JP2526372B2 - Stereotactic radiotherapy device - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a stereotactic radiotherapy device.

[0002]

2. Description of the Related Art In a stereotactic radiotherapy apparatus, the radiation emitted from its gantry is emitted by changing the irradiation direction to the bed side by the movement of the gantry and the bed, which is determined by the configuration of the apparatus itself. It always passes through a point on the space called the isocenter.

The patient on the bed is placed so that the affected part (lesion) is made to coincide with the isocenter, whereby the affected part is irradiated with radiation from various directions. Like

Therefore, it is possible to intensively irradiate only the affected area while keeping the normal tissue other than the affected area healthy.

Further, when a treatment is performed using this stereotactic radiotherapy apparatus, it is necessary to recognize in advance where the affected part of the patient is located.

For this reason, for example, an X-ray CT apparatus is used to photograph a tomographic image including the affected area of the patient, the position of the affected area is known from the obtained photographed image, and based on that information,
The patient is placed on the bed of the stereotactic radiotherapy apparatus so that the affected part is aligned with the isocenter.

[0007]

However, in the stereotactic radiotherapy apparatus configured as described above, first, mechanical bending or mechanical rattling of the sliding portion occurs in the bed or the like. Each time the rotation angle of the gantry is changed, a large amount of labor and time are required to move the bed to match the affected area with the isocenter.

Further, even after the affected part is made to coincide with the isocenter, the deflection of the bed or the rattling changes due to the change in the load distribution due to the movement of the patient, etc., and the displaced part is displaced from the isocenter. There was that.

Therefore, the present invention has been made based on such a circumstance, and its main purpose is stereotactic radiation capable of quickly and easily confirming whether or not the displacement of the affected part with respect to the isocenter occurs. To provide a treatment device.

Another object of the present invention is to provide a stereotactic radiotherapy apparatus capable of promptly coping with the displacement of the affected part with respect to the isocenter.

Further, another object of the present invention is to provide a tomographic imaging method capable of giving a reliable confirmation of whether or not the displacement of the affected part is caused with respect to the isocenter of the stereotactic radiotherapy apparatus. is there.

[0012]

In order to achieve such an object, the present invention is basically based on the following means.

Means 1. In a stereotactic radiotherapy apparatus for locating a diseased part of a subject in an isocenter set by the apparatus itself and irradiating radiation from different directions with the isocenter as a target, a light source for irradiating a laser beam with the isocenter as a target, and this light source, A spherical mirror, which is fixedly arranged with respect to the subject on the optical path between the isocenter and has a curved surface with the affected part as a center point, and the light source on the optical path between the spherical mirror and the light source. And a projection plate that is fixedly arranged and that transmits the irradiation light from the light source and projects the reflected light from the spherical mirror.

Means 2. The means 1 is provided with a detector for detecting the deviation between the projected reflected light of the projection plate and the passing portion of the irradiation light.

Means 3. The means 2 is provided with a mechanism for moving the subject so as to position the affected area on the isocenter based on the detection information from the detector.

Means 4. As a pre-stage of performing radiotherapy using the apparatus shown in the means 1 or 2, the spherical mirror having a curved surface centered on the affected part of the subject is fixedly arranged with respect to the subject. It is characterized in that a tomographic image of the affected part including a spherical mirror is taken.

Means 5. The means 1 is provided with a length measuring device for measuring the distance from the light source for irradiating the laser beam to the spherical mirror by the reflected light from the spherical mirror, and thereby detecting the positional deviation between the isocenter and the affected part. It is characterized by.

Means 6. In the means 4, the displacement of the affected area with respect to the center of the curved surface of the spherical mirror is evaluated.

[0019]

According to the means 1, the laser light from the light source passes through the projection plate and is reflected by the spherical mirror.

When the center point of the spherical mirror, that is, the affected area is completely coincident with the isocenter, the reflected light can be projected on the projection plate in conformity with the optical path of the input light.

Further, when the center point of the spherical mirror does not coincide with the isocenter, it becomes possible to project the reflected light on the projection plate while deviating from the optical path of the input light.

From this, it becomes possible to quickly and easily confirm whether or not the displacement of the affected part with respect to the isocenter has occurred by determining whether or not there is a displacement between the input light and the reflected light on the projection plate. .

Further, according to the means, since the detector is provided, it is possible to easily confirm the deviation.
It is possible to easily determine how much the subject should be moved.

According to the means 3, the mechanism for automatically moving the patient according to the deviation between the input light and the reflected light on the projection plate so that the affected part is located at the isocenter is controlled. Therefore, when the affected part is displaced with respect to the isocenter, it can be dealt with promptly.

Further, according to the means 4, it becomes possible to confirm that the center point of the spherical mirror is surely positioned in conformity with the affected area by inspecting the taken tomographic image. From this, it becomes possible to give reliability to the confirmation as to whether or not the displacement of the affected part has occurred with respect to the isocenter of the stereotactic radiotherapy apparatus.

Further, the means 5 makes it possible to confirm the deviation in the vertical direction.

Furthermore, the means 6 makes it possible to easily determine whether or not the spherical mirror is accurately attached to the subject.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an overall configuration diagram showing an embodiment of a stereotactic radiotherapy apparatus according to the present invention.

In FIG. 1, a stereotactic radiotherapy apparatus composed of a gantry 1, a gantry support 2, and a treatment table is arranged on a floor 10.

The treatment table includes a treatment table turntable 3, a treatment table vertical movement mechanism (movement in the Z direction) 4A, and a back and forth movement of the treatment table (X
Direction movement) left-right movement (Y direction movement) mechanism 4B for top plate 6
Can be rotated in the ω direction in the figure, or can be moved in each of the X, Y, and Z directions, that is, in the three-axis directions.

The gantry 1 has a gantry supporting portion 2
It is possible to rotate in the angle θ direction with respect to.
Then, an X-ray beam thinner than the collimator 9 mounted on the gantry 1 is emitted.

Here, the intersection of the rotation axis XX 'of the gantry 1 and the rotation axis ZZ' of the treatment table is determined as the isocenter A. As a result, the optical axis of the thin X-ray beam emitted from the collimator 9 during the rotation operation of the gantry 1 always passes through this isocenter A.

The patient 8 is fixed to the top plate 6 by a patient fixing jig 7. In this embodiment, in particular, the spherical position indicator 11 is attached and fixed to the patient fixing jig 7.

The indicator 11 is composed of a part of a spherical surface having a radius such that its center is located inside the body of the patient and the spherical surface is located outside the body of the patient 8. The outer surface of the spherical surface is a spherical surface. And has a spherical mirror 11A.

There is a position detecting device 17, and the position detecting device 17 includes a laser beam device 12, a projection plate 13,
The television camera 14, the projector 15, the irradiation light 15A, the fixing jig 16, and the installation jig 18 are included. The position detecting device 17 is attached to, for example, a ceiling 19 of a treatment room.

The laser beam device 12 comprises a laser beam projection device for emitting the laser beam 20 and a distance measuring device for measuring the optical path difference of the laser light.

The projection plate 13 is composed of a circular irregular reflection surface CC 'provided at the center with a slit 21 for passing the laser beam emitted from the laser beam projection device. The incident position of the reflected wave can be displayed as a bright spot.

The projector 15 emits the irradiation light beam 15A to make the periphery of the slit 21 provided in the center of the projection plate 13 brighter, so that the edge of the slit 21 can be photographed by the television camera 14. ing.

The angle between the diffuse reflection surface of the projection plate 13 and the optical axis of the laser beam 20 is 45 degrees, the angle between the photographing direction of the television camera 14 and the reflection surface is 45 degrees, and the emission direction of the projector 15 is perpendicular to the diffuse reflection surface. Laser beam device 1 to make the angle of
2. The projection plate 13 and the television camera 14 are attached and fixed to a fixing jig 16, respectively.

The operation of the stereotactic radiotherapy apparatus configured as described above will be described below.

First, the optical axis of the laser beam 20 emitted in the vertical direction from the laser beam device 12 is set so as to pass through the isocenter A of the stereotactic radiotherapy apparatus.
In addition, the spherical position indicator 11 fixed to the patient fixing jig 7
Is adjusted so that the center point of the spherical mirror 11A coincides with the position of the tumor P of the patient 8.

After the above setting, the laser light source 20 is incident on the spherical surface 11A of the spherical position indicator 11, and the position at which this reflected wave is incident on the projection plate 13 is displayed on the irregular reflection surface CC '. Then, the television camera 14 photographs the position of the reflected wave displayed on the irregular reflection surface CC ′ and the position of the slit 21 through which the laser beam 20 has passed.

On the other hand, when the reflected wave of the laser beam 20 enters the position of the slit 21, it passes through this and enters the distance measuring device inside the laser beam device 12. The distance measuring device measures the optical path difference from the emission of the laser beam 20 to the incidence of the reflected wave, and thereby the distance between the mirror surface 11A and the laser beam device 12 is obtained.

In the image data of the television camera 14, as shown in FIG. 2, the image data processing device 22 identifies a spot in the image from the image, and the position reading device 23 reads the position of the spot in the image.

Then, based on the position of the reflected wave and the position of each spot of the slit 21 in the image, the distance in the X and Y directions between the tumor position and the position of the isocenter A is calculated as a deviation distance. In the position reading device 23 in which the distance between the mirror surface 11A and the laser beam device 12 measured by the distance measuring device of the laser beam device 12 is input, the preset distance and the distance measured by the laser beam device 12 are The difference is calculated as the displacement distance of the treatment table in the Z direction.

In the treatment table control device 24 to which the displacement distances in the X, Y and Z directions are inputted, control data for correcting the position of the treatment table is calculated.

These control data are input to the treatment table vertical movement (Z direction movement) control device 25, the treatment table longitudinal movement (X direction movement) control device 26, and the treatment table left and right (Y direction movement) control device 27, respectively. Drive units 25, 2 connected to each device
The top plate 6 is moved in three axes by 6, 27, and the position of the tumor P of the patient is adjusted so as to match the position of the isocenter A.

Next, the operation of the position detecting device 17 will be described with reference to FIG.

The spherical position indicator 11 mounted on the patient fixing jig 7 with the center B of the spherical mirror 11A aligned with the tumor P is a top plate even if the treatment table is bent or the backlash of the sliding portion occurs.
Since it moves integrally with the patient fixing jig 7, the center B of the sphere is displaced from the position of the isocenter A. However, the state where the center of the spherical sphere coincides with the tumor position is retained, and the tumor P
Since the position of is in the center B of the sphere of the spherical mirror 11A, the tumor P is always positioned in the normal direction of the spherical surface even when the top plate is tilted due to the bending of the treatment table or the backlash of the sliding portion.

The laser beam 20 set so that the beam passes through the isocenter A is reflected at the incident point D on the mirror surface 11 of the spherical position indicator 11. Since the center B of the sphere is deviated from the isocenter A, the optical axis of the laser beam 20 does not pass through the center B of the spherical sphere. Therefore, the reflected light reflected at the reflection angle equal to the incident angle of the incident light is projected onto the projection plate. It is incident on 13 and the incident position is displayed as a bright spot E on the irregular reflection surface CC ′.

The projector 15 emits the irradiation light beam 15A to lighten the edge of the slit 21 provided at the center of the projection plate 13.

Then, the deviation between the bright spot E and the position of the edge of the slit 21 is detected as the deviation of the tumor position with respect to the isocenter A in the X and Y directions from the image of the television camera 14 photographing the irregular reflection surface CC '. it can.

On the other hand, the operation of the position detecting device 17 when the optical axis of the laser beam 20 passes through the center B of the spherical sphere will be described with reference to FIG.

In the figure, since the optical axis of the laser beam 20 passes through the center B of the spherical sphere, the reflected light beam at the incident point D on the mirror surface 11A passes through the optical axis which coincides with the optical axis of the incident light beam. It travels straight in the opposite direction, passes through the slit 21, and is incident on the distance measuring device inside the laser beam device 12.

The distance measuring device measures the optical path difference from the emission of the laser beam 20 to the incidence of the reflected wave, and from this, the distance between the mirror surface 11A and the laser beam device 12 is measured. The distance in the Z direction of the tumor position with respect to the isocenter A can be detected by this distance.

Now, the position detection image of the television camera 14 will be described with reference to FIG.

In FIG. 7A, the reflected light beam is reflected by the slit 21.
It shows the case where the light is incident on the inside of the edge. The image 28 of the projection camera 13 and the slit 2 are included in the image 28 of the TV camera.
The edge image 30 of 1 is displayed. Since the bright spot E of the reflected light disappears, it can be confirmed that the optical axis of the laser light 20 coincides with the center B of the spherical sphere.

In FIG. 6B, the reflected light beam is reflected by the slit 21.
In this case, the X- and Y-direction components Δx and Δy of the distance between the incident point image 31 of the laser beam and the center point of the edge of the slit 21 can be measured as offset distances. .

According to the embodiment described above, the laser beam from the laser beam device 12 passes through the projection plate 13 and is reflected by the spherical mirror 11A.

The center point of the spherical mirror 11A, that is, the tumor P
When is completely coincident with the isocenter A, it becomes possible to confirm that the reflected light is incident on the projection plate 13 in conformity with the optical path of the input light.

Further, when the center point of the spherical mirror 11A does not coincide with the isocenter A, it becomes possible to project the reflected light on the projection plate 13 while deviating from the optical path of the input light.

From this, it is possible to quickly and easily confirm whether or not the displacement of the affected part with respect to the isocenter occurs by determining whether or not there is a displacement between the input light and the reflected light on the projection plate 13. Become.

Further, since the patient is automatically controlled according to the deviation between the input light and the reflected light on the projection plate 13 so that the affected part coincides with the isocenter A, the deviation of the tumor P from the isocenter. If a problem occurs, it can be dealt with promptly.

FIG. 6 is an explanatory view showing another embodiment of the stereotactic radiotherapy apparatus according to the present invention. In the figure, the projection plate 32 is arranged perpendicularly to the optical axis of the laser beam 20, which is a difference from the embodiment shown in FIG.

By doing so, the position detecting device 17 can be downsized.

Another embodiment of the spherical position indicator 11 will be described with reference to FIG.

In the figure, the spherical position indicator 11 comprises a spherical mirror 11A, a front-back direction (X direction) moving mechanism 11B, a left-right direction (Y direction) moving mechanism 11C, and a vertical direction (Z direction) moving mechanism 11D. These are integrally mounted on the patient fixing jig 7.

By the moving mechanisms 11B, 11C and 11D,
The movement in the X, Y, and Z directions is performed, and the central axis B of the spherical mirror 11A can be aligned with the tumor P, and the spherical mirror 11A is located at that position.
Is fixed.

FIG. 8 shows a circuit block diagram provided in the spherical position indicator 11.

In the figure, in the spherical position indicator 11, a control device 11E, a vertical movement control device 11F, a horizontal movement control device 11G, and a front-back movement control device 11H are connected to movement mechanisms 11B, 11C and 11D, respectively. Is configured.

In the controller 11E, the moving mechanisms 11B, 11C and 11D are moved based on the tumor position data input as the three-dimensional coordinates in the positioning jig coordinate system, and the center B of the spherical mirror 11A is positioned on the tumor P. Can be matched.

With this arrangement, the work of aligning the center B with the tumor P can be electrically controlled digitally.

By this digital control, the center of the sphere of the spherical mirror is moved so as to coincide with the tumor trajectory of the respiratory organ which is measured in advance. Further, the displacement of the position is detected to detect the sphere of the spherical mirror. It goes without saying that the treatment table may be moved so that the center thereof coincides with the isocenter.

Still another embodiment of the spherical position indicator 11 will be described with reference to FIG.

In the figure, the spherical position indicator 11 comprises a spherical mirror 11A, a position adjusting jig 11K, and a tooth type position fixing jig 40.

In the case of treating the patient's head 8A, the tooth type position fixing jig 40 is installed in the mouth of the patient 8. Position adjustment jig 11
With K, the center B of the spherical mirror 11A is aligned with the tumor P. The position adjusting jig 11K is formed of a plastic resin so as to match the positions in the three axial directions of the X, Y, and Z directions, or is formed of a metal element wire.

With such a structure, the patient fixing jig can be omitted, and the attachment or detachment can be easily performed during a plurality of treatments by the divided irradiation treatment.

Although the example applied to the head is shown, it is needless to say that the present invention is not limited to this and may be attached to the body surface at other parts.

FIG. 10 is an X-ray CT image of the patient's head 8A with the spherical mirror 11A placed on the body surface of the site to be treated.
It is explanatory drawing which showed the image.

In the figure, the X-ray CT image 34 has X
The line CT head image 36 and the image 35 of the spherical mirror 11A are projected.

In this case, there is an effect that the deviation between the position of the center B and the position of the tumor P obtained from the circular contour of the spherical mirror 11A can be measured. Further, the mounting position of the spherical mirror 11A arranged on the body surface is corrected so as to eliminate the deviation between the position of the center B and the position of the tumor P, and the X-ray CT image is measured again. By repeating such work, the position of the center B can be accurately aligned with the position of the tumor P.

FIG. 11 is an explanatory view showing still another embodiment.

In the figure, spherical position indicators 11 and 11 'are provided on the horizontal and vertical surfaces of the patient fixing jig 7, respectively. Position detecting devices 17 and 17 'are arranged to face the respective display devices 11 and 11'.

Laser beams 20 and 20 'are emitted from the angular position detecting devices 17 and 17', respectively, so as to detect deviations in the three axial directions of the X, Y and Z directions.

With this arrangement, the distance measuring device in the laser beam device 12 can be dispensed with.

FIG. 12 is an explanatory view showing still another embodiment.

The material of the spherical mirror 11A is made of an X-ray permeable material such as plastic or a thin metal thin film, and the displacement in the three axial directions of X, Y and Z is detected even during treatment. In FIG. 12, when the position reading device 23 detects a shift between the positions of the isocenter A and the center B, an abnormal signal is immediately input to the electron accelerator control device 33, and the treatment is stopped.

In such a case, it becomes possible to eliminate the positional deviation between the isocenter A and the center B even during the treatment.

FIG. 13 is an explanatory view showing still another embodiment.

In the figure, the projection plate 13 is different from that shown in FIG. 1 in that the transmission / reflection film 37, the irregular reflection plate 38 of the slit portion, and the reflecting mirror 39 are mounted in the slit 21.

When the laser beam 20 passes through the slit 21, a part of the beam is reflected in the direction of 90 degrees on the surface of the transflective film 37, and the reflected beam 20B is displayed on the diffuse reflection plate 38. . The rest of the laser beam 20 passes through the transmissive / reflecting film 37 and is incident on the spherical mirror 11A.
It becomes 0A and returns to the slit 21. Here, a part of the light ray is reflected and the rest is transmitted. This reflected light 20C
Is reflected by the reflecting mirror 39, part of which passes through the transflective film 37, and is displayed on the diffuse reflector 38.

With such a configuration, the positions of the laser beams 20 and 20A that have passed through the slit 21 can be measured, respectively, so that the accuracy of measuring the deviation can be improved.

[0093]

As is apparent from the above description,
According to the stereotactic radiotherapy apparatus according to the present invention, it is possible to quickly and easily confirm whether or not the displacement of the affected part with respect to the isocenter occurs.

Further, when the affected part is displaced from the isocenter, it can be dealt with promptly.

Further, according to the tomographic image photographing method of the present invention, it becomes possible to make it reliable to confirm whether or not the displacement of the affected part is caused with respect to the isocenter of the stereotactic radiotherapy apparatus.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of a stereotactic radiotherapy apparatus according to the present invention.

FIG. 2 is a circuit diagram provided in an embodiment of the stereotactic radiotherapy apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing the operation of an embodiment of the stereotactic radiotherapy apparatus according to the present invention.

FIG. 4 is an explanatory diagram showing the operation of an embodiment of the stereotactic radiotherapy apparatus according to the present invention.

FIG. 5 is an explanatory diagram showing the operation of an embodiment of the stereotactic radiotherapy apparatus according to the present invention.

FIG. 6 is an explanatory diagram showing another embodiment of the present invention.

FIG. 7 is an explanatory diagram showing another embodiment of the present invention.

8 is an explanatory diagram showing an example of a circuit added to the configuration shown in FIG. 7. FIG.

FIG. 9 is an explanatory diagram showing another embodiment of the present invention.

FIG. 10 is a configuration diagram showing an embodiment of a tomographic imaging method according to the present invention.

FIG. 11 is an explanatory diagram showing another embodiment of the present invention.

FIG. 12 is an explanatory diagram showing another embodiment of the present invention.

FIG. 13 is an explanatory diagram showing another embodiment of the present invention.

[Explanation of symbols]

 11A ………… Spherical mirror 12 ……………… Laser beam device 13 ………… Projection plate A …………………… Isocenter P …………………… Tumor

Claims (6)

(57) [Claims] 1. A stereotactic radiotherapy apparatus for locating a diseased part of a subject at an isocenter set by the apparatus itself and irradiating radiation from different directions with the isocenter as a target, wherein a light source for irradiating a laser beam with the isocenter as a target. A spherical mirror having a curved surface fixed to the subject on the optical path between the light source and the isocenter, and having a curved surface with the affected part as a center point; and on the optical path between the spherical mirror and the light source. And a projection plate which is fixedly arranged with respect to the light source and which allows the irradiation light from the light source to pass through and projects the reflected light from the spherical mirror. 2. The stereotactic radiotherapy apparatus according to claim 1, further comprising a detector for detecting a deviation between a projected reflected light of the projection plate and a passing portion of the irradiation light. 3. The stereotactic radiotherapy apparatus according to claim 2, further comprising a mechanism for moving a subject so as to position a diseased part in an isocenter based on detection information from the detector. . 4. As a pre-stage of performing radiotherapy using the invention according to claim 1, in a state where the spherical mirror having a curved surface centered on an affected part of the subject is fixedly arranged with respect to the subject, A tomographic image capturing method comprising capturing a tomographic image of an affected part including the spherical mirror. 5. The invention according to claim 1, wherein the distance from the light source for irradiating the laser beam to the spherical mirror is measured by the reflected light from the spherical mirror, and thereby the positional deviation between the isocenter and the affected area is detected. A stereotactic radiotherapy device characterized by being provided with a length device. 6. The tomographic imaging method according to claim 4, wherein the displacement of the affected part with respect to the center of the curved surface of the spherical mirror is evaluated.