Calculation method, device, equipment and medium for three-dimensional heat transfer of alveoli in steam ablation

Abstract

The present application discloses a method, device, equipment and medium for calculating three-dimensional heat transfer of alveoli during steam ablation, and relates to the field of three-dimensional bioheat transfer technology. The calculation method comprises: establishing an initial heat conduction equation of the alveoli in the target lung segment, removing the airflow influence term in the initial heat conduction equation based on the actual situation of steam ablation, obtaining a heat conduction equation, treating the alveoli as spherical heat sources, solving the heat conduction equation, and obtaining an analytical solution to the heat conduction equation. For any desired position point in the target lung segment, the distance from the desired position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the desired position point is calculated using the analytical solution. The present application can complete the three-dimensional bioheat transfer calculation of the alveoli during steam ablation, and has high calculation efficiency and accuracy.

Description

Technical Field

[0001] The present application relates to the field of three-dimensional bioheat transfer technology, and in particular to a method, device, equipment and medium for calculating three-dimensional heat transfer of alveoli during steam ablation. Background Art

[0002] Steam ablation is a minimally invasive therapy for treating respiratory diseases in which a steam-releasing catheter is guided to the target lung segment through a bronchoscope, the upstream airway of the target lung segment is blocked by a balloon, and steam is released through the steam-releasing catheter to ablate the lesions in the target lung segment based on the thermal effect.

[0003] Three-dimensional bioheat transfer refers to the heat transfer process in which the heat in a living body changes with the three-dimensional spatial position and time. Currently, there is a lack of relevant technologies for three-dimensional bioheat transfer of alveoli during steam ablation. In similar three-dimensional bioheat transfer fields, when calculating a given heat conduction equation, the iterative calculation simulation method based on finite elements is mainly used, which requires multiple iterative calculations, has a large amount of calculations, and has low calculation efficiency. In addition, low meshing quality and insufficient calculation density will lead to calculation deviations and poor calculation accuracy. Summary of the invention

[0004] The purpose of this application is to provide a method, device, equipment and medium for calculating three-dimensional heat transfer of alveoli during steam ablation, which can complete the three-dimensional bioheat transfer calculation of alveoli during steam ablation with high calculation efficiency and accuracy.

[0005] To achieve the above objectives, this application provides the following solutions.

[0006] In a first aspect, the present application provides a method for calculating three-dimensional heat transfer of alveoli during steam ablation, the method comprising:

[0007] Establishing an initial heat conduction equation for alveoli in a target lung segment; the initial heat conduction equation includes an airflow influence term; the target lung segment is a lung segment to be treated by steam ablation;

[0008] Based on the actual situation of steam ablation, the airflow influence term in the initial heat conduction equation is removed to obtain the heat conduction equation;

[0009] Considering the alveoli as spherical heat sources, the heat conduction equation is solved to obtain an analytical solution to the heat conduction equation;

[0010] For any desired position point in the target lung segment, the distance from the desired position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the desired position point is calculated using the analytical solution.

[0011] In a second aspect, the present application provides a device for calculating three-dimensional heat transfer of alveoli during steam ablation, the device comprising:

[0012] Establishing a module for establishing an initial heat conduction equation of alveoli in a target lung segment; the initial heat conduction equation includes an airflow influence term; the target lung segment is a lung segment to be treated by steam ablation;

[0013] A removal module, used for removing the airflow influence term in the initial heat conduction equation based on the actual situation of steam ablation to obtain the heat conduction equation;

[0014] A solution module, used for treating the alveoli as spherical heat sources, solving the heat conduction equation, and obtaining an analytical solution to the heat conduction equation;

[0015] The calculation module is used for calculating the temperature of any desired position point in the target lung segment by using the analytical solution, taking the distance from the desired position point to the alveoli and the working time of steam ablation as input.

[0016] In a third aspect, the present application provides a computer device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the above-mentioned method for calculating three-dimensional heat transfer of alveoli during steam ablation.

[0017] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the above-mentioned method for calculating three-dimensional heat transfer of alveoli during steam ablation.

[0018] According to the specific embodiments provided in this application, this application discloses the following technical effects.

[0019] The present application provides a method, device, equipment and medium for calculating three-dimensional heat transfer of alveoli during steam ablation. The calculation method includes: establishing an initial heat conduction equation for the alveoli in the target lung segment, removing the airflow influence term in the initial heat conduction equation based on the actual situation of steam ablation, obtaining the heat conduction equation, treating the alveoli as spherical heat sources, solving the heat conduction equation, and obtaining an analytical solution to the heat conduction equation. For any undetermined position point in the target lung segment, the distance from the undetermined position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the undetermined position point is calculated using the analytical solution. The present application can complete the three-dimensional biological heat transfer calculation of the alveoli during steam ablation, and compared with the iterative calculation simulation method based on finite elements, the present application uses an analytical solution to calculate the temperature, and only one calculation is required, which can save multiple iterative calculation processes, greatly reduce the amount of calculation, improve calculation efficiency, and avoid calculation deviations caused by low mesh division quality and insufficient calculation density, thereby improving calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 This is a diagram of the application environment of a method for calculating three-dimensional heat transfer of alveoli during steam ablation provided in Example 1 of the present application.

[0022] Figure 2 A schematic flow chart of a method for calculating three-dimensional heat transfer of alveoli during steam ablation provided in Example 1 of the present application.

[0023] Figure 3 A schematic diagram of the functional modules of a device for calculating three-dimensional heat transfer of alveoli during steam ablation provided in Example 2 of the present application.

[0024] Figure 4 A schematic diagram of the structure of a computer device provided in Example 3 of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] Example 1.

[0027] The method for calculating the three-dimensional heat transfer of alveoli during steam ablation provided in the present application can be applied to Figure 1In the application environment shown. Among them, the terminal communicates with the server through the network. The data storage system can store the data that the server needs to process. The data storage system can be set up separately, integrated on the server, or placed on the cloud or other servers. The terminal can send the data to be processed (i.e., the distance from the position point to be processed to the alveoli and the working time of steam ablation) to the server. After the server receives the data to be processed, the server establishes the initial heat conduction equation of the alveoli in the target lung segment for the data to be processed; based on the actual situation of steam ablation, the airflow influence term in the initial heat conduction equation is removed to obtain the heat conduction equation; the alveoli are regarded as spherical heat sources, and the heat conduction equation is solved to obtain the analytical solution of the heat conduction equation; for any position point to be determined in the target lung segment, the distance from the position point to be determined to the alveoli and the working time of steam ablation are used as input, and the temperature of the position point to be determined is calculated using the analytical solution. The server can feedback the obtained temperature of the position point to be determined to the terminal.

[0028] In addition, in some embodiments, the method for calculating three-dimensional heat transfer of alveoli during steam ablation can also be implemented independently by a server or a terminal. For example, the terminal can directly process the data to be processed, or the server can obtain the data to be processed from the data storage system and process the data to be processed.

[0029] The terminal may be, but is not limited to, various desktop computers, laptops, smart phones, tablet computers, IoT devices, and portable wearable devices. The server may be implemented as an independent server or a server cluster consisting of multiple servers, or may be a cloud server.

[0030] like Figure 2 As shown, a method for calculating three-dimensional heat transfer of alveoli in steam ablation is provided. The method is executed by a computer device, and can be executed by a computer device such as a terminal or a server alone, or by a terminal and a server together. In the embodiment of the present application, the method is applied to Figure 1 Taking the server in as an example, the method for calculating three-dimensional heat transfer of alveoli in steam ablation includes the following steps.

[0031] Step S1, establishing an initial heat conduction equation of alveoli in a target lung segment; the initial heat conduction equation includes an airflow influence term; the target lung segment is a lung segment to be treated by steam ablation.

[0032] Step S2, based on the actual situation of steam ablation, remove the airflow influence term in the initial heat conduction equation to obtain the heat conduction equation.

[0033] Step S3, regarding the alveoli as spherical heat sources, solving the heat conduction equation to obtain an analytical solution to the heat conduction equation.

[0034] Step S4: for any desired position point in the target lung segment, the distance from the desired position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the desired position point is calculated using the analytical solution.

[0035] By implementing the above-mentioned steps S1 to S4, this embodiment can establish a heat conduction equation for the alveoli in the target lung segment during steam ablation treatment, and regard the alveoli as a spherical heat source, solve the heat conduction equation, and obtain an analytical solution. Subsequently, the distance from the position to be determined to the alveoli and the working time of steam ablation are directly used as input, and the temperature of the position to be determined is calculated using the analytical solution, thereby completing the three-dimensional bioheat transfer calculation of the alveoli during steam ablation. The temperature is calculated using the analytical solution, and only one calculation is required to obtain the temperature. Compared with the iterative calculation simulation method based on finite elements, the iterative calculation process can be omitted, the amount of calculation can be greatly reduced, the calculation efficiency can be improved, and the calculation deviation caused by low mesh division quality and insufficient calculation density can be avoided, thereby improving the calculation accuracy.

[0036] In steam ablation therapy, the steam release process lasts for several seconds. After the gaseous water vapor reaches the alveoli at the end of the airway of the target lung segment, the heat is transferred from the alveolar wall to the lung tissue, and then the heat is transferred to the entire area of ​​the target lung segment. Compared with radiofrequency and microwave ablation, non-Fourier heat transfer is required to describe it, that is, the relaxation time of heat conduction is often considered at the nanosecond and nanometer scales, and the heat wave propagates at a finite speed. The alveolar heat transfer scenario of steam ablation therapy at the second level (non-high frequency, pulse, etc.) can be described by typical Fourier heat transfer. In S1, the initial heat conduction equation of the alveoli in the target lung segment is as follows:

[0037] (1).

[0038] In formula (1), is the density of lung tissue; is the specific heat capacity of lung tissue; For the position vector and steam ablation working time The temperature at time, the position vector =(x, y, z), represents a spatial position; is the thermal conductivity of lung tissue; It is a gradient operator, which represents the diffusion of heat from high to low; is the blood flow influence term, which represents the effect of blood flow on heat conduction; is the blood density; is the specific heat capacity of blood; is the blood perfusion rate; is the blood temperature, generally the temperature of the incoming arterial blood; Working time for steam ablation Heat generated per unit volume of steam ablation input power at ; For the position vector and steam ablation working time The heat produced per unit volume by the lung tissue's own metabolism at that time; is the airflow influence term, which represents the effect of airflow in the lungs on heat conduction; is the gas temperature in the airway; is the specific heat capacity of the gas; is the airflow perfusion rate; is the temperature of the gas flowing through the lungs.

[0039] In formula (1), the items on the right side of the equal sign are arranged in order of their influence on heat conduction from large to small.

[0040] When steam ablation is performed, the balloon blocks the upstream airway of the target lung segment and then releases steam for a few seconds. This blockage results in the heat entering and leaving the target lung segment without the influence of respiratory gas. Therefore, the last term of equation (1) can be ignored in the case of steam ablation. That is, based on the actual situation of steam ablation, the airflow influence term in the initial heat conduction equation is removed. Then, in S2, the heat conduction equation for the heat conducted to the terminal alveoli during steam ablation is as follows:

[0041] (2).

[0042] To solve equation (2), we can make a substitution, specifically let , then equation (2) can be transformed into the parabolic equation shown in equation (3):

[0043] (3).

[0044] In formula (3), the first intermediate variable ; The second intermediate variable .

[0045] During steam ablation, steam is conducted to the alveoli at the end of the airway and conducts heat to the surrounding lung tissues through the alveoli for thermal ablation. A single alveolus in the inflated state can be regarded as a spherical heat source. The surrounding lung tissues are heated by the heat conducted by the spherical heat source at a certain power. For an alveolus with a radius of The spherical heat source is solved by using the Green's function method to solve the partial differential equation shown in equation (3), and the analytical solution shown in equation (4) can be obtained. Then, the analytical solution of the heat conduction equation of the alveoli in S3 is as follows:

[0046] (4).

[0047] In formula (4), is the distance from the position to be determined to the alveoli and steam ablation working time The temperature at Specifically, it is the distance from the position to be determined to the center of the alveoli; is the blood temperature, which is the same as the body temperature at the beginning and end; is the first intermediate variable, , is the thermal conductivity of lung tissue, is the lung tissue density, is the specific heat capacity of lung tissue; is the second intermediate variable, , is the blood density, is the specific heat of blood, is the blood perfusion rate; Heat produced per unit volume by the lung tissue's own metabolism; Working time for steam ablation The single alveolar input heat power at ; is the radius of the alveoli; is the integration variable.

[0048] After obtaining the analytical solution shown in formula (4), for any unknown position point in the target lung segment, the distance from the unknown position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the unknown position point is calculated using the analytical solution. There is no need for multiple iterative calculations, which reduces the amount of calculations and improves the calculation efficiency. There will be no calculation deviation caused by low mesh quality and insufficient calculation density, which improves the calculation accuracy.

[0049] Currently, there is no fast, accurate and simplified calculation method for performing three-dimensional bioheat transfer calculations using the analytical solution of the heat conduction equation of the alveoli during steam ablation. Based on the analytical solution of the heat conduction equation, this embodiment directly substitutes the time parameters and space parameters into the analytical solution, and performs a single-step calculation to obtain the spatiotemporal distribution of temperature, which greatly reduces the calculation complexity and amount, and improves the calculation efficiency and accuracy.

[0050] Compared with the repeated iterative calculations of the iterative calculation simulation method based on finite elements, the accurate analytical solution based on equation (4) can directly calculate the temporal and spatial distribution of temperature in one go, saving a lot of calculations. However, the analytical solution of equation (4) still has relatively many calculation items and contains integral items to be numerically solved. Therefore, this embodiment further simplifies the analytical solution of formula (4), realizes simplification based on the analytical solution, and obtains a high-precision simplified formula.

[0051] For any undetermined position point in the target lung segment, the distance from the undetermined position point to the alveoli and the working time of steam ablation are used as input, and the temperature of the undetermined position point is calculated using the analytical solution, specifically including: simplifying the analytical solution to obtain a simplified analytical solution; for any undetermined position point in the target lung segment, the distance from the undetermined position point to the alveoli and the working time of steam ablation are used as input, and the temperature of the undetermined position point is calculated using the simplified analytical solution.

[0052] The analytical solution is simplified to obtain a simplified analytical solution, which specifically includes the following steps.

[0053] (1) Use Euler's formula to process some of the integral terms in the analytical solution and obtain the partial terms after the first processing. The partial terms are: .

[0054] (2) Use the perfect square formula to expand the square terms in the partial terms after the first processing to obtain the expanded partial terms.

[0055] (3) Use the product-to-sum formula to process the expanded partial terms and obtain the second processed partial terms.

[0056] (4) Use Euler's formula to process the partial terms after the second processing to obtain the partial terms after the third processing.

[0057] (5) Let the radius of the alveoli approach 0, process the third processed partial term, and obtain the fourth processed partial term.

[0058] (6) The partial terms after the fourth processing are used to replace some of the terms in the integral term in the analytical solution to obtain a preliminary simplified analytical solution.

[0059] (7) Based on the values ​​of the parameters in the preliminary simplified analytical solution, the preliminary simplified analytical solution is simplified to obtain a simplified analytical solution.

[0060] For the part in brackets (i.e., partial term) in the integral term in equation (4): , we can consider based on Euler's formula , make the following transformations:

[0061] (5).

[0062] The right side of the equal sign in formula (5) is the partial term after the first processing.

[0063] After using the perfect square formula to expand the square terms of the real and imaginary parts in equation (5), we can use the trigonometric function and the difference product formula and the Euler formula in reverse order to get:

[0064] (6).

[0065] In formula (6), the left side of the first equal sign is the expanded partial term, the right side of the first equal sign is the second processed partial term, and the right side of the third equal sign is the third processed partial term.

[0066] when →At 0, we have:

[0067] (7).

[0068] In formula (7), the right side of the second approximately equal sign is the partial term after the fourth processing.

[0069] Substituting equation (7) into equation (4), we can eliminate , the obtained approximate form is as follows:

[0070] (8).

[0071] In formula (8), the term on the right side of the equal sign is the analytical solution after preliminary simplification.

[0072] For formula (8), it can be further simplified by combining the values ​​of specific parameters. On the one hand, due to , and lung tissue blood perfusion rate , is much smaller than 1, so On the other hand, Substitution ,but , similarly, , then equation (8) can be simplified to the following form containing the incomplete gamma function:

[0073] (9).

[0074] In formula (9), the term on the right side of the second equal sign is the simplified analytical solution, It is the incomplete gamma function, which is an extended form of the gamma function, in which one parameter is the independent variable of the gamma function and the other parameter is the upper and lower limits of the integral.

[0075] This embodiment further proposes a convenient and accurate simplified calculation formula (i.e., simplified analytical solution) based on the analytical solution. Compared with the numerical integral calculation contained in the analytical solution of formula (4), formula (9) is further simplified to several arithmetic operations and one table lookup, which further reduces the amount of calculation and improves the calculation efficiency. Compared with the analytical solution of formula (4), the calculation error is at the level of one ten-thousandth.

[0076] In the study of three-dimensional biological heat transfer problems, compared with the repeated iterative calculations based on the iterative calculation simulation method of finite elements, the analytical solution of the heat conduction equation can significantly reduce the amount of calculation. In this embodiment, when the analytical solution of the heat conduction equation of the alveoli is obtained, a more rapid and accurate simplified calculation formula is proposed, with an error of one ten-thousandth level. When dealing with heat conduction problems with more alveolar heat sources, the heat transfer temperature results can be obtained quickly and conveniently based on the superposition principle, which is suitable for more promotion situations. Specifically, the study from the perspective of a single alveolar spherical heat source has corresponding advantages. In addition to being easy to obtain analytical solutions and simplified calculation formulas, on the one hand, based on the superposition principle, the temperature changes of lung tissues adjacent to multiple alveoli can be regarded as the superposition of multiple alveolar heat transfers; on the other hand, the alveolar radius is very small, about 0.1 mm on average, and based on the alveolar-level small unit, the formula (4) is converted to When it is considered to be close to 0, the corresponding conclusion can be transferred from the perspective of the finite element method to the study of heat conduction in a relatively macroscopic physiological structure, such as the bronchial wall, that is, the bronchial wall is divided into many interconnected small units (i.e., finite elements), and each small unit is calculated using the analytical formula and simplified calculation formula proposed in this embodiment, and finally the heat conduction effect is superimposed to obtain the result. For the three-dimensional biological heat transfer of steam ablation alveoli, the spatiotemporal temperature distribution results of heat conduction can be obtained very quickly and accurately, and can be directly superimposed and applied for the case of more alveolar heat sources.

[0077] This embodiment further verifies the accuracy of the simplified calculation formula through numerical calculation.

[0078] In order to verify the effectiveness of the simplified calculation formula proposed, this embodiment takes the same parameters based on the human lung tissue situation, uses formula (4) and formula (9), and performs calculation results at different spatial and time points for comparison. When the steam is continuously released for 10 seconds, =37℃ (normal human body temperature), thermal conductivity of lung tissue =0.5W / (m℃), lung tissue density is equal to blood density, = =1000kg / m 3 , the specific heat capacity of lung tissue is equal to that of blood, = =3800J / (kg℃), blood perfusion rate , heat production per unit volume of lung tissue metabolism =700W / m 3 , single alveolar input heat power , the radius of the alveoli =0.1mm=0.0001m, corresponding to , .

[0079] For formula (4), the temperature calculation results within the range of 0.1 mm to 3 mm from the center of the alveoli and during the treatment period of 1 to 10 seconds are shown in Table 1.

[0080] Table 1 Numerical results of temperature spatial and temporal distribution calculated based on analytical solution

[0081]

[0082] Similarly, for formula (9), the temperature calculation results within the range of 0.1 mm to 3 mm from the center of the alveoli and during the treatment period of 1 to 10 s are shown in Table 2.

[0083] Table 2 Numerical results of temperature spatiotemporal distribution calculated based on simplified calculation formula

[0084]

[0085] Combined with the above results, the simplified calculation formula is verified to be accurate and effective, and can be used as a simplified calculation method to replace formula (4). Its deviation within the verification range is within the range of ±0.011%, that is, the deviation level of one ten-thousandth.

[0086] At present, there is no relevant content on the three-dimensional bioheat transfer of alveoli in respiratory intervention steam ablation, and even the simplified calculation method proposed in this embodiment for the three-dimensional bioheat transfer at a broader level has not been seen. This embodiment proposes the heat conduction equation for steam ablation, the corresponding analytical solution of the heat conduction equation, a further simplified calculation formula, and a derived multi-alveolar heat source superposition calculation method. The analytical solution of the proposed heat conduction equation has a more accurate solution form compared to the iterative simulation theory, and the amount of calculation is greatly reduced. The amount of calculation of the further simplified calculation formula obtained on this basis is further reduced. After substituting the time parameters and space parameters, the temporal and spatial distribution results of the temperature can be obtained by a single-step calculation, and the actual numerical calculation verifies that its error is at the level of one ten-thousandth, and the simplified calculation formula is fast and accurate. This embodiment is based on the heat conduction equation of lung tissue from steam ablation to the alveoli, and obtains an accurate analytical solution, which saves a lot of iterative calculations. On this basis, the analytical solution is further simplified, and the calculation is further simplified while ensuring accuracy. For the three-dimensional bioheat transfer problem of alveolar heat sources in more thermal ablation areas, it can be promoted and applied in the same way based on the superposition principle, and has strong expansibility.

[0087] The method proposed in this embodiment can be applied to the heat transfer of multiple alveoli based on the superposition principle. →0 or based on The simplified calculation formulas with sufficiently small premises can be transferred and extended to more situations (such as more macroscopic physiological structures: three-dimensional bioheat transfer research of bronchial airways) from the perspective of finite element method. The proposed method is universal.

[0088] The embodiment of the present application also provides an application scenario, which applies the above-mentioned three-dimensional heat transfer calculation method of alveoli in steam ablation. Specifically, the three-dimensional heat transfer calculation method of alveoli in steam ablation provided by this embodiment can be applied in the target lung segment temperature calculation scenario. The target lung segment temperature calculation scenario includes a data acquisition link, a data processing link and a result display link. The data acquisition link is used to obtain the distance from the target lung segment to each alveolus in the target lung segment. The data processing link first determines the analytical solution of the heat conduction equation of the alveoli in the target lung segment, and then for each alveolus, the distance from the target lung segment to the alveolus and the working time of steam ablation are used as inputs. The temperature of the target lung segment corresponding to the alveolus is calculated using the analytical solution, and the temperatures of the target lung segment corresponding to all alveoli are superimposed to obtain the final temperature of the target lung segment. The result display link is used to display the final temperature of each target lung segment. The three-dimensional heat transfer calculation method of alveoli in steam ablation provided by this embodiment belongs to the data processing link.

[0089] Example 2.

[0090] Based on the same inventive concept, the embodiment of the present application also provides a steam ablation alveolar three-dimensional heat transfer calculation device for implementing the above-mentioned steam ablation alveolar three-dimensional heat transfer calculation method. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above-mentioned method, so the specific limitations in the embodiment of the steam ablation alveolar three-dimensional heat transfer calculation device provided below can refer to the limitations of the steam ablation alveolar three-dimensional heat transfer calculation method above, and will not be repeated here.

[0091] like Figure 3 As shown, a device for calculating three-dimensional heat transfer of alveoli during steam ablation is provided, and the device for calculating three-dimensional heat transfer of alveoli during steam ablation includes the following modules.

[0092] A module M1 is established to establish an initial heat conduction equation of the alveoli in the target lung segment; the initial heat conduction equation includes an airflow influence term; the target lung segment is the lung segment to be treated by steam ablation.

[0093] The removal module M2 is used to remove the airflow influence term in the initial heat conduction equation based on the actual situation of steam ablation to obtain the heat conduction equation.

[0094] The solving module M3 is used to regard the alveoli as spherical heat sources, solve the heat conduction equation, and obtain an analytical solution to the heat conduction equation.

[0095] The calculation module M4 is used for calculating the temperature of any desired position point in the target lung segment by using the analytical solution, taking the distance from the desired position point to the alveoli and the working time of steam ablation as input.

[0096] Example 3.

[0097] In an exemplary embodiment, a computer device is provided. The computer device may be a server or a terminal. The internal structure diagram thereof may be as follows: Figure 4 As shown. The computer device includes a processor, a memory, an input / output interface (Input / Output, referred to as I / O) and a communication interface. The processor, the memory and the input / output interface are connected through a system bus, and the communication interface is connected to the system bus through the input / output interface. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data to be processed. The input / output interface of the computer device is used to exchange information between the processor and an external device. The communication interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for calculating three-dimensional heat transfer of alveoli in steam ablation is implemented.

[0098] Those skilled in the art will understand that Figure 4 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0099] In an exemplary embodiment, a computer device is also provided, including: a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for calculating three-dimensional heat transfer of alveoli during steam ablation described in Example 1.

[0100] Example 4.

[0101] An embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the method for calculating three-dimensional heat transfer of alveoli during steam ablation described in Example 1 is implemented.

[0102] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0103] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A method for calculating three-dimensional heat transfer of alveoli during steam ablation, characterized in that: The method for calculating three-dimensional heat transfer of alveoli during steam ablation includes: Establishing an initial heat conduction equation for alveoli in a target lung segment; the initial heat conduction equation includes an airflow influence term; the target lung segment is a lung segment to be treated by steam ablation; Based on the actual situation of steam ablation, the airflow influence term in the initial heat conduction equation is removed to obtain the heat conduction equation; Considering the alveoli as spherical heat sources, the heat conduction equation is solved to obtain an analytical solution to the heat conduction equation; For any desired position point in the target lung segment, the temperature of the desired position point is calculated using the analytical solution, taking the distance from the desired position point to the alveoli and the working time of steam ablation as input; The analytical solution is: ； in, is the distance from the position to be determined to the alveoli and steam ablation working time Temperature at is the blood temperature; is the first intermediate variable, , is the thermal conductivity of lung tissue, is the lung tissue density, is the specific heat capacity of lung tissue; is the second intermediate variable, , is the blood density, is the specific heat of blood, is the blood perfusion rate; Heat produced per unit volume by the lung tissue's own metabolism; Working time for steam ablation The single alveolar input heat power at ; is the radius of the alveoli; is the integration variable; is the ratio of pi.

2. The method for calculating three-dimensional heat transfer of alveoli during steam ablation according to claim 1, characterized in that: The initial heat conduction equation is: ； in, is the density of lung tissue; is the specific heat capacity of lung tissue; For the position vector and steam ablation working time Temperature at is the thermal conductivity of lung tissue; is the gradient operator; is the blood density; is the specific heat capacity of blood; is the blood perfusion rate; is the blood temperature; Working time for steam ablation Heat generated per unit volume of steam ablation input power at ; For the position vector and steam ablation working time The heat produced per unit volume by the lung tissue's own metabolism at that time; is the airflow influence term; is the gas temperature in the airway; is the specific heat capacity of gas; is the airflow perfusion rate; is the temperature of the gas flowing through the lungs.

3. The method for calculating three-dimensional heat transfer of alveoli during steam ablation according to claim 1, characterized in that: For any desired position point in the target lung segment, the distance from the desired position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the desired position point is calculated using the analytical solution, specifically including: Simplifying the analytical solution to obtain a simplified analytical solution; For any desired position point in the target lung segment, the distance from the desired position point to the alveoli and the working time of steam ablation are used as inputs, and the temperature of the desired position point is calculated using the simplified analytical solution; The analytical solution is simplified to obtain a simplified analytical solution, which specifically includes: The partial term in the integral term in the analytical solution is processed using the Euler formula to obtain the first processed partial term; the partial term is ; Expanding the square term in the first processed partial term using a perfect square formula to obtain an expanded partial term; Processing the expanded partial term using a sum-difference-product formula to obtain a second processed partial term; Processing the second processed partial term using Euler's formula to obtain a third processed partial term; The radius of the alveoli is set to be 0, and the third processed partial item is processed to obtain a fourth processed partial item; Replacing some of the integral terms in the analytical solution with the partial terms after the fourth processing to obtain a preliminary simplified analytical solution; Based on the values ​​of the parameters in the preliminary simplified analytical solution, the preliminary simplified analytical solution is simplified to obtain a simplified analytical solution.

4. The method for calculating three-dimensional heat transfer of alveoli during steam ablation according to claim 3, characterized in that: The fourth post-processing part is: .

5. The method for calculating three-dimensional heat transfer of alveoli during steam ablation according to claim 3, characterized in that: The simplified analytical solution is: ； in, is the incomplete gamma function.

6. A device for calculating three-dimensional heat transfer of alveoli during steam ablation, characterized in that: The device for calculating the three-dimensional heat transfer of alveoli during steam ablation comprises: Establishing a module for establishing an initial heat conduction equation of alveoli in a target lung segment; the initial heat conduction equation includes an airflow influence term; the target lung segment is a lung segment to be treated by steam ablation; A removal module, used for removing the airflow influence term in the initial heat conduction equation based on the actual situation of steam ablation to obtain the heat conduction equation; A solution module, used for treating the alveoli as spherical heat sources, solving the heat conduction equation, and obtaining an analytical solution to the heat conduction equation; A calculation module, for calculating the temperature of any desired position point in the target lung segment by using the analytical solution, taking the distance from the desired position point to the alveoli and the working time of steam ablation as input; The analytical solution is: ； in, is the distance from the position to be determined to the alveoli and steam ablation working time Temperature at is the blood temperature; is the first intermediate variable, , is the thermal conductivity of lung tissue, is the lung tissue density, is the specific heat capacity of lung tissue; is the second intermediate variable, , is the blood density, is the specific heat of blood, is the blood perfusion rate; Heat produced per unit volume by the lung tissue's own metabolism; Working time for steam ablation The single alveolar input heat power at ; is the radius of the alveoli; is the integration variable; is the ratio of pi.

7. A computer device comprising: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the method for calculating three-dimensional heat transfer of alveoli during steam ablation according to any one of claims 1-5.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the method for calculating three-dimensional heat transfer of alveoli during steam ablation described in any one of claims 1 to 5 is implemented.

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