JPH01254177A - Hyper-thermia treatment device - Google Patents

Abstract

PURPOSE:To obtain the precise simulator result of temperature distribution by successively correcting a temperature parameter, needed to simulate the temperature distribution in a heating cross section in the middle of heating. CONSTITUTION:The CT picture of the heating cross section is photographed by an X-ray tomography apparatus 6 and the tissues of a human body are discriminated from the CT values of respective points. Then, the temperature parameter corresponding to the respective tissues of the human body is set. A computer 12 judges which tissues of the human body is expressed by the point from the CT values of the respective points in the heating cross section to be transmitted from the X-ray tomography apparatus 6. Then, based on the table of the temperature parameter stored to a data base 11 in advance, the temperature parameter of the respective points is determined. Basis on this temperature parameter, power to be added to an applicator 3 is determined while being simulated.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention relates to a hyperthermia treatment device used for thermal treatment of tumors, etc., and particularly relates to a hyperthermia treatment device used for thermal treatment of tumors, etc. The present invention relates to a technology that quickly performs optimal thermal treatment by predicting and controlling the energy applied to a subject.

B. Prior art It is known that when cancer cells are heated to a predetermined temperature (generally said to be 42.5°C) or higher, they can be killed without causing any negative effects on normal cells. It is being

As a hyperthermia treatment device used for the purpose of such thermotherapy, there is one based on the so-called dielectric heating method. This treatment device locally heats the affected area by irradiating high-frequency electromagnetic waves onto the heating section, and at this time, high-frequency T
How to set the power (energy) of the S iff wave is important.

Conventionally, to determine the power of such high-frequency electromagnetic waves,
The power was set as deemed appropriate based on the results obtained from experiments with muscle-equivalent phantoms and past treatment cases. However, unlike the inside of the human body, a muscle equivalent phantom is homogeneous, and there is no blood flow to cool it, so even if the power is set based on these experimental results, the reliability is extremely low. . On the other hand, even in cases of past treatment, since each patient has individual differences, even when high-frequency electromagnetic waves of the same power are applied, the rise in temperature often varies depending on the patient. As a result, sufficient therapeutic effects may not be obtained because the affected area does not reach a predetermined temperature, or the temperature of local areas other than the affected area may rise abnormally, causing pain to the patient.

Therefore, recently, in order to support this type of thermal treatment, information on the temperature distribution that will occur in the heating cross section when high-frequency electromagnetic waves of a certain power are applied is calculated in advance.
A hyperthermia treatment support device that attempts to set appropriate power based on this has also been proposed. This device uses a differential method based on the energy distribution, commonly known as the SAR distribution, which indicates how much energy is accumulated at each point in the heating cross section when high-frequency electromagnetic waves of a reference power are applied to the human body. The purpose is to predict the temperature distribution of the heated cross section using the finite element method or the finite element method, and set the power based on the results.

Problems to be Solved by the C0 Invention However, the above-mentioned conventional example has the following problems.

Temperature parameters that affect the temperature distribution within the body include electrical conductivity, permittivity, and blood flow at each point in the heating cross section. Conventional hyperthermia treatment support devices use these temperature parameters, for example. Since the appropriate data is selected and used from the data measured in the past, the temperature parameters are not necessarily the same as those of the patient receiving thermotherapy. Since the settings were not accurate, the temperature distribution of the heated cross section could not be accurately predicted, and therefore, there was a problem in that a sufficient thermotherapeutic effect could not be obtained.

This invention was made in view of these circumstances, and it is possible to correctly correct the temperature parameters of the heating cross section, ultimately obtain a highly accurate temperature distribution, and perform appropriate thermal treatment based on this. The purpose of the present invention is to provide a hyperthermia treatment device that can perform hyperthermia treatment.

Means for Solving the Problems The present invention has the following configuration to achieve the above object.

That is, the hyperthermia treatment device according to the present invention includes a storage means for storing temperature parameters distributed in a heated cross section in an updatable state, and a storage means for storing temperature parameters distributed in a heated cross section in an updatable state, and a temperature parameter for a predetermined period of time based on the temperature parameters of the heated cross section stored in the storage means. A means for simulating the temperature distribution of the heated cross section, a heating means for irradiating the heated cross section with energy according to the simulated temperature distribution, and a means for measuring the temperature at required points on the heated cross section. temperature measuring means; temperature monitoring means for comparing the simulated temperature distribution and the measured temperature at predetermined time intervals; and a difference between the simulated temperature distribution and the measured temperature that is greater than or equal to a predetermined value. and means for measuring the temperature parameters of the heated cross section and correcting the stored temperature parameters when the heating cross section is present.

89 Effects According to the present invention, the temperature distribution of the heating cross section is simulated based on the temperature parameters stored in an updateable state, and energy according to the simulated temperature distribution is supplied to the heating cross section. Ru.

Then, at predetermined time intervals, the temperatures at required locations on the heated cross section are actually measured and compared with the simulated temperature distribution. If the difference between the measured temperature and the simulated temperature distribution is large, it means that the initially set temperature parameter value is reasonable, so in this case, measure the temperature parameter of the heated cross section. to correct the initially set temperature parameters. Then, the temperature distribution of the heating section is simulated again based on the corrected temperature parameters, and energy corresponding to this is supplied to the heating section. By executing the above processing at predetermined intervals,
The heated section is heated to a desired temperature.

F. Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a schematic block diagram showing the configuration of an embodiment of the present invention.

In the figure, symbol S is a patient receiving thermotherapy.

The patient S lies supine on the top plate 2 of the head 1, and the top plate 2 is configured to be horizontally movable.

Reference numeral 3 denotes an applicator as a heating means for irradiating energy to the heating section of the patient S to heat it, and in this embodiment, it is configured to irradiate high-frequency electromagnetic waves whose amplitude and phase are controllable. . A porous ice bag 4 is interposed between the applicator 3 and the patient S, which efficiently captures the electromagnetic waves emitted from the applicator 3 into the heating section and also serves to cool the skin surface of the affected area S. There is. Also, near the heating cross section of the patient S, a multi-point temperature sensor 5 is provided as a temperature measuring means for measuring the temperature at required points on the heating cross section.
is installed.

Reference numeral 6 indicates X for taking a tomographic image of the heated cross section of patient S.
It is a line tomography device, 7 is a mouse for manually controlling the position of the applicator 3 and the position of the affected area, 8 is a keyboard for setting data such as temperature parameters and heating conditions, and 9 is a simulated Cr? for displaying the temperature distribution of the heated cross section, etc. T, 10 is a time control device for controlling the time for correcting temperature parameters, etc., and 11 is a state in which the temperature parameters of the heating cross section can be updated)
, a and jf) A database as a means. 1
A computer 2 is a means for simulating temperature distribution, monitoring the temperature of the heated cross section, and correcting temperature parameters.

Next, the operation of this embodiment will be explained according to the flowchart shown in FIG.

In step Sl, a CT image of the heated cross section is taken by the X-ray tomography device 6, human body Mi tissue is determined from the CT value of each point, and temperature parameters are set according to each human body tissue.

As is well known, the CT value is generally ±10 when water is O.
It is defined in the range of 00, and has a unique value depending on the human tissue (for example, muscle, fat, bone, tumor area, etc.). In other words, it is possible to determine what kind of human tissue that point is based on the CT value of that point. computer 12
determines what kind of human body tissue that point is based on the CT value of each point on the heated cross section transmitted from the X-ray tomography device 6, and stores it in a table of temperature parameters stored in advance in the database. Based on this, the temperature parameters of each point are determined.

Here, the temperature parameters include, for example, the electrical conductivity σ at each point on the heating cross section, the dielectric constant 8 current iF, and the like. The values of typical temperature parameters for each tissue of the human body are already known as approximate values. It is being In this embodiment, as shown in FIG. 3, a table of temperature parameters associated with human tissues is created using the above-mentioned known temperature parameters such as electric conductivity σ and dielectric constant 8.

In the figure, A1, Ax, . . . indicate addresses of tables corresponding to human tissues.

The computer 12 specifies the address of the temperature parameter table described above based on the CT value of each point on the heating cross section, and sets the temperature parameter written at that address as the temperature parameter of that point.

Although it is preferable to automatically determine the temperature parameters at each point of the heating cross section in this way because it improves the processing efficiency of thermal treatment, it is not necessary to do so.

For example, the temperature parameters for each point on the heating section may be set by operating the keyboard 8 while looking at the CT image displayed on the CRT 9. Further, after the temperature parameters are automatically set as described above, the operator may operate the keyboard 8 to modify some of the temperature parameters.

Also, when the operator operates the mouse 7,
Specify the position of the applicator 3 and the position of the tumor on the CT image of the heated cross section displayed on the CRT9. These data are taken into the computer 12, and the drive mechanism of the bed 1 is controlled 7H, so that the applicator 3 is set at a position corresponding to the tumor part of the patient S.

After setting the temperature parameters of each point on the heating cross section, the SAR distribution of the heating cross section is created by calculating the SAR of each point (step S2).

SAR is expressed by the following formula.

Here, E is the electric field strength, which is calculated from Maxwell's equation shown below.

That is, the conductivity σ read from the table.

The electric field strength E is calculated by substituting the dielectric constant ε into the above 0.0 formula, and the SAR at that point is calculated from the electric field strength E and the tissue density ρ read from the table. By performing such SAR calculation processing for each point on the heated cross section, the SAR distribution of the heated cross section is calculated.

Once the SAR distribution has been calculated as described above, the power to be applied to the applicator 3 in order to bring the affected area (tumor area) in the heated cross section to the target temperature can be calculated using the known difference method or finite element based on this SAR distribution. The temperature distribution of the heating cross section is determined while simulating it by the method (Step S3)
Specifically, since the SAR distribution is the energy distribution when unit power is applied to the applicator 3, if the power applied to the applicator 3 is P, the energy distribution of the heating cross section at this time is PXSAR. . Therefore, by changing P according to the deviation between the simulated temperature distribution and the target temperature, an optimal P value is determined so that the simulated temperature distribution converges to the target temperature.

The method of determining the temperature distribution of a heated cross section using the finite element method is, for example, (a) J, MTCRowAVE P(VERE”
1987P121~P126 r Temperature Distribution
n in HighFrequency Heated
Dielectrics JAuthor: D.M.Van
Doma+elen and P, F, 5Lefen
s(b) Japanese Journal of Hyperthermia Society Volume 2, No. 2
Issue: P447-P453, 1986 Calculation of internal temperature distribution of human body using finite element method during rRF dielectric heating 1 Author: Toshiyuki Fukuhara et al. Furthermore, the method of determining the temperature distribution of the heated cross section by the difference method is, for example, (C) Trans
actions of the ASME306/Vo
1.10B, NOVEMBER1986rAdapti
ve TherIIlal Modeling: ^Co
ceptfor Measurement or L
ocal Blood Perfu-sion in
1lcatcd Ti5sues1 Author: ■, ^rki
n others (d) IE! ! PROCREDING, Vol.
132. t't, l(, No, 60CTOBER198
5P360~P368rField and powe
r-density calculation in c
lost +microwave systems
by three-dimensional fini
te differences JAuthor: M, De
Pourcq+C, Eng.

has been disclosed.

The temperature distribution of the heating cross section as described above is simulated, for example, at intervals of a certain period of time (for example, about 1 degree) after the start of heating. Is the operator a CI? Based on the simulation results displayed on T9, it is determined whether an abnormal spot has occurred. If no abnormal spot occurs in the temperature distribution of the simulated heating cross section, the power of the applicator 3 is turned on (step S4), and the above-mentioned judgment is automatically made by the computer 12. It is also possible to do so.

If an abnormal spot occurs, readjust the position of the applicator 3, simulate the temperature distribution again, make sure that no abnormal spot occurs, and then turn on the power to the applicator 3. .

When the applicator 3 is powered on, step S
Proceed to step 5, turn on the power, and wait for a predetermined time T (
For example, it is determined whether or not the period of time (for example, about 1 degree) has passed. Such time control is performed by the time control device 10 shown in FIG.
carried out by

When the set time T has elapsed, the process advances to step S6.

Based on the signal from the time control device 10, the computer 12 takes in temperature detection signals at desired positions on the heating cross section from the multipoint temperature sensor 5. Then, the difference Δt between the actually measured temperature of the heated cross section and the previously simulated temperature distribution is calculated, and it is determined whether this temperature difference Δt is within a predetermined temperature range δ (step S7).

If the temperature difference Δt is not within the temperature range δ, the process proceeds to step S8 and the temperature parameter is corrected. Generally, among the various temperature parameters, the parameter that most affects the temperature distribution of the heated cross section is the blood flow rate that provides a cooling drop to the heated cross section. Moreover, blood flow has large individual differences compared to other temperature parameters, and also changes in a complicated manner depending on the temperature of the heating section, so it is difficult to determine it uniquely like other temperature parameters. This is because it is impossible.

In other words, because there is an error in the blood flow rate value set in step S1, an error often occurs between the actual measurement result of the heated cross section and the simulation.

Therefore, in this embodiment, the blood flow rate is corrected as follows.

First, cut off the power to the applicator 3, and
Take a T image and then continue for a certain period of time (for example, about 15 seconds)
After this period, a CT image of the heated cross section is taken again.

When the power to the applicator 3 is turned off, the temperature of the heated cross section drops mainly due to the cooling effect of blood flow, and the CT value of the heated cross section changes accordingly. Therefore, it is possible to know the amount of change in the CT value of the heated cross section from the two taken CT images. Since the temperature coefficient of the CT value is known, the temperature drop at each point on the heating cross section is calculated from the amount of change in the CT value and the temperature coefficient of the CT value.

Once the temperature drop at each point on the heating cross section is calculated, the blood flow F at each point on the heating cross section is calculated using the following equation (2) obtained from the so-called biothermal conduction equation.

Here, K is a constant given by the following equation (2).

K"ρIC4/ρC...■ ρ, : Blood density c, : Specific heat of blood ρ : Tissue density C: Specific heat of tissue fibers δ, is the time interval for taking two CT images, θ , -θ is 1. The temperature drop of the heated section obtained from the two CT images mentioned above, θ is the temperature increase when the -th CT image is taken, given by the following formula 〇?K'tL degrees It is.

θ5−Ts To ・・・・・・■Above formula■
Here, T is the temperature of the heated cross section immediately before the power to the applicator 3 is cut off, and this temperature is calculated from the detection signal of the multipoint temperature sensor 5 and the CT value of each point in the first CT image. Ru. T
o is the temperature of the heated section before heating (for example, 37.0°C
).

When the blood flow rate at each point on the heating cross section is calculated, the blood flow rate previously set as a temperature parameter is corrected, and step S3
Return to In step S3, using the corrected blood flow,
The temperature distribution is simulated again to determine how much power should be supplied to the applicator 3 in order to bring the tumor region to the target temperature. Hereinafter, the processes from step S4 to step 8, that is, heating → determination of temperature error, correction of temperature parameters → recalculation of temperature distribution, are repeatedly executed until it is determined that the end of the thermal treatment is completed (step S9). By doing so, the temperature of the affected area (1!1 m area) is accurately focused to the target temperature.

By storing conditions such as the temperature parameters and the power of the applicator 3 obtained through each of the above-mentioned processes in the database 11, when performing thermal treatment on the same patient next time, etc., the conditions are stored in the database 11. By using the data obtained, thermotherapy can be performed more quickly and accurately.

Although the blood flow rate as a temperature parameter is corrected in step S8 above, if the difference between the measured temperature and the simulated temperature is extremely large, the previously set values such as conductivity σ and dielectric constant It is also possible that this is extremely inappropriate. In such a case, the dielectric properties of the heated cross section are also calculated backward based on the temperature drop of the heated cross section detected in step S8, and the temperature parameters such as the conductivity σ and the dielectric constant are corrected accordingly. The SAR distribution may be corrected, and the temperature distribution may be recalculated based on the corrected SAR distribution.

In addition, in the examples, an X-ray tomography device was used to set the temperature parameters of the heated cross section and measure the blood flow, but this can be applied to, for example, a high-resolution tomography device such as a nuclear magnetic resonance tomography device (MRI). A similar effect can be obtained by using a non-invasive temperature measurement device such as a microwave tomography device.

Effects of the G2 Invention As is clear from the above explanation, the hyperthermia treatment device according to the invention corrects the temperature parameters necessary for simulating the temperature distribution of the heating cross section sequentially during heating. Therefore, highly accurate temperature distribution simulation results can be obtained. Therefore, since appropriate energy can be irradiated to the heated cross section based on the simulated temperature distribution, the affected area can be accurately heated to the target temperature, and the effectiveness of thermotherapy can be increased.

Further, according to this invention, addition/! ! Since abnormal spots are less likely to occur in the cross section, pain to the patient is also reduced.

Further, according to the present invention, optimal heating conditions can be quickly determined, so that the processing efficiency of thermotherapy can be improved.

[Brief explanation of the drawing]

1 to 3 are explanatory diagrams of a hyperthermia treatment device according to an embodiment of the present invention, in which FIG. 1 is a schematic block diagram, FIG. 2 is an operation flowchart, and FIG. 3 is a table of temperature parameters. be. 1...Bed 2...Top plate 3...Applicator 4...Porous 5...Multi-point temperature sensor
6... X-ray tomography device 7... Mouse 8
...Keyboard 9...CRT 10...
・Time control device 11...database 12...
Computer patent applicant: Shimadzu Corporation Figure 1 Figure 3

Claims (1)

[Claims] (1) Storage means for storing temperature parameters distributed in the heating cross section in an updatable state, and temperature distribution of the heating cross section at predetermined time intervals based on the temperature parameters of the heating cross section stored in the storage means. heating means for irradiating the heated cross section with energy according to the simulated temperature distribution; temperature measuring means for measuring the temperature at a desired location on the heated cross section; temperature monitoring means for comparing the simulated temperature distribution and the measured temperature at predetermined time intervals; A hyperthermia treatment device characterized by comprising: means for measuring a temperature parameter of and correcting the stored temperature parameter.