JP6190302B2 - Biological function observation apparatus and radiation therapy system - Google Patents

Description

  The present invention relates to a biological function observation apparatus and a radiation therapy system.

  Methods for treating cancer in vivo include surgery, chemotherapy, immunotherapy and radiation therapy. Among them, radiotherapy is a method for treating cancer by intensively irradiating the tumor with radiation, and is expected to be able to cure the cancer at the primary site. The radiation used in radiation therapy is a photon beam such as an X-ray, an electron beam, a proton beam, a neutron beam, and an ion beam.

  Among these, radiations such as proton beams and ion beams lose a large amount of energy in a region immediately before the radiation stops due to the energy stopping power when irradiated to a thick target. As a result, a high dose region called a Bragg peak is formed in that portion. Effective radiation therapy can be realized by adjusting the radiation irradiation position and the incident energy so that the peak position is concentrated on the tumor portion.

  If the dose of radiation to the tumor is insufficient, or if a portion of the tumor is not irradiated, the cancer treatment may be incomplete and the cancer may recur. Also, if radiation is applied to a normal part (particularly an important organ) around the tumor, there is a possibility that a disorder occurs in the normal part. Therefore, in radiotherapy, it is important to irradiate a tumor with a necessary dose of radiation, and it is also important not to irradiate a normal site.

  Therefore, in radiotherapy, the position and shape of the tumor are measured by X-ray CT (Computed Tomography) etc. prior to radiation irradiation in order to carry out radiation irradiation with high dose concentration on the tumor with high accuracy and safety. Then, a radiation treatment plan is determined based on the measurement results to determine the direction, number and dose of radiation, and then the tumor is irradiated according to the treatment plan. It is also important to check whether the tumor has been exposed to radiation as planned. For this confirmation, it is necessary to visualize the radiation irradiation region (region where the irradiated radiation loses large energy) in the living body.

  Patent Document 1 describes a technique for visualizing a radiation irradiation region. The irradiation area visualization technique described in this document detects annihilation gamma rays generated by annihilation of positron and electrons emitted from positron emission nuclei generated by irradiation of living body, and based on this detection result The existence distribution of positron emission nuclei is obtained, and a radiation irradiation region visualization image is acquired from the existence distribution of positron emission nuclei. Further, the radiation irradiation region visualized image as described above is acquired every time the living body is irradiated with radiation. And based on each radiation irradiation area | region visualization image, or based on the time change of a radiation irradiation area | region visualization image, it is confirmed whether the radiation was correctly irradiated with respect to the tumor.

JP 2014-18525 A

  However, the present inventor has a problem that the radiation irradiation region visualization technique described in Patent Document 1 is not sufficient to confirm whether or not the tumor to be irradiated with radiation has been accurately irradiated. I found it. That is, the positron emission nucleus may move in the living body from the generation to the positron emission. Further, the residual state from the generation of the positron emission nucleus to the time of positron emission differs depending on the function of the living body (cell exchange and blood flow). For these reasons, the radiation irradiation region visualization image acquired from the distribution of the presence of positron emitting nuclei is not sufficient to confirm whether or not the tumor to be irradiated has been properly irradiated.

  The present invention has been made to solve the above-mentioned problems, and it is possible to confirm whether or not radiation has been accurately applied to a tumor by observing the function of a living body irradiated with radiation. An object of the present invention is to provide a biological function observation apparatus that can perform such a function. It is another object of the present invention to provide a radiotherapy system that is equipped with such a biological function observation device and can perform accurate radiation irradiation on a tumor.

  The biological function observation device of the present invention is an apparatus for observing the function of a living body in which prompt gamma rays and positron emission nuclei are generated by irradiation over a predetermined period, and (1) detects prompt gamma rays generated during a predetermined period. A first image acquisition unit for acquiring a first image representing a generation distribution of positron emission nuclei based on the detection result; and (2) by annihilation of a positron and an electron emitted from the positron emission nuclei after a predetermined period. A second image acquisition unit for detecting a generated annihilation gamma ray and acquiring a second image representing the presence distribution of positron emission nuclei based on the detection result; and (3) a second image based on the first image. And a function observation unit for obtaining a biological function based on a residual state of the positron emission nucleus in the living body based on a change in the image.

  The radiation therapy system of the present invention observes the function of a radiation irradiated unit that irradiates a living body with radiation for a predetermined period to generate prompt gamma rays and positron emitting nuclei in the living body, and the living body irradiated with radiation by the radiation irradiating unit. The biological function observation device of the present invention described above is provided. The radiotherapy system of the present invention preferably further includes a control unit that adjusts the dose distribution of the next radiation irradiation to the living body by the radiation irradiation unit based on the biological function obtained by the biological function observation device. .

  The biological function observation apparatus of the present invention can confirm whether or not radiation irradiation has been performed accurately and optimally on a tumor by observing the function of a biological body irradiated with radiation. In addition, the radiation therapy system of the present invention can accurately and optimally perform radiation irradiation on a tumor.

It is a figure which shows the structure of the radiotherapy system 1 of 1st Embodiment. It is a graph which shows an example of the relationship between the integrated dose of the radiation irradiation to a biological body, and the residual ratio of the positron emission nucleus in a tumor. It is a figure which shows the structure of the radiotherapy system 2 of 2nd Embodiment.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. The present invention is not limited to these exemplifications, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  FIG. 1 is a diagram illustrating a configuration of a radiation therapy system 1 according to the first embodiment. The radiotherapy system 1 according to the first embodiment includes a first detection unit 11a, a first processing unit 12, second detection units 21a and 21b, a second processing unit 22, a function observation unit 30, a radiation irradiation unit 40, and a control unit 50. Is provided. Among these, the first detection unit 11a, the first processing unit 12, the second detection units 21a and 21b, the second processing unit 22, and the function observation unit 30 are prompt gamma rays by radiation irradiation for a predetermined period by the radiation irradiation unit 40. And an apparatus for observing the function of the living body 90 in which the positron emitting nucleus is generated.

The radiation irradiation unit 40 irradiates the living body 90 with radiation over a predetermined period. The radiation used in radiation therapy is a photon beam such as an X-ray, an electron beam, a proton beam, a neutron beam, and an ion beam. When a photon beam such as an X-ray, an electron beam, a proton beam, a neutron beam, or an ion beam is used, a nuclear reaction occurs with a target nucleus existing in the living body 90. Prompt gamma rays γ _p and positron emission nuclei are generated in the radiation irradiation region in the living body 90 by a nuclear reaction caused by irradiation of the living body 90 with radiation.

For example, when the target nucleus ¹⁶ O in the living body 90 is irradiated with radiation, generation of prompt gamma rays with energy of 2.7 MeV or positron emission nucleus ¹⁵ O is mainly generated. When the target nucleus ¹⁶ O in the living body 90 is irradiated with radiation, positron emission nucleus ¹⁴ O is generated and prompt gamma rays with energy of 2.3 MeV are generated. Further, for example, when the target nucleus ¹² C in the living body 90 is irradiated with radiation, a positron emission nucleus ¹⁰ C is generated and prompt gamma rays with energy 718 keV are generated. Prompt gamma rays are emitted about ^10-15 seconds after irradiation. A positron emitting nucleus has a half-life depending on its type, and decays β ⁺ to release a positron. The emitted positron immediately annihilates with nearby electrons. The pair annihilation generates _a pair of annihilation gamma rays γa having an energy of 511 keV. Photon annihilation gamma gamma _a of the pair, it flies in the opposite direction to each other from the annihilation position.

First detector 11a and the first processing section 12 detects prompt gamma gamma _p that occurred during a predetermined period (radiation irradiation period), the first representative of the occurrence distribution of positron emission nuclei based on the detection result The 1st image acquisition part which acquires an image is comprised. The 1st detection part 11a detects the prompt gamma ray (gamma) _p , and measures the flight direction and energy. For example, a gamma camera or a Compton camera is used as the first detection unit 11a. The Compton camera used as the first detection unit 11a detects the Compton scattering position of the gamma ray photon, the recoil electron energy and the flight direction, and also detects the absorption position and photon energy of the scattered photon, thereby generating the prompt gamma ray γ _p. Can be measured. The Compton camera is preferably an electron track detection type capable of detecting the energy of recoil electrons generated at the Compton scattering position and the flight direction.

The first processing unit 12, the prompt gamma gamma _p detection result by the first detecting portion 11a and the required processing to obtain a first image representing the occurrence distribution of positron-emitting nuclei in irradiated regions of the body 90. In this processing, a physical correlation between prompt gamma rays γ _p generated by radiation irradiation and positron emission nuclei is used.

Second detector 21a, 21b and the second processing unit 22 detects annihilation gamma-rays gamma _a generated by annihilation of positrons and electrons emitted from the predetermined time period (radiation irradiation period) after the positron emission nuclei, A second image acquisition unit is configured to acquire a second image representing the presence distribution of positron emission nuclei based on the detection result. The second detection units 21a and 21b and the second processing unit 22 constitute a PET (positron emission tomography) apparatus. Detector 21a, 21b, respectively, a scintillator for generating scintillation light when annihilation gamma rays gamma _a is incident includes the light detector for detecting the scintillation light and the (e.g. photomultiplier tubes), the incident position of the annihilation gamma-rays gamma _a Can be detected. The detection unit 21a and the detection unit 21b are arranged to face each other so as to sandwich the radiation irradiation region of the living body 90.

The second processing unit 22, detecting unit 21a, and the required processing on the basis of the annihilation gamma ray gamma _a detection result by 21b, and acquires the second image representing the existence distribution of positron-emitting nuclei in vivo 90. During this process, the detection unit 21a, 21b is gamma rays detected is judged whether the annihilation gamma-rays gamma _a energy 511keV are also detecting unit 21a, 21b is simultaneously detected the annihilation gamma rays gamma _a pair 1 whether it is determined, based on the determination result, the image of the occurrence distribution of annihilation gamma-rays gamma _a is obtained. From the image of the generation distribution of the annihilation gamma rays γa, _a second image representing the existence distribution of positron emission nuclei is acquired.

  A second image representing the presence distribution of positron emission nuclei is acquired after the irradiation period. The second image may be acquired over a certain period immediately after the irradiation irradiation period, or may be acquired over a certain period after a certain time has elapsed after the irradiation irradiation period, Moreover, you may acquire repeatedly repeatedly intermittently after an irradiation line irradiation period.

  The function observation unit 30 obtains the residual state of the positron emission nucleus in the living body 90 based on the change in the second image when the first image is used as a reference, and obtains the biological function from the residual state of the positron emission nucleus. The first image is based on the detection result of prompt gamma rays immediately generated by radiation irradiation on the living body 90, and represents the generation distribution of positron emission nuclei in the radiation irradiation region in the living body 90. The second image is based on the detection result of the annihilation gamma ray generated by the annihilation of the positron and the electron emitted from the positron emission nucleus after irradiation of the living body 90, and the positron emission nucleus at the time of the generation of the annihilation gamma ray. Represents the existence distribution of. Therefore, the change in the second image when the first image is used as a reference represents the residual state of the positron emission nucleus in the living body 90.

  The residual state of the positron emitting nucleus in the living body 90 varies depending on the function of the living body (cell exchange and blood flow). That is, when cell exchange and blood flow are active, positron emission nuclei generated by radiation irradiation move from the generation position with the passage of time. Conversely, when cell exchange or blood flow is stagnant, the positron-emitting nuclei generated by radiation irradiation remain at the generation position even if time passes, or movement due to passage of time becomes slight. . From this, the function observation unit 30 obtains the residual state of the positron emission nucleus in the living body 90 based on the change of the second image when the first image is used as a reference, and the biological function is determined from the residual state of the positron emission nucleus. Can be requested.

  FIG. 2 is a graph showing an example of the relationship between the cumulative dose of radiation irradiation to the living body and the residual ratio of positron-emitting nuclei generated in the tumor. The living body was irradiated with a constant dose per day. The horizontal axis shows the cumulative dose of radiation exposure, which is equivalent to the passage of time. The vertical axis represents the ratio of the amount of intra-tumor positron-emitting nuclei measured after each day of irradiation, based on the amount of intra-tumor positron-emitting nuclei measured after irradiation on the first day. As shown in this figure, as the radiotherapy progresses daily, the movement of intranuclear positron-emitting nuclei caused by irradiation increases, and the functions of the living body (cell exchange and blood flow) may become active. confirmed.

  The radiotherapy system 1 of this embodiment shown in FIG. 1 includes a radiation irradiation unit 40 and a control unit 50 in addition to the above-described biological function observation device that observes the function of the living body 90 irradiated with radiation. The radiation irradiation unit 40 irradiates the living body 90 with radiation for a predetermined period to generate prompt gamma rays and positron emission nuclei in the living body. For example, when the radiation is a proton beam, the radiation irradiation unit 40 inputs a proton beam having a predetermined energy (several hundred MeV) by a proton beam accelerator so that a desired region in the living body 90 becomes a radiation irradiation region. Then, the dose distribution of the proton beam is adjusted, and the living body 90 is irradiated with the adjusted proton beam. The control unit 50 controls radiation irradiation to the living body 90 by the radiation irradiation unit 40. In particular, the control unit 50 adjusts the dose distribution of the next radiation irradiation to the living body 90 by the radiation irradiation unit 40 based on the biological function obtained by the biological function observation device.

The radiation therapy system 1 of this embodiment is used as follows. First, the position and shape of the tumor in the living body 90 to be treated are measured by X-ray CT or the like, and a radiotherapy plan is created by the control unit 50 based on the measurement result. This radiation treatment plan may be created by a treatment plan creation device provided separately. Thereafter, radiation is irradiated from the radiation irradiation unit 40 to the living body 90 under the control of the control unit 50 according to the treatment plan. Whether radiation region at this time was as planned, the first image representing an occurrence distribution of positron-emitting nuclei is obtained based on the first detector 11a and the prompt gamma gamma _p detection result by the first processing section 12 Can be confirmed. In addition, the function of the living body 90 can be confirmed from the residual state of the positron emitting nuclei in the living body 90 obtained by the function observation unit 30 based on the change in the second image when the first image is used as a reference.

  As a result of these confirmations, when the radiation irradiation area is different from the plan, or when the function of the living body 90 changes due to radiation irradiation and the radiation irradiation area needs to be changed, the irradiation section 40 moves to the living body 90. The dose distribution of the next radiation irradiation is adjusted by the control unit 50, and the radiation after the adjustment is irradiated from the radiation irradiation unit 40 to the living body 90 at the next radiation irradiation. As described above, in the present embodiment, it is possible to confirm whether or not the radiation has been accurately applied to the tumor by observing the function of the living body 90 irradiated with the radiation. In addition, accurate irradiation can be performed on the tumor.

  FIG. 3 is a diagram illustrating a configuration of the radiation therapy system 2 according to the second embodiment. The radiotherapy system 2 of 2nd Embodiment is 1st detection part 11a, 11b, 1st process part 12, 2nd detection part 21a-21d, 2nd process part 22, function observation part 30, radiation irradiation part 40, and control. Part 50 is provided. Among these, the 1st detection part 11a, 11b, the 1st process part 12, the 2nd detection part 21a-21d, the 2nd process part 22, and the function observation part 30 are the radiation irradiation over the predetermined period by the radiation irradiation part 40. This is an apparatus for observing the function of the living body 90 in which prompt gamma rays and positron emitting nuclei are generated.

In the present embodiment, the first image acquisition unit that acquires the first image representing the generation distribution of the positron emission nuclei based on the detection result of the prompt gamma ray γ _p is the first detection unit 11a, 11b and the first processing unit 12. Composed. For example, a gamma camera or a Compton camera is used as each of the detection units 11a and 11b, and it is preferable to use an electronic track detection type among the Compton cameras. Although the detection part 11a and the detection part 11b may be arrange | positioned so that the radiation irradiation area | region of the biological body 90 may be pinched | interposed, it is preferable to arrange | position so that a radiation irradiation area | region may be faced from a mutually different direction. The first processing section 12, first detector 11a, 1b for prompt gamma gamma _p detection result by each of the required processing, the first image representing an occurrence distribution of positron-emitting nuclei in irradiated regions of the body 90 get.

Further, in this embodiment, the obtaining the second image representing the existence distribution of positron emission nuclei based on annihilation gamma gamma _a detection result generated by annihilation of positrons and electrons emitted from the positron emission nuclei 2 The image acquisition unit includes second detection units 21 a to 21 d and a second processing unit 22. The second detection units 21a to 21d and the second processing unit 22 constitute a PET apparatus. Each detector 21a~21d includes a scintillator for generating scintillation light when annihilation gamma rays gamma _a is incident includes the light detector for detecting the scintillation light and the (e.g. photomultiplier tubes), the incident position of the annihilation gamma-rays gamma _a Can be detected. The detection unit 21a and the detection unit 21b are arranged to face each other so as to sandwich the radiation irradiation region of the living body 90. The detection unit 21c and the detection unit 21d are arranged to face each other so as to sandwich the radiation irradiation region. The second processing unit 22 performs the necessary processing on the basis of the annihilation gamma ray gamma _a detection result by the detection unit 21a to 21d, it obtains a second image representing the existence distribution of positron-emitting nuclei in vivo 90.

  The radiation therapy system 2 of the second embodiment is used in the same manner as the radiation therapy system 1 of the first embodiment, and has the same effects. In particular, the radiotherapy system 2 of the second embodiment has a large number of first detection units for acquiring the first image and a large number of second detection units for acquiring the second image. More accurate first and second images can be acquired, more accurate biological function observation is possible, and more accurate radiotherapy is possible.

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, the type and number of the first detection unit for acquiring the first image are arbitrary, and the type and number of the second detection unit for acquiring the second image are also arbitrary. In the second embodiment, two pairs of second detection units are provided, but three or more pairs of second detection units may be provided, or a plurality of pairs of second detection units may be arranged in a circular shape. Good. The first detection unit for acquiring the first image and the second detection unit for acquiring the second image may be a common detection unit.

DESCRIPTION OF SYMBOLS 1, 2 ... Radiation therapy system, 11a, 11b ... 1st detection part, 12 ... 1st process part, 21a-21d ... 2nd detection part, 22 ... 2nd process part, 30 ... Function observation part, 40 ... Radiation irradiation 50, control unit, 90 ... living body.

Claims (3)

An apparatus for observing the function of a living body in which prompt gamma rays and positron emission nuclei are generated by irradiation over a predetermined period of time,
A first image acquisition unit that detects the prompt gamma rays generated during the predetermined period and acquires a first image representing a generation distribution of the positron emission nuclei based on a detection result;
An annihilation gamma ray generated by annihilation of a positron and an electron emitted from the positron emission nucleus after the predetermined period is detected, and a second image representing the distribution of the presence of the positron emission nucleus is acquired based on the detection result. A second image acquisition unit;
A function observation unit for obtaining a biological function based on a residual state of the positron-emitting nucleus in the living body based on a change in the second image when the first image is used as a reference;
A biological function observation device comprising: A radiation irradiation unit that irradiates a living body with radiation over a predetermined period to generate prompt gamma rays and positron emission nuclei in the living body;
The biological function observation device according to claim 1, wherein the biological function irradiated with radiation by the radiation irradiation unit is observed.
A radiation therapy system comprising: The radiation according to claim 2, further comprising a control unit that adjusts a dose distribution of the next radiation irradiation to the living body by the radiation irradiating unit based on a biological function obtained by the biological function observation device. Treatment system.

Images