DC Block Patient Isolator for Microwave Generators

Abstract

A patient isolator for a microwave generator includes a DC block grounded to a microwave module of the microwave generator, a proximal absorber wrapped around a proximal portion of the DC block, and a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap. In one embodiment, the gap separating the proximal and distal absorbers is approximately 6 mm. The DC block can include a proximal mounting block and a distal mounting block. In one embodiment, the proximal mounting block is conductive, and the DC block is grounded to the microwave module of the microwave generator via the proximal mounting block.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of and priority to U.S. Provisional Application No. 62 / 933,199, filed November 8, 2019, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THEINVENTION The present disclosure relates to microwave generators, and more particularly, to DC block isolators for microwave generators for patient isolation. [Background technology]

[0003] In microwave ablation, electromagnetic fields are used to heat and destroy tumor cells. Treatment may involve inserting an ablation probe into tissue where a cancerous tumor has been identified. Once the ablation probe is properly positioned, it induces an electromagnetic field in the tissue surrounding the ablation probe to ablate the tissue.

[0004] Typically, a system for microwave ablation procedures includes a microwave generator and a microwave instrument, such as an ablation probe having an antenna assembly. The microwave generator and the microwave instrument are operatively coupled to each other by a coaxial cable for transmitting a microwave signal from the microwave generator to the microwave instrument. The microwave generator typically includes circuitry for generating the microwave signal and a controller for controlling operation of the circuitry and a user interface, such as a display. The user interface includes user controls for setting characteristics of the microwave signal, such as buttons for adjusting the power level of the microwave signal.

[0005] Some microwave generators can incorporate a patient isolator to electrically isolate the patient from the microwave generator components. The DC block patient isolator works by using a capacitive gap of a break in the inner and outer conductors of the coaxial waveguide. Low frequency signals see this coupling as a high impedance, but the operating frequency of 2.45 GHz sees this coupling as a low impedance. However, the break in the outer conductor of the coaxial line in the DC block allows radiation of otherwise unwanted high frequency energy outside the waveguide, thereby causing interference to other components of the microwave generator. In some cases, such unwanted radiation can interfere with the sensor signal, the accuracy of which is essential for proper control and operation of the microwave generator. Summary of the Invention [Means for solving the problem]

[0006] According to an aspect of the present disclosure, there is provided a patient isolator for a microwave generator comprising a DC block configured to be grounded to a microwave module of the microwave generator, a proximal absorber wrapped around a proximal portion of the DC block, and a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap.

[0007] In one embodiment, the gap separating the proximal and distal absorbers is a gap of about 6 mm.

[0008] The DC block may include a proximal mounting block and a distal mounting block, in one aspect, the proximal mounting block is conductive and the DC block is grounded to a microwave module of the microwave generator through the proximal mounting block.

[0009] In one aspect, at least one of the proximal absorber or the distal absorber is a high-loss cavity resonating absorber.

[0010] According to another aspect of the present disclosure, a microwave generator is provided comprising: a microwave module configured to deliver a microwave signal to a microwave instrument coupled to the microwave generator; a generator controller configured to communicate with and control the microwave module; and a patient isolator coupled to the microwave module. The patient isolator comprises a DC block grounded to the microwave module, a proximal absorber wrapped around a proximal portion of the DC block, and a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap.

[0011] In one embodiment, the gap separating the proximal and distal absorbers is a gap of about 6 mm.

[0012] The DC block may include a proximal mounting block and a distal mounting block, in one aspect, the proximal mounting block is conductive and the DC block is grounded to a microwave module of the microwave generator through the proximal mounting block.

[0013] In one aspect, at least one of the proximal absorber or the distal absorber is a high-loss cavity resonating absorber.

[0014] According to another aspect of the present disclosure, an ablation system is provided comprising a microwave instrument configured to deliver microwave energy to tissue and a microwave generator configured to couple to the microwave instrument. The microwave generator comprises a microwave module configured to deliver a microwave signal to the microwave instrument, a generator controller in communication with the microwave module, and a patient isolator coupled to the microwave module. The patient isolator comprises a DC block grounded to the microwave module of the microwave generator, a proximal absorber wrapped around a proximal portion of the DC block, and a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap.

[0015] In one embodiment, the gap separating the proximal and distal absorbers is a gap of about 6 mm.

[0016] The DC block may include a proximal mounting block and a distal mounting block, in one aspect, the proximal mounting block is conductive and the DC block is grounded to a microwave module of the microwave generator through the proximal mounting block.

[0017] In one aspect, at least one of the proximal absorber or the distal absorber is a high-loss cavity resonating absorber. [Brief description of the drawings]

[0018] Various embodiments of the present disclosure are described with reference to the drawings. [Figure 1] FIG. 1 is a block diagram of a microwave ablation system. [Figure 2A] FIG. 2 is a circuit block diagram of a microwave generator of the microwave ablation system of FIG. 1. [Figure 2B] FIG. 2 is a block diagram of a microwave device of the microwave ablation system of FIG. [Diagram 3] FIG. 2B is a circuit block diagram of a generator controller of the microwave generator of FIG. 2A. [Figure 4] FIG. 2B is a circuit block diagram of a microwave module of the microwave generator of FIG. 2A. [Diagram 5] FIG. 2B is a circuit block diagram of an instrument monitoring module of the microwave generator of FIG. 2A. [Figure 6A] FIG. 2B is a perspective view of the microwave generator of FIG. 2A including a patient isolator coupled to the microwave module of the generator. [Figure 6B] FIG. 2B is a top view of the microwave generator of FIG. 2A including a patient isolator coupled to the microwave module of the generator. [Figure 6C] FIG. 2B is a perspective view of a patient isolator grounded to the microwave module of the microwave generator of FIG. 2A. [Figure 7] FIG. 2B is a perspective view of a patient isolator of the microwave generator of FIG. 2A. [Figure 8] 1 is a graph showing experimental radiated emissions results and FCC Part 18 limits. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Specific embodiments of the present disclosure are described below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

[0020] As used herein, the term "about" means that the numerical value is approximate and that small variations do not significantly affect the practice of the embodiments of the present disclosure. When numerical limitations are used, unless otherwise indicated by the context, "about" means that the numerical value can vary by ±10% and still remain within the scope of the present disclosure.

[0021] A microwave generator can perform several functions in addition to and related to its primary function of generating microwave signals used by microwave instruments. Although the additional functions provide additional convenience to the microwave generator, they also require more power, use more processing resources, and add to the overall cost of manufacturing. The present disclosure relates to a modular microwave generator system that includes physical modules and components that provide distributed and standalone processing to perform auxiliary functions associated with the microwave generator. One such component is an improved DC block patient isolator that minimizes radiation interference to other components and other modules of the generator.

[0022] FIG. 1 is a block diagram of a microwave ablation system according to an embodiment of the present disclosure. As shown in FIG. 1, the microwave ablation system 100 generally includes a microwave generator 110, a connection device 180 (e.g., a microwave ablation instrument such as a microwave antenna) connected to the microwave generator 110 by a reusable cable 160, and a radiometer 150. The connection device 180 includes a device ID module 170 having a device unique identification resistor ("DUIR") 240 and a device ID memory 260 (see FIG. 2B). The DUIR 240 has a device unique identification ("DUID") resistance value, which is measured by the microwave generator 110, that can be compared to a resistance value indicator stored in the memory of the microwave generator 110 to identify the type of the connection device 180. Based on the identified type of the connection device 180, a determination can be made as to whether the connection device is of a type compatible with the microwave generator 110. The device ID module 170 may be incorporated into the connection device 180 or may be incorporated into a separate connector or adapter configured to mate with the connector of the reusable cable 160. Thus, the reusable cable 160 may be connected to the DUIR 240 and to the device ID memory 260 via a connection to the device 180. Alternatively, the reusable cable 160 may be connected to the DUIR 240 and to the device ID memory 260, which in turn may be connected to the device 180. Similar memory and / or resistors that store device specific information may be included in the reusable cable 160 and the radiometer 150. The microwave generator 110 may also be connected to the foot switch 140 via a foot switch port on the microwave generator 110.

[0023] During use of the microwave ablation system 100, a variety of different subsystems may be employed. Typically, operation of the subsystems is controlled by a microprocessor-driven console (e.g., microwave generator 110). The microprocessor receives mechanical input from an operator of the microwave ablation system 100 or from an assistant. A control input device, such as a foot switch 140, is used to accept mechanical input from the operator, allowing the operator to govern the operation of the subsystems within the microwave ablation system 100. When actuated by the operator, the control input device transmits an electrical signal to the microprocessor control system. The electrical signal is then used to control the operating characteristics of the subsystems within the microwave ablation system 100.

[0024] As shown in FIG. 1, the microwave generator 110 is connected to a remote temperature probe 190. The remote temperature probe 190 may include a temperature sensor, such as a thermocouple or thermistor, but may also include memory to store other information, such as a device ID or status information. The remote temperature probe 190 is operable to measure the temperature of tissue at the surgical site. In one embodiment, the remote temperature probe 190 is configured to continuously output a temperature signal to the microwave generator 110, allowing a user to monitor the temperature or control the microwave generator 110 based on the temperature signal.

[0025] 2A is a circuit block diagram of the microwave generator 110 of FIG. 1 configured to output a microwave signal according to one embodiment of the present disclosure. The microwave generator 110 may include any, a subset, or all of a power supply module or unit 210, a generator control module or controller 220, a microwave module 230, an instrument monitoring module 250, a remote temperature probe monitoring module 270, a user interface module 290, and a patient isolator 1000.

[0026] The power supply unit 210 is electrically connected to the generator controller 220 and the microwave module 230 to provide power to the generator controller 220 and the microwave module 230. The generator controller 220, in turn, is electrically connected to the instrument monitoring module 250, the remote temperature probe monitoring module 270, and the user interface module 290 by electrical conductors, such as wires or traces, for providing power to the connection device 180 or the instrument monitoring module 250, the remote temperature probe monitoring module 270, and the user interface module 290. The generator controller 220 also communicates with the instrument monitoring module 250, the remote temperature probe monitoring module 270, and the user interface module 290 via communication conduits, such as the electrical conductors, optical fibers, or wireless communication links mentioned above.

[0027] In an embodiment of the present disclosure, any, a subset, or all of these modules may be removably connectable to ports or terminals of the microwave generator 110. For example, only the auxiliary modules, such as the instrument monitoring module 250, the remote temperature probe monitoring module 270, and the user interface module 290, may be removably connected to the microwave generator 110, while the other modules may be more permanently incorporated into the microwave generator 110. A detailed description of the remote temperature probe monitoring module and the user interface module according to embodiments of the present disclosure is provided in commonly assigned U.S. Patent Publication No. 2017 / 0333128, filed May 18, 2017, the entire contents of which are incorporated herein by reference.

[0028] 1, the microwave generator 110 also includes a digital port 120 that is configured to receive a connector to establish a connection with a programming device or with a device intended to communicate with the individual components or modules of the microwave generator 110 (see FIG. 2A). While connected to the digital port 120, the programming device can communicate with and program the individual modules via the generator controller 220.

[0029] 2B is a circuit block diagram of the device ID module 170 of FIG. 1 according to one embodiment of the disclosure. The device ID module 170 includes a DUIR 240 and a device ID memory 260, each of which is configured to communicate with any one or more of the microwave generator's modules (e.g., the instrument monitoring module 250) via the reusable cable 160. Upon start-up, with the device connected to the microwave generator 110 via the reusable cable 160, the microwave generator 110 can provide a precise current to the DUIR 240 via the reusable cable 160 to generate a DUID resistance value at any time requested by the generator controller 220 or a user. The instrument monitoring module 250 measures the DUID resistance value and communicates this value to the generator controller 220. To identify the type of connected device 180, the generator controller 220 processes the DUID resistance value received from the instrument monitor module 250 and compares the processed DUID resistance value to a plurality of resistance indicators stored in the memory of the generator controller 220, each corresponding to a particular device type. The identified type of connected device 180 may determine whether the connected device 180 is compatible with the microwave generator 110. The type of device may correspond to a particular capability of the device, a model of the device, a particular series of a model of the device, a particular type of treatment modality of the device, whether the device is electronically controlled, compatibility of the device with the microwave generator, or any combination thereof. Device-specific operational thresholds for configuring operation of the microwave generator 110 for use with the connected device 180 may be determined based on the identified type of the connected device 180. Examples of what device-specific operational thresholds may be for configuring microwave generator operation based on an identified device type according to embodiments of the present disclosure are provided in commonly assigned U.S. Provisional Patent Application No. 62 / 774,927, filed December 4, 2018, the entire contents of which are incorporated herein by reference.

[0030] 3 illustrates the generator controller 220 of the microwave generator 110 according to one embodiment of the present disclosure. The generator controller 220 includes a power isolator 310 that receives an external DC voltage from the power supply unit 210. The power isolator 310 may include a transformer having a primary winding and a secondary winding. Power received by the power isolator 310 passes through the primary winding of the transformer and induces a current in the secondary winding of the transformer that is proportional to the current received by the transformer 310. The induced current provides power to the generator controller microprocessor 330. In one embodiment, the power isolator 310 provides a maximum power consumption of 50 W, for example, to the generator controller microprocessor 330 of 12 VDC. The generator controller microprocessor 330 also provides 12 VDC to the generator subsystems, including the microwave module 230, the instrument monitoring module 250, the remote temperature probe monitoring module 270, and the user interface module 290.

[0031] The generator controller microprocessor 330 is a programmable processor configured through flash programming or other suitable programming methods and languages ​​to digitally communicate with the microwave module 230, the instrument monitoring module 250, the remote temperature probe monitoring module 270, the user interface module 290, the foot switch 140, other remote switches, and devices connected to the digital port 120 of the microwave generator 110. The generator controller microprocessor 330 may be calibrated through software calibration methods, such as radix-based digital self-calibration, background equivalent radix extraction, interference cancellation, and other techniques. The generator controller microprocessor 330 may also be calibrated through hardware calibration methods, such as digitally controllable low pass filters using comparator / digital-to-analog converter (DAC) combinations, digital potentiometers, and calibration multiplexers. The generator controller microprocessor 330 may also be calibrated through any hardware and / or software solutions to improve the digital communication link. As part of its communication with the microwave module 230, the instrument monitoring module 250, the remote temperature probe monitoring module 270, and the user interface module 290, the generator controller microprocessor 330 communicates information about the generator controller microprocessor 330 to each component, such as status information, serial number, firmware version, etc. The generator controller microprocessor 330 in turn receives information about the generator controller microprocessor 330 from each component, such as status information, serial number, firmware version, etc., which the generator controller microprocessor 330 processes and monitors continuously.

[0032] The generator controller microprocessor 330 is in digital communication with the user interface module 290 to receive user input and transmit information that can be communicated to the user by the user interface module 290. The generator controller microprocessor 330 can issue a signal to the user interface module 290, which can prompt the user to input a microwave power level or treatment time. When the user makes a selection, the user interface module 290 transmits a signal to the generator controller microprocessor 330 indicating the selection, which the generator controller microprocessor 330 receives, processes, and issues a signal to the microwave module 230 to set the power level or treatment time. Alternatively, the generator controller microprocessor 330 can delay the signal to the microwave module 230. For example, when the generator controller microprocessor 330 receives the treatment time, the generator controller microprocessor 330 transmits a signal to the microwave module 230 only when the allotted time has expired. While the treatment is being performed, the generator controller microprocessor 330 counts the selected treatment time. In addition to issuing an end signal to the microwave module 230, the generator controller microprocessor 330 communicates with the user interface module 290 throughout the countdown to send signals to the user interface module 290 to present information regarding the remaining treatment, including the remaining treatment time, to indicate to the user how much time is remaining.

[0033] 4 illustrates the microwave module 230 and patient isolator 1000 of the microwave generator 110 according to one embodiment of the present disclosure. The microwave module 230 includes various components including a pulse width modulation (PWM) controller 410, an internal temperature monitor 420, a microwave module subsystem controller 430, an amplifier 440, an applied power monitor 450, a reflected power monitor 460, a digital bus isolator 490, and a power isolator 495. The microwave module subsystem controller 430 receives power, for example, 12VDC with a maximum power consumption of 50W, from the generator controller 220 via the power isolator 495. The power isolator 495 isolates the power provided from the generator controller 220 to the microwave module subsystem controller 430.

[0034] The microwave module subsystem controller 430 is a programmable processor configured via flash programming or other suitable programming methods and languages, and is configured to generate up to 150 W and maintain a power setting within, for example, a range of −5% to +20%, according to a set point set by, for example, a user. The microwave module subsystem controller 430 is configured with associated state settings related to power, current, voltage, temperature, or any other measurable standard suitable for protecting the microwave module 230. If an associated value becomes excessive, the microwave module subsystem controller 430 may stop providing power to any or all of the components included in the microwave module 230.

[0035] Power is received from the generator controller 220 by a power isolator 495. Similar to power isolator 310, power isolator 495 includes one or more transformers, one or more optical couplers, or other suitable circuitry for electrically isolating the microwave module 230 from other modules and circuitry of the microwave ablation system 100. Power isolator 495 provides power to the microwave module subsystem controller 430. In some embodiments, power isolator 495 may also provide power to the amplifier 440.

[0036] The internal temperature monitor 420 continuously measures the temperature of the amplifier 440. The internal temperature monitor 420 may be a thermocouple, a thermistor, or other suitable temperature sensor. The internal temperature monitor 420 then transmits the temperature data to the microwave module subsystem controller 430. The microwave module subsystem controller 430 sends the amplifier 440 temperature data, e.g., as a temperature value in degrees Celsius, to the generator controller 220 via the digital bus isolator 490. While monitoring the amplifier 440 temperature, the internal temperature monitor 420 may cause the cooling system to redistribute and remove heat generated by the amplifier 440.

[0037] The PWM controller 410 generates a pulse width controlled power signal according to instructions from the microwave module subsystem controller 430. The frequency controller 470 generates a frequency controlled power signal according to instructions from the microwave module subsystem controller 430. The amplifier 440 receives a pulse width modulated (PWM) signal from the PWM controller 410, a frequency control signal from the frequency controller 470, and power from the power supply unit 210 with a maximum power consumption of 350 W, for example, 36 VDC. Using the power from the power supply unit, the amplifier 440 amplifies the PWM signal and varies the frequency of the PWM signal according to the frequency control signal to generate a microwave signal. The power signal is provided to the patient isolator 1000 via the applied power monitor 450. The applied power monitor 450 determines the power, voltage, current, and waveform of the microwave signal and communicates information with the microwave module subsystem controller 430 to enable the microwave module subsystem controller 430 to recalibrate the microwave signal.

[0038] In the patient isolator 1000, the patient is electrically isolated from the power source of the microwave module 230. The patient isolator 1000 outputs a microwave signal to the connection device 180 and isolates the connection device 180 and the patient from the remaining components of the microwave module 230, as well as other components and modules of the microwave generator 110. The patient isolator 1000 is described in more detail below in conjunction with Figures 6A-6C and 7.

[0039] The reflected power monitor 460 is connected to the patient isolator 1000 and monitors the reflected return signal. The reflected power monitor 460 may measure voltage, current, power, and / or impedance. Information determined by the reflected power monitor 460 is communicated to the microwave module subsystem controller 430, allowing the microwave module subsystem controller 430 to calibrate the microwave signal. The microwave module subsystem controller 430 may compare information from the reflected power monitor 460 with information from the applied power monitor 450 to determine loss and phase shift between the incident and reflected waves of the microwave signal. Additionally, the microwave module subsystem controller 430 may be configured to communicate raw or processed data via a digital bus isolator 490 to electrically isolate the microwave module subsystem controller 430 from other modules connected to the digital bus using a transformer or other isolation device.

[0040] 5 is a circuit block diagram of the instrument monitoring module 250 of the microwave generator 110, according to one embodiment of the disclosure. The instrument monitoring module 250 includes a digital bus isolator 510, a power isolator 590, an instrument monitoring subsystem controller 530, an instrument temperature monitor 550, a pass-through circuit 570, and a device ID reader 580. The power isolator 590, similar to the power isolator 310, includes one or more transformers, one or more optical couplers, or other suitable circuitry for electrically isolating the user interface module 290 from other modules and circuits of the microwave ablation system 100. The power isolator 590 provides power to the instrument monitor subsystem controller 530.

[0041] The instrument monitor subsystem controller 530 controls and communicates with the instrument temperature monitor 550, the pass-through circuit 570, and the device ID reader 580. The instrument monitor subsystem controller 530 also communicates with the generator controller 220 via a digital bus connected to a digital bus isolator 510, which relays communication signals while electrically isolating the instrument monitor subsystem controller 530.

[0042] Upon power-up, or at any time requested by the generator controller 220 or a user, the generator controller 220 may instruct the device ID reader 580 to measure the DUID resistance of the connected device 180 and communicate the measured DUID resistance value to the instrument monitor subsystem controller 530, which processes and communicates the resistance value to the generator controller 220. If the connected device 180 is identified as an electronically controlled device based on the DUID resistance measurement of the connected device 180, the generator controller 220 may instruct the instrument monitor subsystem controller 530 to pass a request data packet to the device ID memory 260 of the connected device 180 via the reusable cable 160. Upon receiving the request data packet from the instrument monitor subsystem controller 530, the device ID memory 260 of the connected device 180 communicates the requested data packet, including device-specific data, to the instrument monitor subsystem controller 530 via the device ID reader 580 for response to the instrument monitor subsystem controller 530. The device ID reader 580 may receive a single-ended signal containing the requested data packet, which is then communicated to the instrument monitor subsystem controller 530 for processing and communication to the generator controller 220.

[0043] Upon initiating surgery, the instrument monitor subsystem controller 530 instructs the instrument temperature monitor 550 to begin monitoring the temperature of the connected device 180. The instrument temperature monitor 550 determines the temperature of the connected device 180, for example, by determining the voltage difference between two lines connected to a thermocouple or thermistor.

[0044] The pass through circuitry 570 receives digital signals via a receive (Rx) channel and outputs digital signals via a transmit (Tx) channel. The pass through circuitry 570 allows the instrument monitor subsystem controller 530 to communicate with the connecting device 180. The instrument monitor subsystem controller 530 analyzes the data and sends the information to the generator controller 220 via the digital bus and digital bus isolator 510.

[0045] 6A-6C show a patient isolator 1000 connected to a microwave module 230. The patient isolator 1000 shown in FIGS. 6A-6C and 7 includes a high loss cavity resonant absorber split into two parts, each of which is wrapped around a portion of a DC block 1100. The DC block 1100 is grounded to the microwave module 230. Such an arrangement has been found to be effective in reducing the amount of undesirable radiation emitted from the DC block 1100, and is particularly effective in reducing interference imparted to signals related to the measurement of the remote temperature probe 190. In particular, the measurement signal of the remote temperature probe 190 is particularly susceptible to interference generated by the DC block patient isolator during start-up and delivery of microwave energy. The DC block patient isolator operates with a capacitive gap of breaks in the inner and outer conductors of a coaxial waveguide. Low frequency signals see this connection as high impedance, while the operating frequency of 2.45 GHz sees this connection as low impedance. However, a break in the outer conductor of the coaxial line within the DC block allows undesirable, interfering radiation of high frequency energy outside the waveguide, thereby causing interference to other components of the microwave generator 110. In one example, the second harmonic of the operating frequency (approximately 4.9 GHz) is radiated from the DC block into the generator chassis and from the chassis into free space.

[0046] As the output of microwave energy increases, the accuracy of the sensor measurement is reduced due to interference caused to the sensor by radiation emitted by the patient isolator. Accurate sensor measurements ensure successful operation of the microwave generator 110. For example, the accuracy of the readings of the remote temperature probe 190 is reduced as the output of microwave energy increases due to interference caused to the remote temperature probe 190 by radiation emitted by the patient isolator. Accurate readings of the remote temperature probe 190 ensure successful operation of the microwave generator 110 and ensure successful patient safety. Thus, the system described herein ensures that measurements provided by sensors, such as the sensor of the remote temperature probe 190, are accurate and are not interfered with by radiation generated by other components of the system. Inaccurate sensor data impairs the control and output of the microwave generator 110. Incidentally, there are radiation limits set by regulatory authorities (e.g., FCC rules 47 CFR part 18) that could not be met without the improvements detailed herein. Referring briefly to FIG. 8, a graph reflecting experimental data of radiation emissions (below FCC standards) using the disclosed patient isolator is shown.

[0047] It has been found that grounding the patient isolator to the microwave module 230 only slightly reduces the interference caused by the grounded patient isolator to the measurement signal of the remote temperature probe 190. Similarly, it has been found that wrapping the patient isolator along its length with a high loss cavity resonant absorber only slightly reduces the interference the wrapped patient isolator causes to the measurement signal of the remote temperature probe 190. Furthermore, it has been found that both grounding the patient isolator and wrapping the grounded patient isolator along its length with a high loss cavity resonant absorber only slightly reduces the interference caused by the grounded wrapped patient isolator to the measurement signal of the remote temperature probe 190. The slight level of interference reduction achieved by the above design is insufficient to achieve accurate measurements by the remote temperature probe 190. However, in accordance with the present disclosure, it has been found that grounding the patient isolator to the microwave module 230, wrapping a high loss cavity resonant absorber around a proximal portion of the patient isolator, and wrapping a high loss cavity resonant absorber around a distal portion of the patient isolator with a gap between the two portions effectively reduces the interference caused to the remote temperature probe 190 signal.

[0048] In particular, the embodiment of the segmented absorber described above, in which there is a 6 mm gap between the two portions of the absorber, shows a -9 dB improvement in radiation at 4.9 GHz compared to a -5 dB improvement in radiation when using a single centrally located absorber. Furthermore, experiments have shown that grounding only the patient isolator or the microwave amplifier does not effectively reduce the radiation causing interference, but grounding the proximal portion of the DC block itself effectively reduces the 6 cm wavelength radiation at 4.9 GHz. In particular, the use of a ground plate located connecting the proximal portion of the DC block, the microwave amplifier, and the chassis of the microwave generator effectively reduces the 6 cm wavelength radiation at 4.9 GHz.

[0049] As shown in Figures 6A-6C and 7, the patient isolator 1000 includes a DC block 1100, a proximal mounting block 1102, a distal mounting block 1104, a proximal absorber 1106, and a distal absorber 1108. The proximal end of the DC block 1100 is coupled to the output of the microwave module 230, and the distal end of the DC block 1100 is coupled to an output port for coupling the microwave generator to a connection device 180 (Figure 1). At least one of the proximal mounting block 1102 or the distal mounting block 1104 is formed of a conductive material (e.g., aluminum) and is grounded to a portion of the microwave module 230. In one embodiment, the proximal mounting block 1102 is grounded to the microwave module 230 via a ground plate "GP" (Figure 6C), which is grounded to the chassis of the microwave generator 110.

[0050] The DC block 1100 can operate even with a capacitive gap across the break in the inner and outer conductors of the coaxial waveguide. Low frequency signals see this coupling as a high impedance, but the operating frequency of 2.45 GHz sees this coupling as a low impedance. The DC block 1100 is configured to isolate the patient from the other components of the microwave generator 110.

[0051] The proximal absorber 1106 is wrapped around a proximal portion of the DC block 1100 and the distal absorber 1108 is wrapped around a distal portion of the DC block 1100. The proximal absorber 1106 is spaced apart from the distal absorber 1108 such that a gap "G" (FIG. 7) exists between the proximal absorber 1106 and the distal absorber 1108. In one embodiment, the gap "G" is a 6 mm gap, although other gap distances are contemplated. It has been found that grounding the proximal mounting block 1102 to the microwave module 230 and creating a 6 mm gap distance between the proximal absorber 1106 and the distal absorber 1108 provides excellent attenuation of interference radiation. At least one of the proximal absorber 1106 or the distal absorber 1108 may be a high loss cavity resonant absorber. In one embodiment, at least one of the proximal absorber 1106 or distal absorber 1108 is a thin sheet material that is magnetic while being lossy at microwave frequencies, but maintaining the desirable properties of an elastomeric binder. The proximal absorber 1106 or distal absorber 1108 may be designed to exhibit high magnetic loss and attenuate normal and high angle of incidence energy at frequencies between 1 GHz and 18 GHz. In one embodiment, the elastomer of the proximal absorber 1106 or distal absorber 1108 is silicone, although other elastomer formulations are contemplated.

[0052] Although several embodiments of the present disclosure have been shown in the drawings and discussed herein, it is not intended that the disclosure be limited thereby, but rather that the disclosure be given the broadest possible scope in the art, and that the specification be interpreted in the same manner. Therefore, the above description should be interpreted merely as an illustration of certain embodiments, and not as limiting. Other modifications that do not depart from the scope and spirit of the claims appended hereto will occur to those skilled in the art. (Item 1) 1. A patient isolator for a microwave generator, comprising: a DC block configured to be grounded to a microwave module of the microwave generator; a proximal absorber wrapped around a proximal portion of the DC block; a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap; 1. A patient isolator comprising: (Item 2) 2. The patient isolator of claim 1, wherein the gap separating the proximal and distal absorbers is about 6 mm. (Item 3) 2. The patient isolator of claim 1, wherein the gap separating the proximal and distal absorbers is 6 mm. (Item 4) 2. The patient isolator of claim 1, wherein the DC block includes a proximal mounting block and a distal mounting block. (Item 5) 5. The patient isolator of claim 4, wherein the DC block is grounded to a microwave module of a microwave generator via the proximal mounting block. (Item 6) 2. The patient isolator of claim 1, wherein at least one of the proximal absorber or the distal absorber is a high loss cavity resonant absorber. (Item 7) 1. A microwave generator comprising: a microwave module configured to deliver a microwave signal to a microwave instrument coupled to the microwave generator; a generator controller configured to communicate with and control the microwave module; a patient isolator coupled to the microwave module, a DC block grounded to the microwave module; a proximal absorber wrapped around a proximal portion of the DC block; and a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap; a patient isolator comprising: A microwave generator comprising: (Item 8) 8. The microwave generator according to claim 7, wherein the gap separating the proximal absorber and the distal absorber is about 6 mm. (Item 9) 9. The microwave generator according to claim 8, wherein the gap separating the proximal absorber and the distal absorber is 6 mm. (Item 10) 8. The microwave generator of claim 7, wherein the DC block includes a proximal mounting block and a distal mounting block. (Item 11) Item 11. The microwave generator of item 10, wherein the DC block is grounded to the microwave module of the microwave generator via the proximal mounting block. (Item 12) Item 8. The microwave generator according to item 7, wherein at least one of the proximal absorber or the distal absorber is a high-loss cavity resonator absorber. (Item 13) 1. A microwave ablation system, comprising: a microwave instrument configured to deliver microwave energy to tissue; and a microwave generator configured to be operably coupled to the microwave appliance, a microwave module configured to deliver a microwave signal to the microwave appliance; a generator controller in communication with the microwave module; a patient isolator coupled to the microwave module, a DC block grounded to the microwave module; a proximal absorber wrapped around a proximal portion of the DC block; and a distal absorber wrapped around a distal portion of the DC block and separated from the proximal absorber by a gap; a patient isolator comprising: A microwave generator comprising: A microwave ablation system comprising: (Item 14) Item 14. The microwave ablation system of item 13, wherein the gap separating the proximal absorber and the distal absorber is about 6 mm. (Item 15) Item 15. The microwave ablation system of item 14, wherein the gap separating the proximal absorber and the distal absorber is 6 mm. (Item 16) Item 14. The microwave ablation system of item 13, wherein the DC block includes a proximal mounting block and a distal mounting block. (Item 17) Item 17. The microwave ablation system of item 16, wherein the DC block is grounded to the microwave module of the microwave generator via the proximal mounting block. (Item 18) Item 14. The microwave ablation system of item 13, wherein at least one of the proximal absorber or the distal absorber is a high-loss cavity resonant absorber.

Claims

1. 1. A patient isolator for a microwave generator, comprising: a DC block configured to be grounded to a microwave module of the microwave generator; a proximal absorber wrapped around a proximal portion of the DC block; a distal absorber wrapped around a distal portion of the DC block; wherein the distal absorber is separated from the proximal absorber by an unobstructed gap, and a combined length of the proximal absorber, the unobstructed gap, and the distal absorber is equal to a total length of the DC block.

2. 2. The patient isolator of claim 1, wherein the unobstructed gap separating the proximal and distal absorbers is approximately 6 mm.

3. 2. The patient isolator of claim 1, wherein the unobstructed gap separating the proximal and distal absorbers is 6 mm.

4. A patient isolator as described in claim 1, further comprising a proximal mounting block and a distal mounting block.

5. 5. The patient isolator of claim 4, wherein the DC block is grounded to a microwave module of a microwave generator through the proximal mounting block.

6. 10. The patient isolator of claim 1, wherein at least one of the proximal absorber or the distal absorber is a high loss cavity resonating absorber.

7. 1. A microwave generator comprising: a microwave module configured to deliver a microwave signal to a microwave instrument coupled to the microwave generator; a generator controller configured to communicate with and control the microwave module; a patient isolator coupled to the microwave module, a DC block grounded to the microwave module; a proximal absorber wrapped around a proximal portion of the DC block; and a distal absorber wrapped around a distal portion of the DC block; a patient isolator including: a distal absorber separated from a proximal absorber by an unobstructed gap, the combined length of the proximal absorber, the unobstructed gap, and the distal absorber being equal to a total length of the DC block; A microwave generator comprising:

8. 8. The microwave generator of claim 7, wherein the unobstructed gap separating the proximal and distal absorbers is about 6 mm.

9. 9. The microwave generator of claim 8, wherein the unobstructed gap separating the proximal and distal absorbers is 6 mm.

10. The microwave generator of claim 7 , wherein the patient isolator includes a proximal mounting block and a distal mounting block.

11. 11. The microwave generator of claim 10, wherein the DC block is grounded to the microwave module of the microwave generator through the proximal mounting block.

12. 8. The microwave generator of claim 7, wherein at least one of the proximal absorber or the distal absorber is a high-loss cavity resonator absorber.

13. 1. A microwave ablation system, comprising: a microwave instrument configured to deliver microwave energy to tissue; a microwave generator configured to be operably coupled to the microwave appliance, a microwave module configured to deliver a microwave signal to the microwave appliance; a generator controller in communication with the microwave module; a patient isolator coupled to the microwave module, a DC block grounded to the microwave module; a proximal absorber wrapped around a proximal portion of the DC block; and a distal absorber wrapped around a distal portion of the DC block; a patient isolator comprising: a distal absorber separated from a proximal absorber by an unobstructed gap, the combined length of the proximal absorber, the unobstructed gap, and the distal absorber being equal to a total length of the DC block; A microwave generator comprising: A microwave ablation system comprising:

14. The microwave ablation system of claim 13, wherein the unobstructed gap separating the proximal and distal absorbers is about 6 mm.

15. 15. The microwave ablation system of claim 14, wherein the unobstructed gap separating the proximal and distal absorbers is 6 mm.

16. The microwave ablation system of claim 13 , wherein the patient isolator includes a proximal mounting block and a distal mounting block.

17. 17. The microwave ablation system of claim 16, wherein the DC block is grounded to the microwave module of the microwave generator through the proximal mounting block.

18. The microwave ablation system of claim 13 , wherein at least one of the proximal absorber or the distal absorber is a high loss cavity resonant absorber.

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