APPARATUS AND METHOD FOR PASSIVE MARKERS LOCALIZATION WITHIN A BODY

Abstract

A system for localizing a region of interest (ROI) within a patient's body is disclosed. An embodiment of the system may comprise a pad that can be placed in association with the patient's body; one or more markers which are placed within a patient's body in association with the ROI, each marker being associated with one or more antennas and a unique collective ID; a locator comprising one or more antennas for transmitting/receiving a microwave (MW) signal into/from the patient's body in order to identify the one or more markers and a processing unit that is configured to control the operation of the system and for determining the distance from the locator to each one of the one or more markers.

Claims

1. A system for localizing a region of interest (ROI) within a patient's body, comprising: a pad that is configured to be placed in association with the patient's body and to transmit an electromagnetic (EM) field toward the patient's body; one or more markers sized and configured for placement within the patient's body in association with the ROI and each marker is associated with one or more antennas; a locator comprising one or more antennas for transmitting a microwave (MW) signal into the patient's body and receiving responding MW signals from the one or more markers in order to identify the one or more markers within the patient's body; and a processing unit that is configured to control the operation of the system and for determining the distance from the locator to each one of the one or more markers; wherein each one of the one or more markers is associated with a unique collective ID which differentiates it from other markers and wherein the collective ID comprises a unique electronic ID and at least one unique visual ID (VID) feature configured to be visualized by an imaging system.

2. The system of claim 1, wherein each marker of the one or more markers comprises a microelectronic chip that stores an electronic representation of the unique collective ID of that marker.

3. The system of claim 1, wherein the imaging system comprises an X-Ray system.

4. The system of claim 1, wherein the pad is configured to transmit a modulated electromagnetic field, wherein the modulation represents the unique electronic ID of one marker from the one or more markers.

5. The system of claim 4, wherein the modulated electromagnetic field is implemented by a Binary-Phase-Shift Keying (BPSK) code.

6. The system of claim 1, wherein the carrier signal of the electromagnetic field alternates at 13.56 MHz band.

7. The system of claim 4, wherein a marker from the one or more markers that is associated with the electronic ID that is embedded in the modulation of the electromagnetic field is activated and responds to the MW signal that is transmitted by the locator said marker is referred as an activated marker.

8. The system of claim 1, wherein the processing unit is a tablet computer.

9. The system of claim 1, wherein the locator is configured to determine the delay between the MW signal transmitted by the locator and the MW signal responded by the activated marker and to deliver the delay information to the processing unit.

10. The system of claim 1, wherein the responded signal received from the marker by the locator is a transponded signal.

11. The system of claim 9, wherein the locator is configured to determine the phase difference measurement between the signal received from the activated marker and the reference signal received from the pad and to deliver the value of the phase difference information to the processing unit.

12. The system of claim 9, wherein the processor unit is configured to estimate the distance between the locator and the activated marker based on the information sent from the locator.

13. The system of claim 11, wherein the processor unit is configured to estimate the distance between the locator and the activated marker based on the information sent from the locator.

14. The system of claim 1, wherein the frequency of the MW signal is in the 5.8 GHz band.

15. The system of claim 1, wherein two or more markers are organized as joined markers.

16. The system of claim 1, wherein the one or more pads comprise a loop antenna.

17. The system of claim 1, wherein the locator further comprises two or more LEDs that are placed on the circumference of the locator.

18. The system of claim 15, wherein the two or more LEDs are configured to point to a desired direction of movement.

19. The system of claim 1, wherein the locator further comprises one or more XYZ-IMU (Inertial measurement unit) for estimation of distance between two or more markers.

20. The system of claim 19 wherein the XYZ-IMU together with the depth estimation of the two or more markers provide an estimation of 3D coordinates of the markers.

21. The system of claim 1, wherein the marker is made of non-ferrite material.

22. A marker that is configured to be placed in association with a region of interest (ROI) within a patient's body, the marker comprising: an encasement; and one or more antennas; wherein the marker is associated with a unique collective identification (ID) and wherein the VID of the unique collective ID of the marker is configured to be visualized by an imaging system.

23. The marker of claim 22, wherein the marker comprises a microelectronic chip that stores an electronic representation of the unique collective ID of said marker.

24. The marker of claim 22, wherein the imaging system comprises a X-Ray system.

25. The marker of claim 22, wherein the marker is configured to be activated by a modulated electromagnetic field, wherein the modulation represents the unique electronic ID of the marker and wherein said marker is referred as an activated-marker.

26. The marker of claim 25, wherein the modulated electromagnetic field is implemented by a Binary-Phase-Shift Keying (BPSK) code.

27. The marker of claim 25, wherein the electromagnetic field alternates at 13.56 MHz band.

28. The marker of claim 25, wherein the activated marker is configured to respond to Microwave (MW) signal that is transmitted from the hand held device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Exemplary embodiments of the present disclosure will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0038] FIG. 1A shows a first view of an example embodiment of a dual-Band antenna transponder marker or tag that may be implanted or placed within patient's body;

[0039] FIG. 1B shows a second view of an example embodiment of a dual-Band antenna transponder marker or tag that may be implanted or placed within patient's body;

[0040] FIG. 1C shows a third view of an example embodiment of a dual-Band antenna transponder marker or tag that may be implanted or placed within patient's body;

[0041] FIG. 2 depicts different embodiments of marker pairs, illustrating the assembly concept;

[0042] FIG. 3 Illustrates an example embodiment of the disclosed system concept;

[0043] FIG. 4 Illustrates the RF signal paths schematic within the disclosed embodiment;

[0044] FIG. 5 Illustrates a potential embodiment of the Excitation field Pad, in block-diagram form;

[0045] FIG. 6 Illustrates a potential embodiment of the marker's electronic systems, in general schematic form;

[0046] FIG. 7 Illustrates a potential embodiment of the electronic systems within the hand-held locator device, in block-diagram form;

[0047] FIG. 8 Illustrates an example of a pre-operational program executing on the tablet computer, responsible for creating the pre-operational marker database used in future medical tasks;

[0048] FIG. 9 Illustrates an example of using the tablet computer for pre-operation device testing, to validate system readiness for surgery;

[0049] FIG. 10 Illustrates an exemplary flow-chart of the program for marker localization during the surgery; and

[0050] FIG. 11 Illustrates an exemplary of a flow-chart of the marker local direction estimation program.

DETAILED DESCRIPTION OF SOME EXAMPLE EMBODIMENTS

[0051] Turning now to the figures in which like numerals represent like elements throughout the several views, in which exemplary embodiments of the disclosed techniques are described. For convenience, only some elements of the same group may be labeled with numerals.

[0052] The purpose of the drawings is to describe examples of embodiments and not for production purpose. Therefore, features shown in the figures are chosen for convenience and clarity of presentation only and are not necessarily shown to scale. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to define or limit the inventive subject matter.

[0053] In this specification, these implementations, or any other form that the invention may take, may be referred to as techniques. In general, the order of the steps of disclosed processes may be altered within the scope of the invention. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment.

[0054] In the following description, the words “unit,” “element,” “module”, and “logical module” may be used interchangeably. Anything designated as a unit or module may be a stand-alone unit or a specialized or integrated module. A unit or a module may be modular or have modular aspects allowing it to be easily removed and replaced with another similar unit or module. Each unit or module may be any one of, or any combination of, hardware configured to execute the task ascribed to the unit or module. In the present disclosure the terms task, method, and process can be used interchangeably. In addition, the terms element and section can be used interchangeably.

[0055] In the following description, numerous details are set forth in order to provide a more thorough description of the system. It will be apparent, however, to one skilled in the art, that the disclosed system may be practiced without these specific details. In the other instances, well known features have not been described in detail so as not to unnecessarily obscure the system.

[0056] The drawings FIG. 1A-1C show different views of an example embodiment of a transponder marker or tag 100 that may be implanted or placed within patient's body such as within a breast 300 as shown in FIG. 3, for example by a delivery system like a needle assembly (not shown here). Generally, the marker 100 comprises a microchip 110, including all electronic components, magnetic antenna 120 and internal part of microwave antenna 130a enclosed into hermetic bio-compatible case 140. The marker has additionally the external part 130b of the microwave antenna. The components of the marker can be made of non-ferrite material and can be MRI compatible without a bloom artifact.

[0057] In an example embodiment, the magnetic antenna 120 may be a solenoid wired on a paramagnetic core like by not limited to glass. This antenna is tuned to the resonance frequency of an FCC approved for medical applications RF band of 13.56 MHz for the most efficient harvesting of electromagnetic energy irradiated by an excitation electromagnetic field pad 320 (see FIG. 3). The same magnetic antenna 120 structure can serve as a part (single arm) of the microwave dipole antenna 150 (FIG. 1B) working at another FCC approved band of 5800 MHz. At this frequency, the wired layer of the magnetic antenna 120 can be thought of as a solid conducting cylinder due to the commonly known skin effect, in conjunction with the low-impedance RF path established by the turn-to-turn capacitive coupling between neighboring turns/loops of the magnetic antenna solenoid. This conducting cylinder together with the internal part 130a of the dipole antenna and external part 130b of the dipole antenna creates the half-wave resonant dual band antenna 150.

[0058] In an example embodiment, the external part of the microwave antenna 130b can serve as an anchor preventing the migration of the marker after implantation/placement into soft tissues. The antenna can be comprised of memory metals. The antenna can be in the form of a spring or some other visually identifiable configuration. EIE's and VID's can be associated with the marker (not shown). The effect of self-anchoring can be improved by connecting two markers by their external parts, for example, by the connection of the 130 microwave antennas (see FIG. 2). The common connecting part of marker pair 210 can be built from bio-compatible metals like but not limited to tungsten or nitinol and can have spring properties. So-called memory metals can be used.

[0059] Assuming the activation of each marker is performed sequentially at different and independent time intervals, the marker electronics 110 activate the microwave antennas of each marker of the pair independently, without interference of operation of each marker of the pair. Different types of spring connections between marker pairs can be used depending on surgical requirements. The expandable pre-bent spring 210a can be used for example in case of heterogeneous tissue. The fixed spring 210b can be used for example in case of homogeneous soft tissue.

[0060] In an example embodiment, the passive marker 100 is part of a system for localizing marker/s implanted within a patient's body, see FIG. 3. The system comprises the excitation electromagnetic (EM) field pad 320, creating the EM field penetrating the volume of interest 310, wherein the marker/s 100 have been previously implanted or placed. The system also comprises the remote hand-held locator 330, and the tablet computer 340 providing general control and monitoring of entire system. The locator can also be machine, robotic endoscopically, laparoscopically etc operated.

[0061] In an example embodiment, the marker 100 harvests the electromagnetic energy within the volume 310 of the ROI from the external excitation field source pad 320 and simultaneously responds to the MW test signal emanating from the hand-held locator 330. The signal (low-frequency carrier) generated by the pad 320 is modulated by a specific digital identification code. The process of ID activation of the marker can be achieved if and only if the code generated by the pad 320 matches the ID code stored in the selected marker's memory (within the chip 110). The user selected marker 100 is made active and is enabled to respond to the test signal sent from the locator 330.

[0062] In FIG. 4, the external excitation field pad 320 creates an inductive field covering the volume of the region of interest 310 within the patient's body, providing enough energy for harvesting by a plurality of markers 100 within this volume. The signal has a carrier in the range of 13.56 MHz and is modulated by digital ID code using the binary-phase-shift-keying (BPSK) method.

[0063] Additionally, the carrier of this low-frequency RF signal is used as the synchronization signal in realizing the primary system function—coherent measurement of the selected marker's relative location (distance estimation). The BPSK modulation method provides maximum carrier signal power (maximum energy transference to the plurality of passive markers) and the simplest method of carrier recovery. This signal is received by magnetic antenna 120 of the marker (see FIGS. 1A, 1B and 1C) and is used by the passive marker for energy harvesting, ID demodulation, and decoding and generation of the MW response signal, which is triggered by reception of the MW test signal sent by the locator.

[0064] In the same example embodiment, the signal sent by the locator 320 and the response signal created by the marker 100 occupies the same FCC approved frequency band of 5800 MHz but have completely different spectra. For example, the test signal sent by the locator comprises two spectral components 5786.44 MHz and 5813.56 MHz, which represent balance modulated carrier of 5800 MHz by the first harmonic of the system synchronization signal of 13.56 MHz. The marker response is composed of the AM modulated signal having spectral components at 5772.98 MHz, 5800 MHz and 5827.12 MHz, which represent the carrier of 5800 MHz and two side-bands of the second harmonics of the synchronization signal (i.e., 27.12 MHz). This spectral difference allows using the excess energy harvested by the marker 100, for the amplification of the response signal transmitted toward the locator 330. The marker 100 uses the resonant half-wave dipole (microwave antenna) 150 for transponding interactions with the locator 330. Both antenna, one for energy harvesting and another for microwave interactions are combined in a dual-band antenna surrounding the marker electronics.

[0065] In the same exemplary embodiment, the Tablet computer 340 provides pre-operational monitoring and control of the hand-held locator 330 and the pad 320 by using the standard Bluetooth interface and protocol. During the surgery the hand-held locator 330 performs the phase measurements between the synchronization signal coming from the pad 320 and the response signal coming from the marker 100 which fundamentally encodes information about the distance between the locator 330 and the marker 100. Additionally, the locator measures the 3D acceleration of its movements (gliding) over the surface of the patient's skin. All this information is transferred to the computer 340 via Bluetooth IF for estimation of the plurality of marker locations.

[0066] In an example embodiment, the functional block diagram of the excitation electromagnetic field source pad 320 is illustrated in the FIG. 5. According to previous art (“Optimization of output power and transmission efficiency of magnetically coupled resonance wireless power transfer system” by R. Yan, X. Guo, S. Cao and C. Zhang, on-line published 2 Jan. 2018), the power transferred by a wireless coupled magnetic resonance system is proportional to the square of the radius of used coils. To fit within the confines of the small hand-held locator device, the prior art RF markers mentioned above use antennas with diameters less than 30 mm to excite the markers. The currently disclosed embodiment uses magnetic antenna 512 in the excitation pad of diameter (for example) 500 mm allowing significant (more than 270 times) amplification of the energy harvesting potential without modifying the marker geometry.

[0067] In such embodiment, the local controller 502 of the pad 320 receives via the Bluetooth link 503 (after the process of pairing) information regarding the one or more implanted markers within the region of interest. During each marker localization event in time, the local controller 502 commands the code sequence generator 504 to create a code sequence corresponding to the currently active code ID from the list stored in its memory. The code can be changed via a user-issued command into the tablet computer 340 (see FIG. 4). The code sequence is used as input by BPSK modulator 506 which modulates the carrier of the synchronization signal generated by crystal-controlled oscillator 508. The modulated signal is amplified by output power amplifier 510 and transmitted into the patient's body via magnetic loop antenna 512. This antenna generates the electromagnetic near-field which resonantly couples (via magnetic induction) to the plurality of markers' on-board magnetic antennas, ultimately providing operational power to the markers.

[0068] In an example embodiment, the functional block diagram of the microchip 110 (see FIGS. 1A, 1B and 1C) is illustrated in FIG. 6. This system-on-chip device can be a modification of an existing RFID chip, such as NTAG203 NFC (cdn-shop.adafruit.com/productfiles/4034/P4034_datasheet_NTAG_203.pdf). The blocks from 602 to 612 perform standard operations of the RFID system. The rectifier/local power supply 602 receives the signal from the markers magnetic antenna 120 and provides power supply energy for all electronic components of the marker 100. The AC components of this signal are used for PLL (phase-lock loop) 606 tuned to the carrier frequency of the receiving signal (low-frequency synchronization signal) and code demodulator 604. The output of this demodulator represents the code time sequence envelope similar to that generated by 504 (see FIG. 5). This signal is sampled by the local ND convertor 608 and in digital form is transferred to the local Processor/Correlator 610.

[0069] The correlator 610 uses the marker specific code ID stored in its memory 612 for decoding the processing code time sequence. In case of successful decoding (ID code match), the “code coincidence enable” signal is generated by the processor 610. The example embodiment of the chip extensions are represented by blocks 614, 616 and 618. The active circulator 616 (see previous art: “A 60 GHz Analog Phase Shifter in 65 nm Bulk CMOS Process” by S. Harrison, Z. Ping, IJCNC July 2010) receives the MW test signal coming from the hand-held locator 330. This signal has two spectral components of 5786.44 MHz and 5813.56 MHz of the FCC-permitted band 5800 MHz. These components are amplified by RF (LNA) amplifier 618 and are relayed to the Double-Balance Modulator 614.

[0070] In the case of a successful ID code match, the code coincidence enable signal generated by correlator 610 activates the modulator 614 to modulate (mathematical analog multiplication) the amplified MW signal received from the locator with the low-frequency AC signal coming from the pad. The result of this modulation is a signal having three spectral components in the 5800 MHz band, i.e., 5772.88 MHz, 5800 MHz and 5827.12 MHz. This signal is sent to the active circulator 616 and then transmitted via the same dipole antenna 150 of the marker. The spectral difference between the received and the transmitted signals prevent parasitic oscillations in RF Amplifier 618.

[0071] In the example embodiment of the marker localization, the functional block-diagram of the locator 330 is illustrated in FIG. 7. The locator receives the synchronization signal from the pad 320 via magnetic antenna 702. This signal is passed to the carrier recovery circuitry to create a signal in the 13.56 MHz band, which is then used in generating the marker interrogation test signal. The pad signal ultimately serves as a reference signal for the phase difference estimation. The generation of the marker interrogation test signal is performed by modulation of the 5800 MHz carrier produced by oscillator 708 with the low-frequency 13.56 MHz signal coming from the carrier recovery circuit 704 (received from the pad 320).

[0072] The result of the Double-balance modulation 706 is a signal with two spectral components, occupying the 5786.44 MHz and 5813.56 MHz sub-bands. This signal is amplified by RF amplifier 710 and transmitted into the patient's body (toward the one or more implanted markers) via circulator 712 and microwave antenna 714. The same antenna 714 is used for receiving the active marker response. This response (microwave signal) contains 3 spectral components (i.e., 5772.88 MHz, 5800 MHz and 5827.12 MHz). This signal can be thought of as an amplitude modulated (AM) signal, with a modulating (envelope) waveform provided by the second harmonic of the synchronization signal 13.56 MHz. The modulation function is detected by detector 715, and passed through the band-pass-filter (BPF). The BPF is tuned to the required modulation function of 27.12 MHz (second harmonic of the synchronization signal 13.56 MHz). This modulation function contains the “there-and-back” (double-propagation) delay information associated with the microwave signals (centered at 5800 MHz) relayed from the locator 320 to the marker 100 and returned as a different, “response” signal. Accordingly, the harmonic signal at 27.12 MHz contains a scaled copy of the phase shift information (relative to some reference signal) of the fundamental frequency (13.56 MHz) signal.

[0073] Turning to the FIG. 7. In a “there-and-back”, double propagation of the MW signal through (for example) 100 mm of human tissue, the harmonic signal of 27.12 MHz (detected by detector 715) does not vary more than 12Deg in phase. This low measure of phase shift can be significantly increased through the employment of higher harmonics, created from the signals designated for the phase comparison. The pre-distorters 716 and 718 can be used for this harmonic signal generation, acting on the modulation envelope of the MW response and the RF synchronization signals, respectively. Using the 5th harmonic of the 27.12 MHz modulation envelope and the 10.sup.th harmonic of the synchronization signal at 13.56 MHz permits phase comparison at 135.6 MHz, significantly improving the dynamic range of the phase detector 720.

[0074] The result of the phase different measurement is digitized by ND 722 and passed to the local controller 724. Simultaneously, the local controller 724 accepts the information regarding the position of the locator on the skin surface from the XYZ-Accelerometer 726. All this real-time information is transferred to the tablet computer 340 via Bluetooth interface 728. Additionally, in the same embodiment, the local controller 724 can receive (through the Bluetooth interface) feedback information from the tablet computer 340 about the correct “locator search” direction for the currently selected/active marker. This information can be displayed, for example, by means of some LED array indicator 730 deployed for example around the tip of the hand-held locator 330.

[0075] In this example embodiment, the processor or tablet computer 340 can perform the following functions: [0076] 1. Initiate and orchestrate the creation/editing subroutines needed to populate the marker pre-implantation database, including barcode scanning of the marker packages; [0077] 2. Conduct pre-operation system tests (check and verification of all system components, i.e., pad 320 and locator 330). These tests can significantly improve readiness of the system; [0078] 3. Perform real-time control of the system for successful localization of one or more markers during the surgical procedure(s); [0079] 4. Process and analyze the results of the localization process (stored in the database) post-surgery.

[0080] The processing unit 340 can be a personal computer, tablet computer, personal digital assistant (PDA), smartphone, or similar portable device. These terms can be used interchangeably and the term tablet will be used as a representative term for this group. An example of a tablet computer 340 can be an iPad manufactured by Apple Computers. Alternatively, the tablet 340 can be based on the Android operating system. The tablet 340 can be controlled via its touch-screen and may operate in several modes.

[0081] Tablet 340 may execute a plurality of software programs associated with the marker localization system/process. The programs can be used to control the system, to guide the surgeon towards a relevant marker 100, and to calculate the distance from each implanted marker to the locator 330, in real time. In addition, the tablet can be used as a man-machine interface (MMI) for communicating with the surgeon, via audio signal and 2D visual display, etc. Some examples of the software programs are disclosed below in conjunction with FIG. 8-11. The tablet 340 can communicate with the pad 320 and the locator 330 via the Bluetooth communication protocol and hardware stacks. The system is not limited to detecting a finite number of markers. For example, six or more (as an arbitrary number) markers coexisting within an anatomical body of tissue can be simultaneously processed and detected by the system.

[0082] FIG. 8 illustrates a flowchart 800 showing relevant processes that can be implemented during a pre-operation (i.e., pre-surgical) task. Upon initiation 802 of the pre-operation task, the tablet 340 (FIG. 3) can prompt the operator 804 to enter the patient data. The data may include identification and medical details about the patient, information about the surgery, the number of markers to be used, the unique electronic and the unique collective ID of each marker, the ROI, etc.

[0083] Next, the operator may plan 806 the surgery. By placing a diagram of the ROI (for that patient, for that particular procedure) on the tablet screen, the operator may determine where to implant/place each of the markers and accordingly may place 806 an image of each marker in the appropriate location related to the image of the ROI generating an implant-schema.

[0084] Once the implant schema is complete, a loop from block 810 to 822 can be started. Each cycle in the loop can be associated with one of the markers that appears in the implant-scheme. At block 810, a first marker is fetched and its barcode or QR, which constitutes the marker ID, can be scanned 812 by a camera of the tablet. Then the scanned ID can be associated with the ID of the diagram of the relevant marker in the implant-schema and the association of the two IDs can be stored 814 in a pre-operation DB. The marker can then be placed or implanted (not shown here). It should be noted that the term implantation is used generally and is understood to include placement, attachment etc. of the marker to tissue by any means. The placement of the markers can be via an introducer needle with a plunger whereby single, multiple or sequential markers can be placed at one time. The placement (and detection/localization) of markers can be via an endoscope, laparoscope, robot or video assisted device etc.

[0085] Next, a decision is made 820 whether further markers require implantation. If 820 further markers require implantation, then the next marker can be fetched 822 and process 800 loops back to block 812. If 820 there are no additional markers, then at block 824 process 800 can be configured to update the implant-scheme with the ID of the relevant deployed markers. The updated implant-schema with the scanned ID of the markers can be referred to as the Marker-Localization schema and be stored in the DB, to be used for locating the markers and ROI during the surgery. Then process 800 can be terminated 830.

[0086] In some potential embodiments of the disclosed technique, the marker-localization schema may comprise an image of the ROI and the location of each marker around the ROI, wherein each marker is presented with its own unique ID. Further, the schema may diagrammatically present the relative orientation and distance between the markers. In some embodiments the schema may include the order of suggested marker localization, for example to start by localizing marker ID #3, and thereafter marker ID #5, etc. Furthermore, some example embodiments of the disclosed technique may present a 3D rendered image on the display of the tablet 340 (FIG. 3), which can be rotated according to the corresponding movement(s) of the locator 330 (FIG. 3).

[0087] Referring now to FIG. 9 which illustrates a flowchart 900 showing relevant processes that can be implemented upon starting 902 the system for delineating the position of a specific marker/s and hence the ROI within a body tissue. In block 902, two counters, which participate in this process, can be reset. At block 904 the tablet 340 (FIG. 3) can be associated with the pad 320 (FIG. 3) through the pairing process provided by the Bluetooth protocol/chipset. At block 906 a Bluetooth channel with the EM pad 320 can be opened.

[0088] Next, the tablet 340 can instruct the excitation pad 320 to execute 908 the self-test of the pad. At the end of the self-test, a decision is made 910 whether the self-test was successfully performed. If 910 no, then a first counter, which counts the number of attempts, can be incremented 912 by one and a decision is made 914 whether the number of attempts is more than ‘N’ attempts. Typically, ‘N’ can be an integer number between three to five three, for example. If 914 the number of attempts is not more than ‘N’, then process 900 returns to block 804.

[0089] If 914 the number of attempts is more than ‘N’, then process 900 may proceed to block 936 and inform the surgeon that the system configuration/set-up has failed and process 900 can be terminated. Some embodiments of the disclosed technique may display the failed elements/subsystems detected within the pad 320 (FIG. 3).

[0090] Returning now to block 910, If 910 the self-test of the pad was successfully performed and completed, then locator 330 (FIG. 3) can execute its own self-test. At block 920, the tablet 340 (FIG. 3) can be associated with the locator 330 (FIG. 3) through the pairing process provided by the Bluetooth protocol/chipset. At block 922 a Bluetooth channel with the locator 330 can be opened.

[0091] At the end 924 of the self-test, a decision is made 930 whether the self-test was successfully performed. If 930 no, then a second counter, which counts the number of attempts, can be incremented 932 by one and a decision is made 934 whether the number of attempts is more than ‘M’ attempts. Typically, ‘M’ can be an integer number between three to five, four, for example. If 934 the number of attempts is not more than ‘M’, then process 900 returns to block 920.

[0092] If 934 the number of attempts is more than ‘M’, then process 900 may proceed to block 936 and inform the surgeon that the system configuration/set-up has failed and process 900 can be terminated 940. Some embodiments of the disclosed technique may flag the locator 330 (FIG. 3) as the failed element. Returning now to block 930, If 930 the self-test of the locator was successfully completed, then a message can be displayed on the tablet 938 informing the surgeon that the self-test of the system was successfully executed and process 900 can be terminated 940.

[0093] FIG. 10 illustrates a flowchart showing relevant processes that can be implemented prior to and during an operation, for an example method 1000 employed to guide a surgeon to one or more implanted markers. Upon initiation 1002 the method 1000 may fetch 1004 the Marker-Localization-schema (from Surgery Plan DB), relevant to the current operation. Based on the Marker-Localization-schema, the ID of the first marker is fetched 1006 and appears on the tablet screen. Next, at block 1006 the tablet 340 (FIG. 3) may instruct, via Bluetooth, the pad 320 (FIG. 3) to emit an excitation electromagnetic field 310 (FIG. 3) within the 13.56 MHz band permeating the ROI of the patient 300 (FIG. 3). The electromagnetic field 310 can be BPSK modulated, wherein the modulation reflects the ID of the relevant marker 100 (FIG. 3), thus activating only the relevant marker. Simultaneously, the locator 330 transmits a MW test signal, receives a MW response signal from the activated marker 100 and performs the phase difference measurement.

[0094] The Tablet computer 340 receives the Phase/Frequency Data 1008 from the Locator and calculates the distance 1010 between the active marker and the locator. The value of the phase difference and corresponding calculated distance of this specified marker together with the Real-Time Clock Marks is saved (accumulated) in appropriate files of the database 1009. After some predetermined number of marker distance estimates, data will be accumulated in the file allocated for specific marker measurements, and the routine 1100 (Marker direction estimation program) can be initiated. Simultaneously the estimated distance and active marker ID can be displayed 1012 on the computer 340 screen by means of the Tablet-on-screen MMI and the Tablet-generated audio signal 1014 can change its pitch. If the marker-change-interrupt 1016 has not been received the marker localization process can be continued.

[0095] Next, a decision is made whether 1016 a marker-change-interrupt was received from the locator. If 1016 no, method 1000 returns to block 1008 for calculating the current distance between the locator and the relevant marker. If 1016 yes, then a decision is made 1018 whether there are more markers in the marker-localization-scheme. If 1018 yes, then the ID of the next marker in the marker-localization-scheme is fetched 1006 and method 1000 returns to block 1006 for handling the next marker. If 1018 there are no more markers in the marker-localization-scheme, then method 1000 can be terminated.

[0096] In the embodiment currently disclosed, FIG. 11 illustrates an example marker direction estimation program 1100 of the tablet computer 340. The program can be initiated automatically or by some method of instruction pre-programming. In an automatic regime, after accumulating some data (i.e., some specified value) in marker distance file 1112, the computer begins accumulating the XYZ-accelerometer data 1102 from the locator 330. After double integration in time 1104, this data is stored in temporary memory 1106 as a trajectory of the locator 330 movement on the surface of the patient's skin. After time-smoothing the trajectory data by the filter 1108, the spatial gradient 1110 of the trajectory is calculated. This gradient is compared with the result of the distance derivative calculation 1114 by means of the distance change correlator 1116. If the gradient and distance change are correlated, the decision about correct direction 1118 is accepted. Next, the tentative 3D position of the active marker can be calculated 1120. The result of “correct direction” angle (based on attitudes provided by gradient calculation 1110) is transferred to the locator 330 via the Bluetooth interface. This direction can be displayed by using the LED array indicator 730 (FIG. 7). The indication of the “correct” direction to the active marker can guide the surgeon to moving the locator 330 in expediting localization of the active marker 100. The localization information belonging to the active marker, for example; the current locator to marker distance; marker ID; direction to the marker; can be displayed on the screen of the tablet computer 340.

[0097] Turning to FIG. 4, a schematic of potential RF and MW signal paths is shown for estimating the distance from the marker 100 to the locator 330. Assuming the current distance from the center of the excitation (and synchronization) pad 320 and locator 330 as R.sub.0, distance from the center of pad 320 to the marker 100 as R.sub.1, and the distance from the marker 100 and the locator 330 as D, the complex amplitudes of the signals received by the marker 100 and the locator 330 can be presented as the following: S.sub.m=A.sub.1exp(−i2πR.sub.1/λ.sub.1) and S.sub.L=A.sub.0 exp(−i2πR.sub.0/λ.sub.1) respectively, where λ.sub.1 is a wavelength of propagating the frequency band of 13.56 MHz in the patient's body 310.

[0098] The signal transmitted by the locator 330 toward a plurality of markers has the following spectral components:

S.sub.T=A.sub.L exp(i(ω.sub.2+ω.sub.1)t)exp(−i2πR.sub.0/λ.sub.1)+A.sub.L exp(i(ω.sub.2−ω.sub.1)t)exp(−i2πR.sub.0/λ.sub.1),

where ω.sub.2 and ω.sub.1 are angular frequencies of the bands 5800 MHz and 13.56 MHz respectively. The signal responded by the active marker and received by the locator's microwave antenna has three spectral components: ω.sub.2, ω.sub.2+2ω.sub.1, and ω.sub.2−2ω.sub.1. After amplitude detection 715 (FIG. 7) and band pass filtering which is tuned to 27.12 MHz band (2ω.sub.1 frequency) the low frequency signal is proportional to cos(2ω.sub.1 (t−2D/v.sub.2−R.sub.0/v.sub.1), where v.sub.2 and v.sub.1 are velocities of the EM wave propagation in tissue for frequencies of ω.sub.2 and ω.sub.1 respectively. The phase difference measured by phase detector 720 (FIG. 7) allows the distance estimation according to the formula D=Δϕλ.sub.1/(2π√ε.sub.2), where ε.sub.2 is the permittivity of human tissue (for example breast tissue) and Δϕ is the phase difference measured by the phase detector 720.

[0099] The described algorithm provides an estimation of the distance between the locator 330 (FIG. 3) and the active marker 100 in the case where the center of the reference (EM field excitation) pad, activated marker and locator all reside on the same direct line (the co-axial case).

[0100] The marker can be placed at any location within the volume of tissue 310 (see FIG. 3) irradiated by the pad 320. There can be instances of initial, non-zero (axial) distance and (lateral) offset of the marker relative to the center of the excitation pad. In such instances, in the initial localization process, there can be a large initial distance between the locator and the active marker. During the interactive process of marker localization, as the surgeon moves the locator toward the active marker, the distance discrepancy converges to zero. This process of zero convergence can be represented on the computer screen 340 as a series of concentric circles converging to a dot on the screen as and when the locator reaches a site directly over the active marker.

[0101] In the description and claims of the present disclosure, each of the verbs, “comprise”, “include”, “have”, and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements, or parts of the subject or subjects of the verb.

[0102] The present disclosure has been described using detailed descriptions of embodiments thereof that are provided by way of example and are not intended to limit the scope of the invention. The described embodiments comprise different features, not all of which are required in all embodiments of the invention. Some embodiments of the present invention utilize only some of the features or possible combinations of the features. Many other ramification and variations are possible within the teaching of the embodiments comprising different combinations of features noted in the described embodiments.

[0103] It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described herein above. Rather the scope of the invention is defined by the claims that follow.