JP2526369B2 - Radiotherapy equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiotherapy apparatus, and more particularly to a so-called stereotactic radiotherapy apparatus.

[0002]

2. Description of the Related Art A so-called stereotactic radiotherapy apparatus irradiates radiation from various directions to a treatment site of a patient as a target. As a result, radiation is intensively applied to the treatment site, and the radiation can be applied to the surrounding organs without causing any harm.

However, depending on the target organ of radiation, there may be an organ around which it is desired to avoid irradiation of radiation as much as possible.

In the prior art, the number of irradiation directions of selected radiation is small, for example, 2 to 4, so that if the positional relationship between the target organ and the radiation avoiding organ is three-dimensionally understood, the Radiation avoidance Irradiation of organs could be avoided.

[0005]

However, in recent years, the number of selected radiation irradiation directions tends to increase, and in this case, there is a problem that it becomes difficult to avoid radiation irradiation to the radiation avoiding organ. It came to be pointed out.

Therefore, the present invention has been made under such circumstances, and an object of the present invention is to provide a radiotherapy apparatus capable of completely avoiding radiation irradiation to a radiation avoidance site. It is in.

[0007]

In order to achieve such an object, the present invention comprises the following means.

Means 1 The radiation avoidance site is projected from the treatment site based on the information of the slice image in which the treatment site of the patient is located at the origin and the information of the slice image including the radiation avoidance site where radiation irradiation should be avoided. It is characterized by comprising means for calculating the area of the spherical coordinate surface thus obtained and means for controlling the irradiation direction of the radiation based on the information corresponding to the area.

Means 2 The construction of the means 1 is characterized in that it further comprises means for coordinate-converting the spherical coordinates in conformity with the direction in which the patient is observed and displaying the converted information on a display. is there.

[0010]

According to the radiotherapy apparatus having the structure as described in the means 1, when the radiation is applied to the treatment site located at the origin, the other region other than the region on the spherical coordinates is used as a guide. By changing the irradiation direction, it is possible to perform radiation irradiation completely avoiding the radiation avoidance site.

This is because the area on the spherical coordinates is the projection area of the radiation avoidance area starting from the treatment area.

For this reason, if the irradiation direction of the radiation is controlled based on the information of the spherical coordinates where the region is calculated, the radiation is not irradiated to the radiation avoidance region at all and is concentrated only on the treatment region. Will be irradiated.

Further, according to the radiotherapy apparatus having the structure of the means 2, the radiation avoidance region displayed on the display is displayed in conformity with the direction in which the patient is observed. The effect is that the operator who operates can confirm at any time.

[0014]

FIG. 2 is an external view showing an embodiment of the radiation treatment apparatus according to the present invention.

In the figure, there is a support base 13 fixed to the floor, and the gantry 11 is supported on this support base 13.

The gantry 11 has a built-in radiation source (not shown), and the radiation from this radiation source is applied to the floor side in the form of a beam from the radiation irradiation port 12 of the gantry. .

Further, the gantry 11 has a rotation axis aligned with the support table 13 in a direction intersecting with the radiation from the radiation irradiation port 12, and rotates about the rotation axis in the direction of arrow A in the figure. You can do it.

The intersection of the extended line of the rotation axis of the gantry 11 and the emitted radiation is called an isocenter, and the treatment area of the patient 14 on the top plate 17 of the mounting table 15, that is, the target area of radiation is positioned at this isocenter. It is designed to be used.

Further, the mounting table 15 maintains a state in which its direction is always directed to the isocenter side,
A circle centered on a point directly below the isocenter on the floor can be rotated as a locus.

Thus, the irradiation direction of the radiation on the treatment site of the patient 14 can be variously changed by rotating the gantry 11 with respect to the support base 13 or rotating the mounting base 15.

FIG. 1 is a diagram for explaining a procedure for creating information for controlling the above-mentioned radiotherapy apparatus.

First, before treatment, tomographic image information of a patient is obtained by, for example, an X-ray CT apparatus. Among them, tomographic image information including an organ (target organ) to be treated and an organ to avoid irradiation of radiation. Tomographic image information including (radiation avoiding organ) is prepared.

Note that each of the tomographic image information is usually
It consists of multiple adjacent slice images.

Positioning the tomographic image information including the target organ in the x-z-h coordinate system so that the treatment site 1 is at the origin,
In addition, the radiation avoiding organ 2 based on the position of the target organ 2
The tomographic image information including is located. In the case of this embodiment, the body axis of each tomographic image information is matched with the h axis.

Then, the radiation avoiding organ is projected from the target organ 1 on the spherical coordinates of x + z + h = R.

That is, first, P1 (x
1, z1, h1) and P2 (x
2, z2, h2). Then, a point Q (x, z, h) at which a straight line passing through P1 and P2 intersects the spherical coordinates is obtained.
This Q becomes one point of the area corresponding to the radiation avoiding organ if even a part of the target organ is irradiated with irradiation.

Further, if P2 is fixed and P1 is changed within the target organ, and the above-mentioned calculation is repeated each time, the region 4 is obtained in the spherical coordinates. This area 4 is a portion that always passes through the point P2 of the radiation avoiding organ even if the radiation is added to aim and irradiate any part of the target organ.

Further, if P2 is shifted and fixed for each pixel and the above-mentioned calculation is repeated, the projection area of the radiation avoiding organ starting from the target organ can be calculated.
This projection area is a portion that always passes through the radiation avoiding organ even if any portion of the target organ is irradiated by passing the radiation.

Here, the coordinates of Q (x, z, h) are obtained as follows.

[0030]

[Equation 1]

In the above equation, each of A, B and C has the following value.

[0032]

[Equation 2]

Each of l, m, and n in the above equation has the following value.

[0034]

(Equation 3)

Further, each of W, a, b, and c in the above equation has the following value.

[0036]

[Equation 4]

As a result, the target organ 1 on the x-z-h coordinate system is made to correspond to the isocenter of FIG. 2, and the radiation direction of the radiation is adjusted so as to avoid the projection area of the spherical coordinates. If it is changed by the rotation of, the irradiation of the radiation avoiding organ 2 can be completely avoided.

FIG. 3 is an explanatory view showing another embodiment of the present invention.

This figure shows a coordinate-converted diagram of the information shown in FIG. When the coordinates shown in FIG. 1 are observed from a predetermined direction, the display is converted into a display that can be observed according to the direction.

The image displayed in FIG. 3 is designated by the reference numeral 20, and the projection region of the radiation avoiding organ in the image is designated by the reference numeral 4A.

In this case, the monitor arranged near the operator who remotely operates the radiotherapy apparatus can be coordinate-converted in accordance with the observation direction of the patient who is going to receive the treatment. By displaying the information displayed, it becomes possible to confirm at any time when the radiation irradiation is operated.

Here, in the case of coordinate conversion as shown in FIG. 3, this can be achieved by using the following arithmetic expression.

[0043]

(Equation 5)

In this case, α and β indicate the directional angles formed by the straight lines connecting the origin O and the origin of the viewpoint plane with the x axis and the xz plane.

FIG. 4 is a flow chart showing an embodiment in which the above-mentioned calculation is carried out by the CPU so that the above-mentioned other embodiments are carried out at the same time. In the figure, first, a point P2 of the radiation avoiding organ is obtained (step 3).
0). Then, a point P1 of the target organ is determined (step 31). An intersection Q (x, z, h) between a straight line passing through P1 and P2 and a spherical surface having a radius R is obtained (step 32). afterwards,
The coordinates of the point Q are converted into the coordinate system of the viewpoint plane and displayed (step 33).

Change P1 in the target organ and carry out step 3
After steps 2 and 33, it is determined whether or not all P1 have been executed (step 34). When the execution is performed for all P1, P2 is moved (one pixel) in the radiation avoiding organ (step 35).

After steps 32 to 35, it is determined whether or not the process has been executed for all P2 (step 3).
6). If the execution is performed for all P2s, the next slice image in the target organ is designated (step 3).
7).

Step 3 for the designated slice image
2 to 37 are repeated to determine whether or not the processing has been performed for all slice images (step 38). When the execution is performed for all the slice images, the next slice image in the radiation avoiding organ is designated (step 3).
9).

Step 3 for the designated slice image
2 to 39 are repeated to determine whether or not the processing has been performed for all slice images (step 40). When the execution is performed for all slice images, the process ends.

According to the radiation treatment apparatus constructed as in this embodiment, when the treatment organ 1 positioned at the origin is irradiated with radiation, the projection area of the radiation avoiding organ 2 on the spherical coordinates is avoided. By changing the irradiation direction using another region as a guide, it is possible to perform irradiation while completely avoiding the radiation avoiding organ 2.

Therefore, if the irradiation direction of the radiation is controlled based on the information of the spherical coordinates where the projection area is calculated, the radiation avoiding organ 2 is not irradiated at all, and the treatment organ 1 is not irradiated. It will be irradiated only intensively.

Further, since the radiation avoidance region displayed on the display unit is displayed in conformity with the direction in which the patient is observed, the operator operating the radiation irradiation can confirm the radiation at any time. .

[0053]

As is apparent from the above description,
According to the radiotherapy apparatus according to the present invention, it becomes possible to completely avoid radiation irradiation to a radiation avoidance site.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a radiotherapy apparatus according to the present invention.

FIG. 2 is an external configuration diagram showing an embodiment of a radiation treatment apparatus according to the present invention.

FIG. 3 is an explanatory view showing another embodiment of the radiotherapy apparatus according to the present invention.

FIG. 4 is a CP included in the radiotherapy apparatus according to the present invention.
It is a flow chart which shows one example of operation of U.

[Explanation of symbols]

 1 Target organ 2 Radiation avoidance organ

Claims (2)

(57) [Claims] 1. A radiation avoidance site is projected from the treatment site as a starting point from information of a slice image in which a treatment site of a patient is positioned at an origin and information of a slice image including a radiation avoidance site where radiation irradiation should be avoided. A radiation therapy apparatus comprising: a means for calculating a region of the spherical coordinate surface that is made to operate; and a means for controlling a radiation irradiation direction based on information corresponding to the region. 2. The radiotherapy apparatus according to claim 1, further comprising means for coordinate-converting the spherical coordinates in accordance with a direction of observing a patient and displaying the converted information on a display.