JP6455358B2 - Radioscopy equipment - Google Patents

Description

  The present invention relates to a radioscopy apparatus that detects the position of a marker that moves with body movement of a subject by acquiring images including markers placed in the body of the subject from two different directions. .

  A head for irradiating a treatment beam and a gantry for rotating the head about the subject are provided, and radiation treatment is performed by irradiating a treatment beam such as an X-ray or an electron beam to an affected part such as a tumor. In a radiotherapy apparatus, it is necessary to accurately irradiate the affected area with radiation. However, not only the subject may move the body, but the affected part itself may move. For example, a tumor near the lung moves greatly based on respiration. For this reason, in patent document 1, it has the structure which arrange | positions a gold marker near a tumor, detects the position of this marker by radioscopy apparatuses, such as X-ray fluoroscopy apparatus, and controls irradiation of therapeutic radiation Radiotherapy devices have been proposed.

  In such a radiotherapy apparatus, Patent Document 2 discloses an X-ray fluoroscopic apparatus for specifying the position of a marker by fluoroscopying an image including a marker placed near a tumor in the body of a subject. Has been. The X-ray fluoroscopic apparatus described in Patent Document 2 includes a first X-ray tube that irradiates X-rays from the floor side and a first X-ray detector that detects X-rays passing through the subject from the ceiling side. 1 imaging system and a second X-ray system that includes a second X-ray tube that irradiates X-rays from the floor side and a second X-ray detector that detects X-rays passing through the subject from the ceiling side, A marker embedded in the body is detected by template matching or the like. Then, three-dimensional position information is obtained using the two-dimensional perspective image photographed by the first photographing system and the two-dimensional perspective image photographed by the second photographing system. By continuously executing such an operation and calculating the three-dimensional position information of the marker in real time, the marker of the lesion site with movement is detected with high accuracy. And it becomes possible to perform highly accurate radiation irradiation by controlling irradiation of therapeutic radiation based on the position information of this marker.

Japanese Unexamined Patent Publication No. 2000-167072 Japanese Patent Application Laid-Open No. 2014-128412

  As the marker, in addition to a spherical marker that is a gold sphere, a non-spherical curved marker in which a gold wire is coiled is used. When a curved marker is deformed or rotated during movement, the projected shape in the image changes, so the marker cannot be recognized by template matching using a template created in advance, and the marker cannot be tracked was there.

  Further, when detecting a marker placed in the body by template matching, it is necessary to create a marker template. Conventionally, when creating this template, it has been necessary to capture an X-ray image including a marker by photographing a subject who is supine on a treatment table, and a user needs to extract a marker portion to obtain a template image. It took a long time to prepare for the marker tracking. In particular, in the treatment of rotating the treatment table and performing multi-directional irradiation from an arbitrary angle on the affected part, such as non-coplanar irradiation, the orientation of the subject with respect to X-ray imaging changes one after another. Had to be recreated. For this reason, the usage time of the radiotherapy apparatus concerning one patient has become long.

  If the preparation time until the treatment beam is irradiated is long, not only does it cause pain to the patient whose movement on the treatment table is restricted, but also the patient moves during the preparation, There was a possibility that irradiation position accuracy might deteriorate. In addition, in order to allow more patients to have treatment opportunities, it is necessary to reduce preparation time and improve treatment throughput.

  The present invention has been made to solve the above-described problems, and has an object to provide a radioscopy apparatus that can shorten the preparation time until treatment and can accurately detect a marker regardless of the shape of the marker. And

The first invention includes a radiation source and a radiation detector that detects radiation irradiated from the radiation source and transmitted through the subject, and is obtained by fluoroscopy at a predetermined frame rate from a plurality of directions. A radioscopic apparatus that detects a position of the device in an image including the device placed in the body of the human body and tracks the movement of the device, the image including the device based on a detection signal of the radiation detector An image generation unit for generating a local structure, a local structure detection unit for detecting a local structure in an image including the device generated by the image generation unit, and the local structure detected by the local structure detection unit. , a device determination unit that determines whether or not the device, the local structure it is judged that the device in the device determination section, of the device one If it is determined, on the basis of the local structure, it is determined and the local structure expanding portion for detecting one of the global structure corresponding to the whole of the device, to be the device in the device determination unit The device position acquisition unit that acquires the position of the local structure in the image as the position of the device, and the device is tracked based on the position of the device for each frame acquired by the device position acquisition unit A device tracking unit.

  2nd invention is further equipped with the device candidate detection part which detects the candidate of the said device from the image containing the said device, The said local structure detection part in the periphery of the said candidate of the device detected by the said device candidate detection part The local structure is detected.

In the third invention, the device position acquisition unit acquires the center of gravity, the end point, and the midpoint of the global structure obtained by the local structure expansion unit as the position of the device.

The fourth invention includes a radiation source and a radiation detector that detects radiation irradiated from the radiation source and transmitted through the subject, and is obtained by fluoroscopy at a predetermined frame rate from a plurality of directions. A radioscopic apparatus that detects a position of the device in an image including the device placed in the body of the human body and tracks the movement of the device, the image including the device based on a detection signal of the radiation detector A predetermined region of interest centered on the candidate point of the device in an image including the device generated by the image generating unit, and a pattern having regularity in the region of interest A local structure detecting unit that detects a local structure by executing segmentation for extracting the local structure, and the local structure detected by the local structure detecting unit includes: A device discriminating unit that discriminates whether or not the device is a chair; and a device position acquisition that acquires, as the device position, a position in the image of the local structure that is discriminated to be the device by the device discriminating unit And a device tracking unit that tracks the device based on the position of the device for each frame acquired by the device position acquisition unit .

The fifth invention further includes a device candidate detection unit that detects the device candidate from the image including the device and sets it as the candidate point .

In a sixth aspect of the invention, the device position acquisition unit acquires, as the position of the device, the centroid of the local structure that is determined to be the device by the device determination unit .

According to the first to sixth inventions, a local structure detection unit that detects a local structure in an image including a device, a device determination unit that determines whether or not the local structure is a device, and a device comprising a device position acquisition unit that acquires position as the position of a device in the image of the determined local structure and is a device tracking unit for tracking the device based on the position of the device for each frame, the For this reason, it is not necessary to perform fluoroscopy in order to create a template, unlike the conventional device tracking based on template matching. For this reason, it becomes possible to reduce the restraint time in the treatment table of a patient's radiotherapy apparatus. In addition, since it is determined whether or not the device is based on the local structure, multiple templates of curved markers with various orientations, lengths, and shapes depending on the fluoroscopic direction and placement location are created, as in conventional template matching. Thus, it is not necessary to repeat the matching operation for a plurality of templates, the throughput of the radiotherapy apparatus can be improved, and a device whose shape in the image such as a curved marker is changed can be accurately tracked. It becomes possible.

In addition, according to the first invention, it is possible to accurately capture the entire image of the curved marker having various orientations, lengths, and shapes depending on the fluoroscopic direction and the detention location by providing the local structure expanding portion. Become.

According to the second and fifth inventions, since the device candidate detection unit is provided, the device candidate is detected from an image excluding a stationary structure such as a bone imaged in the same image as the device by fluoroscopy. It is possible to reduce device misidentification due to the influence of noise and noise.

According to the third invention, the device position acquisition unit acquires the center of gravity, the end point, and the middle point of the global structure as the position of the device. Even with a curved marker, more accurate tracking can be performed in units of subpixels .

According to the sixth aspect , since the device position acquisition unit acquires the center of gravity of the local structure as the device position, it is possible to track the device more precisely in units of subpixels.

1 is a perspective view of a radiotherapy apparatus to which an X-ray fluoroscopic apparatus according to the present invention is applied. It is explanatory drawing which shows rocking | fluctuation operation | movement of the head 55 and the head support part 54 in a radiotherapy apparatus. It is explanatory drawing which shows the state by which the 1st X-ray tube 1a, the 2nd X-ray tube 1b, the 1st X-ray detector 2a, and the 2nd X-ray detector 2b were each arrange | positioned in the 1st see-through position. It is explanatory drawing which shows the state by which the 1st X-ray tube 1a, the 2nd X-ray tube 1b, the 1st X-ray detector 2a, and the 2nd X-ray detector 2b are each arrange | positioned in the 1st see-through position and the 2nd see-through position. It is explanatory drawing which shows the state by which the 1st X-ray tube 1a, the 2nd X-ray tube 1b, the 1st X-ray detector 2a, and the 2nd X-ray detector 2b were each arrange | positioned in the 2nd fluoroscopic position. It is a block diagram which shows the main control systems of the X-ray fluoroscope which concerns on 1st Embodiment of this invention. FIG. 6 is an explanatory diagram schematically showing the operation of a device candidate detection unit 62. It is explanatory drawing which shows typically operation | movement of the local structure detection part 63. FIG. It is explanatory drawing which shows typically operation | movement of the local structure detection part 63. FIG. FIG. 6 is an explanatory diagram schematically showing the operation of a device determination unit 64. 6 is an explanatory diagram schematically showing the operation of a device tracking unit 67. FIG. It is a block diagram which shows the main control systems of the X-ray fluoroscope which concerns on 2nd Embodiment of this invention. It is explanatory drawing which shows typically operation | movement of the local structure detection part 63. FIG. It is explanatory drawing which shows the operation | movement of the local structure expansion part 65 typically. 6 is an explanatory diagram schematically showing the operation of a device position acquisition unit 66. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a radiotherapy apparatus to which an X-ray fluoroscopy apparatus that is a radioscopy apparatus according to the present invention is applied. FIG. 2 is an explanatory diagram showing the swinging operation of the head 55 and the head support portion 54 in the radiotherapy apparatus.

  This radiotherapy apparatus is for performing radiotherapy by irradiating the affected part of a subject 57 lying on a table 56 with radiation such as X-rays or electron beams, and on the floor surface 51 of the treatment room. A gantry 53 installed on the head, a head support 54 that swings about an axis that faces the gantry 53 in the horizontal direction, and a head support 54 that is supported by the head support 54 to irradiate the subject 57 with radiation. The head 55 is provided. The head 55 can irradiate therapeutic radiation from various angles to the affected part of the subject 57 by the swinging movement of the head support part 54.

  During radiotherapy, it is necessary to accurately irradiate the affected area with radiation. For this reason, a marker is installed near the affected area. Then, the two-dimensional fluoroscopy obtained by the first X-ray fluoroscopy mechanism and the second X-ray fluoroscopy mechanism is obtained by continuously fluoroscopying the marker embedded in the body using the first X-ray fluoroscopy mechanism and the second X-ray fluoroscopy mechanism. The marker is detected with high accuracy by calculating the three-dimensional position information of the marker from the image.

  In order to execute such fluoroscopy, the radioscopy device according to the present invention applied to a radiotherapy device is an X-ray fluoroscopy device including an X-ray tube as a radiation source and an X-ray detector as a radiation detector. is there. The X-ray fluoroscopic apparatus has a first X-ray fluoroscopic mechanism including a first X-ray tube 1a and a first X-ray detector 2a, a second X-ray tube 1b, and a second X-ray fluoroscope for acquiring X-ray fluoroscopic images from two directions. The second X-ray fluoroscopic mechanism including the 2X-ray detector 2b, and the first X-ray tube 1a and the first X-ray detector 2a are moved to a first fluoroscopic position and a second fluoroscopic position, which will be described later, arranged opposite to each other. In addition, there is provided a moving mechanism for moving the second X-ray tube 1b and the second X-ray detector 2b to a first fluoroscopic position and a second fluoroscopic position that are arranged to face each other. An image intensifier (II) or a flat panel detector (FPD) is used as the first X-ray detector 2a and the second X-ray detector 2b.

  The 1st X-ray tube 1a is supported by the 1st base 3a for X-ray tubes. The second X-ray tube 1b is supported by the second pedestal 3b for X-ray tubes. On the bottom surface 52 of the recess formed in the floor surface 51 of the radiographing room, a first rail 21 for a substantially U-shaped X-ray tube in which two linear portions are connected by a connecting portion including an arc portion, and this X-ray Similar to the tube first rail 21, a substantially U-shaped second rail 22 for an X-ray tube in which two linear portions are connected by a connecting portion including an arc portion is disposed. The first rail 21 for X-ray tube and the second rail 22 for X-ray tube are arranged in parallel to each other. The X-ray tube first pedestal 3a and the X-ray tube second pedestal 3b are guided by the first rail 21 and the second rail 22 for the X-ray tube, and will be described later in a first see-through position and a second see-through position. Move to.

  Similarly, the 1st X-ray detector 2a is supported by the 1st base 4a for X-ray detectors. The second X-ray detector 2b is supported by the second pedestal 4b for X-ray detectors. From the ceiling of the radiographing room, the first rail 11 for a substantially U-shaped X-ray detector in which two straight portions are connected by a connecting portion including an arc portion, and the same as the first rail 11 for the X-ray detector. A substantially U-shaped second rail 12 for an X-ray detector, in which two linear portions are connected by a connecting portion including an arc portion, is suspended. The first rail 11 for the X-ray detector and the second rail 12 for the X-ray detector are arranged in parallel to each other. Then, the first pedestal 4a for X-ray detectors and the second pedestal 4b for X-ray detectors are guided by the first rail 11 and the second rail 12 for these X-ray detectors, and a first see-through position and a first position described later. 2 Move to the fluoroscopic position.

  Although not illustrated in FIG. 1, the concave portion formed in the floor surface 51 is covered with a lid member that constitutes a part of the floor, and thus the first X-ray detector 2 a and the second X-ray detector. 2b will be placed under the floor.

  3, 4, and 5, the first X-ray tube 1 a, the second X-ray tube 1 b, the first X-ray detector 2 a, and the second X-ray detector 2 b are disposed at the first fluoroscopic position and the second fluoroscopic position, respectively. It is explanatory drawing which shows the state made.

  This X-ray fluoroscopic apparatus has a configuration in which a subject 57 is seen through from two different directions at three preset positions. FIG. 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 see through the subject 57 from two different directions at the first position. FIG. 4 shows that 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 move the subject 57 from two different directions in the second position. FIG. 5 shows a state of seeing through, and FIG. 5 shows that 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 different from each other in the subject 57 at the third position. The state seen through from two directions is shown.

  As described above, the X-ray fluoroscopic apparatus has a configuration in which the subject 57 is seen through from two different directions at three positions, and therefore, as shown in FIG. Even when the person 57 is irradiated with radiation from various angles, the head 55 can perform X-ray fluoroscopy without interfering with the fluoroscopic field. At these 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 It will be arranged at one of the two perspective positions.

  In the first position shown in FIG. 3, the first X-ray tube 1a is at the first fluoroscopic position, the second X-ray tube 1b is at the first fluoroscopic position, and the first X-ray detector 2a is at the first fluoroscopic position. The second X-ray detectors 2b are respectively disposed at the first fluoroscopic positions. In the second position shown in FIG. 4, the first X-ray tube 1a is in the second fluoroscopic position, the second X-ray tube 1b is in the first fluoroscopic position, the first X-ray detector 2a is in the second fluoroscopic position, The line detectors 2b are respectively arranged at the first see-through positions. In the third position shown in FIG. 5, the first X-ray tube 1a is in the second fluoroscopic position, the second X-ray tube 1b is in the second fluoroscopic position, the first X-ray detector 2a is in the second fluoroscopic position, The line detectors 2b are respectively arranged at the second see-through positions.

  The X-ray tube first pedestal 3a and the X-ray tube second pedestal 3b move along the moving path 20 constituted by the X-ray tube first rail 21 and the second rail 22, whereby the first X-ray tube 1a. And the 2nd X-ray tube 1b is each arrange | positioned in a 1st see-through position and a 2nd see-through position. Further, by moving the first pedestal 4a for X-ray detectors and the second pedestal 4b for X-ray detectors along the movement path 10 constituted by the first rails 11 and the second rails 12 for X-ray detectors, 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.

  In this embodiment, the first rail 11 for the X-ray detector, the second rail 12 for the X-ray detector, the first rail 21 for the X-ray tube, and the second rail 22 for the X-ray tube are all included. The two straight portions have a substantially U-shape connected by a connecting portion including an arc portion. Therefore, from the first position shown in FIG. 3, the second position shown in FIG. 4, and the third position shown in FIG. 5, the first X-ray tube 1a, the second X-ray tube 1b, the first X-ray detector 2a, and the second X-ray. By moving the detector 2b in the horizontal direction in synchronization with each other, the fluoroscopic position can be moved in the horizontal direction. Therefore, for example, even when a marker or the like is removed from the fluoroscopic region during X-ray fluoroscopy, 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 mutually connected. It is possible to track a marker or the like by moving in the horizontal direction in synchronization.

  FIG. 6 is a block diagram showing the main control system of the X-ray fluoroscopic apparatus according to the present invention.

  This X-ray fluoroscopic apparatus is equipped with a CPU that performs logical operations, a ROM that stores operation programs necessary for controlling the apparatus, a RAM that temporarily stores data during control, and the like, and controls the entire apparatus. The unit 60 is provided. The controller 60 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 described above. Further, the control unit 60 includes a display unit 71 that displays an image of the subject 57 during X-ray fluoroscopy, an input unit 72 such as a mouse and a keyboard operated by an operator when inputting various settings, 1 is also connected.

  As a functional configuration, the control unit 60 generates an image including a marker placed in the body of the subject 57 based on the transmitted X-rays detected by the first X-ray detector 2a and the second X-ray detector 2b. A generating unit 61, a device candidate detecting unit 62 that detects a marker candidate, a local structure detecting unit 63 that detects a local structure in a region of interest around the marker candidate point, and a local structure such as a marker A device discriminating unit 64 that discriminates whether or not the device is a device; a device position obtaining unit 66 that obtains the center-of-gravity coordinates of the local structure; a device tracking unit 67 that tracks a marker based on the marker position for each frame; A three-dimensional absolute coordinate acquisition unit 68 that acquires the three-dimensional absolute coordinate of the marker from the tracking result of each marker position and the like, and a gating signal to the radiation therapy apparatus based on the three-dimensional absolute coordinate of the marker It comprises a gating signal transmitting section 69 for transmitting.

  Next, the operation of each functional configuration of the control unit 60 will be described by taking as an example the case where the marker placed in the body of the subject 57 is a spherical marker. FIG. 7 is an explanatory diagram schematically showing the operation of the device candidate detection unit 62. 8 and 9 are explanatory views schematically showing the operation of the local structure detection unit 63. FIG. FIG. 10 is an explanatory diagram schematically showing the operation of the device determination unit 64. FIG. 11 is an explanatory diagram schematically showing the operation of the device tracking unit 67.

  First, using two selected imaging systems, an image from two directions including a marker placed in the body of the subject 57 is acquired at a frame rate of about 20 to 30 fps. That is, the image generation unit 61 generates an X-ray image at a constant frame rate based on electrical signals from the first X-ray detector 2a and the second X-ray detector 2b arranged at a predetermined fluoroscopic position by selection of an imaging system. Is generated.

  The device candidate detection unit 62 detects points that are candidates for the spherical marker BM from the image generated by the image generation unit 61. As shown in the upper part of FIG. 7, the image 91 includes structures and noise other than the spherical marker BM, and a stationary structure such as a bone displayed at a high contrast in the image 91 has a marker detection efficiency. May be reduced. Therefore, the device candidate detection unit 62 detects a candidate for the spherical marker BM from an image 92 obtained by removing a stationary structure such as a bone from the image 91, as shown in the lower part of FIG. Since the spherical marker BM having a large X-ray absorption is recognized as a dark spot that moves between a plurality of consecutive images, a difference from the average of the past several frames with respect to the image of a frame at a certain time is taken. Thus, stationary structures other than the spherical marker BM can be removed from the image. As a result, it is possible to reduce erroneous detection of noise or the like other than the spherical marker BM as a marker candidate point, and to improve the efficiency of marker recognition.

  For the detection of the candidate point of the spherical marker BM in the device candidate detection unit 62, for example, a method using a known Laplacian filter can be adopted for the image obtained by removing the stationary structure from the above-described image. In order to increase the processing speed, a technique such as image reduction according to the size of the spherical marker BM can be employed. Alternatively, the device candidate detection unit 62 may not be provided, and an operator may manually specify a device candidate point from the input unit 72.

  The local structure detection unit 63 performs local segmentation (region division) around the candidate point of the spherical marker BM detected by the device candidate detection unit 62 within the predetermined regions of interest E1 and E2 shown in FIG. A simple structure. In addition, the black circle in FIG. 8 has shown the candidate point of the spherical marker BM. The local structure detection unit 63 performs processing (segmentation processing) for extracting a pattern having regularity in the regions of interest E1 and E2 using the candidate points and the surrounding pixel values. In addition, since the size of the spherical marker BM reflected in the image 93 is known in advance for the predetermined regions of interest E1 and E2, for example, the length of one side is the diameter of the circular spherical marker BM in the image 93. Is set by arranging a rectangular frame about 2 to 3 times as large as the center of the candidate point in the image 93.

  Since the spherical marker BM overlaps with various structures in the body depending on the position where it is placed, the background of the spherical marker BM projected in the image is not uniform, and the pixel value of each spherical marker BM also has various values. Take. Therefore, the parameter setting when performing local segmentation around the candidate point of the spherical marker BM is appropriately changed and set for each candidate point. For example, as shown in FIG. 9, a certain range of values based on pixel values at candidate points (shown in black in FIG. 9) is set for each candidate point, and candidate points satisfying the conditions regarding the set pixel value By performing the operation of attaching the same label (shown by hatching in FIG. 9) to surrounding pixels, a group of regions in which pixels with the same label are continuous is extracted as a local structure. Note that the squares in FIG. 9 indicate one pixel.

  In addition to the segmentation using the pixel values described above, local structure detection in a limited region centered on the candidate point of the spherical marker BM in the image 93 by the local structure detection unit 63 is known. Other approaches can be employed. For example, the local structure may be extracted by detecting the contour of the local structure around the candidate point of the spherical marker BM by using the change in the brightness of the digital image such as edge detection by the Canny method. Alternatively, a local structure may be extracted by binarization using a discriminant analysis method. Note that the image 93 used for detecting the local structure by the local structure detection unit 63 includes the image 91 acquired by the operation of the image generation unit 61 and the stationary of bones and the like by the operation of the device candidate detection unit 62. Either of the images 92 after the structure is removed may be used.

  The device determination unit 64 determines whether the local structure detected by the local structure detection unit 63 is a device such as a marker. The spherical spherical marker BM always appears as a circular shape in the image regardless of the fluoroscopic direction, and the size of the spherical marker BM is known in advance. Therefore, a local structure having a circular shape and an area within a predetermined range is determined as a spherical marker BM. The determination of whether or not the shape of the local structure is a circle can be made by utilizing, for example, that the responses to the eight-direction Gabor filter are equivalent in all directions. Further, it may be determined whether or not the local structure is a spherical marker by calculating a circularity that is an index indicating how close the target shape is to a circle. Thereby, the local structure LS1 around the candidate point in the region of interest E1 in FIG. 10 is determined as the spherical marker BM. On the other hand, the local structure LS2 around the candidate point in the region of interest E2 in FIG. 10 is determined not to be the spherical marker BM, and is excluded from the subsequent processing.

  The device position acquisition unit 66 acquires the local centroid of the structure determined as the spherical marker BM by the device determination unit 64 as the marker position. The barycentric coordinates of the spherical marker BM of the sphere are obtained by the following equation (1).

Incidentally, x _G denotes the center of gravity position vector, x _n is the pixel position vector of a local structure, m _n is the inverted pixel values of local structure. Thus, in the equation (1), the inverted pixel value is used, and the smaller the pixel value, the larger the mass, and the coordinates of the center of gravity that is the center of the spherical marker BM are calculated. Thereby, the barycentric coordinates of the spherical marker BM in each frame can be acquired by subpixels (for example, 1/10 pixel).

  The device tracking unit 67 tracks the marker based on the marker position for each frame acquired by the device position acquisition unit 66. An image 95 in FIG. 11 is obtained by superimposing three consecutive frames where the position of the spherical marker BM has already been acquired. As shown in FIG. 11, the position n of the spherical marker BM in the frame for calculating the position of the device is determined from the positions n-1, n-2, n-3. If the moving speed and acceleration of the spherical marker BM are calculated, the position n of the spherical marker in the next frame can be predicted. As described above, the device tracking unit 67 predicts the position n of the spherical marker BM in the next frame, and uses the vicinity of the predicted position of the spherical marker BM as the device search target area SE of the next frame. For this reason, deviation of device search is prevented, marker position acquisition and tracking in each frame can be performed quickly, and interruption of marker tracking can be prevented.

  Using the result of recognition and tracking of the spherical marker by each functional configuration described above, the calculation of the spatial position of the spherical marker for accurately irradiating the affected part moving by breathing or the like is repeatedly performed. The three-dimensional absolute coordinate acquisition unit 68 uses the relationship between epipolar geometries, and determines the position of each marker in the two-dimensional image from two directions obtained by the device position acquisition unit 66 and the device tracking unit 67 and the tracking result of the marker. , Get the 3D absolute coordinates of the marker.

  After that, the gating signal sending unit 69 irradiates the subject 57 with the treatment beam when the three-dimensional absolute coordinate acquired by the three-dimensional absolute coordinate acquisition unit 68 is within a predetermined range. The gating signal is transmitted to the radiotherapy apparatus. That is, the gating signal transmitting unit 69 controls the ON / OFF of the treatment beam for performing irradiation of the treatment beam only when the affected part is within a specific range from the marker position with respect to the affected part with movement. To generate a signal.

  As described above, in this embodiment, since the marker is not recognized by template matching, the preparation time for seeing through the subject 57 prior to treatment for the creation of a template for template matching can be shortened. Therefore, it is possible to improve the throughput of the radiotherapy apparatus.

  In addition, in conventional template matching, the contrast of markers in the image differs depending on the overlap and positional relationship with internal structures such as bones, so multiple templates with different contrasts are prepared, and matching that exceeds a predetermined threshold It was necessary to repeat the matching operation for the template until the degree was calculated. In this embodiment, since the matching operation is not performed, the marker recognition time can be shortened. Furthermore, by removing the internal structures such as bones from the image by the device candidate detection unit 62, it is difficult to be affected by the difference in contrast, and the marker can be detected efficiently.

  Next, another embodiment of the present invention will be described. FIG. 12 is a block diagram showing a control system of the X-ray fluoroscopic apparatus according to the second embodiment of the present invention. The control unit 60 of this embodiment further includes a local structure expansion unit 65. Note that a detailed description of a functional configuration that performs the same operation as in the first embodiment described above will be omitted.

  In this embodiment, a case where the marker placed in the body of the subject 57 is a non-spherical curved marker will be described as an example. FIG. 13 is an explanatory diagram schematically showing the operations of the device candidate detection unit 62 and the local structure detection unit 63. FIG. 14 is an explanatory diagram schematically showing the operation of the local structure expansion unit 65. FIG. 15 is an explanatory diagram schematically showing the operation of the device position acquisition unit 66.

  First, the device candidate detection unit 62 detects points that are candidates for the curved marker LM from the image generated by the image generation unit 61. As in the first embodiment, an image 92 excluding stationary structures such as bones is generated, and candidate points P0 are detected as shown in FIG.

  The local structure detection unit 63 performs local segmentation around the candidate point P0 of the curved marker LM detected by the device candidate detection unit 62 within the predetermined region of interest E1, and the local structure (hatching in FIG. 13 is performed). Detected). This local structure is detected using a method similar to that of the first embodiment in a predetermined region of interest E1 centered on the candidate point P0.

  The device determination unit 64 determines whether or not the local structure detected by the local structure detection unit 63 is a curved marker LM. Unlike the spherical marker BM described in the first embodiment, the curved marker LM that is a non-spherical shape has various orientations and lengths in the image depending on the fluoroscopic direction. Moreover, the shape also changes with the movement in the body. On the other hand, if the curved marker LM in the image is divided into narrower regions and viewed locally, the shape can be regarded as a collection of lines, and can be regarded as a collection of fine straight lines with different inclinations. it can. Further, the thickness of the line of the curved marker LM appearing in the image can be easily estimated from the size of the curved marker LM. Therefore, the device determination unit 64 determines a local structure having a linear shape and an area within a predetermined range as a part of the curved marker LM. In determining the shape, responsiveness to a known eight-direction Gabor filter that can extract which direction of the line is included is used.

  The local structure expansion unit 65 detects one global structure, that is, the entire structure of the curved marker LM from the local structure that is a part of the curved marker LM. The fact that the local structure detected by the local structure detection unit 63 is a part of the curved marker LM means that the local structure is detected at the end of the predetermined region of interest E1 set by the local structure detection unit 63. There will be an overlap. As shown in the upper part of FIG. 14, the extension in the local structure extension unit 65 is performed by newly setting an end point of a local structure located at the end of a predetermined region of interest E1 centered on the candidate point P0 as a curved marker LM. Further, as shown in the middle part of FIG. 14, predetermined regions of interest E1-1 and E1-2 centered on the candidate points P1 and P2 are set, and the local structure detection unit 63 This is executed by performing local structure detection (segmentation processing) in new predetermined regions of interest E1-1 and E1-2. That is, by repeating the operations of setting new candidate points and regions of interest and segmentation processing, the local structure is expanded to a global structure corresponding to the entire image of the curved marker LM. In this way, the curved marker LM is decomposed into local structures in several regions to determine whether or not the marker is a curved marker LM, so that the influence of deformation and rotation is reduced. Note that such an expansion operation of the structure is performed until there is no local structure reaching the end of the predetermined region of interest.

  As shown in the lower part of FIG. 14, the local structure is expanded to a global structure, and new candidate points P3 and P4 and a predetermined center around these candidate points P3 and P4 are shown. The direction in which the regions of interest E1-3 and E1-4 are set is determined to be a fixed direction. This can be realized by using the local line orientation of the structure obtained by applying an 8-direction Gabor filter. As described above, when the extension direction of the local structure can be determined, even if the curved marker LM overlaps with the noise, the orientation of the local structure determined to be a part of the curved marker LM. The local structure is not expanded in a direction in which noise different from that extends. Therefore, it is possible to accurately detect the curved marker LM having a different orientation, length, and shape in the image depending on the fluoroscopic direction and the placement location.

  In the case of the curved marker LM, the device candidate detection unit 62 may detect a plurality of candidate points for one curved marker LM in the image. However, even if the local structure is detected and expanded from each candidate point, it is eventually collected into a global structure having the shape of one curved marker LM. The overlap of candidate points on the LM does not affect the recognition of the curved marker LM. For this reason, in this embodiment, it becomes possible to recognize a marker with high precision irrespective of the shape of the marker.

  The device position acquisition unit 66 acquires the center of gravity D0, end points T1, T2, and midpoint D1 of the global structure obtained by the action of the local structure expansion unit 65 as the position of the curved marker LM that is the device (FIG. 15). The coordinates of the center of gravity D0 of the curved marker LM are calculated using Expression (1), as in the first embodiment. As shown in FIG. 14, the end points T1 and T2 are also the ends of the expanded local structure, and therefore, using the orientation of the local structure at the end obtained by the multi-directional Gabor filter, The coordinates of the end points T1 and T2 are calculated. The middle point D1 is an intermediate point between both end points of the end points T1 and T2, and is calculated using the coordinates of the end points T1 and T2.

  Thus, in this embodiment, since the device position acquisition unit 66 acquires a plurality of coordinates as the device position, the positional relationship of the curved marker LM with the affected part in the body of the subject 57, deformation, Since the device can be tracked using the position most suitable for tracking the curved marker LM depending on the degree of rotation, the tracking of the curved marker LM can be prevented from being interrupted.

  If the position of the curved marker LM in each frame is acquired, the tracking of the curved marker LM by the device tracking unit 67 is executed as in the first embodiment, and the curved line marker LM is further curved by the three-dimensional absolute coordinate acquisition unit 68. The three-dimensional absolute coordinates of the shape marker LM are acquired. Thereafter, when the three-dimensional absolute coordinates of the curved marker LM are within a predetermined range, a gating signal is generated in the gating signal sending unit 69 so as to irradiate the subject 57 with the treatment beam. The signal is transmitted to the radiation therapy apparatus.

  The device according to the present invention is not limited to the spherical marker BM and the curved marker LM described in the embodiment. For example, the device is inserted into the coronary artery by CAG (Coronary Angiogram) using an X-ray fluoroscope. Also included are guidewires and stents. In CAG, since the guide wire and the stent move violently due to the pulsation of the heart, a configuration in which the image of each frame generated by the image generation unit 61 is affine transformed (translation / rotation / deformation) is added. Or a device such as a stent may be displayed on the display unit 71 as if the device is fixed in the image. Further, by adding a configuration for performing integration in the time direction using a known recursive filter or the like to each frame image after affine transformation, an image of a device with reduced noise without motion blur is obtained. It is also possible.

DESCRIPTION OF SYMBOLS 1a 1st X-ray tube 1b 2nd X-ray tube 2a 1st X-ray detector 2b 2nd X-ray detector 3a X-ray tube 1st base 3b X-ray tube 2nd base 4a X-ray detector 1st base 4b X-ray detector 1st Two pedestals 10 Movement path 11 First rail 12 Second rail 20 Movement path 21 First rail 22 Second rail 51 Floor surface 53 Gantry 54 Head support section 55 Head 56 Table 57 Subject 60 Control section 61 Image generation section 62 Device Candidate detection unit 63 Local structure detection unit 64 Device discrimination unit 65 Local structure expansion unit 66 Device position acquisition unit 67 Device tracking unit 68 Three-dimensional absolute coordinate acquisition unit 69 Gating signal transmission unit 71 Display unit 72 Input unit 91 Image 92 Image 93 Images 95 images

Claims (6)

A radiation source, and a radiation detector that detects radiation that has been irradiated from the radiation source and transmitted through the subject, and is placed in the body of the subject obtained by fluoroscopy at a predetermined frame rate from a plurality of directions. A radioscopic apparatus that detects the position of the device in an image including the device and tracks the movement of the device,
An image generation unit that generates an image including the device based on a detection signal of the radiation detector;
A local structure detection unit for detecting a local structure in an image including the device generated in the image generation unit;
A device determination unit for determining whether the local structure detected by the local structure detection unit is the device;
When the local structure determined to be the device by the device determination unit is determined to be a part of the device, one local area corresponding to the entire device is determined based on the local structure. A local structure extension that detects the global structure;
A device position acquisition unit that acquires a position in the image of the local structure determined to be the device in the device determination unit as a position of the device;
A device tracking unit that tracks the device based on the position of the device for each frame acquired by the device position acquisition unit;
Radioscopy apparatus comprising: The radiographic apparatus according to claim 1,
A device candidate detection unit for detecting a candidate for the device from an image including the device;
The local structure detection unit is a radioscopic apparatus that detects the local structure around the device candidates detected by the device candidate detection unit. The radiographic apparatus according to claim 1 or 2 ,
The device position acquisition unit is a radioscopic apparatus that acquires a center of gravity, an end point, and a midpoint of the global structure obtained by the local structure expansion unit as the position of the device. A radiation source, and a radiation detector that detects radiation that has been irradiated from the radiation source and transmitted through the subject, and is placed in the body of the subject obtained by fluoroscopy at a predetermined frame rate from a plurality of directions. A radioscopic apparatus that detects the position of the device in an image including the device and tracks the movement of the device,
An image generation unit that generates an image including the device based on a detection signal of the radiation detector;
Executing a segmentation for setting a predetermined region of interest centered on the candidate point of the device in an image including the device generated by the image generation unit and extracting a pattern having regularity in the region of interest; A local structure detecting unit for detecting a local structure by
A device determination unit for determining whether the local structure detected by the local structure detection unit is the device;
A device position acquisition unit that acquires a position in the image of the local structure determined to be the device in the device determination unit as a position of the device;
A device tracking unit that tracks the device based on the position of the device for each frame acquired by the device position acquisition unit;
Radioscopy apparatus comprising: The radiographic apparatus according to claim 4, wherein
  A radiation fluoroscopic apparatus, further comprising: a device candidate detection unit that detects the device candidate from an image including the device and sets it as the candidate point. The radiographic apparatus according to claim 4 or 5,
The device position acquisition unit is a radioscopic apparatus that acquires, as the position of the device, the center of gravity of the local structure determined to be the device by the device determination unit.

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