Passive and active sensors for ultrasound tracking

Abstract

A system performs a medical procedure in a region of interest of a patient. The system includes an interventional medical device insertable into the region of interest, and a sensor attached to a portion of the interventional device, the sensor being configured to convert an ultrasonic wave from an ultrasound imaging probe to a corresponding electrical radio frequency (RF) signal. The corresponding RF signal is received by a wireless receiver outside the region of interest, enabling determination of a location of the sensor within the region of interest.

1 . A system for performing a medical procedure in a region of interest of a patient, the system comprising:
 an interventional device insertable into the region of interest;   a passive sensor attached to a portion of the interventional device, the passive sensor configured to convert an ultrasonic wave from an ultrasound imaging probe to a corresponding electrical radio frequency (RF) signal;   an RF transmitter configured to:
 continuously broadcast, via an external antenna remote from the passive sensor, 
   an external RF signal that is received by the passive sensor, and
 detect, on the external antenna, a modulated load indicating when the passive sensor converted the ultrasonic wave to the corresponding electrical RF signal; and 
   a processor configured to determine a location of the passive sensor within the region of interest based on detection of the modulated load on the external antenna by the RF transmitter.   
     
     
         2 . The system of  claim 1 , wherein the location of the passive sensor is determined based on (i) delay between receipt of the ultrasonic wave at the passive sensor and the detection of the modulated load on the external antenna and (ii) information about a transmit pattern of the ultrasound imaging probe. 
     
     
         3 . The system of  claim 1 , wherein the passive sensor is configured to reflect the broadcasted external RF signal received by the passive sensor, wherein the reflected signal is transmitted at a higher harmonic than the broadcasted external RF signal. 
     
     
         4 . The system of  claim 1 , wherein the passive sensor comprises an electronic resonator circuit attached to a local antenna, the electronic resonator circuit tuned to a frequency of the external RF signal, and the passive sensor configured to modulate the electronic resonator circuit in response to receipt of the ultrasonic wave to generate the modulated load detected on the external antenna of the RF transmitter. 
     
     
         5 . The system of  claim 4 , wherein the passive sensor has a resonate cavity that modules the electronic resonator circuit in response to receipt of the ultrasonic wave. 
     
     
         6 . The system of  claim 4 , wherein the electronic resonator circuit includes a capacitive element configured to sense the ultrasonic wave and generate an amplitude modulation based on the broadcasted external RF signal. 
     
     
         7 . The system of  claim 1 , wherein the RF transmitter detects the modulated load based on monitoring power levels going into the external antenna. 
     
     
         8 . The system of  claim 1 , further comprising the ultrasound imaging probe configured to transmit the ultrasonic wave received and converted by the passive sensor. 
     
     
         9 . A method for performing a medical procedure in a region of interest of a patient, the method comprising:
 converting, by a passive sensor attached to a portion of an interventional device, an ultrasonic wave from an ultrasound imaging probe to a corresponding electrical radio frequency (RF) signal;   continuously broadcasting, via an external antenna remote from the passive sensor, an external RF signal that is received by the passive sensor;   detecting, on the external antenna, a modulated load indicating when the passive sensor converted the ultrasonic wave to the corresponding electrical RF signal; and   determining a location of the passive sensor within the region of interest based on detection of modulated load on the external antenna.   
     
     
         10 . The method of  claim 9 , wherein the location of the passive sensor is determined based on (i) delay between receipt of the ultrasonic wave at the passive sensor and the detection of the modulated load on the external antenna and (ii) information about a transmit pattern of the ultrasound imaging probe. 
     
     
         11 . The method of  claim 9 , further comprising:
 reflecting the broadcasted external RF signal received by the passive sensor, wherein the reflected signal is transmitted at a higher harmonic than the broadcasted external RF signal.   
     
     
         12 . The method of  claim 9 , wherein the passive sensor comprises an electronic resonator circuit attached to a local antenna, the method further comprising:
 tuning the electronic resonator circuit to a frequency of the external RF signal; and   modulating the electronic resonator circuit in response to receipt of the ultrasonic wave to generate the modulated load detected on the external antenna of the RF transmitter.   
     
     
         13 . The method of  claim 12 , wherein the passive sensor has a resonate cavity that modules the electronic resonator circuit in response to receipt of the ultrasonic wave. 
     
     
         14 . The method of  claim 9 , further comprising monitoring power levels going into the external antenna to detect the modulated load. 
     
     
         15 . The method of  claim 12 , wherein the electronic resonator circuit includes a capacitive element and the method further comprises generating, using the capacitive element, an amplitude modulation of the broadcasted external RF signal. 
     
     
         16 . A non-transitory computer-readable storage medium having stored a computer program comprising instructions, which, when executed by at least one processor, cause the processor to
 continuously broadcasting, via an external antenna remote from a passive sensor attached to a portion of an interventional device, an external RF signal that is received by the passive sensor, wherein the passive sensor converts an ultrasonic wave from an ultrasound imaging probe to a corresponding electrical radio frequency (RF) signal;   detecting, on the external antenna, a modulated load indicating when the passive sensor converted the ultrasonic wave to the corresponding electrical RF signal; and   determining a location of the passive sensor within the region of interest based on the detected modulated load.   
     
     
         17 . The non-transitory computer-readable storage medium of  claim 16 , wherein the location of the passive sensor is determined based on (i) delay between receipt of the ultrasonic wave at the passive sensor and detection of the modulated load on the external antenna and (ii) information about a transmit pattern of the ultrasound imaging probe. 
     
     
         18 . The non-transitory computer-readable storage medium of  claim 16 , wherein the passive sensor comprises an electronic resonator circuit attached to a local antenna, the electronic resonator circuit tuned to a frequency of the external RF signal, and the passive sensor configured to modulate the electronic resonator circuit in response to receipt of the ultrasonic wave to generate the modulated load detected on the external antenna of the RF transmitter. 
     
     
         19 . The non-transitory computer-readable storage medium of  claim 18 , wherein the passive sensor has a resonate cavity that modules the electronic resonator circuit in response to receipt of the ultrasonic wave. 
     
     
         20 . The non-transitory computer-readable storage medium of  claim 16 , the instructions, when executed by the processor, further cause the processor to monitor power levels going into the external antenna to detect the modulated load.