HIFU And Immune System Activation

Abstract

A method can include placing a high intensity focused ultrasound probe proximate a designated treatment volume of a patient, ablating a first portion of the designated treatment volume with the probe using at least one pulse sequence and set of parameters designed to achieve such an ablation; and applying a nonablative dose of energy to a second portion of the designated treatment volume with the probe using at least one different pulse sequence than that used on the first portion and a set of parameters designed to achieve such a nonlethal dose.

Claims

1. A method comprising: placing a high intensity focused ultrasound probe proximate a designated treatment volume of a patient; ablating a first portion of the designated treatment volume with the probe using a set of parameters designed to achieve ablation, the first portion being at least slightly smaller than the designated treatment volume; and applying a nonablative dose of energy to a second portion of the designated treatment volume with the probe using a set of parameters designed to achieve such a nonlethal dose.

2. The method of claim 1, wherein the ablation of the first portion is completed using at least one pulse sequence and set of parameters designed to achieve such an ablation, and wherein the application of a nonablative dose of energy to the second portion is completed using at least one different pulse sequence than that used on the first portion and a set of parameters designed to achieve such a nonlethal dose.

3. The method of claim 2, wherein the probe is in a first position when the ablative energy is directed to the first portion, and wherein the probe is in the same first position during the application of a nonablative does of energy to the second portion.

4. The method of claim 1, wherein the second portion surrounds the first portion.

5. The method of claim 1, wherein the application of a nonablative does of energy to the second portion provokes an immune system response from a patient.

6. The method of claim 1, wherein the probe includes one or more ultrasound transducers configured to image and treat the designated treatment volume.

7. The method of claim 6, wherein the one or more ultrasound transducers include at least one first crystal optimized for pulsed focused ultrasound (pFUS) and at least one second crystal optimized for ablative focused ultrasound (aFUS).

8. The method of claim 7, wherein the at least one first crystal is located on a first side of the transducer and the at least one second crystal is longed on an opposing second side of the transducer.

9. The method of claim 7, wherein the one or more ultrasound transducers are each single array transducers formed of a two parts, the two parts include at first crystal optimized for pFUS and a second crystal optimized for aFUS.

10. The method of claim 9, wherein the second crystal surrounds at least a portion of the first crystal.

11. The method of claim 1, further comprising: defining the first portion of the designated treatment volume prior to ablating the first portion; defining the second portion of the designated treatment volume prior to ablating the first potion, wherein the second portion surrounds the first portion.

12. A system comprising: a high intensity focused ultrasound probe including a shaft and at least one transducer, the probe being configured to ablate a first portion of a designated treatment volume of a patient and being configured to apply a nonablative does of energy to a second portion of the designated treatment volume.

13. The system of claim 12, wherein the probe uses at least one pulse sequence to ablate the first portion at least one different pulse sequence to apply a nonablative does of energy to the second portion.

14. The system of claim 12, wherein the at least one transducer is configured to image and treat the designated treatment volume, the at least one transducer being configured to deliver both the ablative dose of focused ultrasound in a continuous or semi-continuous manner and nonablative dose of focused ultrasound in a pulsed manner.

15. The system of claim 12, wherein the at least one transducer includes at least one first crystal optimized for pulsed focused ultrasound (pFUS) and at least one second crystal optimized for ablative focused ultrasound (aFUS).

16. The system of claim 13, wherein the at least one first crystal is located on a first side of the at least one transducer and the at least one second crystal is longed on an opposing second side of the at least one transducer.

17. The system of claim 12, wherein the at least one transducer is single array transducers formed of a two parts, the two parts include at first crystal optimized for pFUS and a second crystal optimized for aFUS.

18. The system of claim 17, wherein the second crystal surrounds at least a portion of the first crystal.

Description

DRAWINGS

[0025] The foregoing summary, as well as the following detailed description of the invention, will be better understood when read in conjunction with the appended drawing(s). For the purpose of illustrating the invention, there are shown in the drawings various illustrative embodiments. It should be understood, however, that the invention is not limited to the precise arrangements and instrumentalities shown.

[0026] FIG. 1a is a schematic representation of a probe according to one embodiment of the present disclosure;

[0027] FIG. 1b is a schematic representation of a probe according to another embodiment of the present disclosure

[0028] FIG. 1c is a schematic representation of a portion of the probe of FIG. 1b;

[0029] FIG. 2 is a schematic representation of the operation of a probe of one embodiment of the present disclosure;

[0030] FIG. 3a is a schematic representation of tissue designed to be treated with a probe of one embodiment of the present disclosure;

[0031] FIG. 3b is a schematic representation of a first treatment volume identified by a system of the present disclosure;

[0032] FIG. 3c is a schematic representation of first and second treatment volumes identified by a system of the present disclosure;

[0033] FIG. 4a is a schematic representation of one environment in which a probe of the present disclosure is configured to operate;

[0034] FIG. 4b is a schematic representation of the operation of a probe of one embodiment of the present disclosure;

[0035] FIG. 4c is a schematic representation of the operation of a probe of one embodiment of the present disclosure;

[0036] FIG. 5a is a schematic representation of the operation of a probe of one embodiment of the present disclosure;

[0037] FIG. 5b is a schematic representation of the operation of a probe of one embodiment of the present disclosure; and

[0038] FIG. 6 is a schematic representation of an exemplary computing system useful for performing at least certain processes disclosed herein.

DETAILED DESCRIPTION

[0039] Various embodiments of the present disclosure are described hereinafter with reference to the figures. It should be noted that the figures are not drawn to scale and elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are not intended to facilitate the description of specific embodiments of the invention. The figures are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an aspect described in conjunction with a particular embodiment of the present invention is not necessarily limited to that embodiment and can be practiced in any other embodiments of the present invention. It will be appreciated that while various embodiments of the invention are described in connection with radiation treatment of tumors, the claimed invention has application in other industries and to targets other than cancers. Unless specifically set forth herein, the terms a, an and the are not limited to one element, but instead should be read as at least one.

[0040] In one embodiment, the present disclosure includes a system for performing a surgical procedure. The system can include a probe 100 having a shaft 101 and at least one transducer 102 configured to deliver thermal energy to tissue, generally designated 10, to a designated first treatment volume or region, generally designated 12, and/or to a second treatment volume or region, generally designated 14. The first treatment volume 12 can represent a volume for immune activation and/or an outer periphery of an ablation zone 13. A nonablative or nonlethal region 15 can surround the ablation zone 13. In other words, the nonlethal region 15 can be formed between an outer periphery of the first treatment volume 12 and an inner periphery of the second treatment volume 14.

[0041] The transducer can be configured to also generate images of the designated treatment volume and surrounding tissue. The images can be used to correctly position the delivery of thermal energy. A user input interface or display can be provided to define the first treatment volume 12. The user interface can also allow for the designation of the second region 14, volume, or location of tissue, for example at a periphery of the first treatment volume 12 or spaced outwardly from the first treatment volume 12, which can receive a nonablative or sublethal dose of thermal energy (FIG. 4c, for example). Once the second region 14 slated to receive a nonlethal dose has been defined, the settings for delivering the ablative dose of thermal energy to the first volume 12 can be determined such that the dose falloff region of the ablative dose covers the second volume 14 insuring that the second volume receives a sublethal thermal dose. The size, shape and/or configuration of each of the first and second regions 12, 14 can vary depending upon the desired treatment. For example, as shown in FIG. 3c, each region 12, 14 can be generally circular and the regions 12, 14 can be concentric. Alternatively, the first region 12 can have a first shape, while the second region 14 can have a different shape (see FIG. 4e).

[0042] In addition to being related to the size of the ablation volume, the magnitude of the volume of tissue that needs to be exposed to a sublethal dose of thermal energy may be related to cancer type, organ location, and/or other factors impacting the reliability of immune system activation, or it can be determined arbitrarily. The user interface of the probe 100 can provide a means for allowing these factors to be taken into account by entering any combination of the volume of tissue to be exposed to a sublethal dose, the thickness of the rim of tissue surrounding the zone to be ablated that is to be exposed to a sublethal dose, or other means that will allow the volume of tissue that is to be exposed to a sublethal dose to be inputted or defined. The presence of critical structures, generally designated 16, (e.g., an organ) close to the target volume can also be considered during the definition of the lethal/sublethal volumes. For example, target volumes close to critical structures can receive a sublethal dose 18, while target volumes further away from the critical structures may be chosen to receive a lethal dose 20 (FIGS. 3b and 3c).

[0043] Furthermore, settings used to produce a desired volume of ablation can take into account the dynamics of energy buildup and energy falloff in ablated tissue. With a dose of HIFU sufficient to ablate tissue, the fall-off in thermal energy from ablated to non-ablated tissue can be very sharp in the lateral direction, on the order of a small number of cells. In the direction of the HIFU beam 60 (proximal and distal), the transition zone between ablation and non-ablation is wider. Post-focal (distal) falloff can be fairly steep, comprising a region of dose bleed over from a degree of fuzziness that results from the way the beam is focused onto a relatively small zone, a degree that is relatively independent of the amount of dose delivered to the tissue. Pre-focal (proximal) demarcation between ablation and nonablation is variable and depends to a large degree on the size of the zone of ablation and speed with which energy is deposited in the tissue. In one embodiment, these factors should be taken into account in order to determine the size of the transition zone that will result from a given ablation zone. By knowing the volume of tissue that needs to receive a sublethal dose, and the size of the zone that under ideal circumstances would be ablated, it is possible to determine the volume of ablation that can be realized while still achieving the sublethal volume requirement. An optimization algorithm, such as simulated annealing, combinatorial optimization, dynamic programming, evolutionary algorithm, gradient method, stochastic optimization, and others known to those skilled in the art, may be used to determine the optimal volume of ablation, based on inputted values and tissue characteristics, such that said volume is maximized while still preserving the volume of treated tissue receiving a sublethal thermal dose.

[0044] In an alternative embodiment, the region of tissue slated to receive a sublethal dose can be treated with energy delivery parameters different from those used to deliver a lethal or ablative dose. As an example, the parameters for pulsed focused ultrasound (pFUS), which is nonablative, differ greatly from those of ablative focused ultrasound and are designed to insure that the tissue exposed to pFUS is not ablated. A typical set of parameters for delivering an ablative dose of focused ultrasound include a frequency of approximatley 4 MHz versus a pFUS frequency of approximately 1 MHz; a spatial average temporal average intensity (I.sub.SATA) of approximately 2,500 watts W/cm.sup.2 for an ablative dose compared to approximately 100-1,000 W/cm.sup.2 for pFUS; and a duty cycle for ablation consisting of several seconds of beam ON time followed by several seconds of beam OFF time (such as 3 sec on/3 sec off, 3 sec on/6 sec off; 3 sec ON/3 sec ON, 3 seconds OFF; etc) versus a duty cycle of 100 ms on/900 ms off for pFUS. While parameters such as frequency, intensity, and duty cycle are achievable by changing software settings driving a transducer, changing frequency typically requires the use of separate crystals for each frequency, but can also be accomplished by operating the crystal at its 3rd harmonic, for example.

[0045] Referring to FIGS. 1a-2, the probe 100 can be provided equipped with one or more ultrasound transducers 102 that can be used to image and/or treat a region of interest. The transducer(s) 102 can be able to be powered in such a manner as delivering both an ablative dose of focused ultrasound in a continuous or semi-continuous manner and/or a nonablative dose of focused ultrasound in a pulsed manner. Such a focused ultrasound (FUS) probe, capable of delivering ablative and nonablative treatment, can have many possible configurations, including: [0046] 1) A two sided transducer that is flipped between a side with a crystal optimized for pFUS, generally designated 46, and a second side with a crystal optimized for aFUS (ablative focused ultrasound), generally designated 48 (FIG. 1a); [0047] 2) A single array transducer divided in at least two parts, one with crystals optimized for pFUS, generally designated 50, and one with crystals optimized for aFUS, generally designated 52 (FIGS. 1b and 1c); and [0048] 3) A single element or array transducer where the crystal(s) is driven at its fundamental frequency for pFUS and at its 3.sup.rd and/or 5.sup.th harmonic for aFUS.
The table below outlines some of the characteristics that differentiate the mechanism of action and the expected outcome of HIFU and pHIFU (pulsed high intensity focused ultrasound) (or pFUS).

TABLE-US-00001 Parameter HIFU pHIFU (or pFUS) Frequency 1-4 MHz 100 KHz-1 MHz Temperature rise in C. 30-50 approximately 3-5 Treatment Exposure Mode Continuous Pulsed Beam On Time 3-20 seconds 1-10 m seconds Focal site peak intensity 600-4000 100-1000 (w/cm2) Desired Cellular effect Thermal coagulative Mechanical Stress necrosis Hyperthermia Cellular changes Irreversible Cell Reversible Membrane death and cellular changes

[0049] One or more of the above-described techniques and/or embodiments may be implemented with or involve software, for example modules executed on or more computing devices 210 (see FIG. 6). Of course, modules described herein illustrate various functionalities and do not limit the structure or functionality of any embodiments. Rather, the functionality of various modules may be divided differently and performed by more or fewer modules according to various design considerations.

[0050] Each computing device 210 may include one or more processing devices 211 designed to process instructions, for example computer readable instructions (i.e., code), stored in a non-transient manner on one or more storage devices 213. By processing instructions, the processing device(s) 211 may perform one or more of the steps and/or functions disclosed herein. Each processing device may be real or virtual. In a multi-processing system, multiple processing units may execute computer-executable instructions to increase processing power. The storage device(s) 213 may be any type of non-transitory storage device (e.g., an optical storage device, a magnetic storage device, a solid state storage device, etc. The storage device(s) 213 may be removable or non-removable, and may include magnetic disks, magneto-optical disks, magnetic tapes or cassettes, CD-ROMs, CD-RWs, DVDs, BDs, SSDs, or any other medium which can be used to store information. Alternatively, instructions may be stored in one or more remote storage devices, for example storage devices accessed over a network or the internet.

[0051] Each computing device 210 additionally may have memory 212, one or more input controllers 216, one or more output controllers 215, and/or one or more communication connections 240. The memory 212 may be volatile memory (e.g., registers, cache, RAM, etc.), non-volatile memory (e.g., ROM, EEPROM, flash memory, etc.), or some combination thereof. In at least one embodiment, the memory 212 may store software implementing described techniques.

[0052] An interconnection mechanism 214, such as a bus, controller or network, may operatively couple components of the computing device 210, including the processor(s) 211, the memory 212, the storage device(s) 213, the input controller(s) 216, the output controller(s) 215, the communication connection(s) 240, and any other devices (e.g., network controllers, sound controllers, etc.). The output controller(s) 215 may be operatively coupled (e.g., via a wired or wireless connection) to one or more output devices 220 (e.g., a monitor, a television, a mobile device screen, a touch-display, a printer, a speaker, etc.) in such a fashion that the output controller(s) 215 can transform the display on the display device 220 (e.g., in response to modules executed). The input controller(s) 216 may be operatively coupled (e.g., via a wired or wireless connection) to an input device 230 (e.g., a mouse, a keyboard, a touch-pad, a scroll-ball, a touch-display, a pen, a game controller, a voice input device, a scanning device, a digital camera, etc.) in such a fashion that input can be received from a user.

[0053] The communication connection(s) 240 may enable communication over a communication medium to another computing entity. The communication medium conveys information such as computer-executable instructions, audio or video information, or other data in a modulated data signal. A modulated data signal is a signal that has one or more of its characteristics set or changed in such a manner as to encode information in the signal. By way of example, and not limitation, communication media include wired or wireless techniques implemented with an electrical, optical, RF, infrared, acoustic, or other carrier.

[0054] FIG. 6 illustrates the computing device 210, the output device 220, and the input device 230 as separate devices for ease of identification only. However, the computing device 210, the display device(s) 220, and/or the input device(s) 230 may be separate devices (e.g., a personal computer connected by wires to a monitor and mouse), may be integrated in a single device (e.g., a mobile device with a touch-display, such as a smartphone or a tablet), or any combination of devices (e.g., a computing device operatively coupled to a touch-screen display device, a plurality of computing devices attached to a single display device and input device, etc.). The computing device 210 may be one or more servers, for example a farm of networked servers, a clustered server environment, or a cloud services running on remote computing devices.

[0055] In one embodiment, the present disclosure includes a method for delivering an ablative dose of focused ultrasound that will spare purposefully some portion of a volume of cancer cells targeted for ablation. The steps for doing so can include one or more of the below, in the below-listed or a modified order: [0056] 1. Segmenting or defining the target volume using a variety of imaging tools, including ultrasound (US), MRI, CT, and PET to identify the region targeted for treatment, which is subsequently defined using typical segmentation tools and algorithms resulting in a structure or structures that can be manipulated in a treatment planning system; [0057] 2. Inputting either the type of cancer, which generates the volume of tissue required for immunostimulation based on a nomogram, or inputting directly the volume of tissue required to receive a nonablative dose. In one embodiment, this input occurs into the computer system, which can store the probe properties, and be configured to determine the type of target tissue needed to accomplish the goal(s) described herein. This can occur during the treatment planning stages, for example, but generally after the cancer type is known (e.g., from imaging results, biopsy, etc.); [0058] 3. Determining, either automatically or manually, the thickness of the rim or area of targeted tissue or total volume of tissue required to be dosed sublethally; [0059] 4. Determining, either automatically or manually, the volume and/or location of tissue to be ablated, which is equal to the total target volume defined on the imaging study minus the region to treated with a nonablative dose; [0060] 5. Determining where the fall-off region of an ablative dose of focused ultrasound should fall such that the region to receive a nonablative dose of focused ultrasound actually receives a nonablative dose of focused ultrasound dose falloff projected to occur given the treatment parameters (diameter of dose, type of dose delivery, total dose, time to deliver dose, etc); and/or [0061] 6. Delivering an ablative dose of focused ultrasound to the specified treatment volume thereby ablating the bulk of the targeted volume of cancer cells in the central portion of the tumor while exposing a rim of cancer cells to a sublethal dose of HIFU that will result in enhanced activation of an immune system response.

[0062] Alternatively, the regions targeted for ablation and nonablation can be treated using different focused ultrasound parameters delivered using a single or multiple ultrasound crystals. The steps for doing so can include one or more of the below, in the below-listed or a modified order: [0063] 1. Segmenting the target volume using a variety of imaging tools, including US, MRI, CT, and PET to identify the region targeted for treatment which is subsequently defined using typical segmentation tools and algorithms resulting in a structure or structures that can be manipulated in a treatment planning system; [0064] 2. Inputting either the type of cancer, which generates the volume of tissue required for immunostimulation based on a nomogram, or inputting directly the volume of tissue required to receive a nonablative dose; [0065] 3. Determining, either automatically or manually, the thickness of the rim or area of targeted tissue or total volume of tissue required to be dosed sublethally; [0066] 4. Determining, either automatically or manually, the volume and location of tissue to be ablated which is equal to the total target volume defined on the imaging study minus the region to treated with a nonablative dose; and/or [0067] 5. Delivering to the region to be ablated an ablative dose of focused ultrasound using one set of focused ultrasound delivery parameters and characteristics and to the region to receive immunostimulation a nonablative dose of focused ultrasound using second set of focused ultrasound delivery parameters and characteristics, whereby the region designated to receive an ablative dose of focused ultrasound receives an ablative dose and the region required to receive a nonablative dose of focused ultrasound receives a nonablative dose of focused ultrasound, achieving the goal of ablating as much of the target volume as possible while delivering an immunostimulating dose of focused ultrasound to the volume of tissue required to produce an immunostimulatory response.

[0068] Therefore, the present invention is well adapted to attain the ends and advantages mentioned as well as those that are inherent therein. While numerous changes may be made by those skilled in the art, such changes are encompassed within the spirit of this invention as illustrated, in part, by the appended claims.