TWI446945B - Charged particle dose simulator, charged particle beam irradiation device, simulation method of charged particle dose and charged particle beam irradiation method - Google Patents

Description

Charged particle dose simulation device, charged particle beam irradiation device, charged particle dose simulation method and charged particle beam irradiation method

The present invention relates to a charged particle dose simulation device, a charged particle beam irradiation device, a charged particle dose simulation method for simulating a dose distribution of a charged particle beam in an irradiated body when a charged particle beam such as a proton beam is irradiated onto an object to be irradiated Charged particle beam irradiation method.

A proton beam therapy device that irradiates a charged particle beam such as a proton beam to treat a tumor is known. In the treatment of such a tumor, it is necessary to formulate an irradiation plan such as an absolute dose, a dose distribution, an irradiation position, etc. according to the shape or position of the tumor, and irradiate the charged particle beam with high precision in accordance with the irradiation plan. When the irradiation plan is prepared, the irradiation condition of the proton beam or the like is input to a simulation device mounted on the proton beam therapy device or the like to calculate the dose distribution in advance, and based on the dose distribution, whether or not the proton beam is accurately irradiated onto the tumor is simulated. . As a method of calculating the dose distribution, for example, a method called Monte Carlo Simulation or a Pencil Beam Algorithm (PBA) is known (see Non-Patent Documents 1 to 4).

Non-Patent Document 1: Harald Paganetti, Hongyu Jiang, Katia Parodi, Roelf Slopsema and Martijn Engelsman, IOP Publishing, Physics in Medicine and Biology, 53 (2008) 4825-4853.

Non-Patent Document 2: Department of Radiation Oncology, Massachusetts General Hospital & Harvard Medical School, Boston, MA 02114, USA, IOP Publishing, Physics in Medicine and Biology, 54 (2009) 4399-4421.

Non-Patent Document 3: Nobuyuki Kanematsu, Masataka Komori, Shunsuke Yonail and Azusa Ishizaki, IOP Publishing, Physics in Medicine and Biology, 54 (2009) 2015-2027.

Non-Patent Document 4: Linda Hongyz, Michael Goiteiny, Marta Bucciolinix, Robert Comiskeyy, Bernard Gottschalkk, Skip Rosenthaly, Chris Seragoy and Marcia Urie, Phys. Med. Biol. 41 (1996) 1305-1330.

However, in the Monte Carlo Simulation described above, since the dose distribution is calculated by the statistical processing, the accuracy is high, but the burden of the arithmetic processing is large, and it may take several days to have a problem such as lack of practicality. On the other hand, the accuracy in PBA is always easier than Monte Carlo Simulation, and it is difficult to ensure the desired accuracy.

The present invention has an object of solving the above problems, and an object of the invention is to provide a charged particle dose simulation device, a charged particle beam irradiation device, and a charged device capable of reducing the dose of a charged particle beam in advance while reducing the accuracy of the calculation process. Particle dose simulation method and charged particle beam irradiation method.

In the simulation device of the present invention, it is assumed that the charged particle beam is irradiated onto the object to be irradiated, the charged particle beam is assumed to have a virtual shape having a conical expansion, and the dose distribution core for calculating the spread of the charged particle beam in the irradiated body is simulated. a dose distribution of the charged particle beam in the irradiated body, characterized by comprising: an input means for receiving input of the analog information including the substance information of the irradiated body and the irradiation information of the charged particle beam; and an arithmetic mechanism receiving the signal according to the input means The simulation data and the dose distribution kernel calculate the dose distribution of the charged particle beam in the irradiated body, wherein the operation mechanism operates to refine the charged particle beam extending to a predetermined range in the middle of the charged particle beam, and assume The refinement position is a plurality of virtual shapes having a taper expansion at the starting point, and the dose distribution of the charged particle beam in the irradiated body is calculated based on the simulation data received by the input mechanism and the plurality of virtual shapes of the charged particle beam.

When the irradiated body is composed of only a certain substance, the conventional PBA can be expected to have high accuracy. However, the actual irradiated body is composed of various substances intricately, and thus it is difficult to calculate with high precision in the conventional PBA. The dose distribution of the charged particle beam. However, according to the present invention, a tapered virtual shape assumed to be a charged particle beam is appropriately refined to assume a plurality of virtual shapes, so that it is possible to calculate a charged particle beam while corresponding to each of the reduced virtual shapes and the intricate structure. The dose distribution is effective in improving the accuracy of the dose distribution. Further, in the present invention, the dose distribution of the charged particle beam is obtained on the basis of assuming a charged virtual particle shape as a tapered virtual shape, and thus is more mitigable than Monte Carlo Simulation which derives a dose distribution by a statistical operation process. The burden of arithmetic processing. As a result, it is possible to reduce the accuracy and reduce the burden of the arithmetic processing to calculate the dose distribution in advance.

Further, it is preferable that the position of the charged particle beam is refined so that the charged particle beam is immediately before entering the object to be irradiated. Since the charged particle beam can be refined into a plurality of virtual shapes immediately before entering the inside of the object to be irradiated, it is possible to further improve the accuracy in calculating the dose distribution of the charged particle beam.

Further, it is preferable to further include an output means for notifying the dose distribution calculated by the arithmetic means. By notifying the operator of the text information, image information, or audio information recognizable by the operator, the operator can easily grasp the dose distribution of the charged particle dose as a result of the simulation.

In addition, it is preferred that the output mechanism performs an equal dose linearization or an equal dose surface for the dose distribution. The dose can be easily grasped by performing isotope lined or isodose surface notification.

Further, the charged particle beam irradiation apparatus of the present invention is characterized in that the simulation apparatus is provided. According to the present invention, the charged particle beam can be irradiated according to the dose distribution of the charged particle beam calculated in advance by the above-described simulation device.

Further, in the simulation method of the present invention, a case where a charged particle beam is irradiated onto an object to be irradiated is assumed, a charged particle beam is assumed to have a virtual shape having a conical expansion, and an extended dose distribution core for deriving a charged particle beam in the irradiated body is utilized. Simulating a dose distribution of the charged particle beam in the irradiated body, characterized by comprising: an information acquisition program of the irradiated body, acquiring material information of the irradiated body; an illumination information setting program for determining irradiation information of the charged particle beam; and a simulation program According to the illumination information and the dose distribution core determined in the illumination information setting program, the charged particle beam extended to a predetermined range is refined in the middle of the forward direction before the charged particle beam, and the tapered extension is assumed starting from the refined position The plurality of virtual shapes are calculated based on the substance information acquired in the irradiated body information acquisition program and the plurality of virtual shapes of the charged particle beam, and the dose distribution of the charged particle beam in the irradiated body is calculated. According to the present invention, the dose distribution of the charged particle beam can be calculated in advance while reducing the accuracy and reducing the burden of the arithmetic processing.

Further, the charged particle beam irradiation method of the present invention is characterized in that the charged particle beam is irradiated based on the dose distribution of the charged particle beam calculated by the above-described simulation method. According to the present invention, the charged particle beam can be irradiated according to the dose distribution of the charged particle beam calculated in advance by the above-described simulation method.

According to the present invention, it is possible to reduce the accuracy and reduce the burden of the arithmetic processing to calculate the dose distribution in advance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

When a proton beam (charged particle beam) is irradiated to treat a tumor (cancer lesion), an irradiation plan such as an absolute dose, a dose distribution, and an irradiation position is prepared according to the shape or position of the tumor, and the proton beam is irradiated according to the irradiation plan. As shown in Fig. 1, the proton beam therapy device (charged particle beam irradiation device) 1 includes an imaging device (charged particle dose simulation device) 3 for preparing an irradiation plan, and an irradiation device 5, which is based on the simulation result. The patient X or the like is irradiated with the proton beam B by the irradiated body X.

The irradiation device 5 includes an irradiation unit 51 that irradiates the irradiated body X with the proton beam B, a collimator 52 that adjusts the irradiation range of the proton beam B, and a filler that adjusts the arrival distance of the proton beam B in accordance with the shape of the cancer lesion. (bolus) 53 and so on. The material of the filler 53 is polyethylene or the like. The actual irradiation based on the irradiation device 5 is performed by an input operation of the operator to the irradiation device 5.

In addition, as shown in Fig. 2, in the case of a photon beam, immediately after entering the patient's skin (body surface Xa) (before reaching the cancer lesion), the peak of the damage to the cell (the most therapeutic effect) is ushered in. And gradually decline. On the other hand, in the case of a heavy charged particle such as a proton beam, a very large portion called a Bragg Peak appears at a predetermined depth. Therefore, the shape of the filler 53 through which the proton beam B passes is appropriately adjusted to adjust the depth at which the Bragg Peak appears, thereby suppressing damage to normal tissues and increasing damage to tumor tissues (cancer lesions). .

The simulation device 3 (see FIG. 1) includes a central processing unit having a CPU, a RAM, a ROM, and the like as a hardware, and includes an input unit (input unit) 31, a calculation unit (calculation unit) 33, and an output unit ( The output mechanism 35 is a functional configuration.

The input unit 31 is an operation device such as a touch panel, a keyboard, or a mouse, and receives input of data according to an operation of the operator. Further, the input unit 31 receives, for example, image data including a cancer lesion, data related to an irradiation area, and irradiation parameter data, which are captured by a CT (Computed Tomography) for treatment. The irradiation parameter data is, for example, information such as the irradiation direction and the angle of the patient's bed. In the present embodiment, the image data (the CT image data for treatment) acquired by the therapeutic CT corresponds to the substance information of the irradiated body X, and the data relating to the irradiation region and the irradiation parameter data correspond to the irradiation information of the charged particle beam. Hereinafter, these are collectively referred to as analog data.

The calculation unit 33 has a function of assuming that the proton beam B is irradiated onto the object X to be irradiated, and that the proton beam B is assumed to have a virtual shape having a conical shape (sharp directional beam shape), and the inside of the irradiated body X is derived. The extended dose distribution kernel of the proton beam B simulates the dose distribution of the proton beam B in the interior of the irradiated body X. Here, the conventional method of calculating the dose distribution is, for example, the Pencil-beam method (PBA method), but in the present embodiment, the dose distribution calculation is performed by the Delta-function Multi Segmented PBA method (DMS-PBA method) which further evolves the PBA method. . Hereinafter, the DMS-PBA method will be described in detail after briefly describing the PBA method.

The PBA method is a method in which the proton beam B is regarded as a sharp directional beam shape, and calculation is performed using a spread dose distribution nucleus based on multi-coulomb scattering in consideration of the proton beam B in the substance. Specifically, as shown in FIG. 3, the dose distribution from the deep direction of the irradiation point is obtained by actual measurement, and the proton is derived by considering the extension of the beam obtained by a predetermined calculation (Gaussian-based approximation). The dose distribution in the predetermined location of the beam B in the forward direction. For example, the extension at the point Z ₁ is obtained as the extension σ ₁ by the Gaussian-based approximation, and the extension at the point Z ₂ is obtained as the extension σ ₂ by the Gaussian-based approximation.

According to the conventional PBA method, it is advantageous to derive the dose distribution of the proton beam B within a calculation time of several minutes, but it is also conceivable that there is a heterogeneous substance (for example, a patient's skeleton or the like) in the irradiation range. As a result, the accuracy of the calculation is reduced, so there is room for improvement.

The DMS-PBA method is an advantage of effectively utilizing the advantages of the PBA method, that is, shortening the calculation time, and at the same time, it is possible to improve the accuracy. There are at least two characteristic items of the DMS-PBA method. The first is based on the Surface Map analysis in the body surface Xa of the irradiated body (patient, etc.) X, and the dose distribution calculation considering the scattering from the filler 53 is performed. It is based on a high-resolution dose distribution calculation of the small beam Ba emitted from the body surface Xa as a starting point.

These features of the DMS-PBA method are generally described with reference to Figs. 4 and 5. Fig. 4 is an explanatory view showing the concept of the DMS-PBA method, and Fig. 5 is an explanatory view showing the refinement of the beam in the DMS-PBA method. As shown in Fig. 4, the proton beam (beam) B input to the filler 53 or the like is propagated while being extended by the side multiple Coulomb scattering to reach the body surface Xa. Here, the lateral emittance of the beam B up to the body surface Xa is calculated. This calculation is the same as the previous PBA.

Next, a Surface Map in the body surface Xa is produced. The Surface Map refers to a map of the intensity (component) of the calculated beam B, the remaining track, and the number of beams B of different residual tracks in each of the calculation grids in the body surface Xa. For example, when the filler 53 is assumed to be a block of a cross-sectional L-shape, the beam B passing through the thicker portion is in the body surface Xa as compared with the remaining track in the body surface Xa by the beam B of the thinner portion. The remaining track becomes smaller. Further, in the region where the beam B passing through the thick portion and the beam B passing through the thin portion overlap each other in the body surface Xa, the dose (strength) becomes larger than that in the non-overlapping region. Consider the Surface Map in the surface Xa of these elements. The above is based on the analysis of the dose distribution of the scattering from the filler 53 based on the Surface Map analysis in the body surface Xa of the irradiated body X, which is the first feature of the DMS-PBA method. In addition, the remaining track refers to the range corresponding to the kinetic energy of the proton beam.

Next, the Surface Map is refined, and the initial conditions of a plurality of proton beams (hereinafter referred to as "small beams") Ba that are virtually irradiated are calculated from the refined elements (hereinafter referred to as "voxels"). For example, the dose of the small beam Ba is obtained by dividing the dose distribution of the incident to the body surface Xa into a δ function shape (refer to Fig. 5(a)). Also, the size of the beamlet Ba in the voxel is assumed to be an extremely small size.

Next, a dose distribution calculation based on the small beam Ba irradiated from the body surface Xa into the body is performed. The dose distribution calculation based on the beamlet Ba is generally described with reference to FIG. Fig. 5(a) shows a side profile of the dose in the body surface Xa. As shown in Fig. 5(a), the dose of the small beam Ba is determined based on the division of the above dose distribution. If it is assumed that the small beam (segment) Ba is irradiated into the body, each segment expands as it progresses further (refer to Fig. 5(b)). Moreover, the dose distribution at any depth in the body is derived based on the overlap of the segments (see Fig. 5(c)). Figure 5 (c) shows the side profile of the dose in the body.

By integrating all of the small beams Ba, the dose distribution in the body can be calculated. The above is based on the high-resolution dose distribution calculation of the small beam Ba emitted from the body surface Xa as a starting point, which is the second feature of the DMS-PBA method. In addition, the beam size is specifically calculated based on the following formula (1) and based on the DMS-PBA method.

[Number 1]

(Formula 1)

σ _init : initial beam size

σ _dms : beam size based on DMS-PBA

d: depth based on the body surface

t: filler thickness

g: air-gap from the filler to the body surface

σ _θ : based on the scattering angle of the filler

σ _pt : scattered light in the irradiated body (patient body)

Next, the differences between the PBA method and the DMS-PBA method will be described with reference to FIGS. 6 and 7. Fig. 6(a) is an explanatory view schematically showing PBA, and Fig. 6(b) is an explanatory view schematically showing DMS-PBA. As shown in Fig. 6, in the PBA method, the beam B reaching the body surface Xa is an initial condition for the beam B directly irradiated into the body. That is, in the PBA method, it is assumed that the beam B which reaches the body surface Xa by the filler 53 with the beam sizes σ ₁ , σ ₂ and the remaining tracks R ₁ , R ₂ is irradiated into the body under the original conditions. On the other hand, in the DMS-PBA method, it is assumed that the beam B input to the body surface Xa with the beam sizes σ ₁ , σ ₂ and the remaining tracks R ₁ , R ₂ is refined in the body surface Xa, thereby The beam size σ ₀ is refined into a plurality of small beams Ba which are extremely smaller than σ ₁ and σ ₂ , and each of the small beams Ba is irradiated into the body.

Fig. 7 is a view showing a case where the model B of the irradiated body X in which the bone equivalent substance is disposed in the water equivalent substance is irradiated, and the dose distribution is calculated by the DMS-PBA method and the PBA method, and (a) is The difference between the two is shown by isodose linearization, (b) is the lateral profile of both at a depth of 0 mm, and (c) is the lateral profile of both at a depth of 115 mm.

As shown in Fig. 7(b), when the depth d is "0 mm", that is, the size and dose of the beam B in the body surface Xa are the same. On the other hand, as shown in Fig. 7(c), when the depth d is "115 mm", the dose distribution obtained by the PBA method differs greatly from the dose distribution obtained by the DMS-PBA method. This difference is caused by the fact that the dose distribution is calculated without considering the presence of the bone equivalent substance in the PBA method, and the dose distribution is calculated in consideration of the presence of the bone equivalent substance in the DMS-PBA method.

The output unit 35 is an output device such as a monitor or a speaker, and outputs (notifies) the simulation result in the calculation unit to an image recognizable by an operator or the like, or outputs (notifies) the audio data. That is, the output unit 35 receives the dose distribution data according to the calculation result in the DMS-PBA method from the arithmetic unit 33, and synthesizes the isodized or equal dose surface based on the received dose distribution data, for example, on the treatment CT image. The dose distribution image is generated to generate (notification) an identifiable image data (image information) such as an operator.

Here, the image data displayed from the output unit 35 will be specifically described with reference to FIGS. 8 and 9. Figs. 8 and 9 show an example of an image in which the dose distribution is dosed, and the output unit 35 displays an image as shown in Fig. 8(b) or Fig. 9(b), for example. 8(a) and 9(a) are images showing the dose distribution derived from the PBA method, and FIGS. 8(b) and 9(b) are diagrams derived from the DMS-PBA method. Image of dose distribution.

From the above, it can be inferred that when the dose distribution image obtained by the PBA method (Fig. 8(a)) is compared with the dose distribution image obtained by the DMS-PBA method (Fig. 8(b)), Compared with the dose distribution image obtained by the method, the dose distribution image obtained by the DMS-PBA method has an intricate shape of equal-volume curves, and the dose distribution is calculated with high accuracy corresponding to the heterogeneous substance. Similarly, as shown in Fig. 9, it can be inferred that the dose distribution image obtained by the DMS-PBA method is compared with the dose distribution image obtained by the PBA method (Fig. 9(a)) (9th Figure (b)) shows the intricate shape of each equal curve, and the dose distribution is calculated with high accuracy for the heterogeneous substance.

Next, the actual proton beam treatment method will be briefly described. The dose distribution simulation method and the proton beam irradiation method (charged particle beam irradiation method) performed therein will be described with reference to Figs. 10 and 11. Fig. 10 is a flow chart showing a brief sequence of proton beam therapy, and is a flow chart showing the operation sequence of the dose distribution simulation.

As shown in Fig. 10, the diagnosis is first performed by an operator such as a doctor (step S1), and then the image of the vicinity of the cancer lesion is acquired by the CT for treatment (step S2). Next, the determination of the irradiation area (step S3) and the determination of the irradiation parameter (step S4) are performed. The program for acquiring the CT image for treatment in step S2 corresponds to the subject X acquisition program for acquiring the substance information of the object X to be irradiated, and the determination of the irradiation region and the determination of the irradiation parameter in steps S3 and S4 are performed. The program is equivalent to an illumination information setting program that determines the irradiation information of the charged particle beam.

Next, the processing related to the dose distribution simulation is executed in the simulation device 3 (step S5), and the dose distribution image as a simulation result is displayed (notified) from the output portion 35. Step S5 is equivalent to a simulation program.

The operator confirms the dose distribution image displayed on the output unit 35. For example, the operator performs a determination as to whether or not the Bragg peak of the proton beam B accurately reaches the target region (cancer lesion) and whether it has not reached the target region (determination of the simulation result). Here, if the operator determines that the Bragg peak of the proton beam B does not accurately reach the cancer lesion, the process returns to step S4. The operator repeatedly performs the determination of the irradiation parameter (step S4) and the dose distribution simulation (step S5) until it is determined that the Bragg peak of the proton beam B accurately reaches the cancer lesion, and when it is determined that the cancer lesion is accurately reached, the irradiation device is operated 5, the actual proton beam irradiation is performed (step S7). Step S7 corresponds to a proton beam irradiation method (charged particle beam irradiation method) that irradiates the proton beam B.

Next, the dose distribution simulation performed by the simulation device 3 will be described. The dose distribution is simulated as a method in which the proton beam B is irradiated onto the irradiated body X, the proton beam B is assumed to have a virtual shape having a sharp directional beam shape (tapered) expansion, and the irradiated body X is derived. The extended dose distribution kernel of the inner proton beam B simulates the dose distribution of the proton beam B within the irradiated body X, which is performed according to the DMS-PBA method which further evolves the above PBA method.

The simulation device 3 performs processing related to the dose distribution simulation by receiving the analog data. The input unit 31 of the simulation device 3 receives input of analog data including the CT image data for treatment, the irradiation region data, and the irradiation parameter data (step S11).

When the analog data is received by the input unit 31, the arithmetic unit 33 performs an operation of assuming that the proton beam B is irradiated onto the irradiated body X, and the proton beam is based on the irradiation region data and the irradiation parameter data (substance information) and the dose distribution kernel. B is assumed to be a beam (virtual shape) having a sharp directional beam shape (tapered) spread, and it is assumed that such a beam has been emitted (step S12).

Next, the calculation unit 33 calculates the lateral emittance of the beam up to the body surface Xa by using the dose distribution kernel that derives the spread of the beam in the irradiated body X. Further, the computing unit 33 assumes that the beam extended to the predetermined range reaches the body surface Xa halfway through the beam forward direction (body surface), and creates a Surface Map in the body surface Xa (step S13).

Next, in order to refine the beam on the body surface Xa, the arithmetic unit 33 refines the Surface Map in the body surface Xa to assume a majority of the voxels (step S14). Further, the arithmetic unit 33 assumes a plurality of small beams (virtual shapes) having a sharp directional beam shape (tapered) spread with a majority of voxels as a starting point, and assumes that the refined small beam has been emitted (step S15) . Moreover, the calculation unit 33 calculates the dose distribution of the proton beam B in the irradiated body X based on the CT image data for treatment and a plurality of small beams (step S16). The dose distribution simulation was completed by the above steps.

Next, the effects of the simulation device 3 and the dose distribution simulation method of the present embodiment will be described.

For example, when the irradiated body X is composed of only a certain substance, a high accuracy can be expected by the conventional PBA method. However, since the actual irradiated body X such as a patient is composed of various substances intricately, it is difficult to accurately calculate the dose distribution of the proton beam (charged particle beam) by the conventional PBA method. However, according to the simulation device 3 and the dose distribution simulation method of the present embodiment, since a virtual shape of a sharp directional beam shape (taper) assumed to be the proton beam B is appropriately refined, it is assumed that a plurality of small beams (virtual The shape) can therefore calculate the dose distribution of the proton beam B while corresponding to the intricate structure of the individual beamlets, which is effective for improving the accuracy of the dose distribution.

Further, in the simulation device 3 and the dose distribution simulation method of the present embodiment, the proton beam (charged particle beam) B is assumed to be a virtual shape of a sharp directional beam shape (taper), and the proton beam B is obtained. The dose distribution is therefore more burdensome than the Monte Carlo Simulation that derives the dose distribution by statistical processing. As a result, it is possible to reduce the accuracy and reduce the burden of the arithmetic processing to calculate the dose distribution in advance.

Further, in the present embodiment, since the position of the refining proton beam B is the position (body surface Xa) immediately before the proton beam B enters the object X to be irradiated, it is possible to correspond to the inside immediately before entering the inside of the object X to be irradiated. Since the proton beam B is thinned into a plurality of small beams (virtual shapes), it is expected to have high accuracy in calculating the dose distribution of the proton beam B.

Further, in the present embodiment, the output unit 35 that notifies the dose distribution calculated by the calculation unit 33 is provided, and the output unit 35 can be notified of character information, image information, audio information, and the like recognizable by the operator. Therefore, the operator can easily grasp the dose distribution of the proton beam B as a result of the simulation.

Further, the output unit 35 notifies the operator by outputting an image of the dose distribution that is isodally linearized or isodized, so that the operator can easily grasp the magnitude of the dose.

Next, the experimental results for confirming the superiority of the present embodiment will be described with reference to Figs. 12, 13 and 14. In addition, Fig. 12, Fig. 13, and Fig. 14 show the results of verification using experimental geometry, and each of the figures (a) schematically shows a front view of the proton beam B with respect to the irradiated body model, that is, the simulation model. Each figure (b) is a graph showing a dose distribution profile in the depth direction of the irradiated body X, and each graph (c) shows a graph of the side dose distribution profile at a predetermined depth.

In Experimental Example 1, Experimental Example 2, and Experimental Example 3, a verification experiment was performed using an experimental apparatus (see Fig. 12 (a), Fig. 13 (a), and Fig. 14 (a)), and the experimental apparatus was provided with a section L a glyph filler 61; a polystyrene simulation model 62 reproduces the boundary between air and soft tissue present in the paranasal cavity; a two-dimensional dosimeter (2D-ARRAY) 63 disposed under the simulation model 62; and protons The beam treatment uses a patient bed 64 to support the simulation model 62 and 2D-ARRAY. Further, in each of Experimental Examples 1, 2, and 3, it is assumed that the beam B passes through the simulation model 62, and the dose distribution profile is derived by the PBA method and the DMS-PBA method.

As shown in Fig. 12 (b), Fig. 13 (b), and Fig. 14 (b), in the simulation results (deep direction dose distribution profile) of Experimental Example 1, Experimental Example 2, and Experimental Example 3, For the dose at the Bragg peak, the dose derived by the DMS-PBA method is smaller than the dose derived by the PBA method. Further, Fig. 12(c) shows the side dose distribution profile at the Bragg peak depth (depth d of 123 mm) of Experimental Example 1, and the hot spot was observed in the value (Measured) actually measured by the above experimental apparatus 2D-ARRAY63. . Further, Fig. 13(c) shows the side dose distribution profile at the Bragg peak depth (depth d is 142 mm) in Experimental Example 2, and a cold spot was observed in the actual measurement value (Measured). Further, Fig. 14(c) shows the side dose distribution profile at the Bragg peak depth (depth d is 162 mm) in Experimental Example 3, and a hot spot was observed in the actual measurement value (Measured). In addition, the hot spot refers to the point of high dose, and the cold spot refers to the point of low dose.

Next, the contents estimated from the verification results of Experimental Example 1, Experimental Example 2, and Experimental Example 3 will be described.

(1) In each of Experimental Examples 1, 2, and 3, it can be considered that a hot spot or a cold spot appears at the depth of the Bragg peak due to the influence of the roundabout effect of the proton.

(2) As far as the PBA method is concerned, in the hot spots or cold spots of the Prague peaks, the accuracy reduction of up to about 12% occurs. It can be considered that this is caused by the side expansion of the sharp directional beam shape considering only the expansion along the central axis.

(3) In the case of the DMS-PBA method, the influence of the heterogeneous substance in the body can be considered by the division of the beam B in the body surface, and as a result, the geometric position of the simulation model 62 of about several mm is considered. Shift, it can be confirmed that the side dose distribution profile is consistent with 3% accuracy.

Further, the following verification results can be obtained from the results shown in Table 1.

IF: Irradiation Field (irradiation field area (mm ²⁾⁾

Volume: the total volume calculated by the beam (Litter)

Time: Time required for calculation (sec)

(1) The larger the irradiation field area is, the longer the calculation time (time for arithmetic processing) of the PBA method and the DMS-PBA method becomes longer.

(2) In the PBA method and the DMS-PBA method, as the ratio of the total volume calculated by the beam becomes smaller, the ratio with respect to the calculation time also becomes smaller.

(3) When the irradiation field area is 100 × 100 mm ² , the calculation time of the DMS-PBA method is shorter than the calculation time of the PBA method.

From the above verification results, it can be confirmed that the DMS-PBA method is more accurate in the dose distribution calculation result (simulation result) in the heterogeneous region in the simulation model 62 in the equal calculation time than the PBA method currently applied in the clinical practice. .

Further, although the initial verification using the simulation model was performed, it was confirmed that the DMS-PBA method was effectively utilized in the clinic.

Although the present invention has been described by taking the simulation device and the dose distribution simulation method of the embodiment as an example, the present invention is not limited to the above embodiment. For example, the form notified from the output unit 35 is not limited to a predetermined image data, and may be audio material or the like. Further, the simulation device is not limited to being disposed in the proton beam therapy device, and may be provided separately from the proton beam therapy device.

3. . . Analog device

31. . . Input unit (input mechanism)

33. . . Computing unit (computing mechanism)

35. . . Output unit (output mechanism)

B. . . Proton beam, beam (charged particle beam)

X. . . Irradiated body

Fig. 1 is an explanatory view of a proton beam therapy apparatus equipped with a simulation device according to an embodiment of the present invention.

Fig. 2 is an explanatory diagram showing the effect of proton beam treatment by a graph.

Fig. 3 is an explanatory diagram showing the dose distribution calculation algorithm schematically.

Fig. 4 is an explanatory diagram showing the concept of the DMS-PBA method.

Fig. 5 is an explanatory view of the refinement of the beamlets in the DMS-PBA method.

Fig. 6 is a view schematically showing a difference from the conventional PBA method in the DMS-PBA method, wherein (a) is an explanatory view schematically showing PBA, and (b) is an explanatory view schematically showing DMS-PBA.

Fig. 7 is a view showing the difference in dose distribution between the DMS-PBA method and the conventional PBA method, (a) is a graph showing the difference between the two, and (b) is a view showing the depth at 0 mm. A graph of the dose distribution, (c) is a graph showing the dose distribution at a depth of 115 mm.

Fig. 8 is a view showing a comparison of dose distributions using a clinical image (sagittal section), and (a) is an example of an image represented by isodose linearization of a dose distribution obtained by the PBA method, ( b) is an example of an image represented by isodizing the dose distribution obtained by the DMS-PBA method.

Fig. 9 is a view showing a comparison of dose distributions by a clinical image (axial cross section), and (a) is an example of an image in which dose distribution obtained by the PBA method is equally dosed. (b) is an example of an image represented by isodose linearization of the dose distribution obtained by the DMS-PBA method.

Figure 10 is a flow chart showing a brief sequence of proton beam therapy.

Figure 11 is a flow chart showing the sequence of actions of the dose distribution simulation.

Fig. 12 is a graph showing the results of the simulation of Experimental Example 1.

Fig. 13 is a graph showing the results of the simulation of Experimental Example 2.

Fig. 14 is a graph showing the simulation results of Experimental Example 3.

1. . . Proton beam therapy device

3. . . Analog device

31. . . Input section

33. . . Computing department

35. . . Output department

51. . . Irradiation department

52. . . Collimator

53. . . Filler

5. . . Irradiation device

X. . . Irradiated body

B. . . Proton beam

Xa. . . Body surface

Claims (7)

A charged particle dose simulation device envisions a case where a charged particle beam is irradiated onto an object to be irradiated, and the charged particle beam is assumed to have a virtual shape having a conical expansion, and an extended dose of the aforementioned charged particle beam in the irradiated body is derived. a distribution nucleus simulating a dose distribution of the charged particle beam in the irradiated body; characterized in that: an input mechanism is configured to receive input of the simulation information including the substance information of the irradiated body and the irradiation information of the charged particle beam; and an arithmetic mechanism Calculating a dose distribution of the charged particle beam in the irradiated body according to the analog data received by the input means and the dose distribution core; wherein the computing mechanism operates as follows: refining the direction before the charged particle beam Extending a plurality of the aforementioned charged particle beams of a predetermined range, and assuming a plurality of virtual shapes having a conical expansion starting from the refinement position, and according to the aforementioned simulation data received by the input mechanism and a plurality of the charged particle beams Virtual shape, calculate the aforementioned irradiated body The dose distribution of the charged particle beam. The charged particle dose simulating device according to claim 1, wherein the position of the charged particle beam is refined to a position immediately before the charged particle beam enters the object to be irradiated. The charged particle dose simulation device according to claim 1 or 2, further comprising an output mechanism, wherein the output mechanism is notified by the foregoing The aforementioned dose distribution calculated by the calculation mechanism. The charged particle dose simulating device according to claim 3, wherein the output mechanism performs the same dose linearization or isodized surface to notify the dose distribution. A charged particle beam irradiation device comprising the charged particle dose simulation device according to any one of the first to fourth aspects of the invention. A charged particle dose simulation method, in which a charged particle beam is irradiated onto an object to be irradiated, the charged particle beam is assumed to have a virtual shape having a conical expansion, and an extended dose of the aforementioned charged particle beam in the irradiated body is derived. Distributing a core, simulating a dose distribution of the charged particle beam in the irradiated body, wherein the method includes: acquiring an information of the irradiated body information, acquiring material information of the irradiated body; and determining an irradiation of the charged particle beam by an irradiation information setting program And the simulation program, according to the irradiation information and the dose distribution core determined in the irradiation information setting program, refining a plurality of the charged particle beams extending to a predetermined range in advance of the charged particle beam, and It is assumed that a plurality of virtual shapes having a conical expansion are taken as a starting point, and the irradiated body is calculated based on the substance information acquired in the irradiated body information acquiring program and a plurality of virtual shapes of the charged particle beam. The dose distribution of the charged particle beam. A charged particle beam irradiation method characterized in that the charged particle beam is irradiated according to a dose distribution of the charged particle beam calculated by the charged particle dose simulation method according to claim 6 of the patent application.