JPH1128252A - Forming method and forming device for radiation field - Google Patents

Abstract

PROBLEM TO BE SOLVED: To set a radiation region in a short time and accurately by utilizing a tomographic image photographed by a section photographing device different from a radiographic section photographing device at the time of curing planning to obtain the shape of a diseased part of a section different from the same section in a radiotherapy device adapted to apply radiaton to the diseased part. SOLUTION: This device includes a slide mechanism 245 for moving a multileaf collimator 235 having a leaf moving mechanism for sliding each leaf in the direction along the beam radiation shaft and a rotating device 242 for rotating the same round the beam radiation shaft. The same section as the section of a diseased part photographed by a radiographic section photographing device is photographed by a different section photographing device, the center point of the shape of the diseased part on an image of the photographed same section is obtained, and the distance from the center point to the respective points on the selected contour line is enlarged or reduced to obtain the corresponding points of the respective points on the contour. After that, the respective corresponding points obtained on the image of the same section are connected to each other in order to obtain the shape of the diseased part of a section different from the same section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiotherapy apparatus having a function of accurately irradiating a required amount of radiation to an affected part, for example. Related to device technology.

[0002]

2. Description of the Related Art As a conventional radiation therapy apparatus, an example of a proton therapy apparatus for generating radiation by accelerating a proton beam will be described based on a proton therapy apparatus described in Japanese Patent Publication No. 7-32806.

FIG. 28 is a block diagram of a conventional proton beam therapy system. The proton beam therapy system includes a beam transport system 12, a proton accelerator 10, and a medium energy beam transport system 16. The proton accelerator 10 is composed of a hexagonal synchrotron and has a high-frequency accelerator 14.

[0004] In order to allow the protons to reach the deep treatment area for treatment, protons having a required beam intensity are supplied to the proton accelerator 1.
At zero, it is necessary to accelerate to the required energy. In addition,
FIG. 29 is a diagram viewed from the direction of the beam transport system aa in FIG. 28.

For example, in order for protons to reach a depth of 32 cm in the body, 230 MeV of energy is required. The operation of the proton beam therapy system for accelerating protons up to such energy will be described below.

FIG. 30 is a block diagram of an irradiation controller 34 for controlling the irradiation of protons of the proton beam therapy system. Here, the irradiation controller 34 controls the first treatment room 24 so that
In the case where a set of irradiation control devices is installed, a detailed configuration of a vertical upward device that controls a beam from the vertical upward beam transport system 18 as a representative thereof is shown.

The same applies to the other two sets for controlling the beam of the vertical beam transport system 20 and the beam of the horizontal beam transport system 28. These other two sets are designated by reference numerals 70,72.

A patient 38 is fixed on a central treatment table 36 so that the treatment area is aligned with the central axis of each irradiation control device. The confirmation of the position is performed by moving the X-ray tube 39 and the image intensifier (II) 40 coaxially.

The irradiation field of the proton beam is formed by scanning the fine bundle proton beam with the scanning electromagnet 42 and enlarging the beam by the primary scatterer 44. This is performed by forming the above distribution.

Confirmation of the spread of the beam for forming the irradiation field on the patient surface is performed using the light irradiation field mirror 80. The range adjustment in the beam axis direction is attenuated by the energy fine adjuster 48 to energy corresponding to the required internal range, and the ridge filter 50 is adjusted so that the dose peak width matches the treatment region thickness.
Select to expand its width.

A bolus 82 is provided to adjust the energy of the proton beam in accordance with the shape of the surface of the patient and the treatment area, and the depth of the heterogeneous treatment area in the body.
The thickness of the bolus 82 varies depending on each position, and the energy of the proton beam is absorbed by passing the proton beam through each position.

The shape of the block collimator 52 and the opening shape of the final collimator 54 are adjusted to match the shape of the treatment area. Ridge filter 50 and energy fine adjuster 4
8, a monitor ionization chamber 90 is provided.

The monitor ionization chamber 90 functions as a part of the dose monitoring unit. When the integrated value of the amount corresponding to the output current exceeds the preset value corresponding to the expected dose, an irradiation stop signal is generated and the proton beam is generated. Irradiation is stopped. These controls are performed by a computer (not shown).

Note that a shutter mechanism 84 and a shielding block 86 are provided for the treatment room where irradiation with proton beams is not performed.

The arrangement state, conditions, and the like of the above-described components provided in the irradiation apparatus are adjusted according to the state of the patient 38. Although this adjustment can be performed manually, it is preferable that the adjustment be automatically performed by a computer based on patient data.

If the synchrotron is hexagonal, for example, it is easy to design a high-performance, strong convergence type as compared with a square-shaped one, and it is possible to extract various beams by increasing the number of linear portions. The beam transport system 12 includes a vertical upward beam transport system 18, a vertical downward beam transport system 20, and a horizontal beam transport system 28.

[0017]

In the conventional proton beam therapy system, in order to improve the efficiency of irradiation that the dose is intensively administered to the treatment area and to eliminate the waste of giving radiation to peripheral areas other than the treatment area. The isocenter is the center of the affected area (the center of the affected area)
It is necessary to accurately set the treatment region in accordance with the condition, and it is desirable that the region to be irradiated with the radiation be grasped quickly.

The present invention has been made in order to solve such a problem. For example, when a treatment plan is used, a tomographic image photographed by a cross-sectional imaging apparatus different from a radiation cross-sectional imaging apparatus is used to accurately treat a patient. An object of the present invention is to provide a method and an apparatus for forming an irradiation field, in which a region can be drawn quickly and an irradiation field irradiated with radiation can be easily obtained.

[0019]

According to the present invention, there is provided a method for forming an irradiation field, wherein the same cross section as the cross section of an affected part taken by a radiation section imaging apparatus is imaged by a different section imaging apparatus different from the radiation section imaging apparatus. A second step of obtaining a center point of the affected part shape on the image of the same cross section taken in the first step; and a second step of selecting a plurality of points from the contour line of the affected part shape on the image of the same cross section. In the step 3, the distance from the center point of the affected part shape to each point on the contour line selected in the second step on the image of the same cross section is enlarged or reduced by a predetermined size, and each of the distances on the contour line A fourth step of obtaining corresponding points of the points, and a fifth step of sequentially connecting the corresponding points obtained in the fourth step on the image of the same cross section to obtain a diseased part shape of a cross section different from the same cross section It becomes.

In the first step, instead of photographing the same cross section as the cross section of the affected part taken by the radiation cross section photographing apparatus with a cross sectional photographing apparatus different from the radiation cross section photographing apparatus, the cross section is positioned at each of the cross sectional positions sandwiching the cross section of the affected part. An image generated based on an image photographed by the photographing device is an image of the same cross section.

Before the first step, if the number of pixels of the image of the same cross section is different from the number of pixels of the radiation tomographic image,
The method includes a step of matching the number of pixels of the image of the same cross section with the number of pixels of the radiation tomographic image.

Before the first step, a step of correcting distortion of at least one of the radiation tomographic image obtained by imaging the cross section of the affected part and the image of the same cross section is performed based on a distortion correction amount obtained in advance. It is provided.

Further, after the fifth step, there is provided a step of correcting the affected part shape determined in the fifth step based on a newly designated point on the radiation tomographic image.

An irradiation field forming apparatus according to the present invention is a multi-leaf collimator having a leaf moving mechanism for slidingly moving each leaf, and a multi-leaf collimator moving mechanism for moving the multi-leaf collimator in a direction along a beam irradiation axis. And a multi-leaf collimator rotation mechanism that rotates the multi-leaf collimator about the beam irradiation axis, and a cross-sectional imaging device different from the radiation cross-sectional imaging device is used to image the same cross-section as the cross-section of the affected part taken by the radiation cross-sectional imaging device Find the center point of the affected part shape on the image of the same cross section, select a plurality of points on the contour line of the affected part shape on the image of the same section, and on the contour line selected from the center point of the affected part shape on the image of the same cross section The distance to each point is enlarged or reduced by a predetermined size, and the corresponding point of each point on the contour is The corresponding points obtained on the image of the same cross-section are connected in sequence to obtain a diseased part shape of a cross-section different from the same cross-section. And a controller that determines the amount of sliding movement of the multi-leaf collimator by the multi-leaf collimator moving mechanism and the amount of rotation by which the multi-leaf collimator rotating mechanism rotates the multi-leaf collimator.

In addition, the graphic processing apparatus uses a cross-sectional imaging device different from the radiation cross-sectional imaging device to image the same cross-section as the cross-section of the affected part taken by the radiation cross-sectional imaging device. An image generated based on an image captured by the device is an image of the same cross section.

Further, the graphic processing device matches the number of pixels of the image of the same cross section with the number of pixels of the radiation tomographic image when the number of pixels of the image of the same cross section is different from the number of pixels of the radiation tomographic image. is there.

The graphic processing apparatus first performs distortion correction on at least one of a radiation tomographic image obtained by imaging a cross section of an affected part and an image of the same cross section based on a distortion correction amount obtained in advance. .

Further, the graphic processing apparatus finally corrects the obtained affected part shape based on the position newly specified in the radiation tomographic image.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1 FIG. 1 is an explanatory diagram of a method of forming an irradiation field according to Embodiment 1, in which 101 indicates an affected part,
Reference numeral 102 denotes an X-ray CT image (tomographic image) group including slices 1 to 5 obtained by imaging a tomographic image of the affected part at a pitch of several mm using an X-ray imaging apparatus (not shown).

Normally, since the three-dimensional shape of the diseased part 101 changes continuously and gradually, the contour (shape) of the diseased part in a certain slice n is uniformly enlarged or reduced to obtain the shape of the diseased part in the slice n. Can be approximated to the shape of the affected part in slice n + 1 which is the slice (tomographic slice) adjacent to slice n.

Here, the procedure for obtaining the required shape of the affected part at slice n + 1 from the shape of the affected part at slice n by the first method is obtained based on FIGS. 2 and 3, and by the second method. The procedure will be described with reference to FIGS. 4 and 5, respectively.

In FIGS. 2 and 4, reference numeral 121 denotes a contour line of the affected part in slice n, and 122 denotes a slice n + 1 obtained by uniformly enlarging or reducing the shape of the affected part in slice n around an isocenter described later. And 123, a contact point o between a line obtained by extending the isocenter (focal point for irradiating radiation), which is the center of the affected part, in the radiation irradiation direction and slice n
Is shown.

First, a procedure for obtaining the shape of the affected part in slice n + 1 by the first method based on the shape of the affected part in slice n will be described with reference to FIG. The first method is based on the premise that the shape of the affected area in the slice is enlarged or reduced at a fixed rate around the center point of the shape.

In order to find the center of the shape of the affected part 101 in the slice n + 1, an intersection point p between the line extending the focal point of the beam in the irradiation direction of the radiation and the slice n is determined, and this is determined as the center point of the shape of the affected part in the slice n + 1. (Step S1
1). Here, the center point of the shape of the affected part in slice n is made to coincide with the center point of the shape of the affected part in slice n + 1.

Next, a plurality of points of interest (p ₁ , p ₂ , p ₃ , p ₄ ,...) On the outline of the affected part in slice n are selected (step S12). It is desirable to select many points of interest at as small an interval as possible.

Further, for each of these selected points of interest, the distance from the center point o to the point of interest is determined by changing the distance from the center point to the point of interest at a certain ratio proportional to the distance from the center point o to the point of interest. The corresponding point in slice n + 1 of the point of interest is obtained by enlarging or reducing on the extension line (step S13).

Finally, by connecting these corresponding points in the slice n + 1 in order, a contour line of a corresponding affected part in the slice n + 1 is obtained (step S14). In this way, the required shape of the affected part at slice n + 1 can be obtained.

In FIG. 2, the distance from the center point o to the point of interest is
The constant ratio k for expanding or reducing is b ₁/ A₁= B_Two/ A_Two=
b_Three/ A_Three= B_Four/ A_Four= ... = k₁And slice
The shape of the affected part on the X-ray CT image at n + 1 is the actual affected part
May be appropriately adopted so as to most closely approach the shape of.

Next, a procedure for obtaining the shape of the affected part in slice n + 1 by the second method based on the shape of the affected part in slice n will be described with reference to FIG. The second method is based on the premise that the shape of the affected part in the slice is enlarged or reduced by a certain size around the center point of the shape.

An intersection point p between a line obtained by extending the isocenter, which is the center of the diseased part 101, in the radiation irradiation direction and the slice n is determined, and this is set as the center point of the shape of the diseased part in the slice n + 1 (step S11). Here also, the center point of the shape of the affected part in slice n and the center point of the shape of the affected part in slice n + 1 are matched.

Next, a plurality of points of interest (p ₁ , p ₂ , p ₃ , p ₄ ,...) On the outline of the affected part in slice n are selected (step S12). It is desirable to select many points of interest at as small an interval as possible. Up to this step, the procedure is the same as the procedure of the first method described above. The procedure of the next step is different.

Further, for each of the selected points of interest, a line segment from the center point o to the point of interest is extended to consider an extension line, and a position on the extension line separated by a certain distance c from the point of interest is determined. The slice n of the point of interest is
A corresponding point at +1 is obtained (step S23).

Finally, by connecting these corresponding points in the slice n + 1 in order, a contour line of the corresponding affected part in the slice n + 1 is obtained (step S14). In this way, the required shape of the affected part at slice n + 1 can be obtained.

In FIG. 3, the fixed distance c that extends the line segment from the center point o to the point of interest and determines the position on the line segment distant from the point p from the point p is f ₁ −e ₁ = f ₂ −e ₂ = f ₃ −e ₃ =
f ₄ −e ₄ =... = c and CT of slice n + 1
What is necessary is just to employ | adopt the distance which the shape of the affected part on an image approaches the shape of the actual affected part most.

Then, based on the shape of the affected part obtained by the first method or the second method, an irradiation field may be formed as described later.

Therefore, according to the first embodiment, even if there is no image of the affected part at the target tomographic position, or even if the affected part is not intentionally photographed at that position, the affected part of the image at the adjacent tomographic position can be obtained. By utilizing the fact that the shape of the (treatment region) is similar, the shape of the affected part at the target tomographic position can be quickly obtained from the image of the adjacent tomographic position.

Embodiment 2 6 and 7 are explanatory views of the irradiation field forming method according to the first embodiment. In the first embodiment, it is assumed that the center point of the shape of the affected part in slice n and the center point of the shape of the affected part in slice n + 1, that is, the position of the isocenter, match.

However, since the shape of the diseased part 101 differs depending on the slice, in some cases, the center point of the shape of the diseased part in slice n is slightly shifted from that used as the center point of the shape of the diseased part in slice n + 1. In some cases, it is more appropriate to determine the position as the center point.

Therefore, when determining the shape of the affected part in slice n + 1, the center point of the shape of the affected part in slice n + 1 is determined, for example, at a position that becomes the center of gravity of the shape. A new point may be specified using a device.

For example, in the case of the first and second methods shown in the first embodiment, as shown in FIGS. 6 and 7, the center of the shape of the affected part at slice n + 1 is shifted from point o ₁ to point o. ₂ , the corresponding point in slice n + 1 corresponding to the point of interest in slice n is moved by the amount of vector from point o ₁ to point o ₂ , and the position is changed to a new corresponding point. Position.

Therefore, in the case of the first method shown in the first embodiment, the distance between the steps S13 and S14 is 6; in the case of the second method, the distance between the steps S23 and S14. , The corresponding point in slice n + 1 corresponding to the point of interest in slice n is set to the center point o _1.
Then, a process is performed to move the position to the center point o ₂ by the amount of the vector and set that position as the position of a new corresponding point (step S25 in FIG. 8).

Therefore, as a result of newly moving these corresponding points by the amount of the vector, in the case of the first method shown in Embodiment 1, as shown in FIG. 6, f ₁ / e ₁ = f ₂ / e ₂
= F ₃ / e ₃ = f ₄ / e ₄ =... = K, and in the case of the second method shown in the first embodiment, as shown in FIG.
₁₋ e ₁ = f ₂ −e ₂ = f ₃ −e ₃ = f ₄ −e ₄ =... = C.

As the fixed ratio k and the fixed distance c, a distance at which the shape of the affected part on the CT image of slice n + 1 comes closest to the actual shape of the affected part may be used.

Therefore, according to the second embodiment, even if there is no image of the affected part at the target tomographic position, or even if the affected part is not intentionally photographed at that position, the affected part of the image at the adjacent tomographic position can be obtained. By utilizing the fact that the shape of the (treatment area) is similar, it is possible to quickly obtain the shape of the affected part at the target tomographic position where the isocenter position is a desired position from the image of the adjacent tomographic position.

Embodiment 3 In X-ray CT imaging, the dose applied to the cross-section of the affected part, which is the imaging target, is a function of the area of the affected part area in that cross-section and the density of the radiation, which is a function of the position of the cross-section actually applied to the cross-section. It can be obtained by multiplication.

By the way, grasping (calculation) of the dose irradiated to the affected part is performed based on the X-ray CT image at the time of the irradiation. In general, the shape of the affected part is more visible in the MRI image than in the X-ray CT image. Since it is possible to take images so clearly that they can be easily identified, it is possible to use the MRI image of the same cross section as that of the X-ray CT image only to grasp the area of the affected area required in a certain X-ray CT image. , That is, the dose irradiated to the affected part can be accurately obtained.

In FIG. 9, reference numeral 130 denotes an X-ray CT image of the affected part in a certain slice (cross section);
MRI images obtained by imaging the affected part with slices (same cross-section) equal to the image 130, and 130a and 131a are regions of interest (such as the affected part) in the X-ray CT image 130 and the MRI image 131 as the affected part or the organ of interest, respectively. shape)
It is.

In a certain slice, an MRI image 131 is photographed by an MRI photographing apparatus (not shown) so that the region of interest can be easily identified with the naked eye, and the boundary of the region of interest 131a is extracted on the MRI image 131.

Here, as a method of extracting the boundary of the region of interest 131a on the MRI image 131, for example, a region of interest 1 is extracted using a pointing device such as a mouse.
A method of determining a boundary by specifying a large number of positions on the boundary line of the boundary line 31a and determining whether the luminance data at the specified position is the same level of luminance data for each pixel, or an MRI image 131 using a pointing device Affected part 1 on
It is conceivable to use various methods using an already known image recognition processing technique, such as a method of obtaining a boundary by tracing the boundary line 01.

In this manner, M obtained by photographing a certain slice
An X-ray CT image 130 obtained by capturing the same slice as a boundary line of the region of interest 131a extracted on the RI image 131
Region of interest 13 on the X-ray CT image 130
0a is created.

The X-ray C obtained by photographing the cross section of the affected part 101 in the same slice as the MRI image 131 in this manner
On the T image 130, the required shape of the affected part 101 and the radiation dose actually irradiated can be obtained.

If the shape of the affected part in another slice can be obtained from an MRI image obtained by capturing a certain slice, the shape of the affected part in another slice, that is, the irradiation field, can be changed based on the image. Can be obtained according to the procedure described above.

If irradiation is to be performed on the diseased part 101 in the slice, an irradiation field may be formed based on the shape of the diseased part thus obtained, as described later.

In the third embodiment, the case where the boundary of the region of interest is extracted based on the MRI image has been described. However, in addition to the MRI image, PET (Position Emission) may be used.
Tomography) image, CR (Compute)
An image obtained by photographing a cross section of the affected part more clearly than an X-ray CT image, such as a (d Radiography) image, can be used.

Therefore, according to the third embodiment, the target to be irradiated is obtained by using the MRI image in which the shape and the position of the affected part can be easily identified.
Since the position of the target can be easily set on the T image,
The treatment position can be accurately specified in a short time, and X-ray irradiation can be performed accurately, thereby increasing the treatment effect.

Embodiment 4 In the third embodiment, an MRI image is used to grasp the area of the affected area required in the X-ray CT image obtained by imaging the affected part, and the MRI image has the same cross section (the same slice) as the X-ray CT image A photograph of the affected area is used.

However, generally, an X-ray C
The pitch (slice pitch) interval of the T image does not always coincide with the pitch interval of the MRI image, and the M is obtained by imaging the affected part in the same cross section as the X-ray CT image of a certain cross section of interest.
There may be no RI images.

Therefore, in order to obtain the shape of the affected part in the MRI image of the same cross section as the X-ray CT image of interest, a virtual MRI image of the same cross section as the cross section is obtained from the MRI images taken in the cross sections before and after the cross section. Obtain the shape of the affected area.

In the case shown in FIG. 10, the slice pitch of the X-ray CT image does not match the slice pitch of the MRI image, and the slice n of the X-ray CT image 130 and the slice pitch of the MRI image 13 do not match.
Although the cross-sectional position of one slice m matches, there is no MRI image 131 that matches the cross-sectional position of slice n-1 of the X-ray CT image 130 of interest.

Therefore, slice n of X-ray CT image 130
The shape of the affected part in the virtual MRI image (the image of the virtual slice) matching the cross-sectional position of -1 is obtained by taking the MRI image of slice m and the slice m-1 taken in a cross-section before and after the cross-sectional position of slice n-1. It is determined based on the MRI image.

In this method, as shown in FIG.
A point on the contour line of the affected part of the slice m of the image 131 is virtually connected to a point on the contour line of the affected part of the slice m-1 of the MRI image 131, which corresponds to the slice n-1 of the X-ray CT image 130. Obtaining a contour line intersecting the position of the virtual slice (that is, a slice of the X-ray CT image 130 based on a point on the contour line of the affected part of the slice m of the MRI image 131 and a corresponding slice m-1 of the MRI image 131) An image corresponding to n-1 is obtained, and a target contour line is obtained based on this image). The procedure is, for example, as described with reference to FIG.

First, similarly to the case shown in the first embodiment, the center point of the affected area of the slice m of the MRI image 131 and the center point of the affected area of the slice m-1 are determined, and the two points are made coincident with each other. The two images are superimposed so that there is no twist or deviation (step S31).

Next, a number of points of interest on the contour line of the affected part of either slice m or slice m-1 are selected (step S32).

Further, for each of these selected points of interest, a line is drawn radially from the center point of the matched affected area to the point of interest, and the intersection with the contour line of the affected area of slice m and the affected area of slice m-1 are obtained. An intersection with the contour is obtained (step S33).

Further, slice n of X-ray CT image 130
The distance between the corresponding intersections in the respective radially drawn line segments is (b), where a is the distance between the slice n-1 and the slice n-1 and b is the distance between the slice m and the slice m-1.
-A): Internally divided into a (step S34). This subdivision point is a point corresponding to these intersection points on the plane of the virtual slice.

Finally, a corresponding contour line of the affected part in the virtual slice is obtained by sequentially connecting the subdivision points of the virtual slice (step S35). In this way, the required shape of the affected part at slice n + 1 can be obtained.

Therefore, according to the fourth embodiment, even if there is no image of the affected part at the target tomographic position, or even if the affected part is not intentionally photographed at that position, the affected part of the image at the adjacent tomographic position can be obtained. By utilizing the fact that the shape of the (treatment region) is similar, the shape of the affected part at the target tomographic position can be quickly obtained from the image of the adjacent tomographic position.

Further, by obtaining a target to be irradiated using an MRI image in which the shape and position of the affected part can be easily identified, the position of the target can be easily set on the X-ray CT image. The treatment position can be specified accurately, X-ray irradiation can be performed accurately, and the treatment effect increases.

In the fourth embodiment, a case has been described in which a plane of a virtual slice is generated in an MRI image. However, a case in which a virtual slice between a certain slice and a certain slice is obtained in an X-ray CT image is similar to the above. Can be determined using a simple procedure.

Embodiment 5 In the third embodiment, the X-ray C
An MRI image is used to grasp the required area of the image of the affected part in the T image 130, and the MRI image is an MRI image obtained by imaging the affected part in the same cross section as the X-ray CT image.

However, in general, the number of pixels of an X-ray CT image obtained by imaging an affected part does not always match the number of pixels of an MRI image due to a difference in imaging performance between the two imaging apparatuses.
Although the X-ray CT image and the MRI image are taken at the same cross-sectional position, the size of the two images may be different.

Therefore, in order to obtain an MRI image which has been taken at the same cross-sectional position as an X-ray CT image of interest and has the same number of pixels as that of the X-ray CT image, first, For an MRI image captured at the same cross-sectional position as an X-ray CT image of interest and having a different number of pixels from that of the X-ray CT image, the M
It is necessary to convert the number of pixels of the RI image into the number of pixels of the X-ray CT image.

In FIG. 13, 131A is an X-ray C of interest.
M which was imaged at the same cross-sectional position as the T image and which was imaged with a larger number of pixels than that of the X-ray CT image
The RI image, 131B, was taken at the same cross-sectional position as the X-ray CT image of interest, and was an MRI image taken with a smaller number of pixels than the X-ray CT image,
Reference numeral 132 denotes a virtual MRI image obtained by compressing or expanding the MRI image 131A or 131B and converting the MRI image to the same number of pixels as the X-ray CT image of interest.

When the number of pixels of the X-ray CT image of interest is different from the number of pixels of the MRI image photographed at the same sectional position as that of the X-ray CT image,
After converting the MRI image into the number of pixels of the X-ray CT image, the shape of the affected part (the outline of the region of interest) may be extracted and superimposed on the X-ray CT image.

Here, as a method of converting the number of pixels,
It is conceivable to use a method using various image processing techniques that have become publicly known.

The extraction of the outline of the region of interest on the MRI image is not limited to using the MRI image after the pixel number conversion, but may be using the MRI image before the pixel number conversion. However, when the outline of the region of interest is extracted using the MRI image before the pixel number conversion, it is necessary to enlarge or reduce the extracted outline of the region of interest in accordance with the conversion of the number of pixels.

Therefore, according to the fifth embodiment, the MR
When the shape of the target diseased part obtained from the I image is superimposed on the X-ray CT image, the shape of the diseased part in the X-ray CT image can be easily compared with the shape of the diseased part in the MRI image. it can.

In the above description, an example has been described in which the number of pixels of the MRI image is converted to match the number of pixels of the X-ray CT image.
Similar effects can be obtained even when the number of pixels of the X-ray CT image is converted to match the number of pixels of the MRI image.

Embodiment 6 FIG. In the embodiment described above,
Focusing on a certain X-ray CT image, an MRI image at the same cross-sectional (same slice) position as the X-ray CT image is used.

However, in general, it is conceivable that distortion is generated in the X-ray CT image and MRI image of the affected part as it is, and also in the above-mentioned virtual MRI image which has been subjected to compression or expansion processing.

Therefore, before superimposing the shape of the affected part (boundary line of the region of interest) extracted from the MRI image on the X-ray CT image, a certain X-ray CT image of interest and its X-ray C
By performing distortion correction on the MRI image at the same cross-sectional position as the T image and using the image after the distortion correction, X-ray CT
The required shape of the affected part on the image can be accurately grasped.

Further, in order to superimpose the shape of the affected part (boundary line of the region of interest) extracted from the MRI image on the X-ray CT image, the boundary line extracted from the MRI image has no displacement and the X-ray CT image It is also necessary to perform alignment of the reference position at a stage before the superposition of the two images so that the images can be superimposed.

As shown in FIG. 14, an MRI apparatus and an X-ray C
MRI image 131 before distortion correction as captured by T device
In the X-ray CT image 130 before distortion correction, the image may be distorted.

[0094] Further, when imaging with an MRI apparatus or an X-ray CT apparatus, an MRI image and an X-ray CT image are respectively obtained by fixing a patient on a bed or the like and aligning the patient with the same position.
In the first place, the position of the reference coordinates on the captured image may be different (shifted) between the two devices.

Therefore, before superimposing the shape of the affected part (boundary line of the region of interest) extracted from the MRI image on the X-ray CT image, it is necessary to correct the distortion of the image and align the reference coordinates as follows. There is.

First, distortion correction will be described. Here, an MRI apparatus will be described as a representative of an MRI apparatus and an X-ray CT apparatus, but the same applies to an X-ray CT apparatus.

For example, in the first step, an original image to be used as a reference for distortion correction in the MRI apparatus is photographed in advance by the MRI apparatus and held as a reference image of the MRI apparatus.

Then, in the next step, distortion correction is performed so that the MRI image 131 before distortion correction as captured by the MRI apparatus matches this reference image, and the distortion of the MRI image captured by the MRI apparatus under these conditions is corrected. Find the correction amount.

The amount of distortion correction is determined by the inherent imaging performance of the MRI apparatus. Once the amount of distortion correction under a specific imaging condition is determined in each apparatus, the amount of distortion correction is determined by the imaging of each apparatus. This is not changed until the shooting conditions (parameters) at the time are changed. Further, the image distortion correction is not limited to the above-described method, and can be processed by using an already known image processing technique.

Next, the positioning of the reference coordinate position (coordinate origin) will be described. Before superimposing the shape of the affected part (boundary line of the region of interest) extracted from the MRI image on the X-ray CT image, the MRI image after distortion correction with reference to the origin of the X-ray CT image 131c after distortion correction The origin of 130c is translated and the reference coordinate position is aligned. still,
The positioning of the reference coordinate position can be processed by using a known image processing technique.

As described above, after performing the distortion correction and the positioning of the reference coordinate position, the target image can be obtained by superimposing the two images as described above.

Therefore, according to the sixth embodiment, by performing such a distortion correction, the amount of distortion peculiar to the image pickup apparatus is eliminated, and the shape of the target diseased part obtained from the MRI image can be converted to an X-ray. X-ray CT when superimposed on CT image
An accurate comparison between the shape of the affected part in the image and the shape of the affected part in the MRI image can be made.

In the above description, the distortion correction is performed before the reference position correction. However, it does not matter which of the distortion correction and the reference position correction is performed first, and which one is performed first. Is also good.

Embodiment 7 FIG. As a result of superimposing the shape of the affected part (boundary line of the region of interest) extracted from the MRI image on the X-ray CT image, when the boundary line between the two was slightly different (shifted) or later, the shape of the radiation irradiation field If a shape slightly different from the shape of the affected part is used as the shape of the irradiation field when determining the shape, it is necessary to correct the shape (boundary line) of the affected part in the X-ray CT image extracted from the MRI image .

In FIG. 15, reference numeral 210 denotes the shape (contour line) of the affected part in the X-ray CT image of interest in a certain slice;
Reference numeral 1 denotes a shape of a diseased part (generated contour) obtained from an MRI image or the like by the method described in the above embodiment, and 212 denotes a difference area between the contour 210 and the contour 211.

As shown in FIG. 15, the shape of the affected part obtained from an MRI image or the like does not always completely match the shape of the affected part in the X-ray CT image of interest. Even if they completely match, it may be necessary to correct the shape of the affected part in the extracted X-ray CT image.

Therefore, the contour is edited so that the shape of the affected part obtained from the MRI image or the like becomes close to the shape of the affected part in the X-ray CT image of interest. Contour editing is MR
For the section of the contour line, which is the part to be edited of the shape of the affected part obtained from the I-image, etc., specify both end points of the section, point the movement target point on the section, and determine the position of the point after the movement. The operation of designating is performed by selecting a number of points to be moved, and then smoothly connecting these many points after the movement with, for example, a spline function curve, and bringing the section closer to the desired shape of the affected part.

The processing of sequentially connecting these extracted points and generating a new outline for the section of interest can be realized using various known image processing techniques.

For example, as shown in FIG. 16, a point s and a point e, which are both end points of a section, are designated (the both end points are not moved) to define an edit target section, and a point which is a point on the section is determined. the a ₁ to a point a ₂ by pointing, likewise the point b1 to the point b ₂ by pointing, by specifying the position after each move to a point c ₂ by pointing the point c _1, point s- point a _Two
The point b ₂ -point c ₂ -point e is smoothly connected by a spline curve, and the section is closer to the actual contour of the affected part.

In this way, the desired shape of the affected part can be obtained.

Therefore, according to the seventh embodiment, by correcting the shape of the affected part as described above, when the shape of the target affected part obtained from the MRI image is superimposed on the X-ray CT image, The desired shape of the affected part can be made a desired shape that matches the shape of the affected part in the X-ray CT image.

Embodiment 8 FIG. FIGS. 17 and 18 are explanatory views of an irradiation field forming apparatus according to an eighth embodiment for realizing the formation of an affected area, that is, an irradiation field, obtained by the above-described embodiment. Is used to form an irradiation field based on the shape of the affected area determined in the first to seventh embodiments.

FIG. 17 is a block diagram of a radiotherapy apparatus including an irradiation field forming apparatus. A beam source 229 generates a radiation beam (hereinafter, referred to as a beam).
30 is a Wobbler electromagnet which diffuses the beam in the circumferential direction, 2
31 is a scatterer that scatters the beam flat, 232 is a ridge filter that determines the effective range (called a Bragg peak) in the depth direction (traveling direction) of the beam, 233 is a range shifter that determines the reach of the beam in the body, and 234 is A ring collimator that blocks the beam in the circumferential direction, 235 is a multi-leaf collimator that cuts an extra beam according to the shape of the affected part to limit the beam irradiation area, 236 is a bolus that stops the beam along the depth shape of the affected part, 23
7 indicates a body surface, and 238 indicates an affected part.

The structure for supporting the multi-leaf collimator 235 is as shown in FIG. 18. The multi-leaf collimator 235 can be moved up and down, that is, a drive described later so as to be able to approach the affected part freely. A mechanism is attached.

A multi-leaf collimator slide mechanism 245 for moving the multi-leaf collimator mount 241 up and down by moving the belt up and down is attached to the gantry 243.
, A multi-leaf collimator mounting base 241 is mounted via a belt.

The multi-leaf collimator slide motor 245a drives the belt to move the multi-leaf collimator mount 241 up and down in the beam axis direction.

Furthermore, the multi-leaf collimator mounting table 2
A multi-leaf collimator 235 is attached to 41, and the multi-leaf collimator 235 is driven by a multi-leaf collimator rotating device 242 (by driving a multi-leaf collimator rotating motor 242 a) to have a beam center axis 246.
It is designed to rotate around.

The multi-leaf collimator 235 is composed of a plurality of pairs of leaves (leaves) facing each other, and each leaf is connected to a multi-leaf collimator opening / closing device 240 for adjusting the opening thereof, and opens and closes left and right. It has become.

In the irradiation apparatus shown in FIG.
The beam generated from 29 is scattered by the Wobbler electromagnet 230 and the scatterer 231 to form a flat beam, the width in the depth direction is determined by the ridge filter 232, and the reach in the depth direction is determined by the range shifter 233. Ring collimator 234 and multi-leaf collimator 2
The irradiation shape of the beam in the direction viewed from the front is determined at 35, and finally the shape in the depth direction is shaped using the bolus 236, thus forming an irradiation field that matches the shape of the affected part. ing.

Here, a procedure for forming an irradiation field based on, for example, the shape of the affected part obtained from the above-described embodiment will be described below with reference to FIG. The distance a from the beam focal point 200 to the irradiation plane is predetermined for the irradiation field forming apparatus including the irradiation field forming apparatus, and the distance a from the beam focal point 200 to the collimator mounting position. Assume that b is also required.

First, the collimator opening calculating device 300 including the known graphic recognition processing means adjusts the isocenter (the center of the affected part) to the center axis 246 of the beam (step S51).

The collimator opening calculating device 300 calculates the opening of the leaves from the upper left leaf to the lower left leaf as follows.

The collimator opening degree calculating device 300 divides the shape of the affected part, which is an irradiation target area, according to the left and right leaf division positions and the stacked leaf plate thickness, and performs the left and right leaf A contact point between the target leaf and the perimeter of the affected part is obtained using a method of obtaining a contact point between a line segment (section) corresponding to the target leaf and a perimeter of the affected part among the lines parallel to the dividing line (step S52). .

The distance from the left and right leaf dividing lines (center lines) to this contact point is an opening at which the leaf must be opened when the multi-leaf collimator 235 is located on the beam irradiation surface of the affected part. However, since the leaf is actually far from the beam irradiation surface of the affected part, the actual opening degree is smaller than the opening degree of the affected part on the beam irradiation surface.

Therefore, in this case, if the similarity between figures is used, the actual leaf opening at the collimator mounting position is (the leaf opening on the beam irradiation surface) × a / b. Here, when there is no contact point, the opening of the target leaf is set to zero.

Next, the collimator opening calculating device 300
The leaf opening is obtained in this manner also for the top right leaf from the top right leaf (step S5).
2, 53).

The collimator opening calculating device 300 outputs the opening of each leaf thus obtained to the controller 300 (step S54).

The controller 301 issues a drive command in accordance with the degree of opening of each leaf in this case.
(Step S55).

The controller 300 outputs a drive command according to the degree of opening of each leaf to the collimator driving device 240 (step S56).

The collimator driving device 240 slides and moves each leaf according to the drive command received from the controller 301 to set the opening of each leaf of the multi-leaf collimator 235 (step S57).

As a result of setting the degree of opening of the multi-leaf collimator in this manner, an irradiation field for irradiating the beam to the shape of the affected part is formed, for example, as shown in FIG. In FIG. 20, the degree of opening of the multi-leaf collimator 190 is
The irradiation field is set along the contour of 91 and the irradiation field is formed so that the affected part 191 is irradiated with radiation without leaking.

Therefore, according to the eighth embodiment, it is possible to set a desired irradiation field in accordance with the target shape of the affected part, and to efficiently irradiate the affected part with radiation. An irradiation field can be formed.

Embodiment 9 FIG. In the ninth embodiment, an example will be described in which the affected area is provided with some margins to form an irradiation field that can sufficiently irradiate the affected area. In this case, in the ninth embodiment, the following processing as shown in FIG. 21 is performed.

In step S 56, the collimator opening margin is given to the collimator opening calculating device 300.

In step S57, a position separated by the previous margin from the contact point obtained in step S53 is set as the position of the leaf after the leaf movement as the target, from the left and right leaf division lines (center line) to this position. Is the opening of the target leaf.

That is, for the affected part shape whose shape has been enlarged (or reduced) by the input margin, a contact point between each leaf and the outer periphery of the enlarged affected part is determined. As a result of setting the opening of the multi-leaf collimator in this way,
The irradiation field where the beam is irradiated to the affected part before enlargement is shown in Fig. 2.
It is formed as shown in FIG.

FIG. 22A shows a case where the opening degree of the multi-leaf collimator is set by giving a margin that barely touches the affected part 192, and FIG.
In this case, the opening degree of the multi-leaf is set with a margin of the distance δ.

FIG. 22B shows a case where a plus margin is set. However, when a minus margin is set, the opening of the multi-leaf collimator is smaller than that of the affected part by the margin.

Therefore, according to the ninth embodiment, the irradiation field can be formed in accordance with the shape of the diseased part, and the irradiation field can be formed so that the diseased part is irradiated with radiation sufficiently and without waste. In addition, it is possible to reduce the waste of the dose of the beam that is applied to the periphery of the affected part other than the affected part.

Embodiment 10 FIG. In the tenth embodiment, a method of forming an irradiation field by rotating the multi-leaf collimator 235 in order to minimize the dose of radiation that strikes other than the affected area will be described. In this case, in the eleventh embodiment, the following processing as shown in FIG. 23 is performed.

For convenience of explanation, the margin of the affected part is assumed to be zero. It is to be noted that the area of the given affected part is obtained from the given shape of the affected part using a known graphic recognition processing technique.

The step rotation angle (assumed to be n degrees) of the multi-leaf collimator 235 is designated (step S6).
1).

The opening degree of the multi-leaf collimator 190 at this rotation angle corresponding to the obtained shape of the affected part is obtained by the same procedure as in the eighth embodiment (Eighth Embodiment (FIG. 1)).
9) Steps S51 to S53).

The area of the irradiation field (the degree of opening of the multi-leaf collimator 235) formed under these conditions is determined from the moving distance of each leaf and the plate thickness of the leaf (step S62).

The multi-leaf collimator 235 is rotated stepwise by n degrees so that the multi-leaf collimator 190
The above-described processing is performed at each rotation angle until rotation is performed, and the processing of steps S61 to S62 is performed in the same manner, and the area of the irradiation field at each rotation angle is obtained (steps S61 to S6).
3).

The collimator opening calculating device 300 compares the area of the irradiation field with the area of the shape of the affected part at each rotation angle, and the gap, that is, the difference between the area of the irradiation field and the area of the affected part, becomes the smallest. The angle in the case, that is, the rotation angle when the area of the gap becomes the smallest is selected. This is set as the optimal rotation angle α of the multi-leaf collimator with respect to the affected part (step S64).

The collimator opening calculating device 300 outputs the rotation angle α and the opening of each leaf in this case to the controller 301 (step S65).

The controller 301 outputs a drive command in accordance with the rotation angle α and the degree of opening of each leaf in this case to the collimator drive device 240 (step S66).

The collimator driving device 240 rotates the multi-leaf collimator 235 according to the driving command received from the controller 240, and slides and moves each leaf to set the opening of each leaf of the multi-leaf collimator 235 (step S67). As a result, a clockwise rotation and irradiation field of the multi-leaf collimator 190 as shown in FIG. 24 are obtained.

Therefore, according to the tenth embodiment, the irradiation field can be formed according to the shape of the diseased part, and the irradiation field can be formed so that the diseased part is irradiated with radiation sufficiently and without waste. In addition, it is possible to reduce the waste of the dose of the beam that is applied to the periphery of the affected part other than the affected part.

Embodiment 11 FIG. As described in the first embodiment, since the three-dimensional shape of the diseased part 101 normally changes continuously and slowly, the contour (shape) of the diseased part in a certain slice n is uniformly enlarged. Alternatively, by reducing the size, the shape of the affected part in slice n can be made closer to the shape of the affected part in slice n + 1, which is the slice (tomogram) adjacent to slice n.

Therefore, with respect to the collimator in which the irradiation field is set for the shape of the affected part in a certain slice n, the distance from the affected part is changed while the collimator opening degree is kept unchanged, so that the slice (tomography) adjacent to slice n is changed. The irradiation field of the affected part can be set for the shape of the affected part in a certain slice n + 1.

That is, as shown in FIG. 25, the beam is focused on the isocenter, the shape of the affected area serving as the irradiation field in a certain slice n is the region A, and the beam focus is 200 mm.
When the multi-leaf collimator 235 is attached at a position where the distance from the to the collimator 221 is a,
The desired irradiation field of the affected part for the slice n + 1 adjacent to the slice n is obtained by changing the distance between the multi-leaf collimator 235 and the focal point 200 of the beam to the distance b while keeping the opening of the multi-leaf collimator 235 unchanged, and issuing a command from the controller. By moving the multi-leaf collimator 235 up and down by the multi-leaf collimator slide mechanism 245 based on the above, the area B can be obtained.

In this case, assuming that the distance k from the isocenter to the site where the affected part is located in slice n, the distance of the corresponding portion in slice n + 1 is expanded to b / a.

Therefore, according to the eleventh embodiment, utilizing the fact that the shape of the affected part (the treatment area) in the image of the adjacent tomographic position described above is similar, the shape of the affected part at a certain cross section is irradiated. By setting the installation position of the multi-leaf collimator to be able to move freely toward and away from the beam irradiation surface of the affected part while keeping the opening of the multi-leaf collimator set with, the irradiation field that matches the shape of the affected part in a new cross section This eliminates the trouble of newly setting the opening of each leaf of the multi-leaf collimator.

Embodiment 12 FIG. In the irradiation device, the position 220 of the focal point of the beam is fixed as shown in FIG. 26, so that the size of the penumbra A when the mounting position of the multi-leaf collimator 221 is far from the patient 225 (distance a ) Is larger than the size (distance b) of the penumbra B when the mounting position of the multi-leaf collimator 221 is close to the patient 225.

This penumbra is reflected by the multi-leaf collimator 22.
1. Among the radiations obliquely incident on the open cross section 1, the distance that the leaf shields, that is, the multi-leaf collimator 221
This is a phenomenon that occurs when light incident on a portion with a transmission distance less than the thickness is transmitted obliquely without being blocked by the multi-leaf collimator 221. The penumbra is preferably small.

As described above, the irradiation field forming apparatus allows the proximity adjustment of the mounting position (up and down distance) of the multi-leaf collimator 235 with respect to the patient to be variable. Penumbra can be reduced.

However, if the object is brought too close to the patient, the effect of the so-called edge effect in which radiation is scattered at the opening end face of the multi-leaf collimator 235 increases, or the multi-leaf collimator 221 hits the patient.
It is necessary to set how close to the patient it is depending on the situation.

In the twelfth embodiment, an example in which an irradiation field is formed in consideration of the influence of the penumbra will be described. in this case,
In the twelfth embodiment, the processing shown in FIG. 27 is performed. First, the movable range of the multi-leaf collimator 235 in the beam axis direction is predetermined.

First, an optimum distance from the body surface 237 to the mounting position of the multi-leaf collimator 235 is given to the collimator opening calculating device 300 (step S7).
1).

This distance is desirably a distance as close as possible to the body surface 237 in order to reduce penumbra. However, considering the type of beam, the characteristics of the multi-leaf collimator, and the influence of the edge effect described above, the influence of scattering is considered. To a distance that is practically acceptable.

Next, the collimator opening calculating device 300
The distance from the predetermined isocenter to the body surface 237 along the beam center axis 246 is obtained (step S7).
2).

The distance from the isocenter to the body surface 237 is, for example, 256 × 256 dots or 512 × 512 dots from a direction perpendicular to the beam irradiation direction so that the isocenter and the body surface are imaged in the same screen. From the X-ray CT images separately photographed in the matrix format, the number of matrix-converted dots from the isocenter along the beam center axis to the body surface is determined using a known image recognition processing technique, and this dot number and the It is obtained based on the determined size per dot.

Multileaf collimator opening setting device 30
In step S72, the distance to move the multi-leaf collimator 235 up and down in the beam axis direction is determined so that the mounting position of the multi-leaf collimator 235 is the position given in step S71.

Next, when the moving distance exceeds the movable range, the maximum movable distance is set as the moving distance in the beam axis direction.

The collimator opening calculating device 300 determines the distance by which the multi-leaf collimator 235 obtained in step S72 is moved up and down in the beam axis direction by the controller 30.
1 (step S73).

The controller 301 outputs to the collimator driving device 240 a drive command according to the distance for moving the multi-leaf collimator 235 up and down in the beam axis direction (step S74).

The collimator driving device 240 moves the multi-leaf collimator 235 up and down in the beam axis direction according to the drive command received from the controller 240 to determine the position of the multi-leaf collimator 235 (step S75).

As described above, the multi-leaf collimator 23
After the position of No. 5 is determined, if the opening of the collimator is set according to the above-described embodiment, a desired irradiation field can be set in consideration of the influence of penumbra.

Therefore, according to the thirteenth embodiment, the mounting position of the multi-leaf collimator with the irradiation field set for the shape of the diseased part in a certain cross section is maintained, and the mounting position of the multi-leaf collimator is changed to the beam irradiation surface of the diseased part. , It is possible to set a desired irradiation field in consideration of the influence of penumbra.

In the above embodiment, the case of a proton beam has been described, but an electron beam is used. The same effect is obtained in the case of a meson beam, a neutron beam, an X-ray, a heavy particle beam and the like.

[0173]

According to the present invention, the first step of photographing the same cross section as the cross section of the affected part photographed by the radiation cross-sectional imaging apparatus using a cross-sectional imaging apparatus different from the radiation cross-sectional imaging apparatus;
A second step of obtaining the center point of the affected part shape on the image of the same cross section taken in the step of, and a third step of selecting a plurality of points from the contour of the affected part shape on the image of the same cross section, On the image of the same cross section, the distance from the center point of the affected part shape to each point on the contour line selected in the second step is enlarged or reduced by a predetermined size, and the corresponding point of each point on the contour line is determined. Each of the fourth step is obtained, and the fifth step is to sequentially connect the corresponding points obtained in the fourth step on the image of the same cross section to obtain the affected part shape of a cross section different from the same cross section. By using tomographic images taken with a different cross-sectional imaging device at the time of planning, it is possible to quickly delineate the accurate treatment area of the patient and easily obtain the irradiation field to be irradiated with radiation. it can.

In the first step, instead of photographing the same cross section as the cross section of the affected part taken by the radiation cross section imaging apparatus with a different cross section imaging apparatus different from the radiation cross section imaging apparatus, the first step is performed at a cross section position sandwiching the affected part cross section. Since the image generated based on the image captured by the imaging device was an image of the same cross section, for example, by using a tomographic image captured by a different cross-sectional imaging device and a radiation cross-sectional imaging device during treatment planning,
An accurate treatment region of a patient can be quickly drawn, and an irradiation field to be irradiated with radiation can be easily obtained.

Before the first step, if the number of pixels of the image of the same cross section is different from the number of pixels of the radiation tomographic image,
Since the method includes a step of matching the number of pixels of the image of the same cross section and the number of pixels of the radiation tomographic image, for example, by using a tomographic image captured by a different cross-sectional imaging device and a radiation cross-sectional imaging device during treatment planning, An accurate treatment region of a patient can be quickly drawn, and an irradiation field to be irradiated with radiation can be easily obtained.

Before the first step, a step of correcting distortion of at least one of the radiation tomographic image obtained by imaging the cross section of the affected part and the image of the same cross section is performed based on a distortion correction amount obtained in advance. For example, by using a tomographic image taken by a cross-sectional imaging device different from the radiation cross-sectional imaging device during treatment planning, the irradiation field where radiation is irradiated by rapidly delineating an accurate patient treatment area quickly Can be easily obtained.

Also, after the fifth step, there is provided a step of correcting the affected part shape obtained in the fifth step based on a newly designated point on this radiation tomographic image. By using a tomographic image photographed by a cross-sectional imaging apparatus different from a radiation cross-sectional imaging apparatus, an irradiation field to be irradiated with radiation can be easily obtained by rapidly delineating an accurate treatment region of a patient.

An irradiation field forming apparatus according to the present invention includes a multi-leaf collimator having a leaf moving mechanism for slidingly moving each leaf, and a multi-leaf collimator moving mechanism for moving the multi-leaf collimator in a direction along a beam irradiation axis. And a multi-leaf collimator rotation mechanism that rotates the multi-leaf collimator about the beam irradiation axis, and a cross-sectional imaging device different from the radiation cross-sectional imaging device is used to image the same cross-section as the cross-section of the affected part taken by the radiation cross-sectional imaging device. Find the center point of the affected part shape on the image of the same cross section, select a plurality of points on the contour line of the affected part shape on the image of the same section, and on the contour line selected from the center point of the affected part shape on the image of the same cross section The distance to each point is enlarged or reduced by a predetermined size, and the corresponding point of each point on the contour is The corresponding points obtained on the image of the same cross-section are connected in sequence to obtain a diseased part shape of a cross-section different from the same cross-section. Since the multi-leaf collimator moving mechanism and the multi-leaf collimator rotating mechanism have a controller that determines the amount of sliding to move the multi-leaf collimator and the amount of rotation that the multi-leaf collimator rotating mechanism rotates the multi-leaf collimator, for example, during treatment planning By using a tomographic image photographed by a cross-sectional imaging apparatus different from a radiation cross-sectional imaging apparatus, an irradiation field to be irradiated with radiation can be easily obtained by rapidly delineating an accurate treatment region of a patient.

In addition, instead of using the cross-sectional imaging device different from the radiation cross-sectional imaging device to image the same cross-section as the cross-sectional image of the affected portion taken by the radiation cross-sectional imaging device, the graphic processing device performs cross-sectional imaging at each of the cross-sectional positions sandwiching the affected cross-section. Since the image generated based on the image captured by the device is an image of the same cross section, for example, by using a tomographic image captured by a different cross-sectional imaging device and a radiation cross-sectional imaging device during treatment planning,
An accurate treatment region of a patient can be quickly drawn, and an irradiation field to be irradiated with radiation can be easily obtained.

Further, when the number of pixels of the image of the same cross section is different from the number of pixels of the radiation tomographic image, the graphic processing apparatus matches the number of pixels of the image of the same cross section with the number of pixels of the radiation tomographic image. For example, by using a tomographic image photographed by a cross-sectional imaging apparatus different from a radiation cross-sectional imaging apparatus at the time of treatment planning, an accurate irradiation region of a patient can be quickly drawn to easily obtain an irradiation field to be irradiated with radiation. be able to.

Further, the graphic processing apparatus first performs distortion correction on at least one of the radiation tomographic image obtained by capturing the cross section of the affected part and the image of the same cross section based on the distortion correction amount obtained in advance. By using tomographic images taken with a cross-sectional imaging device different from the radiation cross-sectional imaging device at the time of treatment planning, it is possible to quickly delineate the accurate treatment area of the patient and easily obtain the irradiation field to be irradiated with radiation Can be.

Since the figure processing device finally corrects the determined affected part shape based on the position newly specified in the radiation tomographic image, for example, a cross-sectional imaging device different from the radiation cross-sectional imaging device at the time of treatment planning. By using the tomographic image photographed in the above, an accurate treatment region of a patient can be quickly drawn and an irradiation field to be irradiated with radiation can be easily obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for forming an irradiation field according to a first embodiment.

FIG. 2 is an explanatory diagram of a method for forming an irradiation field according to the first embodiment.

FIG. 3 is an explanatory diagram of a method for forming an irradiation field according to the first embodiment.

FIG. 4 is an explanatory diagram of a method for forming an irradiation field according to the first embodiment.

FIG. 5 is an explanatory diagram of a method for forming an irradiation field according to the first embodiment.

FIG. 6 is an explanatory diagram of a method for forming an irradiation field according to the first embodiment.

FIG. 7 is an explanatory diagram of a method for forming an irradiation field according to a second embodiment.

FIG. 8 is an explanatory diagram of a method for forming an irradiation field according to the second embodiment.

FIG. 9 is an explanatory diagram of a method for forming an irradiation field according to a third embodiment.

FIG. 10 is an explanatory diagram of a method for forming an irradiation field according to a fourth embodiment.

FIG. 11 is an explanatory diagram of a method for forming an irradiation field according to a fourth embodiment.

FIG. 12 is an explanatory diagram of a method for forming an irradiation field according to a fourth embodiment.

FIG. 13 is an explanatory diagram of a method for forming an irradiation field according to a fifth embodiment.

FIG. 14 is an explanatory diagram of a method for forming an irradiation field according to a sixth embodiment.

FIG. 15 is an explanatory diagram of a method for forming an irradiation field according to the seventh embodiment.

FIG. 16 is an explanatory diagram of a method for forming an irradiation field according to the seventh embodiment.

FIG. 17 is an explanatory diagram of an irradiation field forming apparatus according to an eighth embodiment.

FIG. 18 is an explanatory diagram of an irradiation field forming apparatus according to an eighth embodiment.

FIG. 19 is an explanatory diagram of an irradiation field forming apparatus according to an eighth embodiment.

FIG. 20 is an explanatory diagram of an irradiation field forming apparatus according to an eighth embodiment.

FIG. 21 is an explanatory view of an irradiation field forming apparatus according to a ninth embodiment.

FIG. 22 is an explanatory view of an irradiation field forming apparatus according to a ninth embodiment.

FIG. 23 is an explanatory diagram of the irradiation field forming apparatus according to the tenth embodiment.

FIG. 24 is an explanatory diagram of the irradiation field forming apparatus according to the tenth embodiment.

FIG. 25 is an explanatory diagram of the irradiation field forming apparatus according to the eleventh embodiment.

FIG. 26 is an explanatory diagram of an irradiation field forming apparatus according to a twelfth embodiment.

FIG. 27 is an explanatory view of an irradiation field forming apparatus according to a twelfth embodiment.

FIG. 28 is an explanatory diagram of a conventional proton beam therapy system.

FIG. 29 is an explanatory diagram of a conventional proton beam therapy system.

FIG. 30 is an explanatory view of a conventional proton beam therapy system.

[Explanation of symbols]

101 affected part, 102 X-ray CT image group, 130 X-ray CT image, 130a region of interest, 130c distortion correction X
Line CT image, 131 MRI image, 131a region of interest, 131c distortion corrected MRI image 131A MRI image, 131B MRI image, 132 virtual MRI image,
132c position corrected MRI image, 210 contour, 211
Generated contour, 212 Difference area, 230 Wobbler electromagnet, 231 Scatterer, 232 Ridge filter, 233
Range shifter, 234 Ring collimator, 235
Multi-leaf collimator, 235a Multi-leaf collimator rotation center, 236 bolus, 237 body surface,
238 Affected area, 239 MRI image, 240 multi-leaf collimator drive, 241 multi-leaf collimator mount, 242 multi-leaf collimator rotating device, 242a multi-leaf collimator rotating motor, 2
43 mount, 245 multi-leaf collimator slide mechanism, 245a multi-leaf collimator slide motor, 248 diseased part, 249 MRI image, 301 controller, 302 multi-leaf collimator opening calculation device.

Claims (10)

[Claims] 1. A first step of photographing the same cross section as a cross section of an affected part photographed by a radiation cross section photographing apparatus using a cross section photographing apparatus different from the radiation cross section photographing apparatus, and the same step photographed in the first step. A second step of obtaining a center point of the affected part shape on the image of the cross section, a third step of selecting a plurality of points from a contour line of the affected part shape on the image of the same cross section, In step (a), the distance from the center point of the affected part shape to each point on the contour line selected in the second step is enlarged or reduced by a predetermined size to obtain a corresponding point of each point on the contour line. A fourth step, and a fifth step of sequentially connecting the corresponding points obtained in the fourth step on the image of the same cross section to obtain a diseased part shape of a cross section different from the same cross section. Of irradiation field Law. 2. The first step is to use a cross-sectional imaging apparatus different from the radiation cross-sectional imaging apparatus to photograph the same cross-section as the cross-section of the affected area taken by the radiation cross-sectional imaging apparatus, but to use a cross-sectional position sandwiching the affected cross-section. The method of forming an irradiation field according to claim 1, wherein an image generated based on an image captured by each of the cross-sectional imaging devices is set as the image of the same cross-section. 3. Before the first step, when the number of pixels of the image of the same cross section and the number of pixels of the radiation tomographic image are different, the number of pixels of the image of the same cross section and the number of pixels of the radiation tomographic image are different from each other. 2. A step for matching
Or the method for forming an irradiation field according to 2. 4. A step of performing distortion correction on at least one of a radiation tomographic image obtained by imaging a cross section of an affected part and an image of the same cross section before the first step based on a distortion correction amount obtained in advance. The method for forming an irradiation field according to claim 1, wherein the irradiation field is provided. 5. The method according to claim 1, further comprising, after the fifth step, a step of correcting the affected part shape obtained in the fifth step based on a newly designated point on the radiation tomographic image. Item 5. The method for forming an irradiation field according to any one of Items 1 to 4. 6. A multi-leaf collimator provided with a leaf moving mechanism for sliding each leaf, a multi-leaf collimator moving mechanism for moving the multi-leaf collimator in a direction along a beam irradiation axis, and beam irradiation on the multi-leaf collimator. A multi-leaf collimator rotating mechanism that rotates about an axis, and an image of the same cross section taken by a cross section imaging device different from the radiation cross section imaging device and the same cross section as the affected cross section taken by the radiation cross section imaging device. Obtain the center point of the affected part shape in the above-mentioned image of the same cross section, select a plurality of points from the contour line of the affected part shape, and on the image of the same cross section from the center point of the affected part shape to each point on the selected contour line Is enlarged or reduced by a predetermined size to obtain corresponding points for each point on the contour line. A graphic processing device that sequentially connects the corresponding points obtained on the image of the plane and obtains a diseased part shape of a cross section different from the same cross section, and the leaf moving mechanism is configured to control each of the multi-leaf collimators based on an output of the graphic processing device. Irradiation with a controller that determines a slide movement amount for sliding a leaf, a movement amount for moving the multi-leaf collimator by the multi-leaf collimator moving mechanism, and a rotation amount for the multi-leaf collimator rotating mechanism to rotate the multi-leaf collimator. Field forming equipment. 7. The graphic processing apparatus according to claim 1, wherein the same cross section as the cross section of the affected part taken by the radiation cross section imaging apparatus is imaged by a different cross section imaging apparatus different from the radiation cross section imaging apparatus. The irradiation field forming apparatus according to claim 6, wherein an image generated based on an image captured by the cross-sectional imaging apparatus is the same cross-sectional image. 8. When the number of pixels of the image of the same cross section is different from the number of pixels of the radiation tomographic image, the graphic processing apparatus matches the number of pixels of the image of the same cross section with the number of pixels of the radiation tomographic image. The irradiation field forming apparatus according to claim 6 or 7, wherein: 9. The graphic processing apparatus performs distortion correction on at least one of a radiation tomographic image obtained by imaging a cross section of an affected part and an image of the same cross section based on a distortion correction amount obtained in advance. The irradiation field forming apparatus according to any one of claims 6 to 8, wherein: 10. The graphic processing device according to claim 6, wherein the graphic processing device finally corrects the determined affected part shape based on a position newly specified in the radiation tomographic image. An irradiation field forming device.