JP7061741B2 - Particle beam monitoring device, particle beam monitoring method, particle beam monitoring program - Google Patents

Description

The present invention relates to a particle beam monitoring device, a particle beam monitoring method, and a particle beam monitoring program.

In recent years, in the most advanced radiation cancer treatment, "particle beam therapy" has been used, which dramatically reduces the normal tissue dose while irradiating the affected area with a large dose. The particle beam has excellent straightness, and by using the Bragg peak, it is possible to intensively apply a dose to the affected area. As an accelerator or beam technique for irradiating a lesion site with a precise pinpoint particle beam, a pencil beam forming technique or a microbeam forming technique in which a beam is finely focused has already been developed.

Japanese Unexamined Patent Publication No. 2012-170655

However, with the current particle beam monitoring technology, it is not possible to monitor the depth of particle beam reaching the body in real time, which makes it difficult to establish and improve the treatment technique. In addition, it is difficult to measure the dose distribution to the lesion site during irradiation in real time, and treatment is performed based on the treatment plan and the measurement data accumulated experimentally and clinically.

Therefore, if real-time monitoring technology for dose distribution can be realized, it will be possible to treat while confirming and demonstrating that the particle beam is reliably irradiated to the lesion site, which is extremely medically significant from the viewpoint of ensuring reliability. have.

As one of the methods for monitoring the dose distribution, a method of measuring secondary particles generated during particle beam irradiation has been proposed. When a particle beam (primary particle) is incident on a substance (for example, a living body), various particle beams and photon beams (secondary particles) are generated by a nuclear reaction or an electromagnetic interaction. By measuring these secondary particles, the range and dose distribution of the original primary particles are to be measured.

However, secondary particles also interact with surrounding substances in the living body. Therefore, it is difficult to measure the accurate range and dose distribution without knowing the substance distribution information in the living body until it reaches the detector. In order to obtain this substance distribution information in the living body, conventionally, it has been required to prepare and use an X-ray tomography device or the like separately from the particle beam therapy device and the secondary particle measurement device. However, the use of X-ray tomography equipment involves exposure to X-rays. In addition, X-ray tomography is difficult to perform during treatment and is usually performed before or after treatment. Therefore, it was difficult to obtain the substance distribution information during the irradiation of the treatment beam.

An object of the present invention is to provide a method for obtaining substance distribution information in a living body based on the energy distribution of secondary particles.

In order to solve the above problems, the following means will be adopted.
That is, the first aspect is
A detector that detects energy spectral information of secondary particles affected by particle beams incident on the irradiated object, and a detector.
A calculation unit that calculates information on the behavior of particle beams and the behavior of secondary particles in the irradiated object from the energy spectrum information of the secondary particles detected by the detection unit.
It is a particle beam monitoring device equipped with.
Aspects of disclosure may be realized by the program being executed by an information processing device. That is, the configuration of the disclosure can be specified as a program for causing the information processing apparatus to execute the process executed by each means in the above-described embodiment, or as a computer-readable recording medium on which the program is recorded. Further, the configuration of the disclosure may be specified by a method in which the information processing apparatus executes the processing executed by each of the above-mentioned means. The configuration of the disclosure may be specified as a system including an information processing apparatus that performs processing executed by each of the above-mentioned means.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a method for obtaining substance distribution information in a living body based on the energy distribution of secondary particles.

FIG. 1 shows the energy dependence of the amount of secondary particles generated when the primary particles are irradiated on the irradiated object and the amount of detected secondary particles that pass through the irradiated object and reach the detector. It is a figure which shows the example of sex. FIG. 2 is a diagram showing a configuration example of the particle beam monitoring device according to the embodiment. FIG. 3 is a diagram showing a configuration example of the detection unit 11. FIG. 4 is a diagram showing an example 1 of a measurement method in which the detection unit 11 detects the energy spectrum of the secondary particles according to the positional relationship of the irradiated body 2. FIG. 5 is a diagram showing Example 2 of a measurement method in which the detection unit 11 detects the energy spectrum of the secondary particles according to the positional relationship of the irradiated body 2. FIG. 6 is a diagram illustrating energy spectrum detection of secondary particles of the embodiment. FIG. 7 is a graph showing the relationship between R1 and R2 for a plurality of lateral widths w. FIG. 8 is a graph showing the relationship between R1 and R2 with respect to a plurality of axial depths d. FIG. 9 is a graph obtained by extracting a graph having a lateral width of 1 cm from the graph of the relationship between R1 and R2 in FIG. FIG. 10 is a graph showing the relationship between the axial depth and R2 in the same data as in FIG. FIG. 11 is a graph showing the relationship between R1 and R2 for a plurality of lateral widths w. FIG. 12 is a graph showing the relationship between R1 and R2 with respect to a plurality of axial depths d. FIG. 13 is a graph obtained by extracting a graph having a lateral width of 1 cm from the graph of the relationship between R1 and R2 in FIG. FIG. 14 is a graph showing the relationship between the axial depth and R2 in the same data as in FIG. FIG. 15 is a diagram showing an example of an operation flow for calculating the axial depth d and the lateral width w in the irradiated body.

Hereinafter, embodiments will be described with reference to the drawings. The configuration of the embodiment is an example, and the configuration of the invention is not limited to the specific configuration of the disclosed embodiment. In carrying out the invention, a specific configuration according to the embodiment may be appropriately adopted.

[Embodiment]
This embodiment is a particle beam monitoring method by observing secondary particles (X-rays, gamma rays, etc.) generated when a particle beam (primary particles) is irradiated on an irradiated object. The primary particles are, for example, carbon rays and proton rays. The secondary particle in the present embodiment refers to a secondary particle to which a part of the energy of the incident particle beam is applied. Specific examples of secondary particles include X-rays, gamma rays, electrons, neutrons, protons, helium nuclei, lithium nuclei, berylium nuclei, boron nuclei, carbon nuclei and the like. X-rays, which are one of the secondary particles, contain "X-rays emitted when the atoms that make up the irradiated object are excited and cause deexcitation" and "electrons that make up the atoms that make up the irradiated object." X-rays emitted by ionized electrons after being ionized, that is, electron braking radiation, are included. Therefore, both of these X-rays may be detected as secondary particles, or either X-ray may be detected as secondary particles. Since X ^- rays (secondary particles) generated by electron bremsstrahlung are mainly generated by electromagnetic interaction, the reaction probability is about ¹⁰² to 105 larger than that of the nuclear reaction. The energy spectrum of secondary particles has a strong correlation with the ion energy of particle beams.

The secondary particles have a spectrum spread and distributed in an energy of about 20 keV to 1000 keV. Secondary particles (X-rays, gamma rays, etc.) with this level of energy are more likely to interact (Compton scattering, photoelectric absorption, etc.) as the energy is lower, so the probability that the secondary particles will reach the detector is low. On the other hand, when the energy of the secondary particle is high, the probability that the secondary particle reaches the detector is high. Therefore, the shape of the spectrum depends on the distance (passing distance) of the irradiated object that the secondary particles pass from the generation to the detection.

That is, by observing the energy spectrum of the secondary particles at each position of the irradiated body, the energy of the particle beam (corresponding to the reach of the particle beam) and the secondary particles at the secondary particle generation position in the irradiated body can be obtained. The distance of the irradiated object that has passed can be obtained. In this embodiment, real-time particle beam monitoring is performed by observing secondary particles.

FIG. 1 shows the energy dependence of the amount of secondary particles generated when the primary particles are irradiated on the irradiated object and the amount of detected secondary particles that pass through the irradiated object and reach the detector. It is a figure which shows the example of sex. The horizontal axis of the graph of FIG. 1 is the energy of the secondary particles, and the vertical axis shows the amount of generation or detection of the secondary particles. The ratio of the detected amount to the generated amount of the secondary particles increases as the energy of the secondary particles increases. Although the continuous energy spectrum is illustrated in FIG. 1, the energy spectrum of the secondary particles does not have to be the continuous energy spectrum. That is, it may have a discontinuous energy spectrum. Further, the energy spectrum may be a combination of a continuous energy spectrum and a discontinuous energy spectrum.

(Configuration example)
FIG. 2 is a diagram showing a configuration example of the particle beam monitoring device according to the present embodiment. As shown in FIG. 2, the particle beam monitoring device 1 includes a detection unit 11 and a calculation unit 12. The detection unit 11 is connected in a state that can be controlled by the calculation unit 12.

The detection unit 11 detects the radiation information of the secondary particles affected by the particle beam in the irradiated body 2 with respect to the particle beam incident from the accelerator 3 according to the positional relationship of the irradiated body 2. The radiation information of the secondary particles is, for example, an energy spectrum of at least one of X-rays, gamma rays, etc. (secondary particles) generated by the primary particles.

FIG. 3 is a diagram showing a configuration example of the detection unit 11. As shown in FIG. 3, the detection unit 11 includes a detector 111, a charge sensitive amplifier 112, a shaping amplifier 113, and an analog digital converter 114.

The detector 111 is, for example, a cadmium telluride semiconductor detector (CdTe). In the present embodiment, the detector 111 may be any detector as long as it can obtain the energy spectrum of the secondary particles from the electric signal generated by the incident secondary particles. As shown in FIG. 3, the detector 111 is connected to an HV (High Voltage), a coupling capacitor (Cc) and a bias resistor (Rb). As a result, only the change in charge generated in the detector 111 is transmitted to the charge-sensitive amplifier 112 via the coupling capacitor.

The charge-sensitive amplifier 112 reads out the charge generated in the detector 111 and converts it into a voltage. The shaping amplifier 113 performs waveform shaping and amplification of the signal converted into a voltage by the charge-sensitive amplifier 112. Then, the peak value (pulse height) of the signal is read by the analog-digital converter 114.

As described above, the detection unit 11 acquires the energy spectrum of the secondary particles.

4 and 5 are diagrams showing an example of a measurement method in which the detection unit 11 detects the energy spectrum of the secondary particles according to the positional relationship of the irradiated body 2.

As shown in FIG. 4, the detection unit 11 further includes a collimator 120 that creates parallel rays according to the incident direction of the secondary particles, so that the energy spectrum of the secondary particles can be adjusted according to the positional relationship of the irradiated body 2. It may be detected. In this case, the X-rays, gamma rays, etc. (secondary particles) emitted by the irradiation of the particle beam become parallel rays at positions corresponding to the incident direction by the collimator 120. Therefore, it is preferable that the detector 111 included in the detection unit 11 can measure the energy spectrum of X-rays, gamma rays, etc. (secondary particles) emitted by irradiation with particle beams with higher position resolution. Examples of the collimator 120 include a slit type collimator, a cylindrical collimator, a pinhole type collimator, a parallel hole type collimator, and a fan beam type collimator. In FIG. 4, an example of a slit-shaped collimator is given as the collimator 120.

Further, as shown in FIG. 5, the detection unit 11 further includes a drive mechanism 121 that can be controlled by the calculation unit 12, so that the energy spectrum of the secondary particles is detected according to the positional relationship of the irradiated body 2. May be good. The drive mechanism 121 operates, for example, in a direction parallel to the traveling direction of the particle beam. Then, the detection unit 11 detects the energy spectrum of the secondary particles according to the positional relationship of the irradiated body 2 by being moved in a direction parallel to the traveling direction of the particle beam by the driving mechanism 121. The detection unit 11 shown in FIG. 5 may further include a collimator 120 as shown in FIG. The collimator is not limited to the slit-shaped collimator as shown in FIG. 4, and may be another type of collimator as described above.

Further, instead of moving the detection unit 11 by the drive mechanism 121, a plurality of detection units 11 may be arranged. As a result, the measurement error due to the time fluctuation of the background can be offset, and accurate measurement becomes possible.

Next, the arithmetic unit 12 will be described. The calculation unit 12 obtains information on the behavior of the particle beam in the irradiated body from the radiation information (energy spectrum) of the secondary particles according to the positional relationship detected by the detection unit 11. As shown in FIG. 2, the arithmetic unit 12 has existing hardware such as a storage unit 21, a control unit 22, and an input / output unit 24, which are connected by a bus 23, as a hardware configuration.

The storage unit 21 is, for example, a hard disk, and stores various data and programs used in the processing executed by the control unit 22.

The control unit 22 is one or a plurality of processors such as a microprocessor or a CPU (Central Processing Unit), and a peripheral circuit (ROM (Read Only Memory)), a RAM (Random Access Memory), and an interface used for processing of this processor. It has a circuit, etc.).

The input / output unit 24 is, for example, a USB (Universal Serial Bus), a LAN (Local Area Network), or the like, and is an interface for inputting / outputting data. In the present embodiment, the calculation unit 12 is connected to the detection unit 11 via the input / output unit 24. For example, the control unit 22 included in the calculation unit 12 controls the detection unit 11 via the input / output unit 24. More specifically, for example, an electric signal generated by expanding a program or the like stored in the storage unit 21 into a RAM or the like which is a peripheral circuit of the control unit 22 and executing the program by the processor of the control unit 22 is input / output. It is transmitted to the detection unit 11 via the unit 24. As a result, the detection unit 11 is controlled by the control unit 22.

The arithmetic unit 12 may be configured by a general-purpose computer such as a PC (Personal Computer).

As shown in FIG. 2, the control unit 22 includes a calculation unit 31. The calculation unit 31 is realized by expanding the program or the like stored in the storage unit 21 into a RAM or the like which is a peripheral circuit of the control unit 22 and executing the program or the like by the processor of the control unit 22.

The calculation unit 31 obtains information on the behavior of the particle beam in the irradiated object and information on the behavior of the secondary particles from the radiation information (energy spectrum) of the secondary particles according to the positional relationship detected by the detection unit 11. ..

(Operation example)
FIG. 6 is a diagram illustrating the energy spectrum detection of the secondary particles of the present embodiment. As shown in FIG. 6, the particle beam (primary particle) beam accelerated to a predetermined energy by the accelerator 3 is incident on the irradiated body 2 and generates secondary particles after traveling a distance d in the beam axis direction. .. The secondary particles traveling perpendicularly to the beam axis direction from the generation position of the secondary particles travel a distance w in the irradiated body and are detected by the detection unit 11. Here, as the irradiated body 2, for example, a water phantom simulating a substance in a living body is used. The water phantom is, for example, a cylindrical acrylic phantom having a thickness of a distance d or more in the beam axis direction of the particle beam and a radius w in the direction perpendicular to the beam axis. Here, the particle beam monitoring device 1 acquires the energy spectra of the secondary particles for various d and w by changing the position of the detection unit 11 or using an irradiated body having different radii w. .. The distance d corresponds to the reach depth of the particle beam in the irradiated body 2.

As described above, the shape of the energy spectrum of the secondary particle depends on the distance w of the irradiated object through which the secondary particle passes from the generation to the arrival at the detection unit 11. Therefore, if the energy of the particle beam (primary particle) is fixed at one value, the amount of substance in the living body (distance w passed) in the linear locus through which the secondary particle has passed can be obtained. Here, the numbers detected by the detectors at the energies E0 and E1 of the two different secondary particles are N0 and N1, respectively, and the ratio N1 / N0 is R1. Let the number of generations of secondary particles of energies E0 and E1 be M0 and M1, respectively. Assuming that the attenuation coefficients of the secondary particles of energies E0 and E1 in the biological substance are μ0 and μ1, respectively, and the thickness of the biological substance through which the secondary particles pass is w, R1 can be obtained as follows.
R1 = (M1 / M0) × exp ((μ0-μ1) w)

When the energies E0 and E1 are fixed, the value of μ0-μ1 does not change. Further, if the energy of the particle beam is fixed at one value, M1 / M0 does not change either. Therefore, w can be uniquely obtained from R1.

Further, in an actual substance in the living body, the density may change due to the presence of air or bone in the orbit of the particle beam. In this case, since the energy of the particle beam (primary particle) at the position where the secondary particle is generated is unknown, M1 / M0 is not fixed and it is difficult to uniquely obtain w from R1. However, even in this case, it is assumed that the detected amounts of the three different secondary particles at the energies (E0, E1, E2) are N0, N1, N2, respectively, and N1 / N0 and N2 / N0 are R1, R2, respectively. , R1 and R2 are uniquely determined from "the amount of substance in the living body in the linear locus through which the secondary particles have passed" and "the energy of the primary particles at the position where the secondary particles are generated". The "amount of substance in the living body in the linear locus through which the secondary particles have passed" corresponds to the lateral width w. The "energy of the primary particle at the position where the secondary particle is generated" corresponds to the axial depth d. The lateral width w and the axial depth d are converted lengths when the substance in the living body is water. When the substance in the living body contains other than water, the lateral width w and the axial depth d may be different from the physical length. By comparing the physical length with w and d, the ratio of the components (water, bone, air, etc.) of the substance in the living body can be obtained. Further, by comparing the physical length with w and d at a plurality of positions, the position of each component of the substance in the living body can be obtained.

Here, the energies E0, E1 and E2 may be energy regions having a predetermined width, respectively. By setting it in the energy region, the detection amount can be increased and noise can be suppressed. Further, it is assumed that the energy regions do not overlap with each other.

The particle beam monitoring device 1 may determine the relationship between the lateral width w and the axial depth d and R1 and R2 (energy spectra of secondary particles) by numerical simulation such as Monte Carlo simulation.

The particle beam monitoring device 1 acquires R1 and R2 (energy spectra of secondary particles) in advance for a plurality of lateral widths w and axial depths d.

The relationship between the lateral width w and the axial depth d acquired by the particle beam monitoring device 1 and R1 and R2 is shown below.

FIG. 7 is a graph showing the relationship between R1 and R2 for a plurality of lateral widths w. In the graph of FIG. 7, the horizontal axis is R1 and the vertical axis is R2. Here, the energy region is 30 keV ≦ E0 <40 keV, 50 keV ≦ E1 <60 keV, 70 keV ≦ E2 <80 keV. The lateral width w is 0 cm, 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm. Different symbols are plotted for each lateral width. Further, the axial depth d is any one from 10 mm to 90 mm. As shown in the graph of FIG. 7, one lateral width plot resides within a certain area and rarely overlaps with the other lateral width areas. Therefore, by irradiating some irradiated object with a particle beam, obtaining R1 and R2 from the energy spectrum of the generated secondary particles, and comparing with the graph of FIG. 7, the lateral width w of the irradiated body is obtained. be able to. Further, from the graph of FIG. 7, since the lateral width w tends to increase as R1 increases, the lateral width w tends to increase.
It can be seen that the lateral width w can be obtained with some accuracy even with only R1.

FIG. 8 is a graph showing the relationship between R1 and R2 with respect to a plurality of axial depths d. In the graph of FIG. 8, the horizontal axis is R1 and the vertical axis is R2. In the graph of FIG. 8, for the same result as in FIG. 7, different symbols are plotted for each axial depth instead of the lateral width w. Here, the axial depth is divided into three regions (10.0 to 36.7 mm, 36.7 to 63.3 mm, 63.3 to 90.0 mm), and different symbols are plotted for each region. There is. As shown in the graph of FIG. 8, one axial depth plot resides within a certain region and does not overlap much with the other axial depth regions. Therefore, by irradiating some irradiated object with a particle beam, obtaining R1 and R2 from the energy spectrum of the generated secondary particles, and comparing with the graph of FIG. 8, the axial depth d of the irradiated object can be obtained. You can ask.

FIG. 9 is a graph obtained by extracting a graph having a lateral width of 1 cm from the graph of the relationship between R1 and R2 in FIG. It can be seen that one axial depth plot resides within a certain region and hardly overlaps with the other axial depth regions.

FIG. 10 is a graph showing the relationship between the axial depth and R2 in the same data as in FIG. In the graph of FIG. 10, the horizontal axis is the depth in the axial direction, and the vertical axis is R2. Here, the lateral width is 1 cm. The four points in the graph are the averages of R2 and the axial depth of the axial depths of 10 to 30 mm, 30 to 50 mm, 50 to 70 mm, and 70 to 90 mm, respectively, from the left. It can be seen that the smaller R2 is, the longer the axial depth is.

Next, for the graphs from FIG. 7 to FIG. 10, an example in which the energy region settings are different is shown.

FIG. 11 is a graph showing the relationship between R1 and R2 for a plurality of lateral widths w. In the graph of FIG. 11, the horizontal axis is R1 and the vertical axis is R2. Here, the energy region is 20 keV ≦ E0 <30 keV, 30 keV ≦ E1 <40 keV, 60 keV ≦ E2 <70 keV. The lateral width w is 0 cm, 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm. Different symbols are plotted for each lateral width. Further, the axial depth d is any one from 10 mm to 90 mm. As shown in the graph of FIG. 11, one lateral width plot resides within one region and does not overlap with the other lateral width region. Therefore, by irradiating some irradiated object with a particle beam, obtaining R1 and R2 from the energy spectrum of the generated secondary particles, and comparing with the graph of FIG. 11, the lateral width w of the irradiated body is obtained. be able to. Further, from the graph of FIG. 11, it can be seen that the lateral width w tends to increase as R1 or R2 increases, so that the lateral width w can be obtained even with only R1 or R2.

FIG. 12 is a graph showing the relationship between R1 and R2 with respect to a plurality of axial depths d. In the graph of FIG. 12, the horizontal axis is R1 and the vertical axis is R2. In the graph of FIG. 12, for the same result as in FIG. 11, different symbols are plotted for each axial depth instead of the lateral width w. Here, the axial depth is divided into three regions (10.0 to 36.7 mm, 36.7 to 63.3 mm, 63.3 to 90.0 mm), and different symbols are plotted for each region. There is. As shown in the graph of FIG. 12, one axial depth plot resides within a certain region and rarely overlaps with the other axial depth regions. Therefore, by irradiating some irradiated object with a particle beam, obtaining R1 and R2 from the energy spectrum of the generated secondary particles, and comparing with the graph of FIG. 12, the axial depth d of the irradiated object can be obtained. You can ask.

FIG. 13 is a graph obtained by extracting a graph having a lateral width of 1 cm from the graph of the relationship between R1 and R2 in FIG. It can be seen that one axial depth plot resides within a certain region and hardly overlaps with the other axial depth regions.

FIG. 14 is a graph showing the relationship between the axial depth and R2 in the same data as in FIG. In the graph of FIG. 14, the horizontal axis is the depth in the axial direction, and the vertical axis is R2. Here, the lateral width is 1 cm. The four points in the graph are the averages of R2 and the axial depth of the axial depths of 10 to 30 mm, 30 to 50 mm, 50 to 70 mm, and 70 to 90 mm, respectively, from the left. It can be seen that the smaller R2 is, the longer the axial depth is.

By adjusting the energy region used when obtaining the axial depth d and the lateral width w, the axial depth d and the lateral width w can be obtained more accurately.

In the storage unit 21 of the particle beam monitoring device 1, the acquired R1 and R2 are stored in association with the axial depth d and the lateral width w.

Next, an operation example for calculating the axial depth d and the lateral width w in the irradiated body using the above results will be described.

FIG. 15 is a diagram showing an example of an operation flow for calculating the axial depth d and the lateral width w in the irradiated body. For example, the operation is executed by the control unit 22 by executing a program or the like stored in the storage unit 21 based on the user's operation information via a user interface (not shown) included in the calculation unit 12 of the particle beam monitoring device 1. The flow starts.

In S101, the detection unit 11 controlled by the control unit 22 of the calculation unit 12 detects the energy spectrum of the secondary particles emitted in the direction perpendicular to the traveling direction of the particle beam.

In S102, the calculation unit 31 obtains the detected quantities N0, N1, N2 for the energy regions E0, E1, and E2 using the energy spectrum of the detected secondary particles. The calculation unit 31 obtains R1 and R2 from N0, N1 and N2.

In S103, the calculation unit 31 extracts the correspondence between R1 and R2 stored in the storage unit 21 and the axial depth d and the lateral width w. The calculation unit 31 extracts R1 and R2 that match R1 and R2 obtained in S102 from the corresponding relationship. The calculation unit 31 outputs the extracted axial depth d and lateral width w corresponding to R1 and R2 as the axial depth d and lateral width w corresponding to R1 and R2 obtained in S102. When R1 and R2 that match R1 and R2 obtained in S102 do not have the corresponding relationship, R1 and R2 having the closest distance to R1 and R2 obtained in S102 are extracted in the graph as shown in FIG. 7. The calculation unit 31 outputs the extracted axial depth d and lateral width w corresponding to R1 and R2 as the axial depth d and lateral width w corresponding to R1 and R2 obtained in S102. Further, the calculation unit 31 extracts a plurality of (for example, three) R1 and R2 from the distance closest to R1 and R2 obtained in S102 in the graph as shown in FIG. 7, and converts them into the extracted R1 and R2. The average value of the corresponding axial depth d and the average value of the lateral width w may be output as the axial depth d and the lateral width w corresponding to R1 and R2 obtained in S102.

In this way, the particle beam monitoring device 1 can obtain the axial depth d and the lateral width w from the energy spectrum of the secondary particles. The particle beam monitoring device 1 may acquire energy spectra of secondary particles from a plurality of positions. At this time, the axial depth d and the lateral width w can be obtained at each position.

The detection unit 11 detects the amount of secondary particles only in the energy region (E0, E1, E2) used by the calculation unit 31, and detects the amount of secondary particles in the energy region not used by the calculation unit 31. It does not have to be.

(others)
In the above description, the axial depth d and the lateral width w are obtained by using the detected amount of a part of the energy spectrum of the secondary particles. The calculation unit 31 learns the relationship between the energy spectrum of the secondary particle and the corresponding axial depth d and the lateral width w from the neural network by deep learning, and newly acquires the relationship using the learned neural network. The axial depth d and the lateral width w may be calculated for the energy spectrum of the secondary particles. That is, the calculation unit 31 machine-learns the relationship between the energy spectrum of the secondary particle and the corresponding axial depth d and the lateral width w, and uses the machine learning result to newly acquire the secondary particle. The axial depth d and the lateral width w may be calculated for the energy spectrum of. Thereby, the axial depth d and the lateral width w can be obtained more accurately by using the entire region of the energy spectrum of the secondary particles.

(Actions and effects of embodiments)
The configuration of this embodiment realizes a method of calculating the amount of a substance in the living body based on the energy spectrum of the secondary particle as a method of evaluating the influence of the interaction between the secondary particle and the substance in the living body. In the method of the present embodiment, since the secondary particles induced by the primary particles are measured, the additional exposure that occurs in the X-ray tomography apparatus or the like does not occur. Further, since the secondary particles measured by this method are generated almost at the same time as the irradiation of the primary particles, it is possible to acquire the substance distribution information during the irradiation of the treatment beam, which was difficult to realize with an X-ray tomography apparatus or the like.

The particle beam monitoring device 1 moves the detection unit 11 to detect the energy spectrum of the secondary particles in three dimensions, and then measures the distribution of the irradiated object (substance in the living body) in three dimensions. Can be done.

The particle beam monitoring device 1 can monitor the range and dose distribution of the particle beam in real time, so that when the patient is irradiated with the particle beam, it is confirmed and verified that the particle beam is reliably irradiated to the lesion site. However, it becomes possible to treat. Further, according to the particle beam monitoring device 1, it becomes possible to recognize changes in the living body during treatment (for example, filling and discharging of mucus in a cavity region in the body). Real-time monitoring can improve the quality and reliability of treatment.

The configuration of the above embodiments can be implemented by combining them as much as possible.

<Computer readable recording medium>
A program that realizes any of the above functions in a computer or other machine or device (hereinafter referred to as a computer or the like) can be recorded on a recording medium that can be read by a computer or the like. Then, by having a computer or the like read and execute the program of this recording medium, the function can be provided.

Here, a recording medium that can be read by a computer or the like is a recording medium that can store information such as data and programs by electrical, magnetic, optical, mechanical, or chemical action and can be read from a computer or the like. To say. In such a recording medium, elements constituting a computer such as a CPU and a memory may be provided, and the CPU may execute a program.

Further, among such recording media, those that can be removed from a computer or the like include, for example, a flexible disk, a magneto-optical disk, a CD-ROM, a CD-R / W, a DVD, a DAT, an 8 mm tape, a memory card, and the like.

In addition, there are hard disks, ROMs, and the like as recording media fixed to computers and the like.

1: Particle beam monitoring device 2: Irradiated body 3: Accelerator 11: Detection unit 12: Calculation unit 21: Storage unit 22: Control unit 23: Bus 24: Input / output unit 31: Calculation unit 111: Detector 112: Charged Sensitive amplifier 113: Shaping amplifier 114: Analog-to-digital converter 120: Collimeter 121: Drive mechanism

Claims (5)

A detector that detects energy spectral information of secondary particles affected by particle beams incident on the irradiated object, and a detector.
It is provided with a calculation unit for calculating information on the behavior of particle beams and information on the behavior of secondary particles in the irradiated body from the energy spectrum information of the secondary particles detected by the detection unit.
The information regarding the behavior of the particle beam is the reach depth of the particle beam in the irradiated body.
The information regarding the behavior of the secondary particles is the passing distance of the secondary particles in the irradiated body.
Particle beam monitoring device. The energy spectral information of the secondary particles is the amount of detection of the secondary particles in a plurality of energy regions that do not overlap with each other.
The particle beam monitoring device according to claim 1 . The calculation unit uses the result of machine learning of the relationship between the energy spectrum information of the secondary particles, the information on the behavior of the particle beams, and the information on the behavior of the secondary particles, and the particles in the irradiated object. Calculate information about the behavior of lines and information about the behavior of secondary particles,
The particle beam monitoring device according to claim 1 . The computer
The energy spectral information of the affected secondary particles is detected from the particle beam incident on the irradiated object, and the energy spectrum information is detected.
From the detected energy spectrum information of the secondary particles, it is executed to calculate the information on the behavior of the particle beam and the behavior of the secondary particles in the irradiated object.
The information regarding the behavior of the particle beam is the reach depth of the particle beam in the irradiated body.
,
The information regarding the behavior of the secondary particles is the passing distance of the secondary particles in the irradiated body.
Particle beam monitoring method. The computer
The energy spectral information of the affected secondary particles is detected from the particle beam incident on the irradiated object, and the energy spectrum information is detected.
It is a particle beam monitoring program for executing to calculate information on the behavior of particle beams and information on the behavior of secondary particles in the irradiated object from the detected energy spectrum information of the secondary particles.
The information regarding the behavior of the particle beam is the reach depth of the particle beam in the irradiated body.
The information regarding the behavior of the secondary particles is the passing distance of the secondary particles in the irradiated body.
Particle beam monitoring program.

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