WO2018058293A1

WO2018058293A1 - Applicator positioning method based on magnetic resonance imaging, and outer applicator tube

Info

Publication number: WO2018058293A1
Application number: PCT/CN2016/100310
Authority: WO
Inventors: 朱艳春; 李雅芬; 刘勇; 张志诚; 付楠; 谢耀钦
Original assignee: 深圳先进技术研究院
Priority date: 2016-09-27
Filing date: 2016-09-27
Publication date: 2018-04-05

Abstract

An applicator positioning method based on magnetic resonance imaging (MRI), and outer applicator tube (10). The method comprises: inserting an outer applicator tube (10) having an accommodating cavity (11) in a wall thereof into an estimated application portion, and performing three-dimensional magnetic resonance imaging (201); and determining, according to an imaging agent in the accommodating cavity (11), a specific application position (202). The method of the present invention enables the position of an outer applicator tube (10) to be accurately located in an MRI image, and clearly displays morphology and pathological changes of tissues and organs in a periphery the outer applicator tube (10), thus improving the precision of a treatment.

Description

Magnetic resonance imaging based source location method and applicator outer tube

Technical field

The present application relates to the field of applicator positioning technologies, and in particular, to a magnetic field imaging-based application position localization method and an applicator outer tube.

Background technique

Clinically, during the post-loading treatment, the positioning of the applicator is usually obtained by a positive lateral radiograph or a three-dimensional computed tomography (CT) scan. With the development of Magnetic Resonance Imaging (MRI), its advantages of no radiation, high resolution, and high soft tissue contrast make it more and more widely used.

After the 1970s, post-loading radiation therapy was developed, especially in gynecological intracavitary radiotherapy. In the late 1980s, the reactor produced a high-strength micro-铱-192 source, and the development of computer control gradually through the initial mechanical and motor stages, which made the post-loading treatment enter a new stage. Post-loading radiation therapy refers to placing a treatment container (applicator) without a radioactive source on the treatment site, and the computer remote-controlled stepper motor (post-installation machine) sends the radioactive source to the applicator for radiation therapy, so as to avoid prevention. Medical staff were injured by radiation during the treatment. Due to the advantages of accurate placement and close proximity to the body tissue, significant clinical effects have been achieved in the treatment of gynecological, nasopharyngeal, esophageal, bronchial, rectal, bladder, breast and pancreatic tumors. The function of the post-installation machine is to place the radioactive source accurately, safely and regularly into the human lesion through the application tube.

Post-loading therapy is an auxiliary treatment for external irradiation. According to the inverse square law, the dose at the near-source is much larger than the distance from the far source. Using this feature, tumor tissue can achieve an effective killing dose, while adjacent normal tissues can be protected. It can be seen that one of the quality assurances of the post-loading treatment is the accuracy of the radioactive source, which directly affects the therapeutic effect.

At present, the workflow of the post-loading treatment is to insert the disinfected application tube into the patient's treatment site according to the doctor's diagnosis result, and fix it; then, use the simulator to take a positive lateral radiograph or a three-dimensional CT image, and position the application. The location of the source tube, the best treatment time at each point, design The treatment plan; the application tube is connected to the post-loading treatment machine, and then the radiotherapy plan is executed by the post-installation control system; after a certain amount of irradiation is completed, the radioactive source is automatically returned to the storage source under the control of the post-installation computer. , complete a close-up post-loading treatment.

With the development of magnetic resonance imaging technology, magnetic resonance imaging has the advantages of no radiation, high resolution, high soft tissue contrast, etc., which makes magnetic resonance imaging more and more attention. Clinically, the positive side X-ray film is taken by the simulator, and the treatment plan is made according to the coordinate reconstruction result. Although the post-installation internal irradiation treatment can be realized, the treatment plan is simple, the dose accuracy is very low, and the lesion range and the normal tissue cannot be correctly evaluated. The situation in turn gives a personalized and precise radiotherapy dosage regimen.

Chinese patent CN101152090A has published a "single-tube post-loading device for cervical cancer that can be used for CT scanning", which can scan and image the cervical cancer posterior device, which includes a hollow source pipe. One end of the pipeline is connected with the rear application tube, and the other end is a lesion treatment end. The treatment end is composed of an elliptical inner tube made of a shielding functional material, and a circular hole is arranged in the center of the inner tube, and the circular hole is The application pipeline is connected, and the movable sleeve is also provided with a cylindrical outer tube made of CT-compatible polymer material. The invention can obtain a three-dimensional image of the lesion by CT scanning, thereby accurately estimating the lesion. The scope and surrounding normal tissue conditions provide an image data basis for individualized and accurate radiotherapy.

At present, CT three-dimensional imaging can realize the positioning of the applicator and develop a precise radiotherapy plan, but the CT image soft tissue contrast is poor, and usually the internal irradiation therapy is for the soft tissue cavity, and the CT image is not well presented. According to the principle of magnetic resonance imaging, the three-dimensional magnetic resonance image can clearly show the structure of the lesion and surrounding organs, but the current application of the polymer tube for magnetic resonance imaging is often not because of magnetic resonance imaging. The signal is reflected in black on the three-dimensional image, which results in the magnetic resonance three-dimensional image not being able to exert its original advantages to accurately locate the position of the application tube, and also affects the observability of the surrounding tissue lesions.

Summary of the invention

In order to solve the above problems in the prior art, an object of the present application is to provide a magnetic field imaging-based application position localization method and a donor device, which can accurately position the outer tube of the applicator in a magnetic resonance image. And clearly show the shape and pathological changes of the tissues and organs around the outer tube of the applicator, and effectively improve the treatment accuracy.

In order to achieve the above object, the magnetic resonance imaging-based application position localization method proposed by the embodiment of the present application includes: inserting an outer tube of a donor device having a chamber in a tube wall into a predicted application site, and performing three-dimensional magnetic resonance imaging; The imaging agent in the chamber determines a specific source of application.

In order to achieve the above object, the outer tube of the applicator of the magnetic resonance imaging-based applicator according to the embodiment of the present application has a chamber in the tube wall of the applicator outer tube, and the chamber is filled with magnetic Resonance imaging of imaging agents.

It can be seen from the technical solution provided by the above embodiments of the present application that the three-dimensional magnetic resonance scanning can be performed in the three-dimensional magnetic resonance imaging by inserting the outer tube of the tube having the container filled with the imaging agent into the predicted application site for three-dimensional magnetic resonance scanning. Brightly display the outer tube of the applicator, which can accurately locate the position of the outer tube of the applicator, clearly show the morphological structure and pathological changes of the diseased tissue and surrounding tissues and organs, provide better soft tissue contrast, and better display the tissue characteristics of the lesion. Therefore, it can accurately locate the position of the outer tube of the applicator, and provide a basis for accurately designing the radiotherapy plan, accurately controlling the location and time of the radioactive source, and improving the treatment accuracy and safety.

The aspects and advantages of the present invention will be set forth in part in the description which follows.

DRAWINGS

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings to be used in the embodiments or the prior art description will be briefly described below. Obviously, the drawings in the following description are only It is a certain embodiment of the present application, and other drawings can be obtained according to the drawings without any creative work for those skilled in the art.

1 is a schematic flow chart of a method for locating a position based on magnetic resonance imaging according to an embodiment of the present application;

2 is a schematic cross-sectional structural view of an outer tube of an applicator of a magnetic resonance imaging-based applicator according to an embodiment of the present application;

3 is a schematic structural view of a magnetic resonance imaging based applicator according to an embodiment of the present application;

4 is a schematic diagram of an inner tube of an applicator of a magnetic resonance imaging-based applicator according to an embodiment of the present application;

5 is a schematic flow chart of a method for positioning a position based on magnetic resonance imaging according to another embodiment of the present application;

6 is a schematic diagram of a model for calculating a depth position of a source position based on magnetic resonance imaging according to another embodiment of the present application;

Figure 7 is a cross-sectional view of the inner tube of the applicator of another embodiment of the present application.

detailed description

Embodiments of the present application provide a method and device for applying a position based on magnetic resonance imaging.

The technical solutions in the embodiments of the present application are clearly and completely described in the following, in which the technical solutions in the embodiments of the present application are clearly and completely described. The embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present application without departing from the inventive scope shall fall within the scope of the application.

1 is a schematic flow chart of a method for locating a position based on magnetic resonance imaging according to an embodiment of the present application. As shown in FIG. 1, the method includes:

In step 101, the outer tube of the applicator having the chamber in the tube wall is inserted into the predicted application site, and three-dimensional magnetic resonance imaging is performed.

Wherein, the chamber may be, for example, a plurality of apertured spaces uniformly disposed in the wall of the outer tube of the applicator, or an interlayer between the inner and outer walls of the outer tube of the applicator, and other possible forms. The imaging agent filled in the chamber has a high signal-to-noise ratio in magnetic resonance imaging and can be highlighted in 3D magnetic resonance imaging.

Wherein, the imaging agent may be oil, water or other contrast enhancing agent (or imaging agent, contrast agent, etc.) suitable for magnetic resonance imaging, pre-closed in the positioning tube to ensure high in the three-dimensional magnetic resonance image Lights up the position of the outer tube of the applicator. The contrast enhancer is, for example, a complex of DTPA (钆-diethylenediaminepentaacetic acid) or the like.

Step 102, determining a specific application location based on the imaging agent in the chamber.

The applicator outer tube of the present invention is made of an MRI compatible polymer material.

It is to be understood that the three-dimensional magnetic resonance localization treatment has a lower radiation and provides better soft tissue contrast than existing CT-guided internal illumination treatments. Since the internal irradiation treatment is mainly for treating the cavity lesions in the human body, the better presentation of the diseased tissue and the peripheral organs is the basic condition for formulating a precise radiotherapy plan.

In practical applications, the outer tube of the applicator is inserted into the patient in advance, and the imaging agent is pre-filled with magnetic resonance imaging to ensure accurate display of the position of the outer tube of the applicator in the three-dimensional magnetic resonance image. The three-dimensional magnetic resonance scan is completed, and a treatment plan for radiation therapy is prepared according to the condition of the diseased tissue and the normal tissue or organ in the three-dimensional magnetic resonance image and the position of the outer tube of the applicator. Then, according to the needs of the internal irradiation treatment, a suitable inner tube of the applicator is inserted, and the insertion angle of the inner tube is adjusted according to the positioning image, and the radioactive source channel is inserted into the inner tube. For different treatment needs, different configurations of the inner tube of the applicator can be designed to accommodate different requirements for the number and location of the source channels.

In this embodiment, the external tube of the applicator having the chamber filled with the imaging agent in the tube wall is inserted into the predicted application site for three-dimensional magnetic resonance scanning, and the external tube of the applicator can be highlighted in the three-dimensional magnetic resonance imaging. Accurately locate the position of the outer tube of the applicator, clearly show the morphological structure and pathological changes of the diseased tissue and surrounding tissues and organs, provide better soft tissue contrast, better display the tissue characteristics of the lesion, so that it can be accurately positioned outside the applicator The location of the tube, and the precise location Provide a basis for radiotherapy planning, accurate control of the location and time of the radioactive source, and improve treatment accuracy and safety.

Based on the same inventive concept, the embodiment of the present application further provides an external tube of the applicator of the magnetic resonance imaging based applicator, which can be used to implement the method described in the above embodiments, as described in the following embodiments. Since the principle of solving the problem of the application tube outer tube of the magnetic resonance imaging-based applicator is similar to the magnetic field imaging-based application position localization method, the implementation of the magnetic resonance imaging-based applicator can be referred to the magnetic resonance imaging-based method. The implementation of the source location method will not be repeated here. Although the devices described in the following embodiments are preferably implemented in hardware, software, or a combination of software and hardware, is also possible and contemplated.

2 is a schematic cross-sectional structural view of an outer tube of an applicator of a magnetic resonance imaging-based applicator according to an embodiment of the present application.

As shown in FIG. 2, the external tube 10 of the magnetic resonance imaging-based applicator has a chamber 11 in the tube wall of the applicator outer tube 10, and the chamber 11 is filled with magnetic material. Resonance imaging of imaging agents. The chamber may be, for example, a plurality of hole-shaped spaces uniformly disposed in the wall of the outer tube of the applicator, or an interlayer between the inner and outer walls of the outer tube of the applicator. The imaging agent filled in the chamber has a high signal-to-noise ratio in magnetic resonance imaging and can be highlighted in 3D magnetic resonance imaging.

In one embodiment of the present application, the cross section of the chamber is in one-to-one correspondence with the distance from the cross section to the nozzle of the outer tube of the applicator. In particular, the area or width of each cross section may vary with the depth of the cross section in the outer tube of the applicator. When the chamber is an interlayer between the inner wall and the outer wall of the outer tube of the applicator, the thickness of the interlayer may become smaller or larger as the depth in the outer tube of the applicator increases. The relative depth of the cross-section from the orifice of the outer tube of the applicator can be determined from the cross-sectional thickness of the interlayer in the magnetic resonance image. When the chamber is a plurality of radial holes In the space, each or one of the hole-shaped spaces may be tapered such that the cross-section of the hole-shaped space varies with the distance from the cross-section to the nozzle. In the actual design, the depth positioning device can have various designs, such as a reverse conical shape, and the principle is the same, and details are not described herein again.

In one embodiment of the present application, when the chamber is a plurality of hole-shaped spaces uniformly disposed in the wall of the outer tube of the applicator shown in FIG. 2, the plurality of holes are in the cross-sectional direction. In a uniform angular distribution, in the image obtained by performing three-dimensional magnetic resonance scanning after filling the imaging agent, the relative angle between the specific application site and the outer tube of the applicator can be determined according to the position of each hole-shaped space.

FIG. 3 is a schematic structural view of the applicator of the outer tube of the applicator of the present embodiment. When the source is irradiated, the outer tube of the applicator of the embodiment can be matched with the post-installer 20 (not shown) The source channel 30 and the source tube 40 are used.

The applicator outer tube 10 of the present invention is made of an MRI-compatible polymer material, and the surface is provided with a preset precision scale, and the scale may include one or more dimensions of the longitudinal depth and the angle scale. The operator can accurately determine the depth and/or angle of the inner tube of the applicator according to the scale on the outer tube of the applicator, and in the three-dimensional magnetic resonance image, can also assist in positioning the outer tube of the applicator. Position and deviation.

According to an embodiment of the present application, the applicator may include at least one set of the applicator outer tubes. Specifically, the number of outer tubes of the applicator is not limited according to the needs of the treatment, and each of the outer tubes of the applicator is equipped with an exact match (for example, matching of length, diameter, and interface connection). The structure of the inner tube of the source and the inner tube of the source is shown in Fig. 4. When the radiation therapy is performed, the inner tube of the applicator is fixedly engaged with the outer tube of the applicator through a predetermined structure, and the radioactive source channel is inserted through the hole-shaped passage on the inner tube. The specific card fastening method is designed according to actual needs, which is not limited in this application. One end of the source channel is connected to the after-loading machine through a preset interface, and the other end is placed in the inner tube of the applicator to be the treatment end of the lesion. At the time of treatment, the radioactive source is introduced into a preset position in the source channel according to the radiotherapy plan under the computer control of the post-installation machine.

In this embodiment, the external tube of the applicator having the chamber filled with the imaging agent in the tube wall is inserted into the predicted application site for three-dimensional magnetic resonance scanning, and the external tube of the applicator can be highlighted in the three-dimensional magnetic resonance imaging. Accurately locate the position of the outer tube of the applicator, clearly show the morphological structure and pathological changes of the diseased tissue and surrounding tissues and organs, provide better soft tissue contrast, better display the tissue characteristics of the lesion, so that it can be accurately positioned outside the applicator The location of the tube and the basis for accurate design of the radiotherapy plan, accurate control of the location and time of the radioactive source, improve treatment accuracy and safety.

FIG. 5 is a schematic flowchart of a magnetic resonance imaging-based application position localization method according to another embodiment of the present application. As shown in FIG. 5, the method includes:

In step 201, the outer tube of the applicator having the chamber in the tube wall is inserted into the predicted application site, and three-dimensional magnetic resonance imaging is performed.

Specifically, the sterile external tube of the applicator is inserted into the patient's body prior to treatment for magnetic resonance three-dimensional imaging. The operator can predict the position of the application site based on experience or known information, and insert the outer tube of the applicator with the positioning tube inserted into the estimated application site.

Wherein, the imaging agent may be oil, water or other contrast enhancing agent (or imaging agent, contrast agent, etc.) suitable for magnetic resonance imaging, pre-closed in the positioning tube to ensure high in the three-dimensional magnetic resonance image Lights up the position of the application tube. The contrast enhancer is, for example, a complex of DTPA (钆-diethylenediaminepentaacetic acid) or the like.

Step 202, determining a specific application location based on the imaging agent in the chamber.

Three-dimensional magnetic resonance imaging is used to determine the position of the outer tube of the applicator in the body, as well as the surrounding tissues and organs, to accurately assess the extent of the lesion and its relationship with the surrounding vital organs, and to develop an individualized radiotherapy plan based on this, and then Determine the deviation between the position of the outer tube of the current applicator and the actual application position, and adjust the position of the outer tube of the applicator.

The feature such as the area or width of the cross section of the chamber may vary with the distance from the cross section to the nozzle of the outer tube of the applicator, and the cross section corresponds to the distance one-to-one, according to The cross section of the chamber determines the relative depth of the application site to the mouthpiece of the applicator outer tube. Taking the cavity as one or more conical hole-shaped spaces as an example, the depth position calculation method of one embodiment of the present application is as shown in FIG. 6. In the cross-sectional magnetic resonance image of the lesion, the hole-shaped space can be measured. The width d, D and H in the figure are the diameter of the conical bottom surface and the cone height, respectively. D and H are known for the specific outer tube of the applicator, so the distance from the top of the cone to the top of the cone can be determined as h= H × d / D, the actual design can be used for deep positioning of the chamber can also have other shapes of design, the same principle, no longer repeat them.

When the chamber is a plurality of hole-shaped spaces (longitudinal strips, etc.) uniformly disposed in the tube wall of the outer tube of the applicator, it may also be based on the developer in the plurality of holes. A relative angle of the application site to the outer tube of the applicator is determined. The wall outside the chamber is black in the magnetic resonance image. Since the imaging space is filled with the imaging agent, it is easy to accurately find the hole-shaped space capable of positioning the angle in the image. In practice, in order to facilitate direct By observing the angle, more hole-shaped space structures can be designed to make the angle scale finer.

Step 203, adjusting a position of the outer tube of the applicator according to the application position.

After the position of the outer tube of the applicator is adjusted, the application tube is fixed at a determined source position.

In step 204, the radiation dose distribution and the number and distribution structure of the desired source channels are determined.

According to the specific situation of the application site, the radiation treatment plan can be precisely designed, such as the irradiation position of the radiation source, the irradiation angle, the irradiation dose, etc., and the number and distribution structure of the radiation source channels are determined according to the actual radiation source placement requirements.

Step 205, selecting an inner tube of the applicator corresponding to the source channel of the quantity and distribution structure.

In order to meet different treatment needs, the structure of the inner tube of the applicator is various, such as: the number of radioactive source channels on the inner tube of the applicator is different, and the distribution positions of the channels are different. Figure 7 shows a cross section of an applicator inner tube comprising a plurality of source channels, in one embodiment.

Step 206: Fix the applicator inner tube in the applicator outer tube according to the application position.

Step 207, inserting the source channel connected to the installed device into the corresponding inner tube of the applicator, and irradiating the source position with the source.

Embodiments of the present application can highlight the outer tube of the applicator in three-dimensional magnetic resonance imaging by inserting the outer tube of the tube having the chamber filled with the imaging agent into the predicted application site for three-dimensional magnetic resonance scanning. It can accurately locate the position of the outer tube of the applicator, clearly show the morphological structure and pathological changes of the diseased tissue and surrounding tissues and organs, provide better soft tissue contrast, better display the tissue characteristics of the lesion, and thus can accurately locate the application. The position of the external tube is provided, and the basis for accurately designing the radiotherapy plan, accurately controlling the location and time of the radioactive source, and improving the treatment accuracy and safety.

It should be noted that in the description of the present application, the terms "first", "second" and the like are used for descriptive purposes only, and are not to be construed as indicating or implying relative importance. Further, in the description of the present application, the meaning of "a plurality" is two or more unless otherwise stated.

Any process or device description in the flowcharts or otherwise described herein can be understood as a module, segment or portion of code representing executable instructions including one or more steps for implementing a particular logical function or process. And the scope of the preferred embodiments of the present application includes additional implementations, in which the functions may be performed in a substantially simultaneous manner or in the reverse order depending on the functions involved, in accordance with the illustrated or discussed order. It will be understood by those skilled in the art to which the embodiments of the present application pertain.

It should be understood that portions of the application can be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or means may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented by any one or combination of the following techniques well known in the art: having logic gates for implementing logic functions on data signals. Discrete logic Circuit, ASIC with suitable combination logic gate, Programmable Gate Array (PGA), Field Programmable Gate Array (FPGA), etc.

One of ordinary skill in the art can understand that all or part of the steps carried by the apparatus for implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium. When performed, one or a combination of the steps of the device embodiments is included.

In the description of the present specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means a specific feature described in connection with the embodiment or example. A structure, material or feature is included in at least one embodiment or example of the application. In the present specification, the schematic representation of the above terms does not necessarily mean the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples.

While the embodiments of the present application have been shown and described above, it is understood that the above-described embodiments are illustrative and are not to be construed as limiting the scope of the present application. The embodiments are subject to variations, modifications, substitutions and variations.

Claims

A method for locating a position based on magnetic resonance imaging, characterized in that it comprises:

Inserting the outer tube of the applicator having the chamber in the tube wall into the predicted application site, and performing three-dimensional magnetic resonance imaging;

A specific application site is determined based on the imaging agent in the chamber.
The method according to claim 1, wherein after determining the specific application location according to the imaging agent in the chamber, the method further comprises:

Fixing the applicator inner tube in the outer tube of the applicator according to the application position;

The source channel connected to the installed device is inserted into the corresponding inner tube of the applicator, and the source position is irradiated with the radiation source.
The method according to claim 2, further comprising: before the fixing the inner tube of the applicator in the outer tube of the applicator according to the application position, further comprising:

Adjusting a position of the outer tube of the applicator according to the application position;

Determining the radiation dose distribution and the number and distribution structure of the desired source channels;

An inner tube of the applicator corresponding to the source channel of the number and distribution structure is selected.
The method according to claim 1, wherein said chamber comprises a plurality of hole-like spaces uniformly disposed in a wall of said outer tube of said applicator, or an inner wall of said outer tube of said applicator The interlayer between the outer wall and the outer wall.
The method according to any one of claims 1 to 4, wherein the developer filled in the chamber has a high signal to noise ratio in magnetic resonance imaging.
The method according to claim 5, wherein the developer comprises oil or water, which is pre-blocked and filled in the chamber.
The method according to claim 4, wherein when the chamber is a plurality of hole-like spaces uniformly disposed in a wall of the outer tube of the applicator, the method further comprises:

And determining a relative angle between the application position and the outer tube of the applicator according to the imaging agent in the plurality of porous spaces.
The method according to claim 4, wherein the area or width of the cross section of the chamber varies with the distance from the cross section to the nozzle of the outer tube of the applicator, and the cross section Corresponding to the distance, the method further includes:

A relative depth of the application site to the outer tube nozzle of the applicator is determined according to a cross section of the chamber.
An outer tube of an applicator of a magnetic resonance imaging-based applicator, characterized in that a tube chamber is provided in a wall of the outer tube of the applicator, and the chamber is filled with a magnetic resonance imaging image Agent.
The applicator outer tube according to claim 9, wherein said chamber is a plurality of hole-like spaces provided in a wall of said outer tube of said applicator.
The applicator outer tube according to claim 9, wherein said chamber is an interlayer between an inner wall and an outer wall of said outer tube of said applicator.
The applicator outer tube according to claim 9, wherein the developer has a high signal-to-noise ratio under magnetic resonance and is pre-closed and filled in the chamber.
The applicator outer tube according to any one of claims 9 to 12, wherein the developer comprises oil or water.
The applicator outer tube according to claim 10 or 11, wherein the cross section of the chamber is in one-to-one correspondence with the distance from the cross section to the nozzle of the outer tube of the applicator.
The applicator outer tube according to claim 10, wherein the plurality of hole-shaped spaces are uniformly disposed in the tube wall of the outer tube of the applicator, and have a uniform angular distribution in the cross-sectional direction.
The applicator outer tube according to claim 9, wherein the outer tube of the applicator is made of a magnetic resonance imaging compatible polymer material, and the surface is provided with a scale of preset precision.