JP2005027743A - Radiotherapy positioning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiotherapy positioning device allowing an operator to accurately irradiate the position of a tumor of a patient with a radiation beam. <P>SOLUTION: The radiotherapy space in the radiotherapy positioning device is set by a solid image restructuring computer 1 for restructuring solid images of an affected part and the body surface of the patient with three-dimensional data based on X-ray tomographic image data of the patient, a non-contact three-dimensional digitizer 3 for photographing the patient on a treatment bed and obtaining the accurate solid image three-dimensional data on the body surface, and three-dimensional coordinates. The restructured solid image is set at a position/inclination in which the affected part is irradiated with the radiotherapy beam as a reference image, and the solid image from the non-contact three-dimensional digitizer 3 is at a position corresponding to the actual position of the patient as an actual image in the radiotherapy positioning device. The radiotherapy positioning device also has a displacement calculation computer 2 for outputting the displacement of the actual image from the reference image as the displacement on each three-dimensional axis and the inclination around each axis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to a technical field of positioning an irradiation beam or a patient so that the irradiation beam correctly irradiates an affected part in a radiotherapy apparatus that treats a tumor or the like using radiation.
[0002]
[Prior art]
Today, in radiation therapy, X-ray tomography of a site including an affected area of a patient is performed by an X-ray tomography apparatus (referred to as a CT apparatus) prior to treatment. Thereby, the position, shape and size of the tumor in the body can be known.
Tumor location is confirmed as follows.
When the patient is laid on the moving table of the CT apparatus, the moving table is moved in the head-to-tail direction while viewing the tomographic image (CT image), and if a tumor image appears, the size changes. Stop the moving base at the place considered to be the center, hit the body surface of the patient's body surface from the left side surface through the top surface to the right side surface from the projector equipped on the CT device, and see straight from the top Light that appears to be (A straight line), head-to-tail direction on the upper surface of the body surface, light that appears to be a straight line (referred to as B line) perpendicular to the A line, and on both sides of the body surface In the head-to-tail direction, light that appears to be a straight line orthogonal to the A line (for example, the left side is a C line and the right side is a D line and the height is the same) is projected.
[0003]
The relationship between these straight lines is obtained by the intersection of the vertical plane passing through the A straight line, the vertical plane passing through the B straight line, and the horizontal plane passing through the C straight line and the D straight line being the center of rotation around which the X-ray beam rotates. This is the center of the CT image and the origin of the two-dimensional (vertical and horizontal) coordinates in the vertical cross section including the A line.
[0004]
Therefore, when a tumor image appears on the CT image, a straight line A generated on the body surface by projecting light from the projector means that a vertical plane including the straight line A is on the tumor. Further, it means that the intersection of the vertical line passing through the intersection of the A straight line and the B straight line and the horizontal line passing through the intersection of the A straight line, the C straight line and the D straight line is the origin of the vertical sectional image.
[0005]
The position of the tumor is specified by XY two-dimensional coordinates so that the position of the tumor on the vertical section is in the horizontal direction (X axis) from the origin and the position in the vertical direction (Y axis).
[0006]
In order to secure such tumor position information, when the tumor appears on the CT screen, the moving table is stopped, and each straight line of A, B, C, D is projected from the projector onto the patient's body surface. Light up and trace the line with a writing instrument and record it on the body surface. As a result, the A and B straight lines intersect on the upper surface of the body surface, the A and C straight lines intersect on the left side, and the A and B straight lines intersect on the right side. This intersecting line is called a crosshair.
[0007]
Thus, the patient whose crosshairs are written on the body surface is moved to the radiation treatment room and laid down on the treatment table.
In the treatment room, a projector is provided on the side wall or ceiling, and when light is projected onto the patient, the light corresponding to each of the straight lines A, B, C, and D is applied to the patient's body surface as in the case of the CT apparatus. The line is reflected.
[0008]
Therefore, the position of the patient is adjusted so that the cruciform line written on the surface of the patient coincides with the line of light. When each line written on the body surface matches each line of light, the origin in the patient's body matches the isocenter of the radiation therapy apparatus.
[0009]
In this way, the isocenter and the patient's body origin coincide with each other, and the two-dimensional position information of the tumor obtained by the CT apparatus is input to the radiation treatment apparatus, so that the radiation beam can be correctly irradiated to the tumor. It will be.
[0010]
In addition to the above methods, as a method of bringing the tumor whose position is grasped by the CT image to the beam irradiation position of the radiotherapy apparatus, a fixture is attached to the patient in advance prior to CT imaging, and the fixture is used as a reference position. There are methods for patient alignment. In positioning on the treatment table, a fixture holder is prepared in advance on the treatment table side, and the patient is positioned at the aiming position of the treatment beam by aligning the fixture attached to the patient with this fixture. Can do. Fixing tools such as those that fix the metal ring to the patient with bolts, or models that put a thermoplastic mesh on the patient are used (the above prior art is based on the applicant's experience) And there is no prior art document known to the applicant at the time of filing this application).
[0011]
[Problems to be solved by the invention]
However, the above conventional techniques have the following problems.
First, with the technique of drawing a crosshair on the patient's body surface at the time of CT image capture, it is difficult to always ensure positioning accuracy within an irradiation position error of ± 1 mm required for high-precision radiotherapy. There is.
The reason is that the light beam from the projector itself has a width of about 1 to 2 mm, and the line width of the writing tool to be drawn on the surface of the patient has a width of about 2 to 3 mm. In addition, a cotton swab or the like may be used in place of the writing instrument, but in that case, the width of the crosshair is further increased.
[0012]
The device for projecting the crosshairs is installed on the side wall or ceiling of the treatment room, but is about 3 m from the patient's position to the wall in the treatment room and about 1.5 m to the ceiling. That is, the projector is at a distance of 3 m from the patient, and it is difficult to align the light beam emitted from the projector at a right angle to the patient body surface.
Accordingly, when oblique irradiation is performed, the line width on the body surface becomes wide.
[0013]
Moreover, since the mounting position of the wall surface changes depending on the room temperature and humidity, it is necessary to always check whether or not the light emitted from the wall matches the isocenter correctly.
Furthermore, the positioning procedure can be performed only on the left side, top side, and right side of the patient. That is, since the three dimensions cannot be matched at once, it is often time consuming and the accuracy is insufficient.
[0014]
Next, among the methods of attaching a fixture to the patient prior to CT imaging, the method of fixing the metal ring to the patient with a bolt as a fixture has the problem of causing great physical and mental pain to the patient, In the method of covering the patient with a thermoplastic mesh, there is a problem that it is not possible to completely prevent the patient from being displaced with respect to the fixture while the patient is placed on the treatment table in the radiation treatment room from the CT apparatus. is there.
[0015]
An object of the present invention is to provide a radiation treatment positioning apparatus capable of positioning a patient on a radiation treatment table with higher accuracy than before without giving physical or mental pain to the patient in view of the above-mentioned problems of the prior art. There is to do.
[0016]
[Means for Solving the Problems]
In order to achieve the above object, a first configuration of the radiotherapy positioning apparatus of the present invention comprises the following technical means.
(B) A three-dimensional image reconstruction computer that reconstructs a three-dimensional image of a diseased part and a body surface from X-ray tomographic image data of a patient with a three-dimensional data. Non-contact three-dimensional digitizer that outputs three-dimensional data of a three-dimensional image of a patient's body surface with a specific position as a reference position (C) In the three-dimensional coordinates on the computer including the reference position of the radiotherapy apparatus, Based on the reconstructed three-dimensional data, a stereoscopic image of the patient is set as a reference image at a position where the affected area is just irradiated with a radiation beam having a predetermined position and inclination, and the non-contact three-dimensional digitizer A stereoscopic image of the patient's body surface is set at a position corresponding to the actual position of the patient based on the three-dimensional data from the image, and the stereoscopic image is compared with the reference image. Displacement calculating computer calculates outputs the amount of displacement of the rolling for the six parameters of the three-dimensional rotation in each axis direction and the axis [0017]
In the second configuration, in addition to the first configuration, the displacement amount data from the displacement calculation computer is received, and the position and inclination of the treatment table on which the patient is placed are set to zero. It is provided with a treatment table control device that controls to approach.
[0018]
In the third configuration, in addition to the first configuration, the displacement amount data from the displacement calculation computer is received, and the position and inclination of the radiation beam are displaced by the displacement amount data from the predetermined position and inclination. A beam irradiator control device.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, a patient is imaged with an X-ray CT apparatus, and a stereoscopic image of an affected part and a body surface is reconstructed from three-dimensional data from the obtained CT image by a computer, and a radiotherapy space is set for this stereoscopic image. The radiation treatment space is set according to the position and inclination at which the radiation beam is irradiated onto the affected area. This is a reference image.
[0020]
On the other hand, an actual patient is placed on the radiation treatment table, and the patient is photographed with a non-contact three-dimensional object shape measuring device (non-contact three-dimensional digitizer) installed at a position where the patient on the treatment table can be photographed. A three-dimensional three-dimensional image of the body surface is obtained, and this data is input to the computer and set at a position corresponding to the actual position of the patient in the radiation treatment space of the computer.
[0021]
The actual position is set by setting a specific reference point in the radiotherapy apparatus, setting the position data in the radiotherapy space of the computer, and photographing the patient with a non-contact three-dimensional digitizer. Sometimes this specific reference point is photographed together, and the data of the specific reference point is obtained from the non-contact 3D digitizer so as to match the data of the specific reference point preset in the radiotherapy space of the computer. This is possible by setting three-dimensional data, or a method of calibrating the setting position of the non-contact three-dimensional digitizer so that the output data becomes data corresponding to the actual position as it is when input to the computer. But you can.
[0022]
Anyway, in this way, a reference image and a three-dimensional body surface image of the patient on the treatment table (hereinafter referred to as an actual image) exist on the radiation treatment space of the computer.
[0023]
If the actual image matches the body surface image of the reference image, the radiation therapy beam will just irradiate the affected area.
On the other hand, if the actual image deviates from the reference image, the radiation therapy beam will be removed from the affected area, so that the position or inclination of the patient or the radiation therapy beam is adjusted so that the actual image matches the reference image. I need to move it.
[0024]
Therefore, the computer calculates, based on the three-dimensional data of the reference image and the actual image, the deviation data indicating how much the actual image is deviated from the reference image, the deviation on each three-dimensional axis, and the inclination (rotation) around each axis. Is calculated and output.
[0025]
Based on this calculated value, the operator corrects the position and tilt of the treatment table so that the value approaches zero, or conversely changes the position and tilt of the radiotherapy beam by the calculated value to accurately adjust the affected area. Be irradiated with a radiotherapy beam.
[0026]
Among these, when changing the position of the treatment table, the reference image and the actual image may be displayed on the display of the computer, and the position of the treatment table may be operated so that the actual image overlaps the reference image.
[0027]
The above is a case where the position and inclination of the treatment table or the radiation treatment beam are operated by a human hand, but this can also be performed automatically.
When trying to move the treatment table to match the actual image with the reference image, the position of the treatment table is controlled by negative feedback automatic control that controls the displacement of the treatment table so that the deviation data is close to zero. Control is sufficient.
[0028]
When moving the radiation therapy beam, drive control is performed to move and tilt the radiation treatment beam by an amount corresponding to the deviation data.
[0029]
【Example】
Embodiments of the radiation therapy positioning apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the first embodiment of the present invention. The stereoscopic image reconstruction computer 1 receives X-ray CT image data from the X-ray CT apparatus, and based on this, reconstructs a stereoscopic image of the affected area such as a tumor of the patient and the body surface with three-dimensional data. A CT image of one cross section is a two-dimensional image in the horizontal direction (X axis) and the vertical direction (Y axis) with the origin of the CT apparatus in the body, and the position of the affected area or body surface is represented by two-dimensional coordinates. The Since such an image is repeatedly photographed while moving the patient's position in the head-to-tail direction (Z-axis), the position in the Z-axis direction is also recorded. The image can be reconstructed.
[0030]
The reconstructed stereoscopic image three-dimensional data obtained in this way is sent to the displacement calculation computer 2. The sending method may be a method of connecting computers, recording a medium, and mounting the medium on the displacement calculation computer 2.
[0031]
A radiation treatment space is set in the displacement calculation computer 2 in three-dimensional coordinates, and when a reconstructed stereoscopic image is input, an input is made so that the affected area of the patient is exactly at the position irradiated with the radiation beam. This image is used as a reference image.
[0032]
A patient who has finished CT imaging lies on the treatment table 8 of the radiotherapy apparatus, usually in a separate room, in the same manner as when lying on the imaging table of the CT apparatus. In the vicinity of the treatment table 8, a non-contact three-dimensional object shape measuring device (referred to as a non-contact three-dimensional digitizer) 3 for photographing the body surface of the patient 13 on the treatment table 8 and obtaining three-dimensional data of the body surface. Is provided.
[0033]
This non-contact three-dimensional digitizer 3 is a device that measures the surface solid shape of a target object with three-dimensional data by a light cutting method using laser light or white light as a light source, and has a high accuracy of ± 0.01 mm or less, ± The one with high accuracy of 0.25 mm or less is already on the market by optical equipment manufacturers.
[0034]
The non-contact three-dimensional digitizer 3 images the body surface of the patient 13 on the treatment table 8 and sends the obtained three-dimensional body surface data to the displacement calculation computer 2 so that the actual position of the patient in the radiotherapy space in the computer. Is set to a position corresponding to. This is called an actual image.
[0035]
Eventually, the reference image and the actual image exist in the radiation treatment space of the displacement calculation computer 2.
Since the body surface shape of the patient 13 is the same as long as they are the same person in the same posture, the shape of the three-dimensional image is the same for both the reference image and the actual image.
[0036]
Even now, if the actual image is superimposed on the reference image on the computer, the radiation beam hits the affected area at the same position and inclination on the treatment table 8.
This is based on the assumption that if the actual image overlaps the reference image, the affected area is also at the same position as the reference image.
[0037]
On the other hand, when the actual image does not overlap with the reference image, the affected part is out of the radiation beam, so that the patient on the treatment table cannot receive treatment at the same position.
[0038]
Therefore, the displacement calculation computer 2 determines how much the actual image is deviated from the reference image based on the three-dimensional data of the positional deviation in each of the X, Y, and Z axes and the rotational deviation around each axis. A total of 6 deviation data are calculated and output.
[0039]
Based on this data, the treatment is started after adjusting the position and inclination of the treatment table 8 or the position and inclination of the radiation beam 12 of the radiation beam irradiator 7 so as to correct the deviation.
[0040]
This adjustment can be performed manually or automatically.
When manual adjustment of the treatment table 8 is performed based on the first positional deviation data and rotation deviation data without using the treatment table control device 4, the deviation value gradually decreases and becomes zero. The time is when the actual image overlaps the reference image.
[0041]
In this way, adjustment can be performed while viewing the deviation data, or the reference image 9 and the actual image 10 are projected on the display 6 of the displacement calculation computer 2 so that the actual image 10 overlaps the reference image 9 while viewing this. You can also adjust it. However, accurate positioning can be performed by confirming that the numerical value of the deviation data is finally zero or within an allowable range.
[0042]
The above is a case where the treatment table is adjusted manually, but the treatment table can be automatically adjusted by the treatment table control device 4.
When the deviation data from the displacement calculating computer 2 is input, the treatment table control device 4 controls the position and inclination of the treatment table 8 in the direction in which the deviation data approaches zero based on this data. Is configured. By configuring such a circuit, the position and inclination of the treatment table can be automatically controlled so that the actual image overlaps the reference image.
[0043]
Note that the stereoscopic image reconstruction computer 1 and the displacement calculation computer 2 may be separate computers, one computer may be used in time series, or a part of the computer may be shared.
[0044]
FIG. 2 is a block diagram showing the configuration of the second embodiment in which the position and inclination of the radiation beam 12 from the radiation beam irradiator 7 are moved instead of moving the treatment table, unlike the case of FIG.
Deviation data from the displacement calculation computer 2 is input to the beam irradiator controller 5. The beam irradiator control device 5 changes the position and inclination of the radiation beam 12 by an amount corresponding to the numerical value of the input deviation data. In this case, no feedback circuit is formed.
[0045]
Further, the position and inclination of the radiation beam 12 can be manually changed by an amount corresponding to the numerical value of the deviation data without using the beam irradiator control device 5.
In any case, since the radiation beam 12 is shifted by the numerical value of the shift data, the radiation beam irradiates the affected area.
[0046]
【The invention's effect】
As described above, the radiotherapy positioning apparatus of the present invention reconstructs a three-dimensional image of a patient's affected area and body surface from a X-ray CT image using a computer, and converts the three-dimensional image into a three-dimensional space for radiotherapy. Is set in the radiation treatment space at the position and inclination where the radiation beam just irradiates the affected part in the stereoscopic image, and this is used as the reference image, while the treatment table is actually used. The patient lying on top is photographed with a high-precision, high-accuracy non-contact 3D digitizer to obtain 3D data of the body surface, and this data corresponds to the patient's actual position in the radiation treatment space of the displacement calculation computer. The actual image is set at the position to be calculated, and how much the actual image deviates from the reference image is calculated and output as the deviation on each three-dimensional axis and the inclination around each axis. Therefore, accurate deviation data is obtained, and the position and inclination of the treatment table or the radiation beam are adjusted by manual operation or automatic control based on this accurate deviation data, so that the radiation beam irradiates the affected area. Therefore, there is an advantage that positioning with high accuracy and high accuracy becomes possible.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.
FIG. 2 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Stereoscopic image reconstruction computer 2 Displacement calculation computer 3 Non-contact 3D digitizer 4 Treatment table controller 5 Beam irradiation device control device 6 Display 7 Radiation beam irradiation device 8 Treatment table 9 Reference image 10 Actual image 11 Tumor image 12 Radiation beam 13 patient

Claims (3)

A radiotherapy positioning apparatus comprising the following technical means.
(B) A three-dimensional image reconstruction computer that reconstructs a three-dimensional image of a diseased part and a body surface from X-ray tomographic image data of a patient with a three-dimensional data. Non-contact three-dimensional digitizer that outputs three-dimensional data of a three-dimensional image of a patient's body surface with a specific position as a reference position (C) In the three-dimensional coordinates on the computer including the reference position of the radiotherapy apparatus, Based on the reconstructed three-dimensional data, a stereoscopic image of the patient is set as a reference image at a position where the affected area is just irradiated with a radiation beam having a predetermined position and inclination, and the non-contact three-dimensional digitizer A stereoscopic image of the patient's body surface is set at a position corresponding to the actual position of the patient based on the three-dimensional data from the image, and the stereoscopic image is compared with the reference image. Displacement calculating computer calculates outputs the amount of displacement of the rolling for the six parameters of the three-dimensional rotation in each axis direction and the axis In addition to the configuration of claim 1, a treatment that receives displacement amount data from a displacement calculation computer and controls the position and inclination of a treatment table on which a patient is placed so that the calculated displacement amount approaches zero. A radiotherapy positioning apparatus comprising a table control device. 2. A beam irradiator control device which receives displacement amount data from a displacement calculation computer and shifts the position and inclination of a radiation beam by the displacement amount data from the predetermined position and inclination in addition to the configuration of claim 1. A radiotherapy positioning apparatus comprising:

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