TWI510221B - X-ray fluoroscopic apparatus - Google Patents

Description

X-ray fluoroscopy

The present invention relates to an X-ray fluoroscopy apparatus for determining a position of a mark by taking an image including a marker left in the subject.

In radiation therapy for irradiating radiation such as X-rays or electron beams to a affected area such as cancer, it is necessary to accurately irradiate the radiation to the affected area. However, there are cases where the subject moves the body, and there is a case where the affected part itself generates exercise. For example, a tumor near the lung moves largely based on breathing. Therefore, a radiation therapy apparatus having a configuration in which a gold mark is placed beside the tumor and the position of the mark is detected by an X-ray fluoroscopy apparatus is controlled to control the irradiation of the therapeutic radiation (see Patent Document 1).

In the radiation therapy apparatus, a first X-ray fluoroscopy mechanism including a first X-ray tube and a first X-ray detector, and a second X-ray fluoroscopy mechanism including a second X-ray tube and a second X-ray detector are used to capture a mark embedded in the body. The three-dimensional fluoroscopic image of the first X-ray fluoroscopy mechanism and the two-dimensional fluoroscopic image of the second X-ray fluoroscopy mechanism are used to obtain three-dimensional position information. Moreover, the three-dimensional position information of the mark can be calculated real time by continuously performing X-ray fluoroscopy, thereby being high The mark accompanying the moving portion is accurately detected, and high-precision radiation irradiation corresponding to the tumor motion can be performed by controlling the irradiation of the therapeutic radiation based on the position information of the mark. When the location information of the tag is obtained, template matching using a template image is performed.

FIG. 9 is an explanatory diagram showing a conventional template comparison operation.

For template comparison, first, a template 71 corresponding to the mark M is prepared. In this case, an image 70 of the subject including the marker M is taken. Then, the mark M portion is extracted from the image 70, and the template image 71 is obtained. At the time of fluoroscopy, the template image 71 is used for the template comparison in the region 73 in which the marker M in the subject image 72 taken at a fixed frame update rate is framed, and the position of the marker M is determined.

The marker M used in such a radiation therapy apparatus is conventionally used in a shape in which it is spherical. That is, when the template comparison is performed using the template image 71 for the image 72 of the subject photographed at the fixed screen update rate, the shot mark M is obtained from any direction by using the spherical mark M. A circular image, therefore, only a circular shape is prepared as a template image because the template alignment can be performed efficiently.

On the other hand, there is a problem that it is difficult for the spherical mark M to remain in the subject. In other words, when the spherical mark M is used, it has a property of being easily slidable with respect to the internal organs due to its shape, and therefore it is easy to fall off from the indwelling portion even if it is temporarily left in the body. Therefore, the following processing is also performed: the occurrence of shedding is predicted, and a plurality of markers M are left in the body in advance, so that the marker M that has not fallen off is utilized. However, in this case, since a plurality of marks M are left in place, an extra cost is incurred, and in addition, the time for the surgical treatment for indwelling becomes long, and therefore, there is a problem that a burden is placed on the subject.

Therefore, in recent years, a non-spherical mark such as a coil has been provided (see Patent Document 2). In the apparatus described in Patent Document 2, template matching is performed using an image including a mark.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent No. 3053389

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-234932

As described in Patent Document 2, for example, when a coil-shaped mark is used, the mark can be stably placed in the body of the subject. However, in the case of using a non-spherical mark such as a coil shape, the recognized shape differs depending on the photographing angle of the mark, and therefore, there arises a problem that even if a template is created using the image obtained by photographing the mark, it cannot be used for the template. Comparison. Therefore, although the mark described in Patent Document 2 can be used for the purpose of positioning the photographing position, there is a problem that it is difficult to obtain the three-dimensional position information of the mark in real time.

Further, unlike the above problem, in the case where a template image is created using an image including a mark regardless of whether a spherical mark or a non-spherical mark is used, when the bone portion as the internal structure of the subject is photographed together with the mark , the problem that the template comparison cannot be performed accurately. That is, in the case where the bone portion is photographed together with the marker, the contrast of the marker is different in each of the images continuously photographed, so that even if the template alignment is performed using a single marker, the comparison cannot be performed. (matching) situation.

The present invention has been made to solve the above problems, and an object thereof is to provide a An X-ray fluoroscopy apparatus which can accurately recognize a mark by template alignment even when a non-spherical mark is used or when a mark is attached to an internal structure such as a bone part, thereby accurately Determine the location of the marker.

A first aspect of the invention is an X-ray fluoroscopy apparatus comprising: an X-ray tube; and an X-ray detector that detects X-rays that are irradiated from the X-ray tube and pass through the subject, and are included by photographing The position of the marker is determined by the image of the marker in the subject. The X-ray fluoroscopy apparatus further includes: a template image storage unit that memorizes a plurality of images including the mark as a template image; and a template comparison unit that records images taken at regular intervals by using the template image The template image is compared with a plurality of template images of the memory unit, whereby the position of the mark in the image taken at regular intervals is determined.

In the second aspect of the invention, the mark has a non-spherical shape, and the plurality of template images are produced based on an image captured while moving the mark.

In the third aspect of the invention, the plurality of template images are produced by photographing the mark and the internal structure of the subject together by moving the mark.

In the fourth aspect of the invention, the internal structure is a bone portion.

According to a fifth aspect of the invention, the template matching unit performs the template comparison using the plurality of template images stored in the template image storage unit for the image captured at the fixed time, and uses the highest degree of comparison. The template image determines the position of the above-mentioned mark in the image taken at regular intervals as described above.

In the sixth aspect of the invention, the template image storage unit stores a template image corresponding to a period in which the subject breaths once or more.

According to the first aspect of the invention, even when the non-spherical mark is used or the mark is taken together with the internal structure, the mark can be accurately recognized by the template alignment, so that the position of the mark can be accurately determined.

According to the second aspect of the invention, even when the position of the photographing angle of the non-spherical mark changes, the mark can be recognized by the template comparison.

According to the third and fourth inventions, even when the mark is photographed simultaneously with the structure in the body, the mark can be recognized by the template comparison.

According to the fifth aspect of the invention, the template alignment can be performed more accurately by using the template image having the highest degree of comparison, so that the position of the mark can be accurately determined.

According to the sixth aspect of the invention, the movement of the marker accompanying the breathing of the subject can be accurately determined.

1a‧‧‧1st X-ray tube

1b‧‧‧2nd X-ray tube

2a‧‧‧1st X-ray detector

2b‧‧‧2nd X-ray detector

3a‧‧‧1st base for X-ray tube

3b‧‧‧2nd base for X-ray tube

4a‧‧‧1st base for X-ray detector

4b‧‧‧2nd base for X-ray detector

10, 20‧‧‧ moving path

11, 21‧‧‧1 track

12, 22‧‧‧ Track 2

51‧‧‧floor

52‧‧‧Bottom of the recess

53‧‧‧Rack

54‧‧‧Eye head support

55‧‧‧Eye head

56‧‧‧Photography

57‧‧‧ Subjects

61‧‧‧Control Department

62‧‧‧Template Comparison Department

63‧‧‧Memory Department

64‧‧‧Template image memory

65‧‧‧Display Department

Images 70, 72, 80a~80n, 82, 90a~90n, 92‧‧‧

71, 81a~81n, 91a~91n‧‧‧ template image

73, 83, 93‧‧‧ areas

B‧‧‧Bone Department

M‧‧‧ mark

1 is a perspective view of a radiation therapy apparatus to which an X-ray fluoroscopy apparatus of the present invention is applied.

FIG. 2 is an explanatory view showing a swinging operation of the head 55 and the head supporting portion 54 in the radiation therapy apparatus.

3 is an explanatory view showing a state in which the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are disposed at the first see-through position.

4 is an explanatory view showing a state in which the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are disposed at the first perspective position and the second perspective position, respectively.

FIG. 5 is an explanatory view showing a state in which the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are disposed at the second see-through position.

Figure 6 is a block diagram showing the main control system of the X-ray see-through device of the present invention.

FIG. 7 is an explanatory view showing a template matching operation of the first embodiment of the X-ray fluoroscopy apparatus of the present invention.

FIG. 8 is an explanatory view showing a template comparison operation of the second embodiment of the X-ray fluoroscopy apparatus of the present invention.

FIG. 9 is an explanatory diagram showing a conventional template comparison operation.

Hereinafter, embodiments of the present invention will be described based on the drawings. 1 is a perspective view of a radiation therapy apparatus to which an X-ray fluoroscopy apparatus of the present invention is applied. 2 is an explanatory view showing a swinging operation of the irradiation head 55 and the irradiation head supporting portion 54 in the radiation therapy apparatus.

The radiation therapy apparatus is configured to irradiate radiation such as X-rays or electron beams to the affected area of the subject 57 lying on the imaging table 56 for radiation therapy, and includes a gantry 53 provided on the floor of the treatment room. 51; the irradiation head supporting portion 54 is pivoted about the axis in the horizontal direction with respect to the frame 53; and the irradiation head 55 is supported by the irradiation head supporting portion 54 for irradiating the subject 57 with radiation . The irradiation head 55 can irradiate the affected area of the subject 57 with radiation from various angles by the swinging motion of the irradiation head supporting portion 54.

At the time of radiation therapy, the radiation must be accurately irradiated to the affected area. because Therefore, a mark is placed near the affected area. Further, the first X-ray fluoroscopy mechanism and the second X-ray fluoroscopy mechanism are used to continuously fluorinate the mark embedded in the body, and operate based on the two-dimensional fluoroscopic image obtained by the first X-ray fluoroscopy mechanism and the second X-ray fluoroscopy mechanism. The three-dimensional position information of the mark, whereby the mark is detected with high precision.

An X-ray fluoroscopy apparatus according to the present invention for performing such fluoroscopy includes: a first X-ray fluoroscopy mechanism including a first X-ray tube 1a and a first X-ray detector 2a; and a second X-ray fluoroscopy mechanism including a second X-ray tube 1b and a The X-ray detector 2b and the moving mechanism move the first X-ray tube 1a and the first X-ray detector 2a to the following first and second perspective positions, which are disposed opposite to each other, and the second X-ray tube 1b and the second X-ray detector 2b are moved to the first see-through position and the second see-through position which are arranged opposite each other. Further, for example, an image intensifier (I.I.) or a flat panel detector (FPD) is used as the first X-ray detector 2a and the second X-ray detector 2b.

The first X-ray tube 1a is supported by the X-ray tube with the first base 3a. Further, the second X-ray tube 1b is supported by the X-ray tube second base 3b. The first bottom rail 52 of the X-ray tube having a substantially U-shape is disposed on the bottom surface 52 of the recessed portion of the floor 51 of the photographing room, and the two straight portions are connected by a connecting portion including the arc portion; The second rail 22 for the X-ray tube having a substantially U shape is connected to the two straight portions by a connecting portion including an arc portion, similarly to the first rail 21 for the X-ray tube. The X-ray tube first track 21 and the X-ray tube second track 22 are arranged in parallel with each other. Further, the X-ray tube first base 3a and the X-ray tube second base 3b are guided by the X-ray tube first rail 21 and the second rail 22 to move to the first perspective position and the second perspective position described below.

Similarly, the first X-ray detector 2a is the first for the X-ray detector. The base 4a is supported. Further, the second X-ray detector 2b is supported by the X-ray detector second base 4b. The first rail 11 for the X-ray detector having a substantially U-shape is connected to the ceiling of the image capturing room, and the two straight portions are connected by a connecting portion including the arc portion; and the X-ray detector for the substantially U-shaped portion Similarly to the first track 11 for the X-ray detector, the two tracks 12 are connected to the two straight portions by a connecting portion including an arc portion. The X-ray detector first rail 11 and the X-ray detector second rail 12 are arranged in parallel with each other. Further, the X-ray detector first base 4a and the X-ray detector second base 4b are guided by the X-ray detector first rail 11 and the second rail 12 to move to the following first perspective position and second. Perspective position.

3, 4, and 5 show a state in which the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are disposed at the first perspective position and the second perspective position, respectively. Illustrating.

The X-ray fluoroscopy apparatus has a configuration in which three positions are set in advance, and the subject 57 is seen through two directions different from each other. 3 shows a state in which the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are in a first position, and the subject 57 is seen from two different directions. FIG. The first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are in a second position, and the state of the subject 57 is seen from two different directions. FIG. The 1 X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are in a state of seeing the subject 57 from two directions different from each other at the third position.

In this way, the X-ray fluoroscopy device is configured to fluoroscopy the subject 57 in two directions different from each other at three positions, and therefore, as shown in FIG. 2, even if When the irradiation head 55 in the radiotherapy apparatus irradiates the subject 57 with radiation from various angles, the X-ray fluoroscopy may be performed without hindering the movement of the irradiation head 55. Further, in the three positions, the first X-ray tube 1a and the second X-ray tube 1b, and the first X-ray detector 2a and the second X-ray detector 2b are disposed at a predetermined first or second perspective position. Any of the locations.

Further, in the first position shown in FIG. 3, the first X-ray tube 1a is disposed at the first fluoroscopic position, the second X-ray tube 1b is disposed at the first fluoroscopic position, and the first X-ray detector 2a is disposed at the first fluoroscopic position. The second X-ray detector 2b is disposed at the first see-through position. In the second position shown in FIG. 4, the first X-ray tube 1a is disposed at the second perspective position, the second X-ray tube 1b is disposed at the first perspective position, and the first X-ray detector 2a is disposed at the second perspective position, and the second X-ray is disposed. The detector 2b is disposed at the first see-through position. In the third position shown in FIG. 5, the first X-ray tube 1a is disposed at the second fluoroscopic position, the second X-ray tube 1b is disposed at the second fluoroscopic position, and the first X-ray detector 2a is disposed at the second fluoroscopic position, and the second X-ray is disposed. The detector 2b is disposed at the second see-through position.

The X-ray tube first base 3a and the X-ray tube second base 3b are moved along the movement path 20 including the X-ray tube first rail 21 and the second rail 22, whereby the first X-ray tube 1a and the second X-ray tube are moved. 1b is disposed at the first perspective position and the second perspective position, respectively. In addition, the X-ray detector first base 4a and the X-ray detector second base 4b move along the movement path 10 including the X-ray detector first rail 11 and the second rail 12, whereby the first X-ray detector is used. The 2a and the second X-ray detectors 2b are disposed at the first see-through position and the second see-through position, respectively.

Figure 6 is a block diagram showing the main control system of the X-ray fluoroscopy apparatus of the present invention.

This X-ray see-through device has a control unit 61 that controls the entire device. The control unit 61 includes a template matching unit 62 that performs template comparison using images of a plurality of template images for images of the subject 57 taken at regular intervals as described below. The position of the mark in the image of the subject 57 taken every fixed time is determined. The control unit 61 is connected to a display unit 65 including a liquid crystal display panel or the like for displaying a fluoroscopic image. Further, the control unit 61 is also connected to the storage unit 63. The memory unit 63 includes a template image storage unit 64 that stores a plurality of template images.

The control unit 61 is connected to the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b. Further, the control unit 61 is connected to a driving unit (not shown) for driving the X-ray tube first base 3a, the X-ray tube second base 3b, the X-ray detector first base 4a, and the X-ray. The second base 4b is used for the detector. Further, the control unit 61 is also connected to the radiation therapy apparatus shown in Fig. 1 .

Next, a template matching operation which is a technical feature part of the present invention will be described. FIG. 7 is an explanatory view showing a template matching operation of the first embodiment of the X-ray fluoroscopy apparatus of the present invention. Further, in this embodiment, a non-spherical mark is used as the mark M.

For template comparison, a template corresponding to the mark M is first created. In this case, the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray detector 2b are placed at any position shown in FIG. 3, FIG. 4, and FIG. The image of the subject 57 is thereby taken to capture images 80a, 80b, 80c...80n including the marker M. At this time, the frame update rate (frame rate) of, for example, 30 fps (Frames Per Second) is performed during the period in which the subject 57 breathes once or more. The photographing is performed to obtain images 80a, 80b, 80c...80n including the mark M. Then, the mark M portion is extracted from the images 80a, 80b, 80c, ... 80n including the mark M, and the template images 81a, 81b, 81c, ... 81n are obtained. At this time, with the breathing of the subject 57, the image during the movement of the marker M is taken. Therefore, the image of the captured mark M is sequentially deformed as shown in FIG.

Further, when the image is captured at the screen update rate, when the degree of deformation of the image of the mark M between adjacent frames is small, an image including the mark M every other number of screens is acquired. 80a, 80b, 80c, ... 80n, and template images 81a, 81b, 81c, ... 81n may be created based on images 80a, 80b, 80c ... 80n including the mark M every few screens. The template images 81a, 81b, 81c, ... 81n are memorized in the template image storage unit 64 shown in Fig. 6 .

If the above preparation is completed, the treatment of the subject 57 is started. At this time, the position of the marker M is detected by the X-ray fluoroscopy apparatus of the present invention, and the position of the radiation irradiated to the affected part of the subject 57 is adjusted based on the position of the marker M.

At this time, the area including the mark M is seen through at a frame update frame rate of about 30 fps. Then, with the template matching unit 62 shown in FIG. 6, the region 83 including the mark M in the image 82 taken at regular intervals is used, and the plurality of template images 81a stored in the template image storage unit 64 are used. 81b, 81c...81n perform template alignment. That is, for the region 83 including the mark M in the image 82 taken every fixed time, the plurality of template images 81a, 81b, 81c, ... 81n are all sequentially aligned.

Further, when any one of the plurality of template images 81a, 81b, 81c, ... 81n exceeds a threshold value for comparison that is set in advance, it is determined that the comparison is successful. Furthermore, in a case where a plurality of template images 81a, 81b, 81c, ... 81n exceed a threshold value, the template image having the highest degree of correlation among the plurality of template images 81 Recognized as a template image that has been compared. On the other hand, in the case where there is no template image exceeding the threshold value, it is determined that the comparison has failed.

As described above, according to the X-ray fluoroscopy apparatus of the first embodiment of the present invention, the pattern comparison is performed by using the plurality of template images 81a, 81b, 81c, 81n captured during the movement of the marker M, and therefore, That is, in the case where the shape of the inspected mark M is changed by the movement of the body of the subject 57 by using the non-spherical mark M, the mark M can be accurately recognized by the template comparison. Therefore, the position of the mark M can be accurately determined.

At this time, the template image corresponding to the period in which the subject 57 breaths once or more is used, and therefore, the movement of the marker M accompanying the breathing of the subject 57 can be accurately determined. Moreover, in the case where a plurality of template images exceed the threshold value, the position of the mark M is determined by using the template image having the highest degree of contrast among the plurality of templates, and therefore, the template comparison can be performed more accurately, thereby being more accurate The position of the marker M is determined.

Next, another embodiment of the present invention will be described. FIG. 8 is an explanatory view showing a template comparison operation of the second embodiment of the X-ray fluoroscopy apparatus of the present invention. Further, in this embodiment, a spherical mark is used as the mark M. However, the non-spherical mark M can also be used in the same manner as in the first embodiment.

In the second embodiment, when the template corresponding to the marker M is created, the marker M and the skeleton portion B which is the internal structure of the subject 57 are simultaneously captured. In this case, as in the first embodiment, the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the first embodiment are disposed at any position shown in FIG. 3, FIG. 4, and FIG. The 2X ray detector 2b continuously captures an image of the subject 57, whereby the images 90a, 90b, 90c, ... 90n including the mark M are taken. At this time, during the period in which the subject 57 breathes more than once, the screen update rate is, for example, about 30 fps. Take a shot and take this. Images 90a, 90b, 90c...90n including the marker M and the bone portion B are obtained. Then, the mark M portion is extracted from the images 90a, 90b, 90c, ... 90n including the mark M and the bone portion B, thereby obtaining the template images 91a, 91b, 91c, ... 91n. At this time, with the breathing of the subject 57, the image during the movement of the marker M is taken. Therefore, in the image of the captured mark M, as shown in FIG. 8, the area occupied by the bone portion B is sequentially changed to a different state.

Further, in the second embodiment, when the image is captured at the screen update rate, the degree of deformation of the region occupied by the skeleton portion B between adjacent screens is small, and every other screen is acquired. The images 90a, 90b, 90c, ... 90n of the mark M may be created, and the template images 91a, 91b, 91c, ... 91n may be created based on the images 90a, 90b, 90c, ... 90n including the mark M every several screens. The template images 91a, 91b, 91c, ... 91n are memorized in the template image storage unit 64 shown in Fig. 6 .

If the above preparation is completed, the treatment of the subject 57 is started. At this time, the position of the marker M is detected by the X-ray fluoroscopy apparatus of the present invention, and the position of the radiation irradiated to the affected part of the subject 57 is adjusted based on the position of the marker M.

At this time, the region including the mark M is fluoroscopy at a screen update rate of about 30 fps. Then, with the template matching unit 62 shown in FIG. 6, for the area 93 including the mark M in the image 92 taken every fixed time, the plurality of template images 91a stored in the template image storage unit 64 are utilized. , 91b, 91c...91n perform template comparison. That is, for the region 93 including the mark M in the image 92 taken every fixed time, the plurality of template images 91a, 91b, 91c, ... 91n are all sequentially aligned.

Further, when any one of the plurality of template images 91a, 91b, 91c, 91n exceeds a threshold value set for comparison, it is determined that the comparison is successful. Furthermore, several template images in the plurality of template images 91a, 91b, 91c...91n When the threshold value is exceeded, the template image having the highest degree of correlation among the above is recognized as the template image to be compared. On the other hand, in the case where there is no template image exceeding the threshold value, it is determined that the comparison has failed.

As described above, according to the X-ray fluoroscopy apparatus of the second embodiment of the present invention, the pattern comparison is performed by the plurality of template images 91a, 91b, 91c, 91n which are imaged together with the bone portion B during the movement of the marker M, Therefore, even if the ratio of the bone portion B in the template image changes with the movement of the body accompanying the subject 57, and the contrast shape of the region including the marker M in perspective is changed, it is also possible to The template is accurately and accurately identified by the template. Therefore, the position of the mark M can be accurately determined.

In the second embodiment, the case where the skeleton portion B is imaged together with the marker M has been described. However, instead of the skeleton portion B, other in-vivo structures such as a diaphragm may be imaged together with the marker M.

80a~80n, 82‧‧‧ images

81a~81n‧‧‧Template image

83‧‧‧Area

M‧‧‧ mark

Claims (5)

An X-ray fluoroscopy apparatus for determining a position of a mark by photographing a mark including a mark placed in a subject, the X-ray fluoroscopy apparatus comprising: an X-ray tube; and an X-ray detector detecting the X-ray The tube is irradiated and passes through the X-ray of the subject; the template image storage unit stores a plurality of images including the mark as a template image; and the template comparison unit uses memory for images taken at regular intervals. And performing template comparison on the plurality of template images in the template image storage unit, thereby determining a position of the mark in the image captured at a fixed time, wherein the template matching portion is fixed for the above The time-captured image is compared with each of the plurality of template images memorized in the template image storage unit, and the image with the highest degree of comparison is used to determine the image taken at regular intervals. The location of the above mark. The X-ray fluoroscopy apparatus according to claim 1, wherein the mark has a non-spherical shape, and the plurality of template images are produced based on an image captured while moving the mark. The X-ray fluoroscopy apparatus according to claim 1, wherein the plurality of template images are created by simultaneously moving the mark and the image of the internal structure of the subject based on the movement of the mark . The X-ray fluoroscopy device of claim 3, wherein the body structure is a bone portion. X-ray transmission as described in any one of claims 1 to 4 In the visual device, the template image storage unit stores a template image corresponding to a period in which the subject breaths once or more.