WO2016148269A1

WO2016148269A1 - Variable phantom, method for planning radiation treatment, and program

Info

Publication number: WO2016148269A1
Application number: PCT/JP2016/058637
Authority: WO
Inventors: 倫之角谷
Original assignee: 国立大学法人東北大学
Priority date: 2015-03-19
Filing date: 2016-03-18
Publication date: 2016-09-22
Also published as: JPWO2016148269A1; JP6347568B2

Abstract

Provided is a variable phantom, wherein it is possible to highly accurately detect the dose distribution within the variable phantom before and after deformation thereof. This variable phantom is used for a radiotherapy apparatus, wherein the variable phantom has a deformable elastic body, and a radiation dose detection unit 12 provided to the elastic body. The elastic body is formed of, e.g., a freely contractible material. The elastic body is configured from, e.g., a multilayered structure that can be freely assembled and disassembled. For example, the elastic body has holes to removably hold the radiation dose detection unit 12. In addition, the radiation dose detection unit is, e.g., a cumulative-dose-type unit. The radiation dose detection unit is, e.g., a plurality of glass dosimeters, a plurality of two-dimensional dose detectors, a gel dosimeter supported by the deformable elastic body, or the like.

Description

Moving body phantom, radiation therapy planning method, program

The present invention relates to a moving object variable phantom, a radiation treatment plan creation method, and a program.

In recent years, the development of radiation irradiation equipment that can accurately grasp the position of the affected cancer area and emit radiation at a pinpoint has progressed, avoiding radiation damage to healthy body tissues and performing highly accurate cancer treatment It is possible.
In radiation therapy, a radiation treatment plan (planned dose distribution) that prescribes the radiation irradiation position and dose is calculated by the radiation treatment planning device, and the radiation irradiation device irradiates the affected area with radiation based on the planned dose distribution. Has been done. As a radiotherapy planning apparatus, it describes in patent document 1, etc., for example.

In recent years, adaptive radiotherapy, which changes the treatment plan as appropriate in accordance with changes in the tumor and body shape of the patient during the radiotherapy period, has begun to spread, and the number of cases where a retreatment plan is performed during the radiotherapy period has increased. In this way, when summing the planned dose distributions of the radiation therapy planned with different CT images of the same patient at each stage, either CT image is matched with the other CT image by the treatment plan support software (program). By performing the deformation process, it is possible to perform a combined evaluation of the dose distribution planned with different CT images. For example, Patent Document 2 discloses a technique for performing image deformation processing on a CT image or the like.

JP 2014-140431 A JP 2013-146540 A Japanese Patent Laid-Open No. 08-187238

However, there is no known method for evaluating the accuracy of the deformation process necessary for the summation of the planned dose distribution of the above-described radiotherapy.
For example, the above-described problem cannot be solved only by using a phantom (human body model) having a simple structure that does not deform as shown in Patent Document 3.

The present invention is an example of a problem to deal with such a problem. That is, in the moving object variable phantom, it is possible to provide a moving object variable phantom capable of detecting the dose distribution in the phantom before and after deformation with high accuracy, and to evaluate image deformation processing (DIR) used for CT images with high accuracy. Providing a moving object variable phantom, providing a radiation treatment planning method using the moving object variable phantom, providing a program capable of easily and accurately adjusting image deformation parameters related to image deformation processing, CT image The purpose is to calculate the planned dose distribution of radiotherapy with high accuracy without depending on the image deformation processing.

In order to achieve such an object, the moving object variable phantom according to the present invention has at least the following configuration.
A moving body variable phantom for a radiation irradiation device,
It has a deformable elastic body, and a radiation dose detection part provided in the elastic body.

Moreover, the radiation treatment plan preparation method of this invention comprises at least the following structures.
A radiation treatment plan creation method using the moving body variable phantom of the present invention,
Setting the characteristics of the elastic body of the variable moving phantom according to the stage of radiation therapy;
And a step of detecting a radiation dose using the moving object variable phantom and creating a radiation treatment plan for defining a radiation irradiation position and a radiation irradiation dose based on the detection result.

The program of the present invention comprises at least the following configuration.
A program to be executed by a computer,
Using the moving object variable phantom of the present invention, a first combined dose distribution generated by performing image deformation processing on one of the dose distributions of the CT image of the phantom before and after deformation of the elastic body and adding it to the other (Calculated value) and the second combined dose distribution (actual measurement) generated according to the detection result of the irradiation dose by the irradiation dose detector (radiation dose detector) provided in the phantom before and after the deformation of the elastic body Value) and calculating the error from the
Defining a deformation parameter relating to the image deformation processing based on the error.

ADVANTAGE OF THE INVENTION According to this invention, in a moving body variable type phantom, the moving body variable type phantom which can detect the dose distribution in the phantom before and behind a deformation | transformation with high precision can be provided.
Further, according to the present invention, it is possible to provide a moving object variable phantom capable of evaluating an image deformation process (DIR) used for a CT image with high accuracy.
Further, according to the present invention, it is possible to provide a radiation treatment plan creation method using a moving body variable phantom.
According to the present invention, by using the moving object variable phantom, it is possible to calculate the planned dose distribution of radiotherapy with high accuracy without depending on the image deformation process of the CT image.
Further, according to the present invention, it is possible to provide a program that can easily adjust the image deformation parameters related to the image deformation processing with high accuracy.

1 is an overall schematic diagram illustrating an example of a radiotherapy system that employs a moving object variable phantom according to an embodiment of the present invention. The figure which shows an example of the moving body variable type phantom which concerns on embodiment of this invention, (a) is a figure which shows an example when the piston of a phantom is a 1st position (swelling state), (b) is the piston of a phantom The figure which shows an example in the case of the 2nd position (contracted state). The figure which shows an example of the cylindrical phantom which can be assembled and disassembled freely. The figure which shows an example of the phantom shown in FIG. 3, (a) is an exploded view, (b) is an enlarged perspective view of a dosimeter container, (c) is an example of a dosimeter container, a radiation dose detection part, and a cover part. FIG. The figure which shows an example of the spherical phantom which can be assembled and disassembled, (a) is a general view, (b) is an exploded perspective view, and (c) is an enlarged perspective view of a dosimeter container that houses a radiation dose detector. The figure which shows an example of a winding type phantom, (a) is the whole perspective view of the phantom, (b) is a figure which shows an example of the state which the phantom developed. The figure which shows an example of the phantom which employ | adopted the two-dimensional radiation dose detector (imaging device), (a) is side sectional drawing which shows an example of the state which isolate | separated the elastic body and the two-dimensional radiation dose detector, (b) is an assembly. Side surface sectional drawing which shows an example of the state which met. The conceptual diagram which shows an example of the phantom which has a gel-like body. The figure which shows an example of the functional block of a control part. The figure which shows an example of CT image and dose distribution of a phantom, (a) is a figure which shows an example of CT image and dose distribution Pa (treatment plan) of the deformation | transformation phantom before a deformation | transformation, (b) is the state which contracted FIG. 5 is a diagram showing an example of a CT image and a dose distribution of a phantom after deformation. FIG. 10A is a diagram showing an example of a CT image and a dose distribution of a phantom, FIG. 10A is a diagram showing an example of a modified dose distribution Pa and a dose distribution shown in FIG. 10A, and FIG. The figure which shows an example of a total dose distribution. The figure which shows an example of the difference of CT image of the state which the phantom expanded and contracted. The figure which shows an example of the difference of the image (deformation processing image) which deform | transformed the CT image of the state where the phantom swelled by image deformation process (DIR), and the CT image of the state where the phantom contracted. The figure for demonstrating an example of operation | movement of a radiotherapy system. The figure for demonstrating an example of operation | movement of a radiotherapy system. The figure for demonstrating an example of operation | movement of a radiotherapy system. The figure for demonstrating an example of operation | movement of a radiotherapy system. The perspective view which shows an example of the phantom of the radiotherapy system which concerns on one Embodiment of this invention. FIG. 18A is a diagram illustrating an example of the operation of the phantom illustrated in FIG. 18, FIG. 18A is a diagram illustrating an example when the piston is in the first position (inflated state), and FIG. 18B is a diagram when the piston is in the second position ( The figure which shows an example of the state which shrunk. The figure which shows an example of the phantom which has a some press mechanism. The figure which shows an example of the phantom which has a some press mechanism in an axial direction and an orthogonal direction.

A moving body variable phantom according to an embodiment of the present invention is a moving body variable phantom for a radiation irradiation apparatus, and includes a deformable elastic body and a radiation dose detector provided on the elastic body. In this embodiment, the radiation dose detection unit is a dose accumulation type (X-ray energy accumulation type).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The embodiment of the present invention includes the contents shown in the drawings, but is not limited to this. In the following description of each drawing, parts that are the same as those already described are assigned the same reference numerals, and duplicate descriptions are partially omitted.

FIG. 1 is an overall schematic diagram showing an example of a radiation therapy system 100 employing a moving body variable phantom 10 (phantom) according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of the phantom 10. Specifically, FIG. 2A is a diagram showing an example of the case where the piston 16 of the phantom 10 is in the first position (inflated state), and FIG. 2B is a diagram where the piston 16 of the phantom 10 is in the second position. It is a figure which shows an example of a case (contracted state).

In this embodiment, the radiation therapy system 100 includes a phantom 10, a CT apparatus 20 (Computed Tomography apparatus), a phantom dose detection apparatus 30, a radiation therapy apparatus 40, a control apparatus 50 (computer), and the like. The CT apparatus 20 and the radiotherapy apparatus 40 correspond to a radiation irradiation apparatus.

<CT apparatus 20>
The CT apparatus 20 performs CT imaging of a patient (subject) and the phantom 10 using, for example, helical CT (spiral CT) or non-helical CT (conventional CT).
In the present embodiment, an X-ray CT apparatus is employed as the CT apparatus 20. The CT apparatus 20 includes a housing 20a having a gantry (rotary mount), an X-ray generation unit 21 (radiation generation unit), an X-ray detection unit 22, a rotation drive unit 23, a rotation position detection unit 24, and a base unit 25 ( A couch), a couchtop 26 as a cradle, a couchtop position detector 27, a couchtop drive unit 28, and the like.

An X-ray generation unit 21 (radiation generation unit) and an X-ray detection unit 22 are provided in the cylindrical casing 20a. The X-ray generation unit 21 emits X-rays toward the subject and the phantom 10 on the top plate 26 of the base unit 25 under the control of the control device 50. The X-ray detector 22 is disposed at a position facing the X-ray generator 21. The X-ray detection unit 22 is a device that detects transmitted X-rays through the subject and the phantom 10, generates a signal corresponding to the detected X-ray dose, and outputs the signal to the control device 50.
In the present embodiment, the X-ray generation unit 21 and the X-ray detection unit 22 are fixed to a gantry (rotary mount) in the housing unit 20a, and the gantry is rotated by the rotation drive unit 23 under the control of the control device 50. By doing so, the X-ray generator 21 and the X-ray detector 22 are configured to be rotatable while maintaining the relative positions.
The rotational position detection unit 24 detects the rotational position of the X-ray generation unit 21 and the X-ray detection unit 22 based on a signal from a position sensor (angle sensor) provided in the gantry, for example, and controls the detection signal. Output to the device 50.

The top plate 26 on the base unit 25 as a bed is configured to be movable by the top plate driving unit 28 under the control of the control device 50. The top plate position detection unit 27 includes a position sensor and the like, detects the position of the top plate 26, and transmits a detection signal to the control device 50. A subject and the phantom 10 are placed on the top plate 26.

<Radiotherapy device 40>
The radiation therapy apparatus 40 performs treatment by irradiating a lesion (tumor) or the like of a subject (patient) with radiation such as an X-ray or electron beam generated by a radiation irradiation apparatus such as a linear accelerator (linac or linac). In a radiation irradiation apparatus using a linear accelerator, it is possible to irradiate sharp directional radiation. The radiotherapy apparatus 40 can irradiate the phantom 10 on the top plate 26 with radiation such as X-rays.
Moreover, the radiation therapy apparatus 40 irradiates radiation based on the radiation treatment position which prescribes | regulates the radiation irradiation position which is a target area | region, and the radiation irradiation dose to the radiation irradiation position. By carrying out like this, a radiation can be irradiated with high precision with respect to a lesion (tumor) or a simulated lesion, and irradiation to parts other than a target field can be reduced.
The radiotherapy device 40 is controlled by a control device 50 (computer).
As the radiotherapy device 40, a radiation irradiation device that does not use a linear accelerator may be employed, or a device that irradiates a lesion (tumor) with a proton beam or a heavy particle beam may be employed.

<Control device 50>
The control device 50 (computer) comprehensively controls the CT device 20, the radiation therapy device 40, the treatment plan generation device, and the like. The control device 50 is not limited to this form, and may be configured by a plurality of computers, for example.
Specifically, the control device 50 includes a control unit 51, a storage unit 52, a display unit 53, an operation input unit 54, a communication unit 55, an interface 56 (I / F), a communication line 57 such as a bus, and the like. Each component such as the control unit 51 and the storage unit 52 is electrically connected by a communication line 57.

The control unit 51 comprehensively controls each component of the control device 50. In addition, the control unit 51 comprehensively controls each component of the radiation therapy system 100.
For example, the control unit 51 executes a program stored in the storage unit 52 to cause the control device 50 as a computer to realize the function according to the present invention.
Detailed functions of the control unit 51 will be described later.

The storage unit 52 is a storage device such as a RAM, a ROM, an HDD, and an SSD, and stores programs and various data. The control part 51 reads a program, data, etc. from a memory | storage part as needed. In addition, the control unit 51 stores data or the like in the storage unit 52 as necessary.
The display unit 53 is a display device such as a display, and can display various data such as a CT image according to the present invention under the control of the control unit 51.
The operation input unit 54 is an input device such as a keyboard, a mouse, or a touch panel, and outputs an input signal to the control unit 51.
The communication unit 55 performs data communication with an external computer or the like via a wired or wireless communication path under the control of the control unit 51.
The interface 56 (I / F) includes predetermined components of the radiotherapy device 40, the phantom dose detection device 30, and the CT device 20, such as an X-ray generation unit 21, an X-ray detection unit 22, a rotation drive unit 23, and a rotation. The position detection unit 24, the top plate position detection unit 27, the top plate drive unit 28, and the like are electrically connected.

<Phantom 10>
The phantom 10 is a test body used for various calibrations of the CT apparatus 20 and the radiation therapy apparatus 40, for example. In the present embodiment, the phantom 10 is used for accuracy verification of image deformation processing (DIR: Deformable Image Registration) by the control device 50.

The phantom 10 has a portion having a predetermined X-ray absorption coefficient so as to imitate a part of a patient, for example. The phantom 10 includes, for example, a portion that simulates a patient's lesion (lesion), a portion that simulates an X-ray absorption coefficient of normal tissue, and the like. In this embodiment, the moving body variable type phantom 10 is adopted as the phantom 10, and the phantom 10 is configured to be deformable so as to imitate a moving body such as a patient's breathing and heart motion.

In the example shown in FIGS. 1 and 2, a phantom 10 simulating the lung is employed. The phantom 10 has an elastic body 11 disposed in a cylinder 15 as a case, and the elastic body 11 is configured to be deformable by a piston 16.
A piston rod 17 is connected to the piston 16. The piston rod 17 is connected to a piston driving unit 175 such as a motor, and is configured to move the piston 16 under the control of the control device 50.
In the present embodiment, a cylinder 15 (case) that houses the phantom 10 and the piston is disposed on the plate-like member 121. Further, a piston driving unit 175 is disposed on the plate-like member 121 via a base 176. In the vicinity of the end of the plate-like member 121,

grips

122 and 123 are provided. For this reason, the plate-like member 121 is configured such that the plate-like member 121 on which the phantom 10 and the piston driving unit 175 are placed can be easily carried.

Further, an inclined member 171 is provided on the piston rod 17 so as to be movable in conjunction with the piston rod 17. A vertical movement member 172 (stage) is disposed in the vicinity of the upper portion of the inclined member 171 so as to be movable up and down. The vertically moving member 172 is disposed such that the lower end thereof is in contact with the inclined member 171. For this reason, the vertical movement member 172 is configured to move up and down in conjunction with the movement of the piston rod 17 and the piston 16.

In this embodiment, a detection box is provided at the upper end of the vertical movement member 172, and the position of the detection box is detected by a piston position detection unit 173 such as an infrared imaging unit or a position sensor. That is, the piston position detection unit 173 detects the displacement and position of the piston 16 based on the vertical movement displacement of the vertical movement member 172 and outputs a detection signal to the control device 50.

The phantom 10 shown in FIG. 2 includes an elastic body 11, a radiation dose detection unit 12 (irradiation dose detection unit), a balloon 13, a fluid 14 such as water or gas, a cylinder 15 as a case, a piston 16, a piston rod 17, an elasticity. It has a body holding part 18, a lid part 19, and the like.

The elastic body 11 is configured to be deformable by an external force such as a piston 16. In the present embodiment, the elastic body 11 is formed of a shrinkable material. The elastic body 11 is made of, for example, a material having a predetermined elastic modulus and a predetermined X-ray absorption coefficient such as a resin material. In the present embodiment, a sponge-like porous resin material is employed as the elastic body 11.

Moreover, in the embodiment of the present invention, the elastic body 11 is provided with the radiation dose detection unit 12. In the example shown in FIG. 2, a plurality of small glass dosimeters (fluorescent glass dosimeters) or the like are employed as the dose accumulation type (X-ray energy accumulation type) radiation dose detection unit 12. The elastic body 11 is easily detachably disposed at a predetermined position. As a specific example, about 30 to 50 small glass dosimeters having a diameter of 1.5 mm and a length of 8.5 mm are arranged at predetermined intervals on the elastic body 11.

Specifically, the radiation dose detection unit 12 is, for example, a silver activated phosphate glass element containing silver ions, and when this glass element is irradiated with radiation, a fluorescence center is formed by silver divalent ions or the like. The This fluorescent center emits fluorescence when it returns to a stable state after being excited by external ultraviolet irradiation. This amount of luminescence is proportional to the radiation absorbed dose. The fluorescence center does not disappear by this measurement and can be read repeatedly.

In the present embodiment, the dose detector 31 of the phantom dose detector 30 shown in FIG. 1 is taken out from a predetermined position of the phantom 10, irradiates the glass element as the radiation dose detector 12 with ultraviolet rays, and the fluorescence of the glass element. The amount of fluorescence emitted from the center is measured, and the radiation absorbed dose is detected based on the measured amount.

In this embodiment, the position specifying unit 32 of the phantom dose detection device 30 specifies the position of the glass element as the dose detection unit 31 of the phantom 10 and outputs the position information to the control device 50. As a method for specifying the position information of the radiation dose detection unit 12, the radiation dose detection unit 12 of the phantom 10 in which the radiation dose detection unit 12 is arranged at a predetermined position of the elastic body 11 specified by the CT image of the CT apparatus 20. For example, optically specifying the position of.

When the radiation dose detection unit 12 employs a glass element of a glass dosimeter and the position of the glass element in the phantom 10 is specified by the CT apparatus 20, the glass dose element does not generate an artifact (virtual image) on the CT image. Thus, the position of the glass dose element can be accurately identified. For this reason, the glass dosimeter as the radiation dose detection unit 12 can be used for verification of the accuracy of image deformation processing (DIR). Further, the glass dosimeter as the radiation dose detection unit 12 can be used for verification of accuracy of image deformation processing (DIR) and accuracy of dose distribution deformation.

After the radiation absorbed dose of the radiation dose detector 12 is detected and the position is specified by the phantom dose detector 30, the radiation dose detector 12 is arranged at a defined position of the elastic body 11 of the phantom 10.

In the example shown in FIG. 2, an elastic body 11 is disposed in a cylindrical cylinder 15, and a balloon 13 made of an elastic body is provided around the elastic body 11. In a space surrounded by the cylinder 15 and the piston 16, a fluid 14 such as a liquid (water or the like) or a gas is disposed. The cylinder 15 is formed in a cylindrical shape as a specific example, and has a diameter of about 25 cm.

A lid 19 is provided at the end of the cylinder 15, and the fluid 14 can be supplied or discharged by opening and closing the lid 19. The elastic body holding portion 18 abuts on the elastic body 11 and holds the elastic body 11. In the present embodiment, the contact surface of the elastic body holding portion 18 is formed in a curved shape so that the elastic body 11 is securely held even by the compression of the elastic body by the piston 16. Further, the elastic body holding portion 18 is formed with a plurality of vent holes 18a, and air can be exhausted or sucked by movement of the piston 16 in the compression direction or movement in the opposite direction.

The piston rod 17 has one end connected to a piston 16 that is movably disposed in the cylinder 15, and the other end connected to a piston drive unit.

In addition, the elastic body 11 of the phantom 10 is provided with a simulated tumor 1 (simulated lesion) made of a material having a predetermined X-ray absorption coefficient as a pseudo lesion as needed. In addition, a plurality of microspheres (beads) made of a resin such as acrylic may be disposed on the elastic body 11 of the phantom 10 as necessary. The diameter of the beads is about 1 mm to 3 mm as a specific example. This resin bead is defined by a predetermined X-ray absorption coefficient rate and functions as a landmark on the CT image.
Further, a resin wire such as nylon may be disposed on the elastic body 11 of the phantom 10 as necessary. This resin wire is defined by a predetermined X-ray absorption coefficient, and functions as a simulated blood vessel on the CT image.

In the example shown in FIGS. 2A and 2B, the phantom 10 is configured to simulate the movement of the diaphragm due to respiration by displacing the piston 16 that simulates the diaphragm.
The substantially circular (spherical) simulated tumor 1 (1a) shown in FIG. 2A becomes a simulated tumor 1 (1b) deformed into an elliptical shape (elliptical body) as the elastic body 11 is deformed. .
Further, in conjunction with the deformation of the elastic body 11, the positions of the radiation dose detection unit 12, the resin microspheres, and the wires arranged on the elastic body 11 are configured to move.

Further, the piston 16 is configured so that the displacement amount can be adjusted. Specifically, for example, it can be set to a predetermined displacement amount such as ± 5 mm, ± 10 mm, ± 15 mm, ± 20 mm, ± 25 mm, or the like.

Next, an embodiment of the phantom will be described.
<Cylindrical phantom>
FIG. 3 is a view showing an example of a cylindrical phantom 10A that can be assembled and disassembled. FIG. 4 is a diagram showing an example of the phantom shown in FIG. Specifically, FIG. 4A is an exploded view thereof, FIG. 4B is an enlarged perspective view of the dosimeter container 10Ad, and FIG. 4C is a radiation dose detection of the dosimeter container 10Ad and a glass dosimeter. It is a perspective view which shows an example of the part 12 and lid part 10Ae.

The elastic body of the phantom has a multilayer structure that can be disassembled and assembled, and a dosimeter as the radiation dose detection unit 12 can be easily attached to and detached from each component.
Specifically, the columnar phantom 10A shown in FIG. 3 includes a plurality of components formed of an elastic body, for example, a small-diameter columnar body 10Aa, a small-diameter cylindrical body 10Ab, and a large-diameter cylindrical body 10Ac. , Etc.
The large-diameter cylindrical body 10Ac includes a bottomed or bottomless hole h2, and is configured to accommodate the small-diameter cylindrical body 10Ab in the hole h2. The small-diameter cylindrical body 10Ab includes a bottomed or non-bottomed hole h1, and is configured to accommodate the small-diameter columnar body 10Aa in the hole h1.
By assembling the small-diameter cylindrical body 10Aa, the small-diameter cylindrical body 10Ab, and the large-diameter cylindrical body 10Ac, a cylindrical phantom 10A is obtained.

Each component of the phantom 10A has a plurality of holes for detachably holding a plurality of dosimeter housings 10Ad for housing a radiation dose detection unit 12 such as a glass dosimeter. Specifically, as shown in FIG. 4A, the large-diameter cylindrical body 10Ac has a plurality of holes 10Ah at predetermined positions, and the dosimeter container 10Ad can be accommodated in the holes 10Ah. It is configured.

The dosimeter container 10Ad shown in FIG. 4B is formed in a predetermined shape such as a rectangular parallelepiped, has a bottomed or bottomless hole h3, and accommodates a radiation dose detection unit 12 such as a glass dosimeter. It is comprised so that it can be covered with lid | cover part 10Ae. In the example shown in FIG. 4B, the radiation dose detection unit 12 is disposed at a substantially central portion of the dosimeter container 10Ad.

Similarly, the small-diameter cylindrical body 10Ab and the small-diameter columnar body 10Aa have a plurality of holes that detachably hold a plurality of dosimeter containers 10Ad, and a radiation dose detection unit such as a plurality of glass dosimeters. 12 can be held.

As described above, the cylindrical phantom 10A is configured such that a plurality of radiation dose detectors 12 such as a plurality of glass dosimeters can be easily and detachably disposed at predetermined positions in three dimensions.

In addition, although the shape of the dosimeter container 10Ad described above was a rectangular parallelepiped, it is not limited to this form, and may be an arbitrary shape such as a cylindrical shape or an elliptical shape.

Further, the phantom 10A is not limited to the above-described embodiment. For example, each component of the phantom 10A may be provided with a hole portion that directly and detachably holds the radiation dose detection unit 12 such as a glass dosimeter, and the radiation dose detection unit 12 may be disposed in the hole portion.

<Spherical phantom>
FIG. 5 is a view showing an example of a spherical phantom 10B that can be assembled and disassembled. Specifically, FIG. 5A is an overall view, FIG. 5B is an exploded perspective view, and FIG. 5C is an enlarged perspective view of a dosimeter container 10Ad in which the radiation dose detection unit 12 is housed.

A spherical phantom 10B shown in FIG. 5A includes a plurality of components formed of an elastic body, for example, a large-diameter hemispherical dome-shaped body 10Ba, a large-diameter hemispherical dome-shaped body 10Bb, and a small-diameter phantom 10B. A hemispherical dome-shaped body 10Bc, a small-diameter hemispherical dome-shaped body 10Bd, a small-diameter hemispherical body 10Be, a small-diameter hemispherical body 10Bf, and the like.

A hole is formed in the large-diameter hemispherical dome-shaped body 10Ba, and the small-diameter hemispherical dome-shaped body 10Bc can be accommodated in the hole. A small-diameter hole is formed in the small-diameter hemispherical dome-shaped body 10Bc, and the small-diameter hemispherical body 10Be can be accommodated in the hole. A hole is formed in the large-diameter hemispherical dome-shaped body 10Bb, and a small-diameter hemispherical dome-shaped body 10Bd can be accommodated in the hole. A small-diameter hole is formed in the small-diameter hemispherical dome-shaped body 10Bd, and the small-diameter hemispherical body 10Bf can be accommodated in the hole.

As shown in FIG. 5C, each component of the spherical phantom 10B has a plurality of holes 10Bh for detachably holding the dosimeter container 10Ad for housing the radiation dose detector 12. The radiation dose detection unit 12 such as a plurality of glass dosimeters can be held.

As described above, the spherical phantom 10B is configured such that the radiation dose detectors 12 such as a plurality of glass dosimeters can be easily and detachably disposed at predetermined positions in a three-dimensional manner.

The phantom 10B is not limited to the embodiment described above. For example, each component of the phantom 10B may be provided with a hole portion that directly and detachably holds the radiation dose detection unit 12 such as a glass dosimeter, and the radiation dose detection unit 12 may be disposed in the hole portion.

<Winded phantom>
FIG. 6 shows an example of a wound phantom 10C. Specifically, FIG. 6A is an overall perspective view of the phantom 10C, and FIG. 6B is a diagram illustrating an example of a developed state of the phantom 10C.

As shown in FIGS. 6A and 6B, the wound phantom 10C is formed by winding a deformable long rectangular parallelepiped (plate-shaped) elastic body. Further, as shown in FIG. 6B, the expanded phantom 10C has a plurality of holes 10Ch that detachably holds a dosimeter container 10Ad that houses the radiation dose detector 12, and is made of glass. The radiation dose detector 12 such as a dosimeter can be held. By accommodating the radiation dose detection unit 12 in the plurality of holes 10Ch and then winding it, as shown in FIG. 6A, a substantially cylindrical phantom 10C can be obtained.

As described above, the wound phantom 10C is configured such that the radiation dose detectors 12 such as a plurality of glass dosimeters can be easily and detachably arranged at predetermined positions in three dimensions. .
The phantom 10C is not limited to the above-described embodiment. For example, the developed phantom 10C may be provided with a hole portion that directly and detachably holds the radiation dose detection unit 12 such as a glass dosimeter, and the radiation dose detection unit 12 may be disposed in the hole portion and then wound.

<Phantom with a two-dimensional radiation dose detector>
FIG. 7 is a diagram illustrating an example of a phantom 10D that employs a two-dimensional radiation dose detector 12D (imaging device) as the radiation dose detection unit 12. Specifically, FIG. 7A is a side sectional view showing an example of a state where the elastic body of the phantom 10D and the two-dimensional radiation dose detector 12D are separated, and FIG. 7B is a side sectional view showing an example of the assembled state. is there.

The phantom 10D shown in FIGS. 7A and 7B includes a plate-like two-dimensional radiation dose detector 12D on a main body 10Da formed of an elastic body having an arbitrary shape such as a cylindrical shape or a rectangular parallelepiped. A plurality of bottomed or bottomless holes 10Dh (slits) that are detachably disposed are provided, and a two-dimensional radiation dose detector 12D can be disposed in each hole 10Dh. Specifically, the phantom 10D is configured such that a plurality of two-dimensional radiation dose detectors 12D can be arranged at predetermined intervals.

The two-dimensional radiation dose detector 12D is a dose accumulation type (X-ray energy accumulation type). The two-dimensional radiation dose detector is formed, for example, by applying a photostimulable phosphor (BaFX: Eu ²⁺ (X = Br, I) or the like) to a resin plate member.
In this photostimulable phosphor, electrons in the crystal are excited to a metastable state by irradiation of radiation. In this state, when the photostimulable phosphor is irradiated with light having a predetermined wavelength, the electrons excited to the metastable state transition to the ground state and emit stimulable fluorescence.

The dose detection unit 31 and the position specifying unit 32 of the phantom dose detection device 30 (see FIG. 1) irradiate the two-dimensional radiation dose detector 12D with light having a predetermined wavelength, and the brightness from the two-dimensional radiation dose detector 12D. A two-dimensional radiation dose distribution can be obtained by detecting and scanning the exhaustive fluorescence with the light receiving unit. The phantom dose detection device 30 outputs this detection result to the control device.

An afterimage can be erased by uniformly irradiating the two-dimensional radiation dose detector 12D coated with the photostimulable phosphor with light having a predetermined wavelength for erasure, and again the two-dimensional radiation dose detector 12D. Can be used.

Note that the two-dimensional radiation dose detector is not limited to the above-described form. For example, a radiographic film, a radiochromic film (radiation sensitive dye dosimeter film), a plate glass dosimeter, or a combination thereof It may be.
Radiographic films utilize the reducing action of silver halide as the principle of reaction to radiation. A two-dimensional radiation dose distribution can be obtained by developing the radiographic film using a developer or the like.
The radiochromic film is, for example, a resin film to which a substance that develops color upon irradiation is added, and uses a radiochromic reaction of a radiation-sensitive monomer as a reaction principle for radiation. The radiochromic film does not require a developing treatment with a developer, and the two-dimensional radiation dose distribution can be read with an RGB color scanner, a densitometer, a camera, or the like.

<Phantom with gel-like body>
FIG. 8 is a conceptual diagram showing an example of a phantom 10E having a gel-like body.
The phantom 10E has a deformable elastic body 11E (11) in the main body 10Ea, and includes a gel-like body 12E (gel dosimeter) such as a polymer gel as a radiation dose detection unit 12 therein.

The polymer gel is a dose storage type (X-ray energy storage type). Specifically, when the polymer gel absorbs radiation or the like, a polymer reaction is locally generated to generate polymer microparticles of submicron size according to the radiation absorption dose. The fine polymer particles scatter visible light and are trapped in the gel as white cloudy masses.

FIG. 8 shows a portion (white cloudy portion) 10Eb that has been irradiated with radiation and applied to the phantom 10E having a gel-like body, and has been altered according to the radiation absorbed dose. In this case, by adopting an MRI (Magnetic resonance) imaging device, a three-dimensional optical scanner, or the like as the phantom dose detection device 30 (see FIG. 1), the phantom dose detection device 30 has an altered portion (a cloudy portion) of the phantom 10E. ) Is detected, and the detection result is output to the control device. The control device can generate a three-dimensional distribution of the radiation absorbed dose based on the detection result.

FIG. 9 is a diagram illustrating an example of functional blocks of the control unit 51 of the control device.
The control part 51 implement | achieves the function of this invention in the control apparatus as a computer by running a program. In the present embodiment, the control unit 51 includes a CT apparatus drive control unit 511, a CT image generation processing unit 512, an image deformation processing unit 513 (DIR), a treatment plan creation processing unit 514 (dose distribution creation processing unit), and a phantom deformation setting. A processing unit 515, an in-phantom dose identification processing unit 516, an in-phantom light-weight position identification processing unit 517, a combined dose distribution generation processing unit 518, a verification processing unit 519 for image deformation processing, and the like.

The CT apparatus drive control unit 511 controls each component related to the CT apparatus. Specifically, the CT apparatus drive control unit 511 comprehensively controls each component such as an X-ray generation unit, an X-ray detection unit, a rotation drive unit, and a rotation position detection unit of the CT apparatus.

The CT image generation processing unit 512 generates a CT image by image reconstruction processing or the like based on a signal from the X-ray detection unit, a signal indicating position information from the rotation position detection unit, or the like.

The image deformation processing unit 513 performs a process of deforming the CT image by image deformation processing such as DIR (Deformable Image Registration). Specifically, in this image deformation process (DIR), for example, the deformation source CT image can be deformed so as to match an arbitrary part of the reference CT image.
The image deformation process (DIR) performs a process of deforming an image obtained by superimposing the CT image and the dose distribution (treatment plan). By doing so, it is possible to add up the dose distributions (treatment plans) planned with different CT images.
Specifically, this image deformation process (DIR), for example, defines a plurality of deformation control points in a lattice shape (mesh shape) for the CT image, sets the displacement amount and displacement direction of the deformation control points, Based on the set displacement amount and displacement direction of the deformation control point, a process of deforming each region of the CT image is performed.
In this image deformation process (DIR), for example, a plurality of deformation control points are defined in a lattice shape (mesh shape) for a CT image, and the degree of coincidence between the two images at the deformation control points is evaluated using the similarity. Then, optimization is repeated using an optimization algorithm so that the degree of similarity becomes high. A deformation process such as calculating an optimum displacement amount and displacement direction at the deformation control point set by the optimization process and displacing the position of each pixel in the region surrounded by the deformation control point is performed.
Image deformation parameters for image deformation processing (DIR) include the distance and position between deformation control points, similarity (difference square sum, normalized cross-correlation method, mutual information, etc.), and optimization algorithms (Gradient descent, Downhill simplex etc.).
In this image deformation process (DIR), the interval between the deformation control points in the region of interest (for example, a region such as a pseudo lesion) of the CT image is set shorter than the interval between the deformation control points other than the region of interest. Thus, processing is performed so as to achieve high deformation accuracy with respect to the region of interest.

The treatment plan creation processing unit 514 (dose distribution creation processing unit), based on information such as a radiation treatment policy input by a user such as a doctor, a radiation irradiation position (irradiation region) and a radiation irradiation dose by the radiation therapy device 40. A dose distribution (treatment plan) that defines
The treatment plan creation processing unit 514 (dose distribution creation processing unit) may generate an image in which the dose distribution (treatment plan) is superimposed on the CT image.

The phantom deformation setting processing unit 515 performs a process of setting a phantom deformation amount based on information input by a user such as a doctor. For example, when the piston is driven by the piston driving unit to deform the elastic body of the phantom, the phantom deformation setting processing unit 515 sets the displacement amount of the piston. The phantom deformation setting processing unit 515 drives the piston by the piston driving unit based on the set displacement amount.

The intra-phantom dose identification processing unit 516 performs a process of identifying the radiation dose detected by the radiation dose detection unit 12 accommodated in the phantom via the dose detection unit 31 of the phantom dose detection device 30.

The in-phantom lightweight position specifying processing unit 517 performs processing for specifying the position of the radiation dose detecting unit 12 accommodated in the phantom via the position specifying unit 32 of the phantom dose detecting device 30.

The in-phantom lightweight position specifying processing unit 517 specifies the position of the radiation dose detecting unit 12 accommodated in the phantom via the position specifying unit 32 of the phantom dose detecting device 30. As described above, as a method for specifying the position information of the radiation dose detection unit 12, the position of the radiation dose detection unit 12 of the phantom 10 is optically specified and specified by the CT image of the CT apparatus 20. For example, the radiation dose detection unit 12 may be arranged at a predetermined position and set as the arranged position.

The combined dose distribution generation processing unit 518 deforms the dose distribution generated based on the CT image before the phantom deformation, adds up the dose distribution generated based on the CT image after the phantom deformation, and adds up A process for generating a dose distribution is performed.
In addition, the combined dose distribution generation processing unit 518 adds the dose distribution before phantom deformation (actually measured value by radiation irradiation) and the dose distribution after phantom deformation (actually measured value by radiation irradiation) to obtain the actually measured value by radiation irradiation. A process for generating a total combined dose distribution is performed.

The verification processing unit 519 related to the image deformation process is based on the dose distribution before and after the deformation of the moving object variable phantom (actual value) and the dose distribution before and after the image deformation by the image deformation process of the moving object variable phantom (calculated value). Based on the error calculated in this way, a verification process related to the image deformation process is performed.

The verification processing unit 519 related to the image deformation process includes a comparison processing unit 519a.
The comparison processing unit performs a process of comparing the dose distribution before and after the deformation of the moving object variable phantom (actually measured value) and the dose distribution before and after the image deformation by the image deforming process of the moving object variable phantom (calculated value).

Further, the verification processing unit 519 regarding the image deformation process determines that the image deformation process of the image deformation processing unit 513 (DIR) is highly accurate when the error is within the specified range. It is determined that the accuracy of the image deformation processing of the deformation processing unit 513 (DIR) is low.
When it is determined that the accuracy of the image deformation processing of the image deformation processing unit 513 (DIR) is low, for example, the verification processing unit 519 regarding the image deformation processing adjusts the deformation parameter regarding the image deformation processing of the image deformation processing unit 513 (DIR). By performing the process, the accuracy of the image deformation process is improved.

Next, an example of a phantom CT image and a dose distribution will be described.
FIG. 10 is a diagram showing an example of a phantom CT image and a dose distribution. Specifically, FIG. 10A is a diagram showing an example of a CT image of a phantom before deformation and a dose distribution Pa (treatment plan) in a swelled state, and FIG. 10B is a contracted state and deformed. It is a figure which shows an example of CT image and dose distribution of a later phantom.

The control device performs a CT scan with the CT device on the phantom before deformation in an inflated state, generates the CT image shown in FIG. 10A, and based on the CT image, the dose distribution Pa (treatment (Plan) is generated, and the dose distribution Pa (treatment plan) is superimposed on the CT image. In FIG. 10 (a), the phantom elastic body or the like is shown in the substantially central black part, the concentric dose distribution Pa (treatment plan) is shown near the pseudo lesion (pseudo lesion), the piston is shown in the lower part of the figure, Cylinders (cases) are shown at the left and right ends, an elastic body holding part having a vent hole is shown at the top of the figure, and a fluid such as water is shown between the elastic body and the cylinder.
ing. In the concentric circular dose distribution Pa (treatment plan), the central portion indicates that the radiation dose is higher.

The control apparatus performs a CT scan on the deformed phantom with the CT apparatus using the CT apparatus to generate a CT image shown in FIG. 10B, and based on the CT image, the dose distribution Pb (treatment) (Plan) is generated, and the dose distribution Pb (treatment plan) is superimposed on the CT image. In this case, it is shown that the elastic body of the phantom is contracted and deformed by displacing the piston upward in FIG. Further, the position of the pseudo lesion (pseudo lesion) is shifted, and the position of the concentric dose distribution Pa (treatment plan) is shifted.

FIG. 11 shows an example of a phantom CT image and a dose distribution. Specifically, FIG. 11A is a diagram showing an example of an image obtained by modifying the dose distribution Pa shown in FIG. 10A and an example of the dose distribution, and FIG. 11B is a phantom CT image and the combined dose distribution. It is a figure which shows an example.

The control device performs image deformation processing (DIR) so that the shape and position of the elastic body are matched to the CT image and dose distribution Pa shown in FIG. 10A based on the CT image shown in FIG. ) To generate a CT image (deformed image) and a dose distribution after the image deformation process, as shown in FIG.
Next, the control device determines each dose based on the CT image (deformed image) and dose distribution after the image deformation process shown in FIG. 11A and the CT image and dose distribution shown in FIG. 10B. A process for generating a combined dose distribution by adding the distributions is performed. In addition, the control device generates an image obtained by superimposing the combined dose distribution and the CT image (see FIG. 11B).

FIG. 12 is a diagram illustrating an example of a difference between CT images in a phantom inflated state and a contracted state. In detail, the cross section is shown in the upper diagram of FIG. 12, the coronal surface is shown in the lower left diagram, and the sagittal plane is shown in the lower right diagram.
In FIG. 12, the black portion at the substantially central portion corresponds to an elastic body in a contracted state of the phantom, and the gray portion surrounding the black portion corresponds to an elastic body in a swollen state of the phantom, The white part corresponds to each dose distribution (treatment plan).
As shown in FIG. 12, it can be seen that a deviation occurs when the CT images and dose distributions before and after the deformation of the phantom are superimposed in the carrying order.

FIG. 13 is a diagram illustrating an example of a difference between an image (deformation processed image) obtained by image deformation of a CT image with the phantom inflated by image deformation processing (DIR) and a CT image with the phantom contracted. In detail, the cross section is shown in the upper diagram of FIG. 13, the coronal surface is shown in the lower left diagram, and the sagittal plane is shown in the lower right diagram.
As shown in FIG. 13, the CT image with the phantom inflated is highly accurately deformed by image deformation processing (DIR) so as to match the CT image with the reference phantom contracted. Recognize. It can also be seen that the dose distribution is similarly subjected to image deformation processing with high accuracy.

<Example of operation of radiation therapy system>
An example of the operation of the radiation therapy system will be described with reference to the above drawings and the drawings shown in FIGS. 14 to 17 are diagrams for explaining an example of the operation of the radiation therapy system. In the present embodiment, for example, in the treatment of lung cancer, a case will be described in which the patient's body weight is reduced during the treatment and the patient's body shape is changed.

In step S11, a doctor or the like performs various examinations on the patient, makes a diagnosis based on the examination results, and determines a treatment policy such as radiation therapy.

In step S12, the result of measuring the weight of the patient before treatment was Ma [kg].

In step S13, the control unit 51 of the control device 50 performs a CT scan before starting treatment of the patient using the CT device 20, and stores the obtained CT image in the storage unit.

In step S14, the weight of the patient under treatment was measured and found to be Mb [kg]. In the present embodiment, Ma> Mb, and the weight is decreasing.

In step S15, the control unit 51 of the control device 50 performs a CT scan of the patient being treated by the CT device 20, and stores the obtained CT image in the storage unit.

In step S16, the control unit 51 generates a deformed image by image deformation processing (DIR) using the CT image before the start of treatment of the patient and the CT image being treated.

In step S17, the control unit 51 calculates a change amount of the patient's body shape, a change amount of the lesion (tumor), and the like based on the result of the image deformation process (DIR).

Next, in step S21, the characteristics of the moving object variable phantom 10 are set. Specifically, the density and elastic modulus of the elastic body 11 of the phantom 10 are set to the density and elastic modulus of the elastic body close to the anatomical information such as the treatment site of the patient, for example, the lung, the head and neck, and the pelvis. Further, a simulated tumor (simulated lesion) having a predetermined X-ray absorption coefficient is arranged on the elastic body 11 of the phantom 10.
Then, the radiation dose detection unit 12 and the like are arranged on the phantom 10, and the phantom 10 and the like are arranged on the base unit 25 (bed) of the CT apparatus 20.

In step S22, the control unit 51 sets the movement amount of the piston for deforming the phantom so as to be closest to the change amount of the patient's body shape, the change amount of the lesion (tumor) calculated in step S17 (phantom deformation). Movement setting).

In step S23, the control unit 51 assumes the state of imaging before the start of treatment (S13), and drives and controls the piston drive unit 175 so that the phantom 10 is in an expanded state (before deformation). The position of the piston 16 is adjusted.

In step S24, the control unit 51 performs a CT scan with the CT apparatus 20 with the phantom inflated (before deformation), and stores the obtained CT image in the storage unit (see FIG. 10A).

In step S25, the control unit 51 uses the CT image obtained in step S24 to generate a treatment plan (dose distribution Pa) in the same manner as the treatment plan (dose distribution) of the corresponding patient with the simulated tumor in the CT image as a target. It is created and stored in the storage unit (see FIG. 10A).

In step S26, it is assumed that there is a change in body shape during the treatment and the CT for treatment planning is taken again (step S15), and the control unit 51 causes the piston driving unit 175 to be in a contracted state of the phantom 10. And the position of the piston 16 of the phantom 10 is adjusted by the amount of movement set in step S22. The elastic body and simulated tumor of the phantom 10 are deformed by the force of the piston.

In step S27, the control unit 51 performs a CT scan with the CT apparatus 20 in a state where the phantom is contracted (after deformation), and stores the obtained CT image in the storage unit (see FIG. 10B).

In step S28, the control unit 51 creates a treatment plan (dose distribution Pb) using the CT image obtained in step S27 as a target for the simulated tumor of the CT image, and stores it in the storage unit (FIG. 10B). )reference).

In step S31, in order to calculate the sum of the two dose distributions Pa and Pb, the control unit 51 uses the CT image after the phantom deformation as a reference based on the two CT images before and after the phantom deformation and the dose distribution. The CT image before deformation and the dose distribution Pa created by the CT image (see FIG. 10A) are deformed by image deformation processing (DIR) so as to match the region, and the dose distribution Pa is deformed. A dose distribution (image) and a deformed CT image are generated (step S32) and stored in the storage unit (see FIG. 11A).

In step S33, the control unit 51 adds up the dose distribution obtained in step S28 and the dose distribution obtained in step S31, and adds up the dose distribution obtained by the image transformation process (see FIG. 11B). ) Is generated, stored in the storage unit, and displayed as a dose distribution on the CT image on the display unit (step S34). Then, the control unit 51 evaluates the dose to the tumor and the dose of the surrounding normal tissue based on the combined dose distribution.

As described above, in the moving body variable phantom 10 according to the embodiment of the present invention, the dose distribution in the phantom before and after the phantom deformation can be actually measured. An example of the operation of the radiotherapy system in that case will be described.
Steps S21, S22, S23, and S26 shown in FIG. 16 are the same as the above-described operations, and thus description thereof is omitted.
In step S40, the control unit 51 performs a predetermined operation based on the CT image and the treatment plan (dose distribution Pa) obtained in steps S24 and S25 by the radiotherapy apparatus 40 with the phantom 10 inflated (before deformation). A process of irradiating radiation such as X-rays at a predetermined radiation irradiation dose is performed.

In step S41, for example, the control unit 51 measures the radiation dose by the radiation dose detection unit 12 (such as a dosimeter) provided in the phantom by the dose detection unit 31 of the phantom dose detection device 30.

In step S42, the control unit 51 specifies the position information of the radiation dose detection unit 12 (such as a dosimeter) provided in the phantom by the position specification unit 32 of the phantom dose detection device 30.

A specific example of step S41 and step S42 will be described.
For example, when the phantom shown in FIGS. 3, 4, and 5 is used, each component of the phantom having a multilayer structure is disassembled, and a plurality of dose accumulation type radiation dose detectors 12 arranged in the phantom are taken out, The dose of each radiation dose detector 12 is measured by the dose detector 31 of the phantom dose detector 30. The position information of each radiation dose detection unit 12 in the phantom can be specified by the radiation dose detection unit 12 arranged at a predetermined position of the elastic body of the phantom or a CT image. The position specifying unit 32 of the phantom dose detection device 30 acquires this position information.
After the measurement, each radiation dose detection unit 12 is disposed at a predetermined position of the phantom elastic body.

Further, for example, when the phantom shown in FIG. 6 is used, the wound phantom is expanded, and a plurality of dose accumulation type radiation dose detectors 12 arranged in the phantom are taken out, and the dose detection of the phantom dose detector 30 is performed. The dose of each radiation dose detection unit 12 is measured by the unit 31. After the measurement, each radiation dose detector 12 is placed at a predetermined position on the elastic body of the phantom and is in a wound state. Since the position information is the same as in the above example, the description is omitted.

When the phantom shown in FIG. 7 is used, the two-dimensional radiation dose detector as the radiation dose detector 12 is taken out from the phantom, and the dose of each radiation dose detector 12 is measured by the dose detector 31 of the phantom dose detector 30. To do. Since a two-dimensional distribution related to radiation absorption is obtained by the two-dimensional radiation dose detector, position information is specified based on the distribution, CT image, and the like. After the measurement, each two-dimensional radiation dose detector 12D is arranged at a predetermined position of the phantom elastic body.

When the phantom having the gel-like dosimeter shown in FIG. 8 is used, an altered portion (white cloudy portion) of the gel-like body using an MRI apparatus or a three-dimensional optical scanner as the phantom dose detector 30 (see FIG. 1). Etc. can be measured to obtain a radiation absorbed dose and a three-dimensional distribution (positional information).

In step S43, the control unit 51 generates a dose distribution Qa based on the radiation dose and position information obtained in steps S40 and S42. In this case, the control unit 51 performs a process of superimposing the dose distribution Qa on the CT image in step S24 as necessary.

In step S44, the control unit 51 performs predetermined processing based on the CT image and the treatment plan (dose distribution Pb) obtained in steps S27 and S28 by the radiation therapy apparatus 40 in a state where the phantom 10 is contracted (after deformation). A process of irradiating radiation such as X-rays at a predetermined radiation irradiation dose is performed.

In step S45, for example, the control unit 51 measures the radiation dose by the radiation dose detection unit 12 (such as a dosimeter) provided in the phantom by the dose detection unit 31 of the phantom dose detection device 30.

In step S46, the control unit 51 specifies the position information of the radiation dose detection unit 12 (such as a dosimeter) provided in the phantom by the position specifying unit 32 of the phantom dose detection device 30.

In step S47, the control unit 51 generates a dose distribution Qb based on the radiation dose and the position information obtained in steps S45 and S46. In this case, the control unit 51 performs a process of superimposing the dose distribution Qb on the CT image in step S27 as necessary.

In addition, after irradiating the dose accumulation type (X-ray energy accumulation type) radiation dose detection unit in step S40 and reusing it, in step S44, the radiation dose detection unit is irradiated with radiation. In step S47, a combined dose distribution can be obtained. That is, in this case, the dose distribution in step S47 is set as the total dose distribution without performing the summation process in step S48 (step S49).

For example, in step S40, if a dose storage type (X-ray energy storage type) radiation dose detection unit is irradiated with radiation and then a new radiation dose detection unit is adopted without being reused, the process of step S48 is performed. It needs to be done.
In step S48, the control unit 51 performs a summation process of the dose distribution Qa and the dose distribution Qb to generate a summed dose distribution (step S49).

The combined dose distribution obtained in step S49 is generated based on a measurement value by a radiation dose detection unit such as a dosimeter in the phantom.

Next, in step S51, the control unit 51 includes the combined dose distribution generated based on the calculated value obtained by the image deformation process obtained in step S34, and the dosimeter in the phantom obtained in step S49. The accuracy of the image deformation process is verified by performing a process of comparing the combined dose distribution generated based on the measurement value by the radiation dose detection unit.

In step S52, the control unit 51 performs a process of calculating an error of the image deformation process based on the result of the comparison process.

In step S53, if the error is within a specified value (for example, within 5%), the control unit 51 proceeds to the process of step S56, and otherwise proceeds to the process of step S54.

In step S54, the control unit 51 determines that the error is large, adjusts again the image deformation parameter of the image deformation process and the region of interest used for the deformation, and performs a process of defining the optimum image deformation parameter and the region of interest.

In step S55, the control unit 51 sets the image deformation parameter (parameter) determined in step S54, re-executes the image deformation process in step S31, and performs the processes in steps S32, S34, S51, S52, and S53.

In step S56, the control unit 51 determines that the image deformation processing of the image deformation processing unit 513 (DIR) is highly accurate when the error in step S52 is within a specified value.

In step S57, the control unit 51 performs dose evaluation for the patient based on the treatment plan (total dose distribution) generated in step S34, and performs radiation therapy using the radiation therapy apparatus 40 or the like.

As described above, the moving body variable phantom for the radiation irradiation apparatus according to the embodiment of the present invention includes the deformable elastic body 11 and the radiation dose detection unit 12 provided on the elastic body 11.
Therefore, it is possible to provide a moving body variable phantom capable of detecting a dose distribution (actually measured value) in the phantom before and after deformation with high accuracy.
Moreover, the phantom which can acquire the position of the radiation dose detection part in the phantom before and behind a deformation | transformation with high precision can be provided.
Moreover, in this embodiment, the phantom which can acquire easily the position and dose distribution (actual value) of the radiation dose detection part in the phantom before and behind a deformation | transformation can be provided.
By using this phantom, it is possible to evaluate the accuracy of the combined dose distribution calculated by the image deformation process, and to realize a highly accurate radiation treatment plan.

Further, the elastic body 11 of the moving body variable phantom according to the embodiment of the present invention is formed of a shrinkable material. For this reason, the phantom which can deform | transform an elastic body easily can be provided.

In addition, the elastic body of the variable moving phantom according to the embodiment of the present invention has a multilayer structure that can be disassembled and assembled (see, for example, FIGS. 3, 4, and 5).
For this reason, the phantom which can arrange | position a some radiation dose detection part to the elastic body of a multilayer structure easily three-dimensionally can be provided.
For example, even when radiation is applied to the moving object variable phantom a plurality of times, the radiation dose detection unit can be easily attached to and detached from the phantom.
It has a structure in which a plurality of small radiation dose detection units are arranged, and doses before and after deformation, which has been difficult in the past, can be easily measured. In addition, the elastic body can be deformed even when the radiation dose detection unit is arranged, and the combined dose before and after the deformation can be measured with the detector attached.

Moreover, the elastic body of the moving body variable phantom according to the embodiment of the present invention has a nested structure including a member having a hole and a member that can be accommodated in the hole (for example, FIGS. 3 and 4). , See FIG. Specifically, the member having the hole portion of the elastic body of the nested structure is formed in a cylindrical shape or a hemispherical shape. An ionization chamber dosimeter used for a normal radiation dose detector (a cable and an electric circuit are included in the detector) is not a small detector, and there are cables, etc., so there is an elastic body with the detector attached. It was difficult to deform. However, this elastic body can easily arrange a plurality of small radiation dose detection units three-dimensionally in the elastic body, and can measure a three-dimensional dose distribution in the elastic body. Moreover, a radiation dose detection part can be easily removed after a measurement. Since the nested structure can be used not only in a cylindrical shape but also in a hemispherical shape, it can be used for three-dimensional dose distribution measurement of an elastic body simulating a tumor.

Further, the elastic body of the moving body variable phantom according to the embodiment of the present invention is configured to be wound in a roll shape (see FIG. 6). In this case, the radiation dose detector can be easily installed on the elastic body in a state where the elastic body is expanded in a plate shape, and a plurality of radiation dose detectors are three-dimensionally wound by winding in a roll shape. The radiation dose detector can be easily removed by deploying the elastic body into a plate shape after measurement. In the case of a roll, as in the case of the nested structure, a plurality of small radiation detection units can be easily arranged three-dimensionally in the elastic body, and the three-dimensional dose distribution in the elastic body can be measured. Furthermore, in the case of a roll, it is easier to install and remove a small radiation detection unit, and the measurement can be performed efficiently.

In addition, the elastic body of the variable moving phantom according to the embodiment of the present invention has a hole portion that detachably holds the radiation dose detection unit (see, for example, FIGS. 4 and 5).
For this reason, a radiation dose detection part can be easily attached or detached to the elastic body of a phantom.

In the embodiment of the present invention, the radiation dose detector is a dose accumulation type (exposure dose accumulation type).
For this reason, the phantom which can obtain the total dose distribution in a phantom easily can be provided by detecting multiple times of radiation irradiation by a dose accumulation type radiation dose detection part.

Moreover, in the case of the phantom which employ | adopted the several glass dosimeter as a radiation dose detection part, the radiation dose in a phantom can be detected with high precision by simple structure.
As a comparative example, an ionization chamber dosimeter used for a normal radiation dose detector (a cable and an electric circuit are included in the detector) has a detector that is not small and has a cable. It was difficult to deform the elastic body in the state.
The glass dosimeter used in the embodiment of the present invention is, for example, a rod-shaped element having a diameter of 1.5 mm and a length of 12 mm, and is one of the smallest dosimeters. By using a plurality, the three-dimensional dose distribution inside the phantom can be measured with high accuracy.

Further, in the case of a phantom in which a plurality of small glass dosimeters are provided on a deformable elastic body, the radiation dose in the phantom can be detected with high accuracy even when the phantom is deformed.

In addition, information on positional changes of resin-made microspheres (beads) and glass dosimeters (glass dose elements) linked to phantom deformation is monitored with CT images from a CT device, and dose before and after phantom deformation. The dose distribution of the tissue can be accurately evaluated by adding the dose values measured by the meter.
Specifically, glass dosimeters (glass dose elements) are made of glass with a density of 2.61 g / cm ³ and, unlike other radiation detectors, are not metal structures, so metal artifacts on CT images Since (virtual image) does not occur, the position of the glass dosimeter (glass dose element) can be accurately specified.

In addition, according to the present embodiment, by adopting the moving body variable phantom according to the embodiment of the present invention as a simulated organ having a simulated tumor (simulated lesion) having a prescribed radiation absorption coefficient, It is possible to calculate the planned dose distribution of specific radiotherapy.
That is, it is possible to provide a phantom that can easily calculate the planned dose distribution of radiotherapy specific to the organ to be treated.

In addition, in the case of a phantom in which a plurality of two-dimensional radiation dose detectors (imaging plates or the like) are provided as a radiation dose detection unit on an elastic body, in detail, a plurality of slits ( A two-dimensional radiation dose detector is detachably disposed in the slit (see, for example, FIG. 7). With this slit structure, a three-dimensional radiation dose distribution can be easily calculated based on two-dimensional radiation dose distributions detected by a plurality of two-dimensional radiation dose detectors. Moreover, since it has a slit structure, it is easy to remove the two-dimensional radiation detector. By arranging the two-dimensional radiation dose detector perpendicularly to the deformation direction, it is possible to measure while deforming the phantom, and it is possible to accurately measure the dose before and after the deformation of the phantom.

In the case of a phantom having a gel dosimeter (such as a polymer gel dosimeter) held by a deformable elastic body, the phantom has a structure that holds the gel dosimeter in the elastic body. The gel-type dosimeter is a three-dimensional radiation dose measuring device, and the three-dimensional radiation dose distribution in the phantom can be easily detected by using an MRI apparatus or an optical CT apparatus after irradiation. The three-dimensional dose distribution in the phantom can be measured with higher accuracy than the three-dimensional dose distribution calculated using a plurality of glass dosimeters and two-dimensional radiation measuring instruments. In addition, since it has a gel-like structure, even when the phantom is deformed, the shape of the dosimeter can be deformed in accordance with the deformation, and measurement can be performed while the phantom is deformed. The three-dimensional dose distribution before and after can be measured with high accuracy.

Also, the elastic body may be formed in a sponge shape and have a structure in which a gel dosimeter is absorbed and held. For example, in the method of holding the gel dosimeter in an elastic body, the gel dosimeter may not be deformed well with respect to the deformation of the phantom. On the other hand, in a structure in which the elastic body is formed in a sponge shape and the gel dosimeter is absorbed and held, the gel dosimeter is successfully deformed according to the deformation of the elastic body by absorbing the gel dosimeter into the sponge. Therefore, the elastic body can be greatly deformed. Further, the structure in which the polymer gel is absorbed and held in the sponge can be easily handled during transportation.

In addition, the radiation treatment plan creation method using the moving body variable phantom according to the embodiment of the present invention includes the step of setting the characteristics of the elastic body of the moving body variable phantom according to the stage of radiation therapy (S21), And a step (S22 to S49) of detecting a radiation dose using a moving body variable phantom and creating a radiation treatment plan (dose distribution) for defining a radiation irradiation position and a radiation irradiation dose based on the detection result. Therefore, it is possible to provide a radiation treatment plan creation method using a moving object variable phantom capable of creating a highly accurate radiation treatment plan (dose distribution).
In this case, by using the moving object variable phantom, it is possible to calculate the radiation therapy planned dose distribution with high accuracy without depending on the image deformation processing of the CT image.

Further, the program according to the embodiment of the present invention is a program that is executed by a control device that is a computer, and uses a moving body variable phantom, and dose distribution based on CT images of the phantom before and after deformation of the elastic body. A first combined dose distribution (see S34) generated by applying image deformation processing (DIR) to one of the two and adding the other to the other, and a radiation dose detection unit provided in the phantom before and after the deformation of the elastic body ( A step (S52) of calculating an error from the second combined dose distribution (see S49) generated according to the detection result of the irradiation dose (radiation dose) by the irradiation dose detection unit), and an image transformation process ( (S54) for defining deformation parameters relating to DIR).
Therefore, it is possible to provide a program that can easily adjust the image deformation parameters related to the image deformation processing with high accuracy.

Also, a CT device, a radiation treatment device, a control device (computer), etc. used in the radiation treatment system are checked for normal operation using a phantom or the like for each radiation treatment. By using the moving body variable phantom according to the embodiment of the present invention, it is possible to easily check whether each device operates normally and adjust various parameters in a short time with high accuracy.

As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to these embodiments, and there are design changes and the like without departing from the gist of the present invention. Is included in the present invention.
Further, the embodiments described in the above drawings can be combined with each other as long as there is no particular contradiction or problem in the purpose and configuration.
Moreover, the description content of each figure can become independent embodiment, respectively, and embodiment of this invention is not limited to one embodiment which combined each figure.

For example, in the above-described embodiment, the radiotherapy system includes the radiotherapy apparatus, the CT apparatus, and the control apparatus (computer), but is not limited to this form. The radiotherapy system may centrally control the radiotherapy apparatus, the CT apparatus, and the like by a plurality of control apparatuses (computers) that can communicate with each other.

In the phantom of the embodiment shown in FIG. 2 and the like, an elastic body 11 such as a sponge is disposed in a cylindrical cylinder 15, and a liquid (water or the like) or gas is placed in a space surrounded by the cylinder 15 and the piston 16. However, the present invention is not limited to this configuration.
For example, as shown in FIGS. 18 and 19, the phantom is provided with a cylindrical elastic body 11B (11) such as sponge in a cylindrical cylinder 15B (15) made of resin such as acrylic, and the cylinder 15B. (15) The liquid may not be provided in the inside. This elastic body is provided with a radiation dose detector.
In the example shown in FIGS. 18 and 19, the piston 16 is provided so as to be able to move one-dimensionally in the axial direction of the cylindrical cylinder 15B (15), and the piston 16 is a cylindrical elastic body 11B (11). Is pressed in the axial direction, the elastic body 11B (11) is configured to be compressible (see FIG. 19B). From this state, as shown in FIG. 19A, when the piston 16 returns to the initial position, the elastic body 11B is restored to the original state.

Specifically, the phantom 10 is configured to be able to press the piston rod 17 and the piston 16 by moving the movable portion 175K in the axial direction of the cylindrical portion by the drive motor 175M of the piston drive portion 175. In addition, a vertically moving member 172 (stage) is disposed in the phantom so as to freely move up and down, and the vertically moving member 172 is connected to the movable portion 175K by a link 174L. That is, the vertical movement member 172 (stage) is configured to move up and down in conjunction with the movement of the movable portion 175K, the piston rod 17, and the piston 16. Moreover, the phantom of this embodiment detects the position of the upper end part 172a of the vertical movement member 172 with an imaging part, a position sensor, etc., The displacement, position, etc. of the piston 16 by displacement of the vertical movement of the vertical movement member 172 etc. Is configured to be detectable.

As shown in FIGS. 18 and 19, the elastic body 11 B (11) is compressed or expanded in the axial direction by the movement of the piston 16 in the axial direction, and the movement in the direction orthogonal to the axial direction is a cylindrical cylinder. Since it is restricted by the inner wall of 15B (15), the reproducibility of the deformed state or the original state of the elastic body 11B (11) is high.
That is, by using this highly reproducible phantom for verifying the accuracy of image deformation processing by a computer, highly reliable verification can be performed.

The phantom 10 is not limited to the above-described embodiment, and may be configured to be deformable by a plurality of pressing mechanisms as shown in FIG. 20, for example.
Specifically, in the example shown in FIG. 20, the cylindrical elastic body 11B (11) is arranged in the cylindrical cylinder 15B (15), and can be pressed in the axial direction at both axial ends thereof.

Pistons

16A and 16B may be provided. The

pistons

16A and 16B are configured to be movable in the axial direction by a piston rod or a piston driving unit (not shown).

Further, in the example shown in FIG. 20, the

pistons

16A and 16B are respectively constituted by a plurality of small pistons 16Aa and 16Ba, and the elastic body 11B (by the predetermined pistons 16Aa and 16Ba is controlled by a control device (computer). 11) The both ends of 11) can be locally pressed. That is, the elastic body 11B (11) is configured to be two-dimensionally deformable, and verification of image deformation processing by a computer can be performed with high accuracy.

Further, for example, as shown in FIG. 21, the phantom 10 may have a plurality of pressing mechanisms in the axial direction and the orthogonal direction of the cylinder 15B (15). Specifically, in the example shown in FIG. 21, the elastic body 11 B (11) has a plurality of pistons 16 Aa, 16 Ba, a piston rod 17 (rod), and a piston driving unit 175 that can locally press both ends of the elastic body 11 B (11). A plurality of movable portions 177 that can press the side surface of the elastic body 11B (11) in a direction orthogonal to the axial direction are disposed on the side surface of the cylindrical cylinder 15B (15). The movable part 177 is configured to be movable by a drive part 178 and a connection part 179. As a driving method of the movable part 177, for example, a predetermined driving method such as a pneumatic driving method, a hydraulic driving method, a driving method using a link mechanism, or the like can be adopted. In order to reduce the influence of absorption of X-rays radiated from the X-ray generation unit 21 toward the X-ray detection unit 22, a material having a low X-ray absorption rate is provided on the side of the cylindrical cylinder 15B (15). It is preferable to provide the movable part 177 formed by the above and arrange the driving part 178 and the like outside the X-ray irradiation region. Moreover, when a link mechanism is employ | adopted, it is preferable to form a link mechanism with resin materials, such as an acryl. Moreover, you may employ | adopt the drive system using water, gas, etc. with a low X-ray absorption factor.

10 ... Phantom (movable body variable type phantom)
DESCRIPTION OF SYMBOLS 11 ... Elastic body 12 ... Radiation dose detection part (irradiation dose detection part)
13 ... Balloon 14 ... Fluid (liquid, gas, etc.)
15 ... Cylinder (case)
DESCRIPTION OF SYMBOLS 16 ... Piston 17 ... Piston rod 18 ... Elastic body holding part 19 ... Lid part 20 ... CT apparatus 30 ... Phantom dose detection apparatus 31 ... Dose detection part 32 ... Position specification part 40 ... Radiation therapy apparatus 50 ... Control apparatus (computer)
100 ... Radiation therapy system

Claims

A moving body variable phantom for a radiation irradiation device,
A deformable elastic body;
And a radiation dose detection unit provided on the elastic body.
The moving body variable phantom according to claim 1, wherein the elastic body is made of a shrinkable material.
The moving body variable phantom according to claim 1 or 2, wherein the elastic body has a multilayer structure that can be disassembled and assembled.
The moving body variable phantom according to claim 3, wherein the elastic body has a nested structure including a member having a hole and a member that can be accommodated in the hole.
5. The moving body variable phantom according to claim 4, wherein the member having a hole portion of the elastic body of the nested structure is formed in a cylindrical shape or a hemispherical shape.
The moving body variable phantom according to claim 1 or 2, wherein the elastic body is configured to be freely wound in a roll shape.
The moving body variable phantom according to any one of claims 1 to 4, wherein the elastic body has a hole for detachably holding the radiation dose detection section.
The moving body variable phantom according to any one of claims 1 to 7, wherein the radiation dose detection unit has a dose accumulation type.
The moving body variable phantom according to any one of claims 1 to 8, wherein the radiation dose detection unit is a plurality of glass dosimeters.
The moving body variable phantom according to claim 1 or 2, wherein the elastic body is provided with a plurality of two-dimensional radiation dose detectors as the radiation dose detector.
The elastic body has a plurality of slits,
The moving body variable phantom according to claim 10, wherein the two-dimensional radiation dose detector is configured to be detachably disposed in the slit.
3. The moving body variable phantom according to claim 1, further comprising a gel dosimeter held by the deformable elastic body.
13. The moving body variable phantom according to claim 12, wherein the elastic body has a structure in which a gel dosimeter is accommodated.
The moving body variable phantom according to claim 12, wherein the elastic body is formed in a sponge shape and has a structure in which a polymer gel of a gel dosimeter is absorbed and held.
A radiation treatment plan creation method using the moving object variable phantom according to any one of claims 1 to 14,
Setting the characteristics of the elastic body of the variable moving phantom according to the stage of radiation therapy;
A radiation treatment plan creating method comprising: detecting a radiation dose using the moving body variable phantom; and creating a radiation treatment plan for defining a radiation irradiation position and a radiation irradiation dose based on the detection result. .
Using the moving body variable phantom according to any one of claims 1 to 14, image deformation processing is performed on one of dose distributions based on CT images of the phantom before and after deformation of the elastic body, and the other is added to the other And the second combined dose distribution generated according to the detection result of the irradiation dose by the irradiation dose detector provided in the phantom before and after the deformation of the elastic body. Calculating an error;
Defining a deformation parameter for the image deformation process based on the error;
A program that causes a computer to execute.