PULSED-LIGHT EMITTING MARKER DEVICE

Abstract

The invention relates to an active marker device (100) for being introduced into a human tissue and for tracking a region of interest of a human body. The active marker device comprises a light source (101) for emitting light such that the emitted light can be detected by an optical sensor. In this way, the active marker device and/or the region of interest can be tracked by a tracking system comprising the optical sensor. The active marker device (100) further comprises a switch (102) for turning the light source on and off and for operating the light source in a pulsed mode.

Claims

1. An active marker device configured to be implanted into a tissue prior to a procedure, for tracking a region of interest of a subject during the procedure, the active marker device comprising: a light source for emitting light such that the active marker device is detectable by an optical sensor; and a switch for operating the light source in a pulsed mode, wherein the switch is configured to be operated in a contactless manner for remotely activating the light source during the procedure.

2. Marker device according to claim 1, wherein the switch is configurable for operating the light source in one specific pulsed mode of a plurality of different pulsed modes.

3. Marker device according to claim 1, the marker device comprising: a receiving unit for receiving an activation signal for the light source; wherein the switch is configured to switch the light source on when the receiving unit receives the activation signal.

4. Marker device according to claim 3, wherein the receiving unit is configured for receiving a signal comprising information about a property of the pulsed mode; and wherein the switch is configured for operating the light source in the pulsed mode having said property.

5. Marker device according to claim 4, wherein the property of the pulsed mode is a frequency and/or a pulse pattern.

6. Marker device according to claim 3, wherein the receiving unit is configured for receiving a triggering signal triggering the generation of a pulse by the light source; and wherein the switch is configured for turning the light source on, only when the triggering signal is received by the receiving unit.

7. Marker device according to claim 1, comprising: an energy source adapted for supplying the light source with electrical energy.

8. Marker device according to claim 7, wherein the energy source comprises an LC circuit for a wireless power supply of the energy source.

9. Marker device according to claim 1, wherein the marker device is configured for being introduced into a cannula of an insertion needle.

10. Marker device according to claim 9, wherein the active marker device comprises a capsule into which the light source and the switch are encapsulated.

11. Tracking system for tracking a region of interest in a subject, comprising: an optical sensor configured to detect light emitted by a light source of an active marker device according to any one of the preceding claims; and a processing unit configured to determine a position of the active marker device on the basis of the light detected by the optical sensor, wherein the optical sensor comprises at least one time-of-flight camera for receiving a light pulse emitted by the active marker device and generating information associated with a receipt of said light pulse, and wherein the processing unit is configured to determine the position of the active marker device based on the information from the at least one time-of-flight camera.

12. Tracking system according to claim 11, wherein the system comprises at least two time-of-flight cameras; and wherein the processing unit is configured to determine the position of the active marker device based on a phase delay between pulse-shaped signals of the first and second time-of-flight cameras caused by a light pulse emitted by the active marker.

13. Tracking system according to claim 11, wherein the system comprises a single time-of-flight camera having at least three pixels configured to receive the light pulse of the active marker device emitted from a plurality of corresponding points on the surface of the body, and wherein the processing unit is configured to determine the position of the active marker device based on a phase delay in signals of the time-of-flight camera representing a receipt of the emitted light pulse at the at least three pixels.

14. Tracking system according to claim 12, wherein the processing unit is configured for determining the position of the active marker device by triangulation.

15. Tracking system according to claim 11, wherein the processing unit is configured for identifying the active marker device on the basis of the pulsed mode of the light received by the camera.

16. Medical imaging system, comprising: a medical imaging device; and a tracking system according to claim 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0059] FIG. 1 shows an active marker device according to an exemplary embodiment of the invention.

[0060] FIGS. 2A, 2B and 2C show the introduction of an active marker device according to an exemplary embodiment into a human tissue.

[0061] FIGS. 3A and 3B show insertion needle comprising a cannula, into which an active marker device according to an exemplary embodiment is introduced.

[0062] FIGS. 4A and 4B show electrical circuits for an active marker device according to exemplary embodiments of the invention.

[0063] FIG. 5 shows an electrical circuit for wirelessly providing an active marker device with electrical energy.

[0064] FIG. 6 shows a medical examination apparatus according to an exemplary embodiment.

[0065] FIG. 7 shows a tracking system according to an exemplary embodiment of the invention.

[0066] FIG. 8A shows a tracking system according to an exemplary embodiment of the invention.

[0067] FIG. 8B shows a tracking system according to an exemplary embodiment of the invention.

[0068] The figures are schematic and not true to scale. If in the following description elements of different figures are labeled with the same reference signs, they refer to the same or similar elements. The same or similar elements may, however, also be labeled with different reference signs.

DETAILED DESCRIPTION OF EMBODIMENTS

[0069] In FIG. 1, an active marker device 100 according to an exemplary embodiment of the invention is shown. The active marker device is adapted for being introduced into human tissue for marking and for tracking an object of interest, e.g. a tumor, of a human body. The active marker device comprises 100 a light source 101 adapted for emitting light 104 such that the active marker device 100 is visible to an optical sensor. Furthermore, the active marker device 100 comprises a switch 102 adapted for turning the light source 101 on and off and for operating the light source 101 in a pulsed mode. Furthermore, the active marker device 100 comprises an energy source 103, e.g. a battery or a LC circuit for wireless power transfer to the active marker device 100. The light source 101, the switch 102, and the energy source 103 are encapsulated in a capsule 105 of the active marker device 100.

[0070] For example, the active marker device 100 comprises a low power LED 101 such as a Nichia NESL 157AT-H3 LED. This LED typically has a luminous flux of 11.5 lm and a luminous intensity of 4.0 cd. The LED 101 may, e.g., be connected to a small battery 103 and the switch 102 may be switchable from the distance. The LED can also be an HSMW white ChipLED having a size of 1.5×0.8×0.6 mm. Furthermore, the LED can be a PICOLED of ROHM having a size of 1.0×0.52×0.2 mm. The LED and the electronics of the active marker 100 may be capsulated in a capsule 105 of epoxy resin (e.g. EPO-TEK 301) that is biocompatible and optically transparent. The capsule 105 is made in an elongated shape such hat it fits inside a cannula of an insertion needle.

[0071] In FIGS. 2A to 2C the introduction of an active marker device 100 according to an exemplary embodiment of the invention into a human body 201 is shown. The active marker device 100 is located in a cannula of an insertion needle 200. The human body 201 comprises a region of interest 203, e.g. a tumor. Furthermore, the human body has a body surface 202.

[0072] In FIG. 2B, the introduction or insertion of the active marker device 100 into the human body 201 at or near the region of interest 203 is shown. For that purpose, the insertion needle 200 is pierced into the human body 201 through the body surface 202 and the active marker device 100 is implanted in or near the region of interest 203.

[0073] In FIG. 2C, it is shown that the active marker device 100 implanted in or near the region of interest 203 emits light 104 in a pulsed mode for tracking the active marker device 100 and the region of interest 203, respectively. The light source of the active marker device 100 can be activated before implanting the active marker device into the body 201, e.g. by manually operating a switch. Alternatively, the light source can be activated in a contactless manner when the active marker device is already implanted in the human body 201, e.g. by sending an RF activation signal.

[0074] FIG. 3A shows an insertion needle 301 and a stylet 302, the insertion needle 301 comprising a cannula 303 for introducing an active marker device according to an exemplary embodiment of the invention. In FIG. 3B, an enlarged section of the cannula 303 is shown. It can be gathered that an active marker device is located inside the cannula 303 of the insertion needle.

[0075] FIG. 4A shows an example electrical circuit 400 for operating the light source 401 of the active marker device according to an exemplary embodiment of the invention. The light source is embodied as a light emitting diode (LED) 401. Furthermore, the electrical circuit comprises an energy source 402, e.g. a battery. Moreover, the light source 401 is coupled to a switching circuit 408 comprising a field-effective transistor 404, an RF antenna 403, a diode 405, a resistor 406, and a capacitor 407. The RF antenna 403, the diode 405, the resistor 406, and the capacitor 407 are part of an AM receiver of the switching circuit 408. FIG. 4B shows a simple circuit 410 for operating the light source 411 of the active marker device according to an exemplary embodiment of the invention. Again, the light source 411 is embodied as a light emitting diode (LED). In this case, the AM receiver comprises the RF antenna 413, the diode 415, and the transistor 414 and uses the input capacitance of the transistor 414.

[0076] In FIG. 5, electrical circuits 501 and 502 for wirelessly providing an active marker device 501 with electrical energy are shown.

[0077] The active marker device 501 comprises an LC circuit 503 having a coil 504 and a capacitor 505. Furthermore, the active marker device comprises a load circuit 506 including a coil 508 and a LED driving electronics 507.

[0078] The electrical energy is wirelessly provided to the active marker device 501 by an energy supplying device 502. The energy supplying device 502 comprises an LC circuit 509 including a coil 510 and a capacitor 511. The energy supplying device 502 further comprises a source circuit including an alternating energy source and a coil 514.

[0079] The source circuit 512 is configured to couple the energy into the resonant LC circuit 509 via the coils 514 and 510. The LC circuit 503 of the active marker device receives a part of the electromagnetic flux generated by the LC circuit 509 and couples the energy into the load circuit 506 which supplies the LED driver electronics with electrical energy.

[0080] In FIG. 6, a medical examination apparatus 600 comprising a medical imaging apparatus 601 according to an exemplary embodiment of the invention is shown. In this exemplary embodiment, the medical imaging apparatus 601 comprises a C-arm having an X-ray source 603 and an X-ray detector 602. The C-arm 601 further comprises a tracking system having optical sensors 604 and 605 as well as a processing unit 610.

[0081] Furthermore, a human body 606 is located between the X-ray source 603 and the X-ray detector 602 of the C-arm. The human body 606 comprises a region of interest, e.g. a tumor. Moreover, an active marker device 608 is implanted into the human body at or near the region of interest 607. In this way, the active marker device 608 and/or the region of interest can be tracked without having to activate the X-ray source, e.g., when the human body is moved during surgery. The processing unit 610 is adapted for determining a position, e.g. a 3D position, of the active marker device 608 on the basis of the light detected by the optical sensors 604, 605. The processing unit 610 is adapted to determine the position of the active marker device 608 by applying triangulation.

[0082] In FIG. 7 a tracking system 700 according to an exemplary embodiment of the invention is shown. The tracking system comprises a support structure 701 for the time-of-flight cameras 702, 703, 704, 705. The support structure 701 is, e.g., a C-arm of a medical examination apparatus.

[0083] A body of a patient 706 having a tumor (region of interest) 707 is schematically shown. Furthermore, three implanted active marker devices 708, 709 and 710 circumscribing the tumor are shown. The tracking system 700 is configured for determining the position of the active marker devices 708, 709 and 710 by determining an intersection of the three spherical surfaces determined by at least three time-of-flight cameras of the four time-of-flight cameras 702, 703, 704 and 705. In other words, the position of the active marker device in 3D space is determined using path information of the pulsed light emitted by the active marker devices 708, 709, 710, as detected by the time-of-flight cameras. The estimated time of flight of the light pulse, which represents a path length for the emitted light from the active marker device to the camera, is used for determining the spherical surface on which the active marker device is located.

[0084] In order to explain the working principle of the time-of-flight camera, exemplary embodiments in a simplified 2D representation are shown in FIGS. 8A and 8B.

[0085] In FIG. 8A a tracking system according to an embodiment of the invention is shown. Furthermore, a body having a surface 801 is depicted, in which an active marker device 802 is implanted. The active marker device is configured to emit light in a pulsed mode. A signal curve 803 of the switch of the active marker device causing a light pulse of the active marker device 802 is further shown. The tracking system comprises a first time-of-flight camera 804 and a second time-of-flight camera 806. It is further shown that the first time-of-flight camera 804 generates a pulse-shaped signal 805 caused by the light pulse 803 of the active marker device 802. The second time-of-flight camera 806 generates a pulse-shaped signal 807 caused by the light pulse 803 of the active marker device. Furthermore, the tracking system comprises a device 808 for determining a phase delay between the pulses 805 and 807 of the first and second time-of-flight cameras 804 and 806. The phase delay between the pulses 805 and 807 correlates to the average path delay from the active marker device 802 to the patient surface 801 plus the distance from the patients surface 801 to the time-of-flight cameras 804, 806. In other words, the phase delay corresponds to the difference in path length between the sum of the paths 810 and 811 and the sum of the paths 814 and 815. The path 810 corresponds to the path between the active marker device 802 and the point 809 on the surface 801 and the path 811 corresponds to the path between the point 809 on the surface and the time-of-flight camera 804. Equally, the path 814 corresponds to the path between the active marker device 802 and the point 813 on the surface 801 and the path 815 corresponds to the path between the point 813 on the surface and the time-of-flight camera 806. In this way, the tracking system can triangulate the position of the active marker device 802 by determining the intersection of spherical surfaces 812 and 816.

[0086] Preferably, an additional third time-of-flight camera (not shown) may be used so that a 3D position of the active marker device 802 corresponds to a single intersection point of three spherical surfaces, one for each camera device.

[0087] In FIG. 8B, the determination of the position of the active marker device 802 with one single time-of-flight camera 817 is shown. A plurality of pixels of the time-of-flight camera receives the light pulse from the active marker. A first pixel receives the light being emitted from point 809 of the surface 801 of the body and a second pixel receives the light emitted from point 813 of the surface 801 of the body. For each of these of pixels, the distance between the camera and the corresponding points 809,813 on the patient surface is known, e.g. from registering the camera position with an existing patient outline scan, from standard reflective time-of-flight measurement or from any other suitable distance measurement.

[0088] At the first pixel that receives light from the surface point 809, the measured value is composed of sum of the distances 810 and 818. Equally, at the second pixel that receives light from the surface point 813, the measured value is composed of sum of the distances 814 and 819. Similar to the previous embodiment, the phase delay measured at the first and second pixel of the time-of-flight camera corresponds to the difference in path length between the sum of the paths 810 and 818 and the sum of the paths 814 and 819.

[0089] As the length of the paths 818 and 819 are known from the 3D position of points 809 and 813 and the 3D position of the time-of-flight camera 817, the tracking system can determine the distances 810 and 814 and subsequently triangulate the position of the active marker device by determining the intersection of spherical surfaces 820 and 821.

[0090] In 3D, preferably the position of the active marker device is determined using signals from at least three separate pixels of the time-of-flight camera. That is, based on a phase delay between these signals, the distances from the active marker device to at least three surface points observed by the corresponding pixels of the single time-of-flight camera may be determined. Again, the position of the active marker device is subsequently triangulated by determining the single intersection point of the three spherical surfaces corresponding to these distances.

[0091] A typical image may have many more surface points visible to different pixels of the TOF camera. Thus, preferably, signals from additional pixels receiving the light pulse from the marker at different time instances may be relied upon in order to further improve the accuracy of the marker position determination.

[0092] Optionally, a collimator may be used to restrict the image information received by the different pixels to a limited area of the total surface. That is, for example, the first pixel may receive light from surface point 809 but the collimator prevents light from surface point 813 from reaching the first pixel. Similarly, the collimator prevents light from surface point 809 from reaching the second pixel of the time-of-flight camera.

[0093] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

[0094] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measured cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

LIST OF REFERENCE SIGNS

[0095] 100 active marker device [0096] 101 light source [0097] 102 switch [0098] 103 energy source [0099] 104 light [0100] 105 capsule [0101] 200 insertion needle [0102] 201 human body [0103] 202 body surface [0104] 203 object of interest (e.g. tumor) [0105] 301 insertion needle [0106] 302 insertion needle [0107] 303 cannula [0108] 304 active marker device [0109] 400 electrical circuit [0110] 401 light source (LED) [0111] 402 energy source (battery) [0112] 403 receiving unit (RF antenna) [0113] 404 field effective transistor [0114] 405 diode [0115] 406 resistor [0116] 407 capacitor [0117] 410 electrical circuit [0118] 411 light source (LED) [0119] 412 energy source (battery) [0120] 413 receiving unit (RF antenna) [0121] 414 transistor [0122] 415 diode [0123] 501 active marker device [0124] 502 energy supplying device [0125] 503 LC circuit [0126] 504 coil [0127] 505 capacitor [0128] 506 load circuit [0129] 507 LED driver electronics [0130] 508 coil [0131] 509 LC circuit [0132] 510 coil [0133] 511 capacitor [0134] 512 source circuit [0135] 513 alternating current source [0136] 514 coil [0137] 600 medical examination apparatus [0138] 601 C-arm [0139] 602 X-ray detector [0140] 603 X-ray source [0141] 604 optical sensor [0142] 605 optical sensor [0143] 606 body [0144] 607 region of interest (tumor) [0145] 608 active marker device [0146] 609 tracking system [0147] 610 processing unit [0148] 700 tracking system [0149] 701 camera support [0150] 702 time-of-flight camera [0151] 703 time-of-flight camera [0152] 704 time-of-flight camera [0153] 705 time-of-flight camera [0154] 706 body [0155] 707 region of interest (tumor) [0156] 708 active marker device [0157] 709 active marker device [0158] 710 active marker device [0159] 801 surface of the body [0160] 802 active marker device [0161] 803 signal of a light pulse [0162] 804 first time-of-flight camera [0163] 805 signal generated by the first time-of-flight camera [0164] 806 second time-of-flight camera [0165] 807 signal generated by the second time-of-flight camera [0166] 808 device for determining a phase delay [0167] 809 first point on the surface of the body [0168] 810 path between active marker and the first point [0169] 811 path between the first point and the first time-of-flight camera [0170] 812 first spherical surface [0171] 813 second point on the surface of the body [0172] 814 path between the active marker and the second point [0173] 815 path between the second point and the second time-of-flight camera [0174] 816 second spherical surface [0175] 817 single time-of-flight camera [0176] 818 distance between the first point and the single time-of-flight camera [0177] 819 distance between the second point and the single time-of-flight camera [0178] 820 first spherical surface [0179] 821 second spherical surface