CN1331954A - Deep heat field optimizing control method for capacitive RF thermotherapeutic equipment - Google Patents

Abstract

The computerized method uses the human body tissue model based on computerized tomography and introduces target function and relative weighting coefficient according to the required target zone heating temperature and no overheat of normal tissue. By means of genetic algorithm to correct heating physical parameters iteratively, the object function is made to reach its minimum value and the physical parameters for ideal heat field distribution are obtained. The method has great significance to establishment and performance of clinical thermotherapeutic scheme of tumor, as well as the design of capacitive RF thermotherapeutic equipment.

Description

The deep heat field optimizing control method of capacitive RF thermotherapeutic equipment

The present invention relates to a kind of radio-frequency (RF) thermotherapeutic method, relate in particular to a kind of capacitive RF thermotherapeutic method.

Capacitive RF thermotherapeutic (capacitive radio-frequency hyperthermia) is hyperthermia treatment of carcinoma (Hyperthermic Oncology) technology commonly used in the clinical tumor.Wherein polarity plate capacitor type and tri-electrode capacitor type are two kinds, and described two-plate capacitor type abbreviates two electric capacity thermotherapies as, and the tri-electrode capacitor type abbreviates three electric capacity thermotherapies as.The Capacitance Coupled heating mainly is to produce heat effect by the ohmic loss of radio-frequency current in tissue, and its main thermal field scope increases with electrode area and progressively deepens.But radio-frequency current causes electric current density to increase with the treatment degree of depth and reduce, so the effect of deep heating weakens along with increasing with electrode distance and dispersing.During two electric capacity thermotherapies, thermal field distributes and mainly adjusts by electrode size, its effective hot-zone is many near small size electrode one side, for reaching the deep heating purposes, need to use the larger area electrode, have only when the pole plate diameter equals or exceeds polar plate spacing, most of radio-frequency current could flow through in the cylinder of being made up of pole plate, its corresponding deep tissue just can be heated, but because of heating surface (area) (HS increases and the degree of depth increases electric current density is reduced, is difficult to satisfy the requirement that heat in the deep.Concerning three electric capacity thermotherapies, distribute though can adjust thermal field by the phase place, amplitude and the power division mode that change three polar plate voltages, but still being concentrated on, radio-frequency current organizes the deep.For these reasons, capacitive RF thermotherapeutic is controlled cancer to the deep and often is difficult to prove effective.Therefore, how to adjust effectively and control that deep heat field distributes is the difficult point that can capacitive RF thermotherapeutic obtain good efficacy when being used for the deep hyperthermia treatment of carcinoma, still do not have solution preferably so far.

One of most important also promptly the most difficult problem is in the tumor thermotherapy: how to control human body internal heating temperature field and distribute, make it both to cover the tumor tissues target area of desire heating, reach 43 ~ 45 ℃ of effective treatment high-temperature regions, but do not damage the normal structure around it, guarantee that its temperature is lower than 40 ℃.For this reason, selecting to add thermophysical parameter, as irradiator power, electrode position size and voltage-phase etc. with formulate before the clinical thermotherapy scheme, should carry out temperature field forecast of distribution in the human body.But the temperature field Non-Destructive Testing is still a still unsolved difficult problem in biomedical hot physical study and the clinical practice in the organism.

At present, the insider thinks that adopting the computer numerical emulation mode to carry out the harmless reconstruct in organism temperature field is the approach that application prospect is arranged most.Usually, find the solution thermal field by known heating physical condition and distribute, be called direct problem; Otherwise, find the solution the required thermophysical parameter that adds by the distribution of re-set target thermal field and be called inverse problem.Because tissue has anisotropy, up to now, in tumor thermotherapy, mostly be the direct problem prediction, do not see that inverse problem finds the solution.

The objective of the invention is to, overcome the deficiencies in the prior art, a kind of deep heat field optimizing control method of capacitive RF thermotherapeutic equipment is provided, the ideal that can reach the distribution of expection hyperthermia treatment of carcinoma target thermal field with direct acquisition adds thermophysical parameter.This all has great importance and practical value to relevant heat treatment therapeutic device design and the formulation of thermotherapy clinical protocol.

For achieving the above object, the present invention adopts following steps to realize: (1) organizes the image information behind the image film digitized to be input in the computer tomography; (2) thus handle the finite element subdivision image information that above-mentioned image information obtains section simplified structure model with having the processing image information functional programs, and it is stored in the storage device; (3) will be scheduled to the data storage of target temperature profiles of target area heating in storage device; (4) thermophysical parameter that adds with capacitive RF thermotherapeutic equipment is stored in the storage device; (5), obtain the data that accounting temperature distributes according to above-mentioned finite element subdivision with add thermophysical parameter and carry out direct problem and find the solution; (6) find the solution according to the data of aforementioned calculation Temperature Distribution and target temperature profiles and obtain the temperature objectives function; (7) numerical value according to the said temperature object function carries out following selection: if this numerical value keeps off 0, then adopt genetic algorithm to be optimized and find the solution, correction adds thermophysical parameter, and returns step (4), carries out circular treatment; If this numerical value is near 0, then the thermophysical parameter that adds described in the above-mentioned steps (4) is added thermophysical parameter output as the optimum of the deep heat field of capacitive RF device.

Described genetic algorithm preferably adopts following substep: (a) select five individualities or four individualities again together with the optimized individual of previous generation at random, constitute population of new generation; (b) calculate individual adaptability, optimized individual is designated as individual 5 directly sends into the next generation, do not lose to guarantee hereditary information; (c) all the other individualities are bred according to finishing tournament rules, and optimized individual also participates in the competition, and avoids inbreeding; (d) individuality of selecting in the population carries out copulation with certain probability; (e) detect population and whether restrain,, make circular treatment if convergence goes to step (b); If do not restrain, then carry out next step; (f) do following selection according to the numerical value of iteration algebraically:, carry out circular treatment if this numerical value then returns step (a) less than the maximum algebraically that allows; If this numerical value is equal to or greater than the maximum algebraically of permission, then finish genetic algorithm.Behind the described group mating, make a variation.The algorithm of described temperature objectives function is expressed in the following way: $J=\underset{\mathrm{\Ω}}{\∫}\mathrm{\λ}{F}_T\[T\left(\mathrm{\φ}\right)\]\mathrm{d\Ω}$

φ is a border Potential distribution to be optimized in the formula, and Ω is for optimizing the finite element divided region of finding the solution, and λ is the optimization weight of corresponding different divided regions in the object function; R _rBe the temperature objectives function, comprise the temperature objectives function F of tumor tissues _T1Temperature objectives function F with normal structure _T2Two parts;

The temperature objectives function F _TIntegration discrete be following form: $\underset{\mathrm{\Ω}}{\∫}{F}_T\[T\left(\mathrm{\φ}\right)\]\mathrm{d\Ω}={\mathrm{\λ}}_1\underset{l=1}{\overset{N_1}{\mathrm{\Σ}}}{F}_{T1}\[\mathrm{Ti}\left(\mathrm{\φ}\right)\]+{\mathrm{\λ}}_2\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}{F}_{T2}\[\mathrm{Tj}\left(\mathrm{\φ}\right)\]$

N in the formula ₁Be the tumor tissues node number of needs heating, N ₂For avoiding superheated normal structure node number, T ₁And T ₂Be respectively the respective nodes temperature, λ ₁And λ ₂Be respectively the optimization weight of tumor tissues and normal structure.The ratio λ of the optimization weight of tumor tissues described in the formula and normal structure ₁/ λ ₂Be advisable with 8 ~ 14.

The invention has the beneficial effects as follows: when the thermotherapy of human body deep, no matter be to use the capacitive based capacitive RF thermotherapeutic equipment of two-plate capacitor type and tri-electrode, adopt method of the present invention all can effectively, accurately, directly obtain to reach and expect that the ideal that hyperthermia treatment of carcinoma target thermal field distributes adds thermophysical parameter.Thereby improve the overheating effect of electrode rim, can make the deep tumor position reach expection thermotherapy target temperature, can avoid damaging deep tumor normal structure on every side again.

Below in conjunction with the drawings and specific embodiments the present invention is described in further detail.

Fig. 1 is the workflow diagram of the deep heat field optimizing control method of capacitive RF thermotherapeutic equipment of the present invention;

Fig. 2 is that the present invention extracts the flow chart that tomography is simplified the finite element subdivision of organize models and model;

Fig. 3 is that direct problem of the present invention is found the solution the flow chart that the temperature field distributes;

Fig. 4 is that the present invention utilizes genetic Optimization Algorithm to obtain to add the flow chart of thermophysical parameter;

Fig. 5 (a) and Fig. 5 (b) are respectively that the present invention heats the section simplified structure model of body and the finite element subdivision sketch map of model;

Fig. 6 is the curve chart of temperature objectives function of the present invention;

Fig. 7 (a), Fig. 7 (b) and Fig. 7 (c) be respectively tumor of the present invention when being positioned at the deep two electric capacity thermotherapies optimize that heating condition electromotive force (φ) down distributes, SAR distributes and the sketch map of temperature (T) distribution;

Fig. 8 (a), Fig. 8 (b) and Fig. 8 (c) be respectively the present invention when having deep and superficial part tumor simultaneously two electric capacity thermotherapies optimize that heating condition electromotive force (φ) down distributes, SAR distributes and the sketch map of temperature (T) distribution;

Fig. 9 (a), Fig. 9 (b) and Fig. 9 (c) be respectively tumor of the present invention when being positioned at the deep two electric capacity thermotherapies optimize that heating condition electromotive force (φ) down distributes, SAR distributes and the sketch map of temperature (T) distribution;

Figure 10 (a), Figure 10 (b) and Figure 10 (c) be respectively the present invention when having deep and superficial part tumor simultaneously three electric capacity thermotherapies optimize that heating condition electromotive force (φ) down distributes, SAR distributes and the sketch map of temperature (T) distribution.

Fig. 1 to Fig. 6 illustrates workflow of the present invention, in Fig. 1, utilizes the medical image device, and described medical image device can be X-ray tomograph, i.e. X-CT; Or magnetic resonance imaging, i.e. MRI; And other medical image equipment, the tomography that obtains the heating target area is organized film, through the digitized Film scanner fault image is imported computer then, in machine by craft or program simplification organization structural model, determine section and organ boundaries, and finish the finite element subdivision of section structure model, shown in Fig. 5 (a) and Fig. 5 (b); Can analyze from Fig. 5 (a) and contain two tumors in this heating body, wherein one 7 is positioned at shallow table, and another piece 8 is positioned at the deep; The triangular unit number that draws the finite element subdivision from Fig. 5 (b) is 1555, and the node number is 826, but heating electrode needs to determine in optimizing process with the pairing node location of cooling water bag, number and magnitude of voltage in the boundary point.

Find the solution in order to carry out direct problem, establish human body initial temperature and blood heat and be 37 ℃, initial electrode position, size and magnitude of voltage are all obtained at random; According to thermotherapy theory and clinical experience, the final goal temperature of definition expection heating is: 43 ~ 45 ℃ of tumor tissues temperature, 30 ~ 40 ℃ of normal structure temperature.

Add thermophysical parameter and mainly be made of each battery lead plate position shape and heating power on the capacitive RF thermotherapeutic equipment, the battery lead plate position shape of saying here refers to the size dimension and the position of battery lead plate, draws polar plate voltage according to heating power.Polar plate voltage and position shape have determined the distribution of human body external boundary current potential φ, { φ }={ φ ₁, φ ₂... φ _m.Here φ ₁~ φ _mFor each node potential of border in the finite element subdivision, comprising the node potential of battery lead plate place.In addition, between human body skin and battery lead plate, fill up usually with the cooling water bag to avoid the overheated of electrode edge electric field.Because recirculated water cooling effect cooling water bag has stable chilling temperature.

For the capacitive RF thermotherapeutic occasion of heating, carry out direct problem according to the finite element subdivision of Fig. 5 (b) and the initial heating physical parameter determined at random and find the solution to obtain the data that accounting temperature distributes.Its direct problem is found the solution and is comprised two parts as shown in Figure 3: electromagnetic problems---find the solution the Laplace equation to obtain the Electric Field Distribution in the biological tissue; The temperature field problem---find the solution the Temperature Distribution of biological heat transmission equation to produce by the electric field heating in obtaining organizing.

Because the radio frequency value is about 10MHz, its wavelength is much larger than the human body depth dimensions, can adopt the quasi-static electric field to describe electric field in the human body.Electromotive force φ in, satisfy the Laplace equation:

ε is the dielectric constant of biological tissue in (ε φ)=0 (1) formula.Distribution by electromotive force φ can solve electric field intensity Distribution: $\stackrel{\→}{E}=-\▿\mathrm{\φ}----\left(2\right)$ Electric field In biological tissue, cause radio-frequency current, produce the Ohmic heating effect.For tri-electrode radio frequency electric capacity heat treatment therapeutic device, the electromotive force φ of its three pole plates also should satisfy vector and be zero phase equilibrium:

φ1＋φ2＋φ3＝0?(3)

The heat that thermotherapy is absorbed the unit organization quality clinically is that electric field energy is referred to as specific absorption rate (SpecificAbsorption Rate-SAR), is designated as Q _s, provide by following formula: $Q_S=\frac{1}{2}{\mathrm{\σ}}_1{\left|E\right|}^2----\left(4\right)$ Heating region inner tissue temperature (T) distributes by the biological heat transfer equation decision of following Pennes: ${\mathrm{\ρ}}_t{C}_t\frac{\∂T}{\∂t}-\▿(K_t\▿T)=Q_t+Q_s+Q_b--\left(5\right)$

ρ in the formula _t, Ct, Kt are respectively tissue density, specific heat and thermal conductivity.Q _tBe physiology heat production item, Q _sBe SAR heat production item, Q _bBe blood perfusion heat radiation item.Q _bCan describe by following formula:

Q _b＝(F _b) _t(ρ _bC _b)(T-T _b)????????(6)

(F in the formula _b) _tBe blood flow (b) groundwater increment in the tissue (t), ρ _b, C _bBe density of blood and specific heat, T _bBe the blood perfusion temperature.Supposition (F in the calculating _b) _tBe the constant that does not change with heating-up temperature, blood heat is decided to be 37 ℃.Q generally speaking _tCompare Q _sAnd Q _bMuch smaller, can omit.

Direct problem is promptly found the solution above (1) ~ (5) formula.The present invention adopts two-dimensional finite element method (2D-FEM) to carry out numerical solution, is applicable to two electric capacity and two kinds of thermal therapy systems of three electric capacity.Required electricity, thermophysical parameter when table 1 is calculating.

The electricity of table 1 biological tissue and thermal parameters

Tissue	????ε r	????σ (s/m)	????κ (W/m/℃)	????ρ (kg/m 3)	????c (J/kg/℃)	????F b(m 3/kg/s)
							Blood	????118.0	?1.1	????0.0	?1.06e3	?3.96e3	??????--
Skeleton	????7.3	?0.028	????0.436	?1.79e3	?1.30e3	?4.20e-7
							Fat	????20.0	?0.047	????0.22	?0.90e3	?2.30e3	?5.00e-7
Feces	????113.0	?0.6	????0.6	?1.00e3	?3.90e3	?0.0
							Bone marrow	????200.0	?0.65	????0.515	?1.10e3	?3.96e3	?7.50e-6
Muscle	????113.0	?0.61	????0.6	?1.02e3	?3.50e3	?8.30e-6
							Tumor (edge)	????60.0	?0.8	????0.57	?1.04e3	?3.90e3	?1.67e-6
Tumor (deep)	????60.0	?0.8	????0.57	?1.04e3	?3.90e3	?5.00e-7

In Fig. 4, distribute the optimization temperature objectives function J that is defined as follows according to target temperature profiles and accounting temperature: $J=\underset{\mathrm{\Ω}}{\∫}\mathrm{\λ}{F}_T\[T\left(\mathrm{\φ}\right)\]\mathrm{d\Ω}----\left(7\right)$

φ is a border Potential distribution to be optimized in the formula, and Ω is for optimizing the finite element divided region of finding the solution, and λ is the optimization weight of corresponding different divided regions in the object function.F _rBe the temperature objectives function, contain the temperature objectives function F of tumor tissues _T1Temperature objectives function F with normal structure _T2Two parts.

Fig. 6 illustrates, when tumor temperature is in 43～45 ℃, and F _T1=0; When normal structure temperature during at 30～40 ℃, F _T2=0.If carry out numerical computations this moment, F in the formula (6) _TIntegration can disperse and be following form: $\underset{\mathrm{\Ω}}{\∫}{F}_T\[T\left(\mathrm{\φ}\right)\]\mathrm{d\Ω}={\mathrm{\λ}}_1\underset{i=1}{\overset{N_1}{\mathrm{\Σ}}}{F}_{T1}\[\mathrm{Ti}\left(\mathrm{\φ}\right)\]+{\mathrm{\λ}}_2\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}{F}_{T2}\[\mathrm{Tj}\left(\mathrm{\φ}\right)\]---\left(10\right)$

N in the formula ₁Be the tumor tissues node number of needs heating, N ₂For avoiding superheated normal structure node number, T _iAnd T ₂Be respectively the respective nodes temperature, λ ₁And λ ₂Be respectively the optimization weight of tumor tissues and normal structure.

Fig. 4 illustrates the processing procedure of optimizing algorithm, under the heating condition of given target temperature profiles, optimize the position shape parameter of electrode drive voltage and pole plate, make that finding the solution the distribution of gained accounting temperature through direct problem approaches the preset target temperature distribution as far as possible, in other words, find the solution the value of the temperature objectives function that obtains near 0 through direct problem exactly.The present invention adopts genetic algorithm (Genetic algorithms-GA) to be optimized and to find the solution, and genetic algorithm is that a class adopts genetic mechanism to carry out the numerical optimization technique of parameter search.Find the solution all kinds of optimization problems because of it has good robustness to be produced the general fields such as engineering, science, economics that are used in recent years, become multiple target, non-smooth, the complicated strong instrument of optimizing a difficult problem of solving.Genetic algorithm is used three operators such as selection, copulation, variation usually, goes through number for obtaining satisfied optimization result.Optimize finding the solution of task and be to use genetic algorithm that the border Potential Distributing is carried out the iteration correction, when the pairing object function of the optimum in adjacent generation changes less than a certain threshold value or reach the highest algebraically that allows to evolve, stop.

The step of genetic algorithm is as follows:

(a) select five individualities or four individualities again together with the optimized individual of previous generation at random, constitute population of new generation;

(b) calculate individual adaptability, optimized individual is designated as individual 5 directly sends into the next generation, do not lose to guarantee hereditary information;

(c) all the other individualities are bred according to the rules of contest, and optimized individual also participates in the competition, and avoid inbreeding;

(d), the individuality selected in the population carries out copulation with certain probability, post-coitum can not make a variation;

(e), whether restraining selection according to the detection population carries out: if convergence then goes to step (b), carry out circular treatment; If do not restrain, then carry out next step;

(f), do following selection according to the numerical value of iteration algebraically:, carry out circular treatment if this numerical value then returns step (a) less than the maximum algebraically that allows; Otherwise finish genetic algorithm.

For two electric capacity thermal therapy systems, less relatively because of its optimization aim, the present invention uses little genetic algorithm; Then use common genetic algorithm for three electric capacity thermal therapy systems.

Fig. 7 (a), Fig. 7 (b) and Fig. 7 (c) have provided the optimization result calculated of two electric capacity thermotherapies when only containing tumor in the deep.Wherein Fig. 7 (a) is for when alternating voltage is got maximum, and the electromotive force of optimizing under the heating condition (φ) distributes, and Fig. 7 (b) distributes for SAR, and Fig. 7 (c) is that temperature (T) distributes.Total 900 seconds heat time heating times.The heating target area is that the final temperature of tumor tissues is 43.7 ± 0.9 ℃; In non-heating target area is that the normal structure temperature is 37.7 ± 3.1 ℃; Consumed power is 2300W.The position dimension of optimizing the heating condition bottom electrode is shown in the peripheral thick black line in border among the figure.The deep tumor position has reached expection thermotherapy target substantially as we can see from the figure.

Fig. 8 (a), Fig. 8 (b) and Fig. 8 (c) have provided the optimization result of calculation of three electric capacity thermotherapies when tumor is positioned at the deep, wherein Fig. 8 (a) is for when alternating voltage is got maximum, the electromotive force of optimizing under the heating condition (φ) distributes, and Fig. 8 (b) distributes for SAR, and Fig. 8 (c) is that temperature (T) distributes.Total 900 seconds heat time heating times.The heating target area is that the final temperature of tumor tissues is 43.0 ± 0.7 ℃; In non-heating target area is that the normal structure temperature is 38.6 ± 3.0 ℃; Consumed power is 2880W, and consumed power increased to some extent when this power ratio tumor was positioned at shallow table.Compare with two electric capacity thermotherapies, when making the deep tumor position reach expection thermotherapy target, also improved the overheating effect of electrode rim during three electric capacity thermotherapies, it is more outstanding promptly to optimize the result.This mainly be because during three electric capacity thermotherapies not only the position dimension of electrode more adjustment leeway is arranged, and the electromotive force of three pole plates can also adjust phase assignments, makes it to have stronger optimization ability.

The result of the example that the optimization of two electric capacity thermotherapies was calculated when Fig. 9 (a), Fig. 9 (b) and Fig. 9 (c) had provided deep and superficial part and have tumor simultaneously, wherein Fig. 9 (a) distributes for the electromotive force of optimizing under the heating condition (φ), Fig. 9 (b) distributes for SAR, and Fig. 9 (c) is that temperature (T) distributes.Total 900 seconds heat time heating times.Deep tumor target area final temperature is 43.2 ± 0.7 ℃; The final temperature of tumor target area, edge is 43.2 ± 1.6 ℃; The temperature that in non-heating target area is normal structure is 38.7 ± 3.1 ℃; Consumed power is 3150W, needs to increase when only having single tumor consumed power.As can be seen from the figure the tumor of deep and superficial part has all entered effective high-temperature region, but still has the superheating phenomenon of local normal structure.What is interesting is when optimizing the effect ratio this moment only has deep tumor better.Its reason may be because dark, when there is tumor in superficial part simultaneously, deep tumor can distribute by means of the boundary electric potentials that the superficial part tumor heating optimization aim driving effect that is positioned at the border obtains to optimize heating; And when only deep tumor being arranged, the border only exists avoids the superheated constraints of normal structure, so heating is optimized the driving effect and is difficult to prove effective to deep tumor.

The optimization result of calculation of three electric capacity thermotherapies when Figure 10 (a), Figure 10 (b) and Figure 10 (c) have provided deep and superficial part and have tumor simultaneously, wherein Figure 10 (a) distributes for the electromotive force of optimizing under the heating condition (φ), Figure 10 (b) distributes for SAR, and Figure 10 (c) is that temperature (T) distributes.Total 900 seconds heat time heating times.The deep tumor finishing temperature is 43.2 ± 0.7 ℃; The final temperature of tumor target area, edge is 43.2 ± 1.6 ℃; The temperature that in non-heating target area is normal structure is 38.7 ± 3.1 ℃; Consumed power is 3150W, needs equally to increase when only having single tumor consumed power.It is good to optimize effect when this moment is than the individualism deep tumor equally as can be seen from figure, and the optimization better effects if of ratio two electric capacity thermotherapies.

The operating process of the optimization result of calculation shown in Fig. 7, Fig. 8, Fig. 9 and Figure 10 series is: the tomography that uses the X-CT device to obtain the heating target area is earlier organized film, through the digital scanning instrument film image is imported computer again; Operator can determine to organize section and organ boundaries by craft and program by keyboard, finish the finite element subdivision of section structure; The initial heating physical parameter of heat treatment therapeutic device is set then at random, i.e. electrode position, size and magnitude of voltage, and the final goal temperature of definition expection heating; Through starting thermal field optimal control program, according to initial heating physical parameter and the final goal temperature set, system adopts two-dimensional finite element method (2D-FEM) to carry out the direct problem in numerical solution electromagnetic field and temperature field, the then temperature field of finding the solution according to finite element subdivision and direct problem, using little heredity or common genetic algorithm to carry out inverse problem optimization calculates, under given target temperature profiles, optimize the position shape parameter of electrode drive voltage and pole plate, finally make genetic Optimization Algorithm draw the temperature objectives function, so just reached and found the solution the gained accounting temperature through direct problem and distribute and approach preset target temperature as far as possible and distribute near 0 result.

When optimization is found the solution, optimize weight factor λ ₁And λ ₂Choose outbalance.In principle, tumor tissues is heated and avoids the overheated of normal structure is a pair of contradiction, and being reflected to optimization is multi-objective optimization question when finding the solution.If λ ₁And λ ₂Get close value, then optimizing process is very slow, almost is difficult to obtain result preferably.So λ ₁And λ ₂Which is more important need decide on optimization aim.Occasion of the present invention, it is better to optimize the result when optimization weights are got 8 to 14 value ranges than λ 1/ λ 2.

Above example is a typical application technology effect of the present invention.Though the present invention's supposition blood perfusion rate does not vary with temperature, if the blood perfusion rate changes with temperature, optimization thought of the present invention and main algorithm stand good.Applying of the reconstruct in temperature field and optimal control technology will design and new way is opened up in the clinical protocol formulation for heat treatment therapeutic device in this organism that the present invention proposes.

Claims (5)

1. the control method that the deep heat field that utilizes computer system to carry out capacitive RF thermotherapeutic equipment is optimized comprises the following steps:

(1) tomography is organized the image information behind the image film digitized be input in the computer;

(2) thus handle the finite element subdivision image information that above-mentioned image information obtains section simplified structure model with having the processing image information functional programs, and it is stored in the storage device;

(3) will be scheduled to the target temperature profiles data storage of target area heating in storage device;

(4) thermophysical parameter that adds with capacitive RF thermotherapeutic equipment is stored in the storage device;

(5), obtain the data that accounting temperature distributes according to above-mentioned finite element subdivision with add thermophysical parameter and carry out direct problem and find the solution;

It is characterized in that it is further comprising the steps of:

(6) distribute according to above-mentioned accounting temperature and the data of target temperature profiles are found the solution and obtained the temperature objectives function;

(7) numerical value according to the said temperature object function carries out following selection:

If this numerical value keeps off 0, then to adopt genetic algorithm to be optimized and find the solution, correction adds thermophysical parameter, and returns step (4), carries out circular treatment.

If this numerical value is near 0, then the thermophysical parameter that adds described in the above-mentioned steps (4) is added thermophysical parameter output as the deep heat field optimum of capacitive RF device.

2. capacitive RF thermotherapeutic equipment deep heat field optimizing control method according to claim 1 is characterized in that described genetic algorithm comprises the following steps:

(a), at random select five individualities or four individualities again together with the optimized individual of previous generation, constitute population of new generation;

(b), calculate individual adaptability, optimized individual is designated as individual 5 directly sends into the next generation, do not lose to guarantee hereditary information;

(c), all the other individual breed according to tournament rules unexpectedly, optimized individual also participates in the competition, and avoids inbreeding;

(d), the individuality of selecting in the population carries out copulation with certain probability;

(e), whether restrain, do following selection according to detecting population:

If convergence goes to step (b), carry out circular treatment;

If do not restrain, then carry out next step;

(f), do following selection according to the numerical value of iteration algebraically:

If this numerical value then returns step (a) less than the maximum algebraically that allows, carry out circular treatment; If this numerical value is equal to or greater than the maximum algebraically of permission, then finish genetic algorithm.

3. capacitive RF thermotherapeutic equipment deep heat field optimizing control method according to claim 2, it is characterized in that described group mating after, make a variation.

4. capacitive RF thermotherapeutic equipment deep heat field optimizing control method according to claim 1 is characterized in that the algorithm of described temperature objectives function is expressed in the following way: $J=\underset{\mathrm{\Ω}}{\∫}\mathrm{\λ}{F}_T\[T\left(\mathrm{\φ}\right)\]\mathrm{d\Ω}$

φ is a border Potential distribution to be optimized in the formula, and Ω is for optimizing the finite element divided region of finding the solution, and λ is the optimization weight of corresponding different divided regions in the object function; F _TBe the temperature objectives function, comprise the temperature objectives function F of tumor tissues _T1Temperature objectives function F with normal structure _T2Two parts:

The temperature objectives function F _TIntegration discrete be following form: $\underset{\mathrm{\Ω}}{\∫}{F}_T\[T\left(\mathrm{\φ}\right)\]\mathrm{d\Ω}={\mathrm{\λ}}_1\underset{i=1}{\overset{N_1}{\mathrm{\Σ}}}{F}_{T1}\[\mathrm{Ti}\left(\mathrm{\φ}\right)\]+{\mathrm{\λ}}_2\underset{j=1}{\overset{N_2}{\mathrm{\Σ}}}{F}_{T2}\[\mathrm{Tj}\left(\mathrm{\φ}\right)\]$

N in the formula ₁Be the tumor tissues node number of needs heating, N ₂For avoiding superheated normal structure node number, T ₁And T ₂Be respectively the respective nodes temperature, λ ₁And λ ₂Be respectively the optimization weight of tumor tissues and normal structure.

5. capacitive RF thermotherapeutic equipment deep heat field optimizing control method according to claim 4 is characterized in that the ratio λ of the optimization weight of described tumor tissues and normal structure ₁/ λ ₂Be 8～14.

Images