JP2000107161A - Position measurement method with computerized tomograph, computerized tomograph with position measuring function and flat pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure accurately the position of a lesion even when the cradle of a computerized tomograph is deflected greatly. SOLUTION: A marker identifiable on a tomogram is installed in the direction of movement of the cradle on the cradle of a computerized tomograph or a flat pad mounted on the cradle for use, and with a subject positioned, a tomogram is obtained, and the position of the marker on the tomogram is measured with the scan center as a reference (ST3). And then a tomogram where the interesting part of the subject is imaged is obtained, and the position of a lesion on the tomogram is measured with the marker as a reference (ST5). And then, by using the position of the interesting part measured using the scan center as a reference and the position of the interesting part measured with the marker as a reference, the position of the interesting part measured with the scan center as a reference is obtained (ST6), thereby measuring accurate the position of the interesting part measured using the scan center as a reference even if the cradle is deformed or displaced problematically with a radiotherapeutic instrument.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an X-ray CT (Computed T
omography) Position measuring method by apparatus, X-ray CT apparatus having position measuring function, and flat pad
More specifically, even if the cradle of the X-ray CT apparatus flexes, the position of the lesion can be accurately measured.
The present invention relates to a position measuring method using a line CT apparatus, an X-ray CT apparatus that executes the position measuring method, and a flat pad used to execute the position measuring method.

[0002]

2. Description of the Related Art FIG. 12 is a block diagram showing an example of a conventional X-ray CT apparatus having a position measuring function. This X-ray CT
The device 500 includes an operation console 51 and a table device 1
0, a scanning gantry 20, and a flat pad 80. The operation console 51 includes an input device 2 that receives instructions and information from an operator, a central processing device 53 that executes a scan process, an image reconstruction process, a lesion position measurement process (FIG. 13), and the like, a control signal, and the like. 4 for transmitting and receiving data to and from the table apparatus 10 and the scanning gantry 20, a data collection buffer 5 for collecting data acquired by the scanning gantry 20, a CRT 6 for displaying X-ray images and the like, and storing programs and data. And a storage device 7 for performing the operations.

[0003] The table apparatus 10 includes a cradle 12 for placing a subject thereon and taking it into and out of a bore (middle cavity) of the scanning gantry 20. In normal imaging, the subject is placed on the cradle 12 without using the flat pad 80. However, in imaging when performing a treatment plan for radiation irradiation treatment, the flat pad 80 is placed on the cradle 12. The subject is placed on the flat pad 80. This is because the upper surface of the cradle 12 is concave and the condition is not met, while the bed of the irradiation treatment machine is flat.
Is placed on the cradle 12 so that the upper surface is flat and the conditions are adjusted. The lower surface of the flat pad 80 is a convex surface that matches the concave surface of the upper surface of the cradle 12.

The scanning gantry 20 has an upper positioning light 22, a left positioning light 23, and a left positioning light 24 for emitting light beams UL, LL, RL for positioning the subject. Further, although not shown, the apparatus includes an X-ray tube, a collimator, an X-ray controller, a detector, a data acquisition unit, a rotation controller for rotating the X-ray tube and the like around a virtual rotation axis AX, and the like. The intersection of the light beams UL, LL, RL is on the virtual rotation axis AX.

[0005] FIG.
FIG. 7 is a flowchart of a lesion position measurement process executed by the line CT apparatus 500. In step JT1, as shown in FIGS. 14 and 15, the subject H having the body surface mark M attached to the upper surface and both side surfaces is placed on the flat pad 80, and has the same posture as that of the radiation irradiation treatment machine. The light beam U
Positioning is performed so that L, LL, and RL match the body surface mark M, respectively. Thus, the origin Rsc in the subject H defined by the body surface mark M matches the virtual rotation axis AX. In step JT2, as shown in FIG. 16, the cradle 12 is protruded from the table device 10 by a predetermined distance (for example, the scanning gantry 2).
0), and scan is performed, and an X-ray image G as shown in FIG.
Get 1 In step JT3, as shown in FIG. 18, the position (X1, X1) of the lesion K with reference to the scan center (point on the X-ray image corresponding to the rotation axis AX) SC
Y1) is measured.

At the time of radiotherapy, the subject H is placed on a bed of a radiation irradiation treatment machine, and the body surface mark M
The subject H is positioned so that the position of the subject H matches the positioning light of the radiation irradiation treatment machine. Accordingly, the scan center S of the X-ray CT apparatus 500 is moved through the origin Rsc in the subject H defined by the body surface mark M.
Since C and the origin of the radiation therapy machine match, the position (X1,
By irradiating radiation to Y1), it is possible to irradiate the lesion K.

[0007] A related prior art is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-76020.

[0008]

In the above-described conventional lesion position measurement processing (FIG. 13), the origin Rsc in the subject H defined by the body surface mark M matches the scan center SC (FIG. 13). 18) is assumed. However, as shown in FIG. 19, the cradle 12 and the flat pad 80 bend downward due to gravity as they exit the table device 10. For this reason, as shown in FIG.
The actual image position of the subject H (solid line) is
In addition, the distance is lower than the image position (broken line) when the flat pad 80 is not bent by the distance y1. Then
Origin Rs in subject H defined by body surface mark M
c is also lower than the scan center SC by the distance y1. Therefore, the position (X1, Y1) of the lesion K measured with reference to the scan center SC is the cradle 12
And the position of the lesion K measured when the flat pad 80 is not bent is deviated by the distance y1. As a result, the position (X1,
If the radiation is applied to Y1), the radiation will be applied to a position deviated from the lesion K by a distance y1. Therefore, an object of the present invention is to provide a position measuring method using an X-ray CT apparatus capable of accurately measuring the position of a lesion even when a cradle of the X-ray CT apparatus is bent, and an X-ray CT apparatus implementing the position measuring method. And a flat pad used for performing the position measuring method.

[0009]

According to a first aspect, the present invention provides a cradle of an X-ray CT apparatus or a flat pad mounted on the cradle and having a marker identifiable on an X-ray image. It is installed along the direction of movement of the cradle, acquires an X-ray image with the subject positioned, measures the position of the marker on the X-ray image with reference to the scan center, and then determines the region of interest of the subject. Obtaining the reflected X-ray image, measuring the position of the part of interest on the X-ray image with reference to the marker, and then determining the position of the marker measured with reference to the scan center and the interest measured with reference to the marker Provided is a position measurement method using an X-ray CT apparatus, wherein a position of a site of interest is determined based on a scan center using the position of the site. In the position measurement method using the X-ray CT apparatus according to the first aspect, the position of the marker with respect to the scan center is in a state where the subject is positioned, that is, a state in which the deformation of the cradle does not cause a problem in the radiation irradiation treatment machine. Since it is measured on the X-ray image acquired in step (a), the position of the marker is based on the origin in the subject defined by the body surface mark. And even if the cradle is deformed enough to cause a problem in the irradiation treatment machine, the origin and the position of the marker in the subject defined by the body surface mark are similarly displaced, so that the positional relationship between the two remains unchanged. . Therefore, if this is used, regardless of whether the cradle is deformed or not, the position of the region of interest based on the marker is set to the position of the region of interest based on the origin in the subject defined by the body surface mark. Can be converted. That is, the position of the site of interest can be determined based on the scan center in a state where the deformation of the cradle does not matter. Therefore, in the radiation irradiation treatment, the lesion can be accurately irradiated with radiation. The cradle may be displaced right and left due to mechanical accuracy, but in this case also, the position of the site of interest can be accurately measured.

In a second aspect, the present invention provides an operation console, a table device, a scanning gantry, and a cradle of the table device or a flat pad mounted and used on the cradle in a moving direction of the cradle. A marker installed along the X-ray image that can be identified on the X-ray image, a scan center reference marker position measurement unit that measures the position of the marker on the X-ray image captured in a state where the subject is positioned with reference to the scan center, A marker-based region-of-interest position measuring means for measuring the position of the region of interest on the X-ray image in which the region of interest of the sample is reflected, with reference to the marker; and the position of the marker measured with reference to the scan center and the marker. Using the measured position of the part of interest and the position of the part of interest based on the scan center It was equipped with a scanning center reference region of interest position calculating means for determining to provide an X-ray CT apparatus having a position measuring function according to claim. In the X-ray CT apparatus having the position measurement function according to the second aspect, the position measurement method using the X-ray CT apparatus according to the first aspect can be suitably implemented.

According to a third aspect of the present invention, in the present invention, the marker is a rod-like member embedded in the cradle or the flat pad along a moving direction of the cradle. A position measuring method using an X-ray CT apparatus or an X-ray CT apparatus having a position measuring function according to claim 2 is provided. If a bar-shaped member made of a material having a CT value greatly different from that of the cradle or the flat pad is used as the marker, the marker position can be easily detected on the X-ray image.

In a fourth aspect, the present invention is characterized in that the marker is a groove, a hole, or an edge formed in the cradle or the flat pad along a moving direction of the cradle. According to a first aspect of the present invention, there is provided an X-ray CT apparatus having a position measurement function using the X-ray CT apparatus according to the first aspect. If a specific shape portion of a cradle or a flat pad is used as a marker, a separate marker member is not required, and the configuration can be simplified.

In a fifth aspect, the present invention is a flat pad having a lower surface that is used by being placed on a cradle of an X-ray CT apparatus and whose lower surface is a convex surface conforming to the concave surface of the upper surface of the cradle and whose upper surface is flat. Thus, there is provided a flood pad characterized in that a marker identifiable on an X-ray image is provided along a moving direction of a cradle. The flood pad according to the fifth aspect can be suitably used for implementing the position measuring method using the X-ray CT apparatus according to the first aspect.

According to a sixth aspect of the present invention, the marker is a bar-shaped member embedded in the flat pad or a groove, hole, or edge formed in the flat pad along the moving direction of the cradle. The flat pad according to claim 5, wherein: If a bar-shaped member made of a material whose CT value is significantly different from that of the flat pad is used as the marker, the marker position can be easily detected on the X-ray image. In addition, if the unique shape portion of the flat pad is used as a marker, a separate marker member is not required, and the configuration can be simplified.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited by this.

FIG. 1 is a block diagram of an X-ray CT apparatus having a position measuring function according to an embodiment of the present invention. The X-ray CT apparatus 100 includes an operation console 1, a table apparatus 10, a scanning gantry 20, and a flat pad 3.
0. The operation console 1 includes an input device 2 that receives instructions and information of an operator, a central processing device 3 that performs a scan process, an image reconstruction process, a lesion location measurement process (FIG. 3), and the like, a control signal, and the like. 4 for transmitting and receiving data to and from the table apparatus 10 and the scanning gantry 20, a data collection buffer 5 for collecting data acquired by the scanning gantry 20, a CRT 6 for displaying X-ray images and the like, and storing programs and data. And a storage device 7 for performing the operations.

The table apparatus 10 includes a cradle 12 for placing a subject on and out of a bore (middle cavity) of the scanning gantry 20. In normal imaging, the subject is placed on the cradle 12 without using the flat pad 30, but in imaging for performing a treatment plan for radiation irradiation treatment, the flat pad 30 is placed on the cradle 12. The subject is placed on the flat pad 30. This is because the bed of the radiation therapy machine is flat, whereas the upper surface of the cradle 12 is concave and the conditions are not met.
Is placed on the cradle 12 so that the upper surface is flat and the conditions are adjusted.

The scanning gantry 20 includes an upper positioning light 22, a left positioning light 23, and a left positioning light 24 for emitting light beams UL, LL, RL for positioning the subject. Further, although not shown, the apparatus includes an X-ray tube, a collimator, an X-ray controller, a detector, a data acquisition unit, a rotation controller for rotating the X-ray tube and the like around a virtual rotation axis AX, and the like. The intersection of the light beams UL, LL, RL is on the virtual rotation axis AX.

As shown in FIG.
Reference numeral 0 denotes a resin plate whose lower surface is a convex surface conforming to the concave surface of the upper surface of the cradle 12 and whose upper surface is flat. Then, a marker 32 made of an aluminum bar is embedded along the moving direction of the cradle 12.

FIG. 3 is a flowchart of a lesion position measurement process executed by the X-ray CT apparatus 100 when performing a treatment plan. In step ST1, as shown in FIGS. 4 and 5, the subject H with the body surface mark M attached to the upper surface and both side surfaces is placed on the flat pad 30, and the same posture as that in the radiation irradiation treatment machine is set. And the light beams UL, LL, R
Positioning is performed so that L respectively matches the body surface mark M. Thus, the origin Rsc in the subject H defined by the body surface mark M matches the virtual rotation axis AX. In step ST2, as shown in FIG. 4, scanning is performed without moving the cradle 12, and an X-ray image G0 as shown in FIG. 6 is obtained. Note that 32i on the X-ray image G0 is an image of the marker 32. In step ST3, as shown in FIG. 7, the position (X0, Y) of the marker 32 (image 32i) with reference to the scan center (point on the X-ray image corresponding to the rotation axis AX) SC.
Measure 0). Since the X-ray image G0 is obtained by scanning without moving the cradle 12, there is no displacement of the cradle 12, and the origin Rsc in the subject H defined by the body surface mark M is the scan center. It matches SC.

In step ST4, as shown in FIG.
The cradle 12 is protruded from the table device 10 by a predetermined distance (for example, the cradle 12 is protruded by a distance that the body surface mark M matches the scanning surface SP of the scanning gantry 20), and scanning is performed to obtain an X-ray image G1 as shown in FIG. . In step ST5, as shown in FIG.
The position (H1, V1) of the lesion K based on 2i) is measured.

In step ST6, as shown in FIG. 10, the position (H1, V1) of the lesion K with respect to the marker 32 (image 32i) is determined by the origin in the subject H defined by the body surface mark M. Rsc is converted to the position (X0 + H1, Y0 + V1) of the lesion K based on Rsc. The position (X0 + H1, Y0 + V1) of the lesion K is in cradle 1
Since No. 2 is no different from the position of the lesion K with reference to the scan center SC when it is not deformed, it is transferred to the radiation irradiation treatment machine. Note that the scan center SC in the X-ray image G1 is not used for measurement.

At the time of radiation therapy, the subject H is placed on the bed of the radiation irradiation treatment machine and the body surface mark M
The subject H is positioned so that the position of the subject H matches the positioning light of the radiation irradiation treatment machine. Thereby, the scan center SC and the origin of the radiation irradiation treatment machine when the cradle 12 of the X-ray CT apparatus 100 is not deformed coincide with the origin Rsc in the subject H defined by the body surface mark M. Therefore, the position (X0 + H1, Y0 +
By irradiating radiation to V1), it is possible to accurately irradiate the lesion K.

Note that, as shown in FIG.
The groove portion engraved along the moving direction of No. 2 is marked with a marker 32 '.
May be used.

[0025]

According to the position measuring method using the X-ray CT apparatus, the X-ray CT apparatus having the position measuring function, and the flat pad of the present invention, an X-ray image is taken in a state where deformation or displacement of the cradle poses a problem. Even in this case, it is possible to accurately measure the position of the site of interest with respect to the scan center in a state where deformation or displacement of the cradle does not matter. Therefore, for example, even when the cradle is bent, the position of the lesion can be accurately measured, so that the radiation can be accurately irradiated to the lesion in radiation irradiation treatment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an X-ray CT apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a flat pad according to one embodiment of the present invention.

FIG. 3 is a flowchart of a lesion position measurement process according to an embodiment of the present invention.

FIG. 4 is a schematic side view illustrating positioning of a subject.

FIG. 5 is a schematic sectional view illustrating positioning of a subject.

FIG. 6 is an exemplary diagram of an X-ray image obtained by scanning the subject in a positioned state.

FIG. 7 is an explanatory diagram of measurement of a marker position with reference to a scan center.

FIG. 8 is a schematic side view illustrating scanning in a state where the cradle is largely bent.

FIG. 9 is an explanatory diagram of measurement of a lesion position based on a marker.

FIG. 10 is an explanatory diagram of conversion from a lesion position based on a marker to a lesion position based on a scan center.

FIG. 11 is a perspective view of a flat pad according to another embodiment of the present invention.

FIG. 12 is a configuration diagram of an example of a conventional X-ray CT apparatus.

FIG. 13 is a flowchart of a conventional lesion position measurement process.

FIG. 14 is a schematic side view illustrating positioning of a subject.

FIG. 15 is a schematic cross-sectional view illustrating positioning of a subject.

FIG. 16 is a schematic side view illustrating a scan in a state where the cradle is not bent.

FIG. 17 is an exemplary diagram of an X-ray image obtained by scanning in a state where the cradle is not bent.

FIG. 18 is an explanatory diagram of measurement of a lesion position based on a scan center.

FIG. 19 is a schematic side view illustrating scanning in a state where the cradle is bent.

FIG. 20 is an explanatory diagram of measurement of a lesion position based on a scan center.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Operation console 3 Central processing unit 10 Table device 12 Cradle 20 Scanning gantry 30 Flat pad 32, 32 'Marker 100 X-ray CT apparatus AX Rotation axis H Subject M Body surface mark Rsc Inside the body defined by body surface mark Origin SC Scan Center UL, LL, RL Light beam

Claims (6)

[Claims] 1. A cradle of an X-ray CT apparatus or a flat pad used by being placed on the cradle, a marker identifiable on an X-ray image is set along a moving direction of the cradle, and a subject is positioned. An X-ray image is acquired in a state where the X-ray image is obtained, the position of the marker is measured on the X-ray image with reference to the scan center, and then an X-ray image in which the region of interest of the subject is reflected is acquired. The position of the region of interest is measured with the marker as a reference, and the position of the marker measured with the scan center as a reference and the position of the region of interest measured with the marker as a reference are used as the region of interest with respect to the scan center. A position measurement method using an X-ray CT apparatus, wherein the position of the object is determined. 2. An operation console, a table device, a scanning gantry, and a cradle of the table device or a flat pad mounted on the cradle and used along the direction of movement of the cradle and provided on an X-ray image. And a scan center reference marker position measuring means for measuring the position of the marker on the X-ray image taken in a state where the subject is positioned with reference to the scan center, and a region of interest of the subject reflected A marker reference region of interest position measuring means for measuring the position of the region of interest on the X-ray image with reference to the marker; and a position of the marker measured with reference to the scan center and a position of the region of interest measured with reference to the marker. Scan center base to find the position of the part of interest based on the scan center An X-ray CT apparatus having a position measuring function, comprising a quasi-interest part position calculating means. 3. The marker according to claim 1, wherein the marker is a rod-like member embedded in the cradle or the flat pad along a moving direction of the cradle.
An X-ray CT apparatus having a position measurement function according to claim 2, wherein the X-ray CT apparatus has a position measurement function. 4. The X-ray CT according to claim 1, wherein the marker is a groove, a hole, or an edge formed in the cradle or the flat pad along a moving direction of the cradle. An X-ray CT apparatus having the position measuring function according to claim 2 or a position measuring method using the apparatus. 5. A flat pad which is used by being placed on a cradle of an X-ray CT apparatus and whose lower surface is a convex surface conforming to the concave surface of the upper surface of the cradle and whose upper surface is flat,
A flood pad, wherein a marker identifiable on an X-ray image is provided along a moving direction of a cradle. 6. The marker according to claim 1, wherein the marker is a bar-like member embedded in the flat pad along a moving direction of the cradle or a groove, a hole, or an edge formed in the flat pad. 5. The flat pad according to 5.