnetic field generator 12, being different from the first linear magnetic field generator 11a and the second linear magnetic field generator 11b, serves to generate a diffuse magnetic field whose magnetic field direction has a positional dependency, i.e., in the first embodiment, a magnetic field which diffuses as distanced from the diffuse magnetic field generator 12.
Further, the diffuse magnetic field generator 12 includes a coil 58, and an electric current source 59 which serves to supply electric currents to the coil 58. Here, the coil 56 is arranged so as to generate a magnetic field whose advance direction is set to a predetermined direction, and in the first embodiment, the coil 56 is arranged so that the advance direction of the linear magnetic field generated by the coil 56 is aligned with the y-axis direction on the reference coordinate axes. Further, the coil 58 is fixed at a position where the coil 58 generates the diffuse magnetic field with the same magnetic field direction as that stored in the magnetic-field line orientation database 47.
Next, an operation of the body insertable system according to the first embodiment will be described. In the first embodiment, the receiving apparatus 3 is configured with the receiving unit 6 and the position detecting unit 7, and as to the mode of use, the receiving unit 6 operates alone in one mode of use and the receiving unit 6 and the position detecting unit 7 operate in a combined state in another mode of use.
The magnetic field detection controller 31 determines whether the radio receiving unit 33 receives the control signals from the position detecting unit 7 or not (step S102), and when the radio receiving unit 33 receives the control signals (Yes in step S102), controls the magnetic field sensor 16 to start the magnetic field detection (step S103), then, the intra-subject information acquiring unit 14 acquires the intra-subject information and at the same time the magnetic field sensor 16 performs the magnetic field detection, and then, the acquired intra-subject information and the result of magnetic field detection are transmitted via the radio transmitting unit 19 (step S104).
When the radio receiving unit 33 does not receive the control signals (No in step S102), the operations in step S101 and S102 are repeated. Time when the radio receiving unit 33 does not receive the control signals means a time when the receiving unit 6 is used alone without being combined with the position detecting unit 7 as described later, and at such a time, the capsule endoscope 2 repeats the operation of step S101.
Next, an operation of the receiving apparatus 3 will be described.
First, the position detecting unit 7 determines whether the receiving unit 6 is connected thereto or not by the magnetic field generation controller 52 (step S201). In step S201, the “connection” means that the information delivery through the input/output interfaces 41 and 44 is possible, and the magnetic field generation controller 52 determines by detecting the presence/absence of such a state. When there is no connection (No in step S201), the step S201 is repeatedly performed, whereas when the receiving unit 6 is connected (Yes in step S201), the magnetic field generation controller 52 instructs the control signal generator 48 to generate the control signals, and the generated control signals are radio transmitted via the transmitting unit 54 (step S202). Further, the magnetic field generation controller 52 controls the first linear magnetic field generator 11a and the like so as to start driving, and the first linear magnetic field generator 11a and the like generate predetermined magnetic fields for position detection (step S203). The capsule endoscope 2, by receiving the control signals transmitted in step S202, starts the detection of the magnetic fields for position detection, and transmits radio signals including the result of detection. On the other hand, the position detecting unit 7 acquires the magnetic field signal included in the transmitted radio signals via the receiving unit 6 (step S204), performs position detection processing of the capsule endoscope 2 based on the acquired magnetic field signals (step S205), and outputs the detected position to the receiving unit 6 (step S206). Thereafter, through the repetition of the operations in step S203 to step S206, positions of the capsule endoscope 2 at various times are detected.
Among the processing performed by the position detecting unit 7, the position detection processing in step S205 will be described below. In the body insertable system according to the first embodiment, the structure is made so that the position relations between the reference coordinate axes fixed relative to the subject 1 and the target coordinate axes fixed relative to the capsule endoscope 2 are calculated, and specifically, after the orientations of the target coordinate axes relative to the reference coordinate axes are calculated, the position of an origin of the target coordinate axes on the reference coordinate axes, i.e., the position of the capsule endoscope 2 inside the subject 1 is calculated based on the calculated orientation. Therefore, in the following, an orientation calculation mechanism will be first described, followed by the description on the position calculation mechanism using the calculated orientation. Needless to say, however, devices to which the present invention can be applied are not limited to systems including such position detection mechanism.
The orientation calculation mechanism of the orientation calculator 45 will be described.
On the other hand, the first linear magnetic field generator 11a and the second linear magnetic field generator 11b are fixed relative to the subject 1. Therefore, the first linear magnetic field and the second linear magnetic field generated respectively by the first linear magnetic field generator 11a and the second linear magnetic field generator 11b advance in predetermined directions, respectively, with respect to the reference coordinate axes, and specifically, the first linear magnetic field advances in the z-axis direction on the reference coordinate axes and the second linear magnetic field advances in the y-axis direction on the reference coordinate axes.
The orientation calculation in the first embodiment is performed with the use of the first linear magnetic field and the second linear magnetic field. Specifically, the magnetic field sensor 16 provided in the capsule endoscope 2 detects the advance directions of the first linear magnetic field and the second linear magnetic field that are supplied in a time-sharing manner. The magnetic field sensor 16 is configured so as to detect the magnetic field components in the X-axis direction, the Y-axis direction, and the Z-axis direction on the target coordinate axes, and information concerning the detected advance direction of the first linear magnetic field and the second linear magnetic field on the target coordinate axes is transmitted to the receiving apparatus 3 via the radio transmitting unit 19.
The radio signals transmitted by the capsule endoscope 2 are output as the magnetic field signals S1 and S2 after processing in the signal processing unit 37 and the like. For example, in an example of
Next, the position calculation mechanism by the position calculator 46 of the capsule endoscope 2 will be described. The position calculator 46 is configured so as to receive inputs of the magnetic field signals S2 and S3 from the signal processing unit 37, to receive an input of the orientation information from the orientation calculator 45, and to receive information stored in the magnetic-field line orientation database 47. The position calculator 46 performs the position calculation of the capsule endoscope 2 based on the supplied information as described below.
The position calculator 46 calculates a distance between the second linear magnetic field generator 11b and the capsule endoscope 2 using the magnetic field signal S2. The magnetic field signal S2 corresponds to the result of detection of the second linear magnetic field in a region where the capsule endoscope 2 is present, and the second linear magnetic field has a property that the strength thereof decreases as distance from the second linear magnetic field generator 11b increases, due to the arrangement of the second linear magnetic field generator 11b outside the subject 1. The position calculator 46, utilizing the above property, compares the strength (which can be found based on the electric current value which flows through the second linear magnetic field generator 11b) of the second linear magnetic field near the second linear magnetic field generator 11b and the strength, which can be found from the magnetic field signal S2, of the second linear magnetic field in the region where the capsule endoscope 2 is present, and calculates a distance r between the second linear magnetic field generator 11b and the capsule endoscope 2. As a result of calculation of the distance r, it becomes clear that the capsule endoscope 2 is present on a curved surface 61 which is a collection of points distance r away from the second linear magnetic field generator 11b as shown in
Then, the position calculator 46 calculates the position of the capsule endoscope 2 on the curved surface 61 based on the magnetic field signal S3, the orientation information calculated by the orientation calculator 45, and the information stored in the magnetic-field line orientation database 47. Specifically, the position calculator 46 calculates the advance direction of the diffuse magnetic field at the position where the capsule endoscope 2 is present based on the magnetic field signal S3 and the orientation information. Since the magnetic field signal S3 is a signal corresponding to the result of detection of the diffuse magnetic field based on the target coordinate axes, when the coordinate transformation processing is performed on the advance direction of the diffuse magnetic field based on the magnetic field signal S3 from the target coordinate axes to the reference coordinate axes with the use of the orientation information, the advance direction of the diffuse magnetic field at the position where the capsule endoscope 2 is present and on the reference coordinate axes can be calculated. Since the magnetic-field line orientation database 47 records the correspondences between the advance direction and the position of the diffuse magnetic field on the reference coordinate axes, the position calculator 46 calculates the position corresponding to the calculated advance direction of the diffuse magnetic field by referring to the information stored in the magnetic-field line orientation database 47 as shown in
Next, advantages of the body insertable system according to the first embodiment will be described. Firstly, in the body insertable system according to the first embodiment, as shown in
Thus, the body insertable system according to the first embodiment has an advantage that the burden on the subject 1 at the use can be restricted to a minimum degree according to the purpose of use. Specifically, in the first embodiment, when the position detection is not performed, the subject 1 does not need to carry the first linear magnetic field generator 11a, the second linear magnetic field generator 11b, the diffuse magnetic field generator 12, and the processing device 13, that are used for position detection, whereby the burden on the subject 1 at the use can be alleviated.
Further, the body insertable system according to the first embodiment has an advantage that the burden on the subject 1 can be restricted to a minimum degree according to the purpose of use, while the increase in the operational cost can be suppressed. In other words, the body insertable system according to the first embodiment alone can satisfy both purposes of use, i.e., the acquisition of the intra-subject information alone, and the acquisition of the intra-subject information and the position detection, whereby the operational cost can be decreased in comparison with the cost incurred when different systems are used.
Further, with respect to the capsule endoscope 2, which is an element of the body insertable system, the reduction of the operational cost is realized. Specifically, in the first embodiment, as shown in the flowchart of
Further, the body insertable system according to the first embodiment has an advantage that the accurate position detection can be performed while the burden on the subject 1 is reduced when the body insertable system is used for position detection. As is clear from the description based on FIGS. 9 to 11, the position detection is carried out based on the advance direction and the strength of the magnetic field for position detection, and hence, the first linear magnetic field generator 11a, the second linear magnetic field generator 11b, and the diffuse magnetic field generator 12 which generate the magnetic fields for position detection are required to be fixed at given positions relative to the subject 1 until the use of the body insertable system is finished. Therefore, the first linear magnetic field generator 11a and the like are of course arranged in close contact with and fixed relative to the subject 1, and further, the first linear magnetic field generator 11a and the like are usually connected to the position detection mechanism by a cable as shown in
Therefore, in order to safely prevent the displacement of the first linear magnetic field generator 11a and the like at the change of posture of the subject 1, for example, the position detection mechanism which is connected to the first linear magnetic field generator 11a and the like by a cable is required to be fixed relative to the subject 1. Therefore, when the system including the receiving apparatus in which the receiving unit and the position detecting unit are integral as in the conventional system is employed, the receiving apparatus is arranged so that the receiving apparatus assumes a fixed state relative to the subject 1. However, the conventional receiving apparatus is more bulky and heavier since the receiving unit and the position detecting unit are integral, whereby the burden on the subject 1 becomes significant if such a receiving apparatus is fixed to the subject 1 and used for several hours.
On the other hand, in the first embodiment as described above, in the receiving apparatus 3, the receiving unit 6 and the position detecting unit 7 are formed separately and independently of each other, and only the position detecting unit 7 is connected to the first linear magnetic field generator 11a by a cable as shown in
Specifically, it is preferable that the position detecting unit 7 be fixed to the subject 1 by a belt-like holder, for example, and the receiving unit 6 be arranged with a shoulder-strap-like holder in such a manner that the position thereof relative to the subject 1 can be changed. With such an arrangement, the degradation in the position detection accuracy can be prevented, and with respect to the receiving unit 6, the fatigue of the subject 1 can be alleviated by changing the position of the receiving unit 7 relative to the subject 1 every few hours.
Next, a body insertable system according to a second embodiment will be described. In the second embodiment, the receiving apparatus is configured with a receiving unit and a position detecting unit that are formed separately and independently of each other, similarly to the first embodiment, and the capsule endoscope 2 is configured so as to start magnetic field detection in response to the generation of the magnetic field for position detection by the position detecting unit.
As shown in
The magnetic field strength calculator 64 serves to calculate the strength of the magnetic field as detected by the magnetic field sensor 16. Specifically, electric signals corresponding to the magnetic field detected by the magnetic field sensor 16 are, after being amplified by the amplifying unit 17, converted into digital signals by the A/D converter 18. The magnetic field strength calculator 64 has functions of calculating the magnetic field strength based on the digital signals obtained as a result of conversion by the A/D converter 18, and outputting the magnetic field strength to the magnetic field detection controller 65.
The magnetic field detection controller 65 has a function of controlling a period of magnetic field detection performed by the magnetic field sensor 16 based on the magnetic field strength calculated by the magnetic field strength calculator 64. Specifically, the magnetic field detection controller 65 has functions of determining whether the magnetic field for position detection is generated by the first linear magnetic field generator 11a and the like based on the magnetic field strength calculated by the magnetic field strength calculator 64, and switching the period of the magnetic field detection operation by the magnetic field sensor 16 between a long period and a short period which is shorter than the long period.
Next, a receiving apparatus constituting the body insertable system according to the second embodiment will be described.
The position detecting unit 67 includes the first linear magnetic field generator 11a, the second linear magnetic field generator 11b, the diffuse magnetic field generator 12, and a processing device 68. The processing device 68 is configured to have, similarly to the processing device 13 of the first embodiment, the input/output interface 44, the orientation calculator 45, the position calculator 46, the magnetic-field line orientation database 47, and the power supply unit 53, and on the other hand, the control signal generator 48, the transmitting circuit 49, the transmitting antenna selector 50, and the selection controller 51 are eliminated. Corresponding to the above structure, the magnetic field generation controller 52 controls the driven states of only the first linear magnetic field generator 11a, the second linear magnetic field generator 11b, and the diffuse magnetic field generator 12, and the transmitting antennas 10a to 10d for transmitting the radio signals including the control signals in the first embodiment are eliminated.
Next, an operation of the body insertable system according to the second embodiment will be described.
The capsule endoscope 2 operates as follows. Specifically, as shown in a flowchart of
Next, advantages of the body insertable system according to the second embodiment will be described. Firstly, in the body insertable system according to the second embodiment, similarly to the first embodiment, the receiving unit 6 and the position detecting unit 67 are formed separately and independently of each other, whereby the burden on the subject 1 can be restricted to a minimum degree according to the purpose of use, while the increase in the operational cost is prevented.
Further, the second embodiment is configured so as to detect the use of the position detecting unit 67 utilizing the magnetic field sensor 16 provided in the capsule endoscope 63. Specifically, as described above, the magnetic field sensor 16 is configured so as to perform the magnetic field detection operation by repeatedly performing the detection operation in long periods according to the control by the magnetic field detection controller 65 at a stage where it is not known whether the position detecting unit 67 is combined or not, and is configured to recognize that the position detecting unit 67 is combined according to the determination on the presence/absence of the generated magnetic field for position detection by the magnetic field detection controller 65 based on the detected magnetic field strength. Therefore, in the second embodiment, the capsule endoscope 63 does not need to include the radio receiving unit, the signal processing unit, and the like, whereby a simplified structure allows for downsizing of the capsule endoscope 63 and reduction of power consumption. Though the magnetic field sensor 16 of the second embodiment is continuously driven regardless of the generation of the magnetic field for position detection, there is no inconvenience related with a substantial increase in power consumption since the magnetic field sensor 16 is driven in long periods until the magnetic field for position detection is detected as described above.
The structure of the position detecting unit 67 is simplified as well. Specifically, since the generation and the transmission of the control signals are not necessary, the control signal generator and the transmitting unit can be eliminated from the position detecting unit 67, whereby decreases in size, weight, and power consumption are allowed. In particular, since it is desirable to arrange the position detecting unit 67 in a fixed state relative to the subject 1 for the suppression of degradation in the position detection accuracy as described with respect to the first embodiment, there is an advantage that the decrease in size and weight of the position detecting unit 67 allows for further reduction in the burden on the subject 1. Further, since the transmitting antenna constituting the transmitting unit can be eliminated, the members attached to the outer surface of the subject 1 is reduced, and the burden on the subject 1 can be alleviated in this respect as well.
Next, a body insertable system according to a third embodiment will be described. The body insertable system according to the third embodiment is configured so as to perform the position detection in the position detecting unit by using earth magnetism instead of the first linear magnetic field. In the following description, a structure based on the first embodiment will be described as an example, although it is obvious that a structure using the earth magnetism in place of the first linear magnetic field can be applied to the structure of the second embodiment.
The earth-magnetism sensor 73 basically has the same structure as the magnetic field sensor 16 provided in the capsule endoscope 2. Specifically, the earth-magnetism sensor 73 has functions of detecting strength of magnetic field components in three predetermined axis directions in a region where the earth-magnetism sensor 73 is arranged, and outputting electric signals corresponding to the detected magnetic field strength. On the other hand, the earth-magnetism sensor 73 is, dissimilar to the magnetic field sensor 16, arranged on a body surface of the subject 1, and has a function of detecting the strength of the magnetic field component corresponding to each of the x-axis direction, the y-axis direction, and the z-axis direction on the reference coordinate axes fixed relative to the subject 1. In other words, the earth-magnetism sensor 73 has a function of detecting an advance direction of the earth magnetism, and is configured to output electric signals corresponding to the magnetic field strength detected in the x-axis direction, the y-axis direction, and the z-axis direction to the processing device 72.
Next, the processing device 72 according to the third embodiment will be described.
When the earth magnetism is utilized as the first linear magnetic field, the calculation of the advance direction of the earth magnetism on the reference coordinate axes fixed relative to the subject 1 is problematic. Since the subject 1 can freely move while the capsule endoscope 2 travels through inside the body, positional relations between the reference coordinate axes fixed relative to the subject 1 and the earth magnetism are expected to fluctuate along with the movement of the subject 1. On the other hand, for the calculation of the positional relations between the target coordinate axes relative to the reference coordinate axes, it is problematic that the correspondence between the reference coordinate axes and the target coordinate axes cannot be made clear with respect to the advance direction of the first linear magnetic field, when the advance direction of the first linear magnetic field on the reference coordinate axes become unknown.
Therefore, in the third embodiment, the earth-magnetism sensor 73 and the earth-magnetism orientation calculator 74 are provided to monitor the advance direction of the earth magnetism which varies on the reference coordinate axes due to the movements of the subject 1, for example. Specifically, the earth-magnetism orientation calculator 74 calculates the advance direction of the earth magnetism on the reference coordinate axes based on the result of detection by the earth-magnetism sensor 73, and outputs the result of calculation to the orientation calculator 45. In response, the orientation calculator 45 calculates the correspondence between the reference coordinate axes and the target coordinate axes with respect to the advance direction of the earth magnetism using the input advance direction of the earth magnetism, thereby allowing the calculation of the orientation information together with correspondence with respect to the second linear magnetic field.
Depending on the direction of the subject 1, the advance direction of the earth magnetism may be parallel to the second linear magnetic field generated by the second linear magnetic field generator 11b. The detection of the position relation is still possible with the use of data concerning the orientation of the target coordinate axes and a position of an origin of the target coordinate axes at an immediately previous time point. Further, it is effective to make the coil 34 constituting the second linear magnetic field generator 11b extend not in the y-axis direction on the reference coordinate axes as shown in
Next, advantages of the body insertable system according to the third embodiment will be described. The body insertable system according to the third embodiment has further advantages attributable to the use of the earth magnetism, in addition to the advantages of the first embodiment. When the structure utilizing the earth magnetism as the first linear magnetic field is adopted, a mechanism for generating the first linear magnetic field can be eliminated, whereby it is possible to calculate the positional relations of the target coordinate axes relative to the reference coordinate axes while alleviating the burden on the subject 1 at the introduction of the capsule endoscope 2. Since the earth-magnetism sensor 73 can be configured with an MI sensor or the like, the downsizing is well possible, and the addition of the earth-magnetism sensor 73 would not cause the increase in the burden on the subject 1.
Further, the structure utilizing the earth magnetism as the first linear magnetic field is advantageous in terms of reduction of power consumption. When the first linear magnetic field is generated by the coil or the like, the amount of consumed power increases due to the electric current flow through the coil. The use of the earth magnetism eliminates the need of such power consumption, whereby a system with low power consumption can be realized.
In the above, the present invention is described with reference to the first to the third embodiments. The present invention, however, should not be interpreted as to be limited to the above embodiments, and those skilled in the art can reach various embodiments and modifications. For example, the capsule endoscope as the body insertable apparatus in the first to the third embodiments is described as the structure having a function of acquiring the intra-subject information and a function of detecting the magnetic field for position detection as necessary in a single structure, however, as a more simple structure, a body insertable apparatus which can only acquire intra-subject information and a body insertable apparatus which is provided with both the function of acquiring the intra-subject information and the function of detecting the magnetic field for position detection may be separately prepared. Further, though the receiving apparatus is described as being provided with the power supply unit or the electric current source corresponding to each element in the above, the power supply unit provided in the receiving unit, for example, may be configured so as to supply driving power to each element, or alternatively, a battery park or the like formed separately and independently of the receiving unit and the like may be employed to supply driving power to the receiving unit and the like.
As can be seen from the foregoing, the body insertable system, the receiving apparatus, and the body insertable apparatus according to the present invention are useful for a medical observation apparatus which is introduced inside a human body and employed for an observation of an examined area, and in particular, is suitable for restricting a burden of a subject at the use to a minimum degree according to the purpose of use while suppressing the increase in the operational cost, with respect to the body insertable system provided with the body insertable apparatus such as the capsule endoscope.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-266064 | Sep 2004 | JP | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11658379 | US | |
| Child | 11804908 | May 2007 | US |
