JP4130024B2 - Position measuring method using X-ray CT apparatus, X-ray CT apparatus having position measuring function, and flat pad - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a position measuring method using an X-ray CT (Computed Tomography) apparatus, an X-ray CT apparatus having a position measuring function, and a flat pad, and more specifically, accurate even if the cradle of the X-ray CT apparatus is bent. In particular, the present invention relates to a position measurement method using an X-ray CT apparatus capable of measuring the position of a lesion, an X-ray CT apparatus for performing the position measurement method, and a flat pad used for performing the position measurement method.
[0002]
[Prior art]
FIG. 12 is a block diagram of an example of an X-ray CT apparatus having a conventional position measurement function.
The X-ray CT apparatus 500 includes an operation console 51, a table apparatus 10, a scanning gantry 20, and a flat pad 80.
The operation console 51 includes an input device 2 that receives an operator's instructions and information, a central processing unit 53 that executes a scan process, an image reconstruction process, a lesion position measurement process (FIG. 13), a control signal, and the like. The interface 4 that performs transmission / reception between the table device 10 and the scanning gantry 20, the data collection buffer 5 that collects data acquired by the scanning gantry 20, the CRT 6 that displays an X-ray image, and the like, stores programs and data And a storage device 7.
[0003]
The table device 10 includes a cradle 12 on which a subject is placed and put into and out of a bore (inner 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 for performing a treatment plan for radiation irradiation treatment, the flat pad 80 is placed on the cradle 12. Then, the subject is placed on the flat pad 80. This is because the upper surface of the cradle 12 is concave and the conditions are not met while the bed of the radiation irradiation treatment machine is flat, so that the upper surface can be obtained by placing a flat pad 80 having a flat upper surface on the cradle 12. This is for making the conditions flat. 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.
[0004]
The scanning gantry 20 includes an upper positioning light 22, a left positioning light 23, and a left positioning light 24 that respectively emit light beams UL, LL, and RL for positioning the subject. Further, although not shown, an X-ray tube, a collimator, an X-ray controller, a detector, a data collection unit, a rotation controller that rotates the X-ray tube and the like around a virtual rotation axis AX, and the like are provided. The intersection of the light beams UL, LL, RL is on the virtual rotation axis AX.
[0005]
FIG. 13 is a flowchart of a lesion position measurement process executed by the X-ray CT apparatus 500 when performing the treatment plan.
In step JT1, as shown in FIGS. 14 and 15, the subject H with the body surface mark M attached to the upper surface and the surfaces on both sides is placed on the flat pad 80, and the same posture as that in the radiation irradiation treatment machine. Then, positioning is performed so that the light beams UL, LL, and RL are aligned with the body surface mark M, respectively. Thereby, the origin Rsc in the subject H defined by the body surface mark M coincides with the virtual rotation axis AX.
In step JT2, as shown in FIG. 16, the cradle 12 is protruded by a predetermined distance from the table device 10 (for example, protruded by a distance where the body surface mark M matches the scanning surface SP of the scanning gantry 20), and scanning is performed. An X-ray image G1 as shown in FIG. 17 is acquired.
In step JT3, as shown in FIG. 18, the position (X1, Y1) of the lesion K with respect to the scan center (a point on the X-ray image corresponding to the rotation axis AX) SC is measured.
[0006]
In radiotherapy, the subject H is placed on the bed of the radiation treatment machine, and the subject H is positioned so that the body surface mark M of the subject H is aligned with the positioning light of the radiation treatment machine. As a result, the scan center SC of the X-ray CT apparatus 500 matches the origin of the radiation treatment machine via the origin Rsc in the subject H defined by the body surface mark M. If radiation is irradiated to the position (X1, Y1) based on the origin of the treatment machine, the lesioned part K can be irradiated with radiation.
[0007]
Related prior art is disclosed in, for example, Japanese Patent Laid-Open No. 10-76020.
[0008]
[Problems to be solved by the invention]
The conventional lesion position measurement process (FIG. 13) is based on the assumption that the origin Rsc in the subject H defined by the body surface mark M matches the scan center SC (FIG. 18).
However, as shown in FIG. 19, the cradle 12 and the flat pad 80 bend downward due to gravity as they exit the table apparatus 10. For this reason, as shown in FIG. 20, the actual image position (solid line) of the subject H is lowered by a distance y1 from the image position (broken line) when the cradle 12 and the flat pad 80 are not bent. Then, the origin Rsc in the subject H defined by the body surface mark M is also lowered by the distance y1 from the scan center SC. Accordingly, the position (X1, Y1) of the lesion K measured with reference to the scan center SC is deviated by a distance y1 from the position of the lesion K measured when the cradle 12 and the flat pad 80 are not bent. As a result, if radiation is irradiated to the position (X1, Y1) with reference to the origin of the radiation treatment machine, radiation is irradiated to a position that is separated from the lesion K by the distance y1.
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a position measuring method using an X-ray CT apparatus that can accurately measure the position of a lesion even if the cradle of the X-ray CT apparatus is bent, and an X-ray CT apparatus that implements the position measuring method. And providing a flat pad used for carrying out the position measuring method.
[0009]
[Means for Solving the Problems]
In a first aspect, the present invention provides an X-ray CT apparatus cradle or a flat pad placed on the cradle for use with a marker identifiable on an X-ray image along the moving direction of the cradle. The X-ray image is acquired with the subject positioned, the marker position is measured on the X-ray image with reference to the scan center, and then the X-ray image in which the region of interest of the subject is reflected is acquired. The position of the region of interest on the X-ray image is measured with reference to the marker, and then the position of the marker measured with reference to the scan center and the position of the region of interest measured with reference to the marker are used as the scan center. A position measuring method using an X-ray CT apparatus is provided, wherein the position of a region of interest is obtained with reference to.
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 a state in which the subject is positioned, that is, a state that does not cause a problem in the radiation treatment machine even when the cradle is deformed. Since the measurement is performed on the X-ray image acquired in step 1, the marker position is based on the origin in the subject defined by the body surface mark. And even if the cradle is deformed so as to cause a problem with the radiation treatment machine, the origin in the subject defined by the body surface mark and the position of the marker are misaligned in the same way, so the positional relationship between the two remains unchanged. . Therefore, using this, regardless of whether the cradle is deformed or not, the position of the region of interest relative to the marker is set to the position of the region of interest relative to the origin in the subject defined by the body surface mark. It can be converted. That is, it is possible to obtain the position of the region of interest with reference to the scan center in a state where cradle deformation is not a problem. Therefore, in the radiation irradiation treatment, it is possible to accurately irradiate the affected area with radiation.
Although the cradle may be displaced from side to side due to mechanical accuracy, the position of the region of interest can be accurately measured in this case as well.
[0010]
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 used by being mounted on the cradle along the moving direction of the cradle. A marker that can be identified on the X-ray image, a scan center reference marker position measuring unit that measures the position of the marker on the X-ray image taken with the subject positioned, and the subject's interest Marker reference region-of-interest position measuring means for measuring the position of the region of interest on the X-ray image in which the region is reflected, the marker position measured on the basis of the scan center, and the interest measured on the basis of the marker The position of the region of interest with reference to the scan center. To provide an X-ray CT apparatus having a position measuring function, characterized by comprising a down center reference region of interest position calculating means.
In the X-ray CT apparatus having the position measuring function of the second aspect, the position measuring method by the X-ray CT apparatus of the first aspect can be suitably implemented.
[0011]
In a third aspect, the present invention provides the X-ray CT 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. A position measuring method using the apparatus or an X-ray CT apparatus having the position measuring function according to claim 2 is provided.
If a bar-shaped member made of a material having a CT value significantly different from that of the cradle or flat pad is used as the marker, the marker position can be easily detected on the X-ray image.
[0012]
In a fourth aspect, the present invention provides the marker 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. A position measuring method using the X-ray CT apparatus described above or an X-ray CT apparatus having the position measuring function according to claim 2 is provided.
If a unique shape part 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.
[0013]
In a fifth aspect, the present invention is a flat pad that is used by being placed on a cradle of an X-ray CT apparatus, the lower surface is a convex surface that fits the concave surface of the upper surface of the cradle, and the upper surface is a flat pad. Provided is a flood pad characterized in that a marker identifiable on a line image is installed along a moving direction of a cradle.
The flood pad of the fifth aspect can be suitably used for performing the position measuring method by the X-ray CT apparatus of the first aspect.
[0014]
In a sixth aspect, the present invention is that the marker is a rod-like member embedded in the flat pad along the moving direction of the cradle, or a groove, hole or edge formed in the flat pad. A flat pad according to claim 5 is provided.
If a rod-shaped member made of a material having a CT value that 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. Further, if a specific 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]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. Note that the present invention is not limited thereby.
[0016]
FIG. 1 is a block diagram of an X-ray CT apparatus having a position measurement function according to an embodiment of the present invention.
The X-ray CT apparatus 100 includes an operation console 1, a table device 10, a scanning gantry 20, and a flat pad 30.
The operation console 1 includes an input device 2 that receives an operator's instructions and information, a central processing device 3 that executes a scan process, an image reconstruction process, a lesion position measurement process (FIG. 3), a control signal, and the like. The interface 4 that performs transmission / reception between the table device 10 and the scanning gantry 20, the data collection buffer 5 that collects data acquired by the scanning gantry 20, the CRT 6 that displays an X-ray image, and the like, stores programs and data And a storage device 7.
[0017]
The table device 10 includes a cradle 12 on which a subject is placed and put into and out of a bore (inner cavity) of the scanning gantry 20. In normal imaging, the subject is placed on the cradle 12 without using the flat pad 30. However, in imaging for performing a treatment plan for radiation irradiation treatment, the flat pad 30 is placed on the cradle 12. Then, the subject is placed on the flat pad 30. This is because the upper surface of the cradle 12 is concave and the conditions are not met, while the bed of the radiation treatment machine is flat, and the condition does not meet. This is for making the conditions flat.
[0018]
The scanning gantry 20 includes an upper positioning light 22, a left positioning light 23, and a left positioning light 24 that respectively emit light beams UL, LL, and RL for positioning the subject. Further, although not shown, an X-ray tube, a collimator, an X-ray controller, a detector, a data collection unit, a rotation controller that rotates the X-ray tube and the like around a virtual rotation axis AX, and the like are provided. The intersection of the light beams UL, LL, RL is on the virtual rotation axis AX.
[0019]
As shown in FIG. 2, the flat pad 30 is a resin plate whose lower surface is a convex surface that matches the concave surface of the upper surface of the cradle 12 and whose upper surface is a flat surface. And the marker 32 of the rod-shaped member made from aluminum is embed | buried along the moving direction of the cradle 12. As shown in FIG.
[0020]
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 FIG. 4 and FIG. 5, the subject H with the body surface mark M attached to the upper surface and the surfaces on both sides is placed on the flat pad 30, and the same posture as that in the radiation treatment machine. Then, positioning is performed so that the light beams UL, LL, and RL are aligned with the body surface mark M, respectively. Thereby, the origin Rsc in the subject H defined by the body surface mark M coincides with 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 acquired. 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, Y0) of the marker 32 (image 32i) with reference to the scan center (a point on the X-ray image corresponding to the rotation axis AX) SC is measured. Since this X-ray image G0 is obtained by scanning without moving the cradle 12, there is no positional deviation 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.
[0021]
In step ST4, as shown in FIG. 8, the cradle 12 is protruded by a predetermined distance from the table device 10 (for example, protruded by a distance where the body surface mark M matches the scanning surface SP of the scanning gantry 20), and scanning is performed. An X-ray image G1 as shown in FIG.
In step ST5, as shown in FIG. 9, the position (H1, V1) of the lesion K with reference to the marker 32 (image 32i) is measured.
[0022]
In step ST6, as shown in FIG. 10, the position (H1, V1) of the lesioned part K with reference to the marker 32 (image 32i) is used as a reference with the origin Rsc in the subject H defined by the body surface mark M. To the position of the lesion K (X0 + H1, Y0 + V1). The position (X0 + H1, Y0 + V1) of the lesion K is nothing but the position of the lesion K with reference to the scan center SC when the cradle 12 is not deformed.
Note that the scan center SC in the X-ray image G1 is not used for measurement.
[0023]
In radiotherapy, the subject H is placed on the bed of the radiation treatment machine, and the subject H is positioned so that the body surface mark M of the subject H is aligned with the positioning light of the radiation treatment machine. As a result, the scan center SC and the origin of the radiation treatment machine coincide with each other when the cradle 12 of the X-ray CT apparatus 100 is not deformed via the origin Rsc in the subject H defined by the body surface mark M. Therefore, if the radiation is irradiated to the position (X0 + H1, Y0 + V1) with the origin of the radiation irradiation treatment machine as a reference, the lesion K can be accurately irradiated with the radiation.
[0024]
In addition, as shown in FIG. 11, you may use flat pad 30 'which uses the groove part carved along the moving direction of the cradle 12 as the marker 32'.
[0025]
【The invention's effect】
According to the position measuring method using the X-ray CT apparatus, the X-ray CT apparatus having a position measuring function, and the flat pad according to the present invention, even when an X-ray image is taken in a state where deformation or misalignment of the cradle becomes a problem, the cradle It is possible to accurately measure the position of the region of interest with reference to the scan center in a state in which the deformation or misalignment does not matter. Therefore, for example, even when the cradle is bent, the position of the lesioned part can be accurately measured, so that it is possible to accurately irradiate the lesioned part in the radiation 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 an 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 for explaining positioning of a subject.
FIG. 5 is a schematic cross-sectional view for explaining positioning of a subject.
FIG. 6 is an exemplary view of an X-ray image obtained by scanning a subject in a positioned state.
FIG. 7 is an explanatory diagram of measurement of a marker position based on a scan center.
FIG. 8 is a schematic side view for explaining scanning in a state where the cradle is largely bent.
FIG. 9 is an explanatory diagram of measurement of a lesion position with reference to 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 for explaining positioning of a subject.
FIG. 15 is a schematic cross-sectional view illustrating the positioning of a subject.
FIG. 16 is a schematic side view for explaining scanning in a state where it is assumed that the cradle is not bent.
FIG. 17 is a view showing an example of an X-ray image obtained by scanning under the assumption that the cradle is not bent.
FIG. 18 is an explanatory diagram of measurement of a lesion position with reference to a scan center.
FIG. 19 is a schematic side view for explaining scanning in a state where the cradle is bent.
FIG. 20 is an explanatory diagram of measurement of a lesion position with reference to a scan center.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Operation console 3 Central processing unit 10 Table apparatus 12 Cradle 20 Scan gantry 30 Flat pad 32, 32 'Marker 100 X-ray CT apparatus AX Rotation axis H Subject M Body surface mark Rsc In the subject prescribed | regulated by the body surface mark Origin SC Scan Center UL, LL, RL Light beam

Claims (6)

An X-ray CT apparatus having a function of measuring the position of a region of interest of a subject for treatment planning using a radiotherapy machine,
The X-ray CT apparatus
An operation console;
A table device having a flat placement surface on which the subject is placed;
A scanning gantry,
A marker installed on the table device along the moving direction of the mounting surface of the subject and identifiable on an X-ray image;
Scan center reference marker position measuring means for measuring the position of the marker on the basis of the scan center on the X-ray image obtained by positioning the subject so that the origin in the subject and the scan center coincide with each other And a marker reference region-of-interest position measuring means for measuring the position of the region of interest on the basis of a marker on an X-ray image in which the region of interest of the subject is reflected, and the position of the marker measured on the basis of the scan center And the position of the region of interest measured using the marker as a reference, and the position of the region of interest relative to the origin in the subject at the same time as the position of the region of interest relative to the scan center X-ray CT comprising: position measuring means including center reference region-of-interest position calculating means apparatus. The X-ray CT apparatus according to claim 1, wherein the table device includes a cradle and a flat pad having a flat placement surface on which the subject placed on the cradle is placed.  The X-ray CT apparatus according to claim 2, wherein the marker is a bar-like member embedded in the cradle or the flat pad along a moving direction of the cradle.  The X-ray CT apparatus according to claim 2, wherein the marker is a groove, a hole, or an edge formed in the cradle or the flat pad along the moving direction of the cradle. A flat pad used in the X-ray CT apparatus according to claim 2,
A flood pad, wherein a lower surface is a convex surface conforming to a concave surface of the upper surface of the cradle, and an upper surface is a flat surface, and a marker identifiable on an X-ray image is installed along a moving direction of the cradle.  6. The flat according to claim 5, wherein the marker is a rod-shaped 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. pad.

Images