JP2017209333A - Radiotherapy system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the distortion of a pixel (voxel) and acquire an axial cross-sectional image with high image quality to thereby improve the accuracy of positioning and monitoring of a subject in radiotherapy.SOLUTION: Provided is a radiotherapy system, comprising: a therapeutic irradiation unit 22 mounted on a therapeutic rotation mechanism 21 and irradiating a target 110 of a subject 1 with therapeutic radiation while rotating about the subject; an X-ray source 12 mounted on an X-ray source rotation mechanism 11 and irradiating the target with a monitoring X ray while rotating about the subject; and a detector 13 mounted on a detector rotation mechanism and detecting the X ray which is projected from the X-ray source and transmitted through the subject while rotating about the subject in synchronization with the X-ray source rotation mechanism. In the radiotherapy system, the X-ray source and the detector rotate on a rotation axis P common therebetween, and the therapeutic rotation mechanism, the X-ray source rotation mechanism, and the detector rotation mechanism are arranged such that the rotation planes of the therapeutic irradiation unit, X-ray source, and detector are different from one another and do not interfere with one another.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a radiotherapy system, and more particularly, to a system having a monitoring X-ray CT imaging function for imaging a subject image during radiotherapy.

  Conventionally, as a method for visualizing the inside of a subject in a non-destructive manner for use in medical diagnosis and defect inspection of industrial products, an X-ray examination method in which the subject is irradiated with X-rays and X-rays transmitted through the subject are detected. It has been known. In order to grasp the inside of the subject three-dimensionally, as a method for obtaining a cross-sectional image of the subject, the subject is irradiated with X-rays while rotating around the subject, and X-rays transmitted through the subject are obtained. An X-ray CT (Computed Tomography) inspection method is known in which a cross-sectional image is obtained by detecting and performing a reconstruction calculation process on detected transmission X-ray information.

  CT inspection methods include fan beam CT imaging using a line detector, cone beam CT (hereinafter referred to as CBCT) imaging using a surface detector, tomosynthesis imaging using transmission X-ray information of a limited rotation angle, and rotation axis. There is laminography photography that tilts. In addition to the method of rotating the subject, there are a method of fixing the subject and rotating the X-ray source and the detector, and a method of rotating both. Instead of rotating the X-ray source or detector, there are a method of linearly moving in the tangential direction of the rotating track, and a method of moving both in the opposite direction in the tangential direction of the rotating track.

  A system for monitoring radiation therapy in which medical radiation is irradiated to a target in a subject by the above-described CBCT imaging is known. In such a radiotherapy system, an axial cross-sectional image (perpendicular to the body axis of the subject) obtained by separately performing CT imaging as a preoperative plan by a doctor in advance is obtained from an image obtained by performing CBCT imaging during radiotherapy. Compared with (cross-section), target position recognition, radiotherapy monitoring, etc. are performed.

  For example, Patent Document 1 includes an X-ray imaging apparatus, and selects an image in which the target position of the subject satisfies the therapeutic radiation irradiation condition of moving body tracking treatment from the X-ray images acquired by the X-ray imaging apparatus. A radiotherapy system that acquires a three-dimensional CT image in a therapeutic radiation irradiation state by performing image reconstruction is disclosed.

  Patent Document 2 discloses that X-rays for observation are applied to a pair of arms that are vertically disposed on both sides of a therapeutic radiation source while irradiating the subject with radiation from the therapeutic radiation source disposed on the upper part of the subject. Disclosed is a radiotherapy system that images a subject by rotating a pair of arms around a vertical axis while irradiating an X-ray for observation from obliquely above the subject by arranging a source and a detector. Yes.

  Further, in Patent Document 3, a radiation source for treatment and the like, and two pairs of observation X-ray sources and detectors are mounted on beams fixed to different disks arranged concentrically, respectively. A radiation system is disclosed that is capable of rotating independently about a subject by rotating a disk. Further, Patent Document 3 discloses a mechanism for inclining the therapeutic radiation source along the body axis direction of the subject with respect to the disc, so that the radiation can be irradiated to the subject from an oblique direction in the body axis direction. .

Japanese Patent Laying-Open No. 2015-029793 US Patent Application Publication No. 2012/0309773 US Pat. No. 8,934,605 (FIG. 8A-8C, FIG. 9A)

  However, in the radiation treatment system described in Patent Document 1 described above, the therapeutic radiation source and the observation X-ray source are arranged on the same rotating body of the gantry. Simultaneously rotate with the X-ray source. During radiotherapy, it is generally desirable to set a slow rotation speed of about once per minute. Therefore, X-rays are applied to the subject at this rotation speed to acquire data for reconstructed images. Then, images are taken with a period longer than the period of breathing. Therefore, since the displacement of the subject due to respiration is included, the image quality of the reconstructed image is degraded.

  On the other hand, in the radiotherapy system described in Patent Document 2, an X-ray source and a detector are mounted on a pair of arms vertically arranged on both sides of a subject, and the subject's X-ray source The X-ray source and the detector are rotated around the vertical axis while maintaining the positional relationship in which X-rays are irradiated obliquely from above and detected by the detector of the other arm. Therefore, the locus of the central axis P of the X-ray accompanying rotation draws a conical surface and is different from the axial cross section. Although it is possible to obtain an axial cross-sectional image from the reconstructed image obtained by the radiotherapy system of Patent Document 2, the image is compared with the voxel of the axial cross-sectional image obtained by separately performing CT imaging for preoperative planning in advance. Voxels are distorted and the quality of the reconstructed image is degraded.

  The radiotherapy system described in Patent Document 3 has a configuration in which an X-ray source and a detector are rotated within an axial cross section, and the therapeutic radiation source is rotated within the axial cross section or a plane inclined with respect to the axial cross section. However, when using proton beams or heavy particle beams that have been attracting attention in recent years as therapeutic radiation, it is very large-scale equipment using synchrotron, so it is difficult to tilt the therapeutic radiation source. . Specifically, the therapeutic radiation source focuses the proton beam or heavy particle beam generated by the synchrotron by applying an electric field or magnetic field in a vacuum conduit and bending the traveling direction according to the electric field or magnetic field distribution. The structure leads to the vicinity of the specimen. Therefore, the entire facility cannot be moved, and in order to tilt the radiation source in the vicinity of the subject, it is necessary to adjust the distribution of the magnetic field generated by the magnetic field generator, and to reduce the length of the vacuum conduit. It is necessary to change or change the slope. Therefore, it is very difficult to realize the technique of Patent Document 3 with proton beams or heavy particle beams, and even a device only around the exit of proton beams or heavy particle beams becomes large. In the technique of Patent Document 3, when both the therapeutic radiation source and the X-ray source are rotated in the axial cross section, the therapeutic radiation source rotates inside the X-ray source. Data cannot be acquired at a position where the specimen is in the shadow of the exit aperture such as a proton beam, and it is difficult to acquire a high-quality CT image.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to acquire an axial cross-sectional image with low distortion and high image quality during radiotherapy.

  In order to solve the above problems, the present invention provides the following means.

  One aspect of the present invention includes a therapeutic radiation irradiation unit that is disposed in a therapeutic rotation mechanism and irradiates therapeutic radiation to a target of the subject while rotating around the subject, and an X-ray source rotation mechanism. And an X-ray source that irradiates the target with X-rays for monitoring while rotating around the subject, and a rotation mechanism for the detector, and in synchronization with the rotation mechanism for the X-ray source, A detector for detecting X-rays irradiated from the X-ray source and transmitted through the subject while rotating around, the X-ray source and the detector rotating about a common rotation axis, and the treatment Radiation therapy system in which the rotation planes of the radiation source, the X-ray source, and the detector are different from each other and the therapeutic rotation mechanism, the X-ray source rotation mechanism, and the detector rotation mechanism are arranged so as not to interfere with each other I will provide a.

  ADVANTAGE OF THE INVENTION According to this invention, a pixel (voxel) is hardly distorted and an axial cross-sectional image with high image quality can be acquired during radiotherapy. Thereby, the positioning and monitoring accuracy of the subject in the radiotherapy can be improved.

It is a block diagram which shows the schematic structure of the radiotherapy system which concerns on the 1st Embodiment of this invention, and the positional relationship seen from the front of the rotation frame for treatment, and the rotation frame for scanners. In the radiotherapy system concerning a 1st embodiment of the present invention, it is a side view showing the positional relation of a rotation frame for treatment, and a rotation frame for scanners. It is a flowchart which shows operation | movement of the radiotherapy system which concerns on the 1st Embodiment of this invention. It is a side view which shows the positional relationship of the rotation frame for treatment and the rotation frame for scanners concerning the modification 1 of the 1st Embodiment of this invention. It is a side view which shows the positional relationship of the rotation frame for a treatment, the rotation frame for X-ray tubes, and the rotation frame for detectors concerning the modification 2 of the 1st Embodiment of this invention. It is a side view which shows the positional relationship of the rotation frame for a treatment, the rotation frame for X-ray tubes, and the rotation frame for detectors concerning the modification 3 of the 1st Embodiment of this invention. It is a side view which shows the positional relationship of the flame | frame for treatment, the flame | frame for X-ray tubes, and the rotation frame for detectors concerning the modification 4 of the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement of a radiotherapy system concerning the modification 6 of the 1st Embodiment of this invention. It is a side view which shows the positional relationship of the rotation frame for a treatment, and the rotation frame for scanners in the radiotherapy system which concerns on the 2nd Embodiment of this invention.

  Hereinafter, a radiotherapy system according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
The radiotherapy system according to the present embodiment acquires an observation image in real time by rotating a pair of an X-ray source and an X-ray detector on a rotation plane having an angle close to an axial section during radiotherapy on the subject 1. indicate. As a result, the real-time observation image and the CT image of the preoperative plan can be compared during the treatment, and accurate treatment by the doctor is supported while correcting the displacement of the treatment target portion (target) of the subject. . For this reason, the radiotherapy system of this embodiment includes a bed 5 on which a subject is placed, an observation X-ray CT scanner 10, a radiotherapy apparatus 20, and a control apparatus 30, as shown in FIG. . Note that both the therapeutic X-ray CT scanner 10 and the radiation therapy apparatus 20 are controlled by the control device 30.

  The observation X-ray CT scanner 10 is rotatably supported by a support base 17 (not shown in FIG. 1) and a support base 17, as shown in a front view of the gantry in FIG. 1 and a side view in FIG. The scanner rotation frame 11, the X-ray tube 12 (X-ray source), the X-ray detector 13, the high voltage generation unit 14, the scanner rotation drive unit 15, the scanner control unit 16, and the support shaft 3. And a support base 17.

  In the present embodiment, a so-called C-arm CT scanner can be applied as the observation X-ray CT scanner 10. Accordingly, as shown in FIGS. 1 and 2, in the present embodiment, the scanner rotation frame 11 is C-shaped, and the X-ray tube 12 and the X-ray detector 13 are provided in the scanner rotation frame 11. It is supported by support mechanisms 112 and 113, respectively. These support mechanisms 112 and 113 have a structure that can move on a C-shaped scanner rotation frame (hereinafter also referred to as C-arm) 11, and the X-ray tube 12 and the X-ray tube 12 at a desired position of the scanner rotation frame 11. The line detector 13 can be supported. In this embodiment, an X-ray tube 12 is attached to one end of the rotating frame 11 for the scanner, an X-ray detector 13 is attached to the other end, and the X-ray tube 12 and the X-ray detector 13 are connected to the FOV (field of view) 100 are arranged so as to face each other.

  As shown in FIG. 2, the scanner rotation frame 11 is rotatably supported by the support base 17 via the support shaft 3. The high voltage generator 14, the scanner rotation driving unit 15, and the scanner control unit 16 are arranged inside the support base 17. The scanner rotation driving unit 15 rotates the support shaft 3 around the rotation axis O. The support shaft 3 is provided with a mechanism for changing the position for supporting the C-shaped scanner rotation frame 11, and the C-shaped scanner rotation frame 11 is inclined at an arbitrary angle along the circumferential direction thereof. And support it rotatably.

  In the present embodiment, as shown in FIG. 2, the support shaft 3 is disposed so as to support the scanner rotation frame 11 at a position close to the X-ray tube 12. Therefore, the X-ray tube 12 and the X-ray detector 13 have the support shaft 3 that is a common rotation axis when the scanner rotation driving unit 15 rotates the support shaft 3 with the C-shaped scanner rotation frame 11. The rotating surface 120 of the X-ray tube 12 and the rotating surface 130 of the X-ray detector 13 do not interfere with each other and are in a positional relationship parallel to each other. In the present embodiment, the rotation surfaces 120 and 130 are arranged perpendicular to the body axis of the subject 1 by arranging the rotation axis O of the support shaft 3 to coincide with or parallel to the body axis of the subject.

  As a result, the scanner rotation drive unit 15 rotates the support shaft 3 under the control of the scanner control unit 16, whereby the scanner rotation frame 11 rotates about the rotation axis O, and the X-ray tube 12 and the X-ray detector. 13 are rotated around the subject 1. At this time, the scanner rotation frame 11 has a C-shaped curved shape, and is supported by a support shaft 3 disposed at a position away from the top of the subject 1 (or the tip of the foot) as shown in FIG. Both ends of the scanner rotation frame 11 are positioned on the head side and the foot side from the center of the subject 1 and rotate around the support shaft 3. The X-ray tube 12 and the X-ray detector 13 supported at both ends do not contact the subject 1. Thereby, the X-ray tube 12 and the X-ray detector 13 are positioned closer to the center of the subject in the body axis direction than the top of the subject 1 and the toes, and the rotation surface 120 and the rotation surface intersecting the body axis Each rotates within 130. The bed 5 includes a top plate 6 on which the subject 1 is placed. The top plate 6 is cantilevered on the foot side (or the top of the subject) side of the subject 1 so that the top plate is placed at a predetermined position. It has a structure that can be moved up to. By using the bed 5 having a structure in which the top plate 6 is cantilevered, the C-shaped scanner rotation frame 11 passes through the lower portion of the top plate 6 without contacting the bed 5 as it rotates. be able to.

  The X-ray tube 12 is electrically connected to the high voltage generator 14 via a slip ring mechanism (not shown) provided on the support shaft 3. The high voltage generator 14 applies a high voltage to the X-ray tube 12 rotating in the rotation surface 120 according to the control by the scanner controller 16. The X-ray tube 12 generates X-rays when a high voltage is applied by the high voltage generator 14. The generated X-ray is irradiated to the subject 1.

  The X-rays irradiated to the subject 1 pass through the subject 1 and reach the X-ray detector 13 facing the FOV 100 while rotating within the rotation surface 130. The X-ray detector 13 includes a plurality of detection elements arranged two-dimensionally, and each detection element detects X-rays that have passed through the subject and corresponds to the detected X-ray intensity. Generate electrical signals. The generated electrical signal is output to the scanner control unit 16. The scanner control unit 16 includes an image reconstruction unit 16 a, reconstructs a 3D image (volume data, CBCT image (cone beam CT image)) in the FOV 100 from the output of the detection element, and outputs the 3D image to the control device 30. An image processing unit 32 (to be described later) of the control device 30 can generate an axial cross-sectional image of the subject 1 by rendering a 3D image.

  The scanner control unit 16 controls the scanner rotation driving unit 15, the high voltage generation unit 14, and the like in accordance with instructions from the control device 30. Specifically, the scanner control unit 16 controls the scanner rotation driving unit 15 so that the scanner rotation frame 11 rotates at a constant angular velocity during the CT scan. The scanner control unit 16 controls the high voltage generation unit 14 so that the X-ray tube 12 emits X-rays having a predetermined energy.

  On the other hand, the radiotherapy apparatus 20 is mounted on the annular rotating frame 21 for treatment, a radiation (proton beam or heavy particle beam) generating unit 23 such as synchroton, and the therapeutic rotating frame 21 to send radiation to the subject 1. A radiation irradiation unit 22 that irradiates the FOV 100, a treatment rotation drive unit 24, and a treatment control unit 25 are provided. The rotational axis of the therapeutic rotating frame 21 is arranged to coincide with the rotational axis O of the C-shaped scanner rotating frame 11.

  The treatment rotation drive unit 24 rotates the treatment rotation frame 21 around the rotation axis O in accordance with an instruction from the treatment control unit 25. The radiation irradiation unit 22 mounted on the therapeutic rotating frame 21 treats the radiation (proton beam or heavy particle beam) generated by the radiation generation unit 23 while rotating around the subject 1 around the rotation axis O. The subject 1 is irradiated at a predetermined angle in accordance with an instruction from the control unit 25. In the present embodiment, the rotation surface 122 of the radiation irradiation unit 22 is perpendicular to the body axis of the subject 1. The rotating surface 122 of the radiation irradiation unit 22 may be disposed obliquely with respect to the body axis of the subject 1.

  At this time, the rotation surface 122 of the radiation irradiation unit 22 is disposed so as to be positioned between the rotation surface 120 of the X-ray tube 12 and the rotation surface 130 of the X-ray detector 13. In other words, the scanner rotation frame 11 is arranged such that the rotation surface 120 of the X-ray tube 12 and the rotation surface 130 of the X-ray detector 13 sandwich the rotation surface 122 of the therapeutic radiation irradiation unit 22.

  The irradiation direction of therapeutic radiation (the axis of therapeutic radiation) by the therapeutic radiation irradiation unit 22 and the irradiation direction of X-rays (X-ray axis) by the X-ray tube 12 are the rotational axes of the therapeutic radiation irradiation unit 22. A predetermined angle α is formed in the (Z-axis) direction. Therefore, even when the irradiation direction of the therapeutic radiation by the therapeutic radiation irradiation unit 22 and the X-ray irradiation direction by the X-ray tube 12 seem to coincide when projected onto the XY plane in FIG. The X-ray irradiation direction and the X-ray irradiation direction are always inclined by an angle α in the Z-axis direction. That is, the axis of therapeutic radiation and the axis of X-ray do not interfere with each other, and monitoring can be performed by irradiating X-rays while always irradiating therapeutic radiation.

  In addition, the distance between the rotation surface 122 of the radiation irradiation unit 22 and the rotation surface 120 of the X-ray tube 12 and the rotation surface 130 of the X-ray detector 13 is such that the inclined end portion of the X-ray detector 13 or the X-ray tube 12. Are determined in consideration of the sizes of the X-ray detector 13 and the X-ray tube 12 so as to be as small as possible without causing interference (contact and intersection) with the rotation surface 122 of the radiation irradiation unit 22. Yes.

  That is, as shown in FIG. 2, an angle α formed by the rotation plane of the therapeutic radiation irradiation unit 22 and a straight line (X-ray central axis P) connecting the X-ray tube 12 and the X-ray detector 13 is as much as possible. Specifically, it is desirable that α is 40 ° or less, since voxel distortion is small when an image of an axial cross section of the subject 1 is generated.

  Further, assuming that the width of the X-ray detector is about 400 mm, the distance between the X-ray tube and the X-ray detector is about 1000 mm, and the subject is approximately halfway between the X-ray tube and the X-ray detector, the X-ray detector 13. In consideration of the size, α is about 20 ° or more. However, if α is about 20 ° to 40 °, voxel distortion generated in the generated axial section can be allowed. If the voxel distortion in the axial section is reduced, the voxel distortion in the coronal section and the sagittal section in the direction orthogonal to the axial direction is also reduced. The angle α is determined by moving the X-ray tube 12 and the X-ray detector 13 on the scanner rotation frame 11 or changing the position of the scanner rotation frame 11 relative to the treatment rotation frame 21. Can be changed as appropriate. For example, as the distance between the subject and the X-ray detector is increased, α can be reduced and voxel distortion can be reduced.

  Thus, in the present embodiment, the scanner rotation frame 11 and the treatment rotation frame 21 are provided separately and independently and are rotationally driven independently by separate drive units. The X-ray tube 12 and the X-ray detector 13 rotate around the support shaft 3 that is a common rotation axis, and the rotation surface 120 of the X-ray tube 12 and the rotation surface 130 of the X-ray detector 13 The positional relationship is such that they do not interfere and are parallel to each other. The rotating surface 122 of the radiation irradiation unit 22 is located between the rotating surface 120 of the X-ray tube 12 of the therapeutic rotating frame 12 and the rotating surface 130 of the X-ray detector 13. Further, since the rotation axis O of the therapeutic rotating frame 21 coincides with the support shaft 3, the therapeutic radiation irradiation unit 22, the X-ray tube 12, and the X-ray detector 13 rotate around the common rotating axis O. And each rotation surface is arrange | positioned so that it may become mutually parallel.

  The control device 30 is a dedicated or general-purpose computer device that manages and controls the entire radiation therapy system, and includes a system control unit 31, an image processing unit 32, a bed driving unit 33, an image display unit 34, a storage unit 36, and an operation unit. 35.

  The system control unit 31 controls the scanner control unit 16 and the treatment control unit 25 to control the observation X-ray CT scanner 10 and the radiation treatment apparatus 30. Thus, while rotating the therapeutic rotating frame 21 of the radiotherapy apparatus 20, the radiation irradiation unit 22 irradiates the target 110 in the FOV 100 of the subject 1 from a predetermined angle at a predetermined timing to execute the treatment. The X-ray tube 12 emits X-rays while rotating the C-shaped scanner rotating frame 11 of the observation X-ray CT scanner 10, and the X-rays transmitted through the subject 1 are detected by the X-ray detector 13. Then, the 3D image of the subject 1 is generated in the image reconstruction unit 16a of the scanner control unit 16.

  The system control unit 31 includes a target recognition unit 31a. The target recognizing unit 31 a recognizes the position of the target (treatment target site) 110 in the 3D image of the scanner control unit 16. For example, the target position in the 3D image is recognized by a template matching technique that searches for a similar region using a preset CT image or X-ray fluoroscopic image of the target 110 as a template. Further, the system control unit 31 controls the image processing unit 32, the bed driving unit 33, the image display unit 34, the storage unit 36, and the operation unit 35. The system control unit 31 may control the scanner control unit 16 and the treatment control unit 25 via a network (not shown).

  The image processing unit 32 performs preprocessing and reconstruction processing on the image data acquired from the observation X-ray CT scanner 10, generates a reconstructed image of the subject 1 immediately before treatment, and generates a rendering image from the reconstructed image. To do. The image processing unit 32 outputs data related to the reconstructed image and the rendered image via the system control unit 31 to the display unit 34 for display.

  The bed 5 has a top plate 6 on which the subject 1 is placed, and is driven by a bed driving unit 32. The couch driving unit 32 moves the top 6 according to an instruction from the system control unit 31 described later. The subject 1 placed on the top 6 is positioned by moving the top 6 by the bed driving unit 32.

  The display unit 34 displays the reconstructed image and the rendered image generated by the image processing unit 32 and other necessary data in accordance with instructions from the system control unit 31. As a display device for realizing the display unit 34, for example, a CRT display, a liquid crystal display, an organic EL display, a plasma display, or the like can be applied.

  The operation unit 35 receives various commands and information input from the user via the input device, and outputs the input information to the system control unit 31. As an input device for realizing the operation unit 35, a keyboard, a mouse, a switch, or the like can be applied.

  The storage unit 36 stores various data such as data related to the reconstructed image generated by the image processing unit 32 and data related to the rendering image.

  Next, the operation of each part of the radiation therapy system of this embodiment will be described using the flow of FIG. In addition, the user can identify a treatment plan image in which the position of a treatment target region (target) 110 to be irradiated with radiation is specified with a mark or the like on one or more axial cross-sectional images taken with respect to the subject 1 using an X-ray CT apparatus. It is assumed that a treatment plan in which the irradiation angle of the radiation to the target 110, the number of times of irradiation, and the like are determined is created in advance.

  The system control unit 31 via the operation unit 35 treats treatment plan image data, radiation irradiation conditions (the number of rotations of the therapeutic rotating frame 21, radiation irradiation intensity, etc.), and CT image imaging conditions (of the X-ray CT scanner). X-ray irradiation conditions such as tube voltage and tube current, and the rotational speed of the C-shaped scanner rotating frame 11 are received (step 201).

  If the subject 1 is mounted on the top board 6 and the user instructs the position of the top board 6 via the operation section 35, the system control unit 31 accepts the position and moves the top board 6 to the designated position. Move (step 202).

  The system control unit 31 instructs the scanner control unit 16 of the observation X-ray CT scanner 10 to perform imaging. The scanner control unit 16 supplies X-rays by supplying predetermined tube voltage and tube current from the high voltage generation unit 14 to the X-ray tube 12 and operates the scanner rotation driving unit 15 to rotate the support shaft 3. Let As a result, as shown in FIG. 2, the C-shaped scanner rotation frame 11 rotates at a predetermined speed, and accordingly, the X-ray tube 12 rotates around the subject 1 within the rotation surface 120. The X-ray detector 13 rotates around the subject 1 within the rotation plane 130. X-rays emitted from the X-ray tube 12 pass through the subject 1 located in the FOV 100 and are detected by the X-ray detector 13. The scanner control unit 16 collects the outputs of the detection elements of the X-ray detector 13 at predetermined time intervals, and the image reconstruction unit 16a reconstructs a 3D image (CBCT image) in the FOV 100 (step 203).

  The target recognition unit 31a of the system control unit 31 receives the 3D image from the image reconstruction unit 16a, recognizes the target 110 in the 3D image by the target matching with the target image of the treatment plan image data, and the position of the target 110. Is obtained (step 204). The system control unit 31 causes the image processing unit 32 to generate an axial cross-sectional image of the position including the target 110 in the 3D image by the reconstruction process, and the display unit 34 together with the axial cross-sectional image of the position including the target 110 of the treatment plan image. (Step 205). Since the axial cross-sectional image generated by this processing is generated by tilting the voxel of the 3D image by the angle α, the voxel has a voxel distortion of the angle α, but in the present embodiment, the angle α is small (40 °) Voxel distortion can be reduced because it is set to be below.

  Further, the system control unit 31 calculates a positional deviation amount between the target position of the treatment plan image and the target position of the image captured by the observation X-ray CT scanner 10 and displays it on the display unit 34 (step 206). If the amount of positional deviation of the target 110 is greater than or equal to the predetermined value, the system control unit 31 moves the table 6 by the bed driving unit 33 so as to correct the calculated positional deviation, and returns to Step 203 (Step 203). 207, 208). Further, the top plate 6 may be moved according to the operation of the operation unit 35 by the user.

  Note that instead of the above-described step 205, similarly to the axial section, the image processing unit 32 generates a coronal section image at a position including the target 110 in the 3D image, and a coronal section at a position including the target 110 in the treatment plan image. Along with the image, it can be displayed on the display unit 34 (step 205 ′). In this case, the system control unit 31 calculates the amount of positional deviation in the coronal direction between the target position of the treatment plan image and the target position of the image captured by the observation X-ray CT scanner 10 and displays it on the display unit 34 ( Step 206 '). When the amount of positional deviation of the target 110 in the coronal direction is equal to or greater than a predetermined value, the system control unit 31 moves the table 6 by the bed driving unit 33 so as to correct the calculated positional deviation, and proceeds to Step 203. Return (steps 207 ′, 208 ′). Thereby, the amount of positional deviation in the coronal direction can be calculated and the positional deviation can be corrected.

  Further, instead of the above-described step 205 or step 205 ′, a sagittal cross-sectional image of the position including the target 110 in the 3D image is generated by the image processing unit 32, and the sagittal cross-sectional image of the position including the target 110 of the treatment plan image It is also possible to display it on the display unit 34 (step 205 ″). In this case, the system control unit 31 sets the target position of the treatment plan image and the target position of the image taken by the observation X-ray CT scanner 10. The amount of displacement in the sagittal direction is calculated and displayed on the display unit 34 (step 206 "). If the amount of positional deviation of the target 110 in the sagittal direction is greater than or equal to a predetermined value, the system control unit 31 moves the table 6 by the bed driving unit 33 so as to correct the calculated positional deviation, and proceeds to Step 203. Return (steps 207 ", 208"). Thereby, the amount of positional deviation in the sagittal direction can be calculated and the positional deviation can be corrected. By displaying as a cross-sectional image, the shift amount in the axial direction, coronal direction, and sagittal direction can be accurately displayed.

  It is also possible to generate a rendered image from the reconstructed image in the image processing unit 32 and display the rendered image on the display unit 34 instead of the cross-sectional image. By calculating the position including the target 110 in the treatment plan image and displaying it on the rendering image, the deviation amount in all directions can be shown as one image.

  As described above, the image processing unit 32 generates a reconstructed image and a rendered image of the images taken by the observation X-ray CT scanner 10, and superimposes the position including the target 110 calculated in the treatment plan image on these images. Thus, a real-time image can be used as a reference. On the other hand, it is also possible to generate a reconstructed image and a rendered image of the treatment plan image, and to superimpose a position including the target 110 calculated in the cross-sectional image taken by the observation X-ray CT scanner on these images. The treatment plan image can be used as a reference.

  In step 206, when the amount of displacement of the target position is smaller than the predetermined value, the system control unit 31 instructs the treatment control unit 25 of the radiation treatment apparatus 20 to perform treatment by radiation irradiation (step 209). Specifically, radiation is generated by the radiation generating unit 23 while rotating the therapeutic rotating frame 21 at a predetermined speed by the therapeutic rotation driving unit 24, and from the radiation irradiating unit 22 at a timing when a predetermined angle is reached. The target 110 of the subject is irradiated with radiation. At that time, using the 3D image captured by the observation X-ray CT scanner 10, the image processing unit 32 generates an axial sectional image of the position including the target 110 in the 3D image, and the position including the target 110 of the treatment plan image Are displayed on the display unit 34 together with the axial sectional image (step 210).

  Here, by displaying the image obtained in step 205 on the display unit 34, the exposure of the subject can be reduced. Alternatively, a real-time image can be displayed by displaying an image generated using a 3D image newly taken by the observation X-ray CT scanner 10. In addition to an axial cross-sectional image, a coronal cross-sectional image, a sagittal cross-sectional image, and a rendering image can be displayed.

  As a result, the user can view the axial cross-sectional image including the real-time target 110 displayed on the display unit 34 in contrast to the axial cross-sectional image including the target 110 of the treatment plan. Changes can be confirmed. Similarly, a coronal cross-sectional image, a sagittal cross-sectional image, and a rendered image can be compared with each other.

  As described above, according to the radiation therapy system of the present embodiment, the X-ray tube 12 and the X-ray detector are attached to the scanner rotating frame 11, and the therapeutic radiation irradiation unit 22 is independent from the scanner rotating frame 11. Therefore, the X-ray tube 12, the X-ray detector 13, and the therapeutic radiation irradiation unit 22 can be rotated at different speeds.

  Further, the X-ray tube 12 and the X-ray detector 13 rotate around a common rotation axis O while facing each other, and each rotation of the therapeutic radiation irradiation unit 22, the X-ray tube 12 and the X-ray detector 13 is performed. Since the therapeutic rotary frame 21 and the scanner rotary frame 11 are arranged so that the surfaces 122, 120, and 130 do not interfere with each other, the X-ray tube 12 can perform X-rays without tilting the therapeutic radiation irradiation unit 22. A 3D CT image can be obtained by inclining the central axis P of the X-ray reaching the detector 13 by a predetermined angle α with respect to the axial cross section. Therefore, an X-ray CT image can be acquired during radiotherapy even when a proton beam or a heavy particle beam that cannot easily tilt the radiation source is used.

  In addition, the radiation therapy system according to the present embodiment can reduce the inclination angle α of the X-ray central axis P according to the size of the X-ray detector 13 and the distance from the X-ray tube and the subject. Therefore, even when the X-ray central axis P is positioned at an angle close to the axial cross section and an axial cross-sectional image is generated from a 3D image, distortion of the voxel can be suppressed, and a high-definition axial cross-sectional image can be generated by radiation Can be obtained in real time during treatment. Therefore, the axial cross-sectional image of the preoperative plan and the real-time axial cross-sectional image can be compared and displayed to the user. Similarly, high-definition coronal, sagittal, and rendering images can be obtained in real time during treatment with radiation, and the preoperative plan and real-time images can be compared and displayed to the user. it can.

  In the radiotherapy system of the present embodiment, the central axis P of the X-ray that reaches the X-ray detector 13 from the X-ray tube 12 is inclined by an angle α with respect to the direction in which the therapeutic radiation is irradiated. Therefore, it is possible to prevent the component that travels straight ahead in the largest amount among the components that are scattered by the subject from the therapeutic radiation, from entering the X-ray detector 13. Therefore, a high-quality reconstructed image can be acquired.

  As described above, the radiotherapy system of this embodiment can improve the positioning and monitoring accuracy of the subject in radiotherapy.

  In addition, although this embodiment demonstrated the example in which a radiotherapy apparatus irradiates a proton beam or a heavy particle beam as a radiation, this embodiment is not limited to this, It is set as the structure which irradiates an X-ray or a gamma ray. It is also possible to do. When the radiation generating unit 23 is a small device, the radiation generating unit 23 can be mounted on the therapeutic rotating frame 21 and rotated together with the therapeutic rotating frame 21.

  In the present embodiment, the case where the rotation axis of the therapeutic rotation frame 21 and the rotation axis O of the scanner rotation frame 11 are coaxial has been described. However, the two rotation axes do not necessarily have to be coaxial. , They may be shifted in parallel. Further, the rotation axis O of the scanner rotation frame 11 may be inclined with respect to the rotation axis of the treatment rotation frame 21. When the rotation axis O is inclined, the rotation surface 120 of the X-ray source 12 and the rotation surface 130 of the X-ray detector are inclined with respect to the rotation surface 122 of the radiation irradiation unit 22. It is desirable that 120 or the rotating surface 130 does not intersect. However, when the irradiation angle of the radiation is limited to a predetermined angle, the rotating surface 122 and the rotating surface are not crossed (interfered) with the X-ray source 12 and the X-ray detector 13. Since it is possible to incline the rotation axis O so that 120 or the rotation surface 130 intersects, the rotation axis O may be inclined at such an inclination angle.

  In this embodiment, the CT image is captured by the observation X-ray CT image scanner, but it is also possible to obtain an X-ray fluoroscopic image or an X-ray captured image. When the top plate 6 is moved in step 202, the user can align the position while viewing the X-ray fluoroscopic image or the X-ray image.

(Modification 1)
In the above-described embodiment, an example in which there is one X-ray tube and one X-ray detector for the scanner has been described. However, a configuration in which two of them are provided may be employed.

  As shown in FIG. 4, a therapeutic rotating frame 21 provided with a therapeutic radiation source 21 and a scanner rotating frames 11a and 11b provided with X-ray tubes 12a and 12b and X-ray detectors 13a and 13b are separately and independently provided. It can also be arranged.

  That is, in this modification, two C-arms are provided, which are attached to the X-ray tube 12a attached to the first C-arm scanner rotating frame 11a and the second C-arm scanner rotating frame 11b. The X-ray detector 13b is disposed opposite to the FOV 100, and the X-ray tube 12b attached to the scanner rotation frame 11b and the X-ray detector 13a attached to the scanner rotation frame 11a sandwich the FOV 100. It is arranged facing each other.

  The scanner rotation frame 11a rotates about the support shaft 3a, and the scanner rotation frame 11b rotates about the support shaft 3b. The support shaft 3a and the support shaft 3b are arranged in substantially the same straight line, and the first C arm and the second C arm rotate about substantially the same rotation axis.

Therefore, X-rays emitted from the X-ray tube 12a attached to the first C arm are detected by the X-ray detector 13b attached to the second C arm, and the X-ray attached to the scanner rotation frame 11b is detected. X-rays irradiated from the ray tube 12b can be detected by an X-ray detector 13a attached to the scanner rotation frame 11a.
In FIG. 4, the C-arm is inserted from the head side and the foot side of the subject. In this case, the X-ray tube and the detector can be rotated around the rotation axis similarly to the above by sliding on the C arm along the arm.

(Modification 2)
Further, as shown in FIG. 5, there is one therapeutic radiation source, a scanner X-ray tube and an X-ray detector, respectively, and a therapeutic rotating frame 21, an X-ray tube rotating frame 18, and an X-ray detection. The detector rotation frames 19 to which the detectors 13 are attached can be arranged separately and independently.

  The therapeutic rotating frame 21, the X-ray tube rotating frame 18, and the detector rotating frame 19 are all in an annular shape and rotate around the same rotation axis. Further, the X-ray tube rotation frame 18 and the detector rotation frame 19 are arranged so as to sandwich the treatment rotation frame 21. Further, the X-ray tube 12 provided on the X-ray tube rotary frame 18 and the X-ray detector 13 provided on the detector rotary frame 19 are arranged to face each other with the FOV 100 interposed therebetween. The X-ray tube rotating frame 18 and the detector rotating frame 19 rotate synchronously, and the detector 13 detects X-rays emitted from the X-ray tube 12.

(Modification 3)
Further, as shown in FIG. 6, there is one therapeutic radiation source, a scanner X-ray tube, and an X-ray detector, respectively, a therapeutic rotating frame 21, an X-ray tube rotating frame 28, and a detector rotating. The frames 29 can also be arranged separately and independently.

  The therapeutic rotating frame 21 is on a ring, and the X-ray tube rotating frame 28 and the detector rotating frame 29 are rod-shaped, and both rotate around the same rotation axis. Further, the X-ray tube rotation frame 28 and the detector rotation frame 29 are arranged so as to sandwich the treatment rotation frame 21. Further, the X-ray tube 12 provided on the X-ray tube rotary frame 28 and the X-ray detector 13 provided on the detector rotary frame 29 are arranged to face each other with the FOV 100 interposed therebetween. The X-ray tube rotation frame 28 and the detector rotation frame 29 rotate in synchronization with each other, and the detector 13 detects X-rays emitted from the X-ray tube 12.

(Modification 4)
Further, as shown in FIG. 7, there is one therapeutic radiation source, a scanner X-ray tube, and an X-ray detector, respectively, a therapeutic rotating frame 21, an X-ray tube moving frame 38, and a detector moving. The frames 39 can also be arranged separately and independently.

The therapeutic rotating frame 21 is on an annulus, and the X-ray tube moving frame 38 and the detector moving frame 39 are rod-shaped and arranged in parallel. Further, the X-ray tube moving frame 38 and the detector moving frame 39 are arranged so as to sandwich the therapeutic rotating frame 21. Further, the X-ray tube 12 provided on the X-ray tube moving frame 38 and the X-ray detector 13 provided on the detector moving frame 39 are arranged to face each other with the FOV 100 interposed therebetween.
The X-ray tube 12 moves linearly on the X-ray tube moving frame 38, and the X-ray detector 13 moves linearly on the detector moving frame 39. The X-ray tube 12 and the X-ray detector 13 move in synchronization, and the detector 13 detects the X-rays emitted from the X-ray tube 12, and tomosynthesis imaging is possible.

(Modification 5)
In the above-described embodiment, as shown in FIG. 2, the positions of the X-ray tube 12 and the X-ray detector 13 on the scanner rotation frame 11 are not changed during imaging, and the angle α is kept constant. However, under the control of the system control unit 31, the mechanisms 112 and 113 are operated during imaging, and the positions of the X-ray tube 12 and the X-ray detector 13 on the scanner rotation frame (C-arm) 11 are moved. May be. However, the positional relationship in which the X-ray tube 12 and the X-ray detector 13 face each other with the FOV 100 interposed therebetween is maintained.

  Since the angle α changes by moving the positions of the X-ray tube 12 and the X-ray detector 13 on the scanner rotation frame 11, the data of the FOV 100 can be acquired at various X-ray incident angles. Thereby, a highly accurate 3D image (CBCT image (cone beam CT image)) can be obtained as compared with the case where the angle α is fixed. For example, the occurrence of blur due to the cone angle can be suppressed. As a result, the image processing unit 32 can reconstruct a more accurate axial cross-sectional image and display it on the display unit 34, for example, in steps 205 and 210 of FIG. In this case, α is not limited to 40 ° or less.

(Modification 6)
In the embodiment described above, as shown in FIG. 3, when the amount of displacement of the target position is larger than a predetermined value, the position of the top plate 6 is corrected. When the target 110 is located at a position where the position varies, a 3D image is captured in real time by the CT image scanner for observation, and the target 110 is irradiated with radiation at a timing when the target position is within a predetermined range. Is also possible. Thereby, it is possible to accurately irradiate the target 110 with radiation without being affected by the fluctuation of the target 110 due to respiratory motion or pulse.

  For example, as shown in the flowchart of FIG. 8, the system control unit 31 performs steps 201 to 204 in the same manner as in the above-described embodiment, and compares the preoperative plan with the current position of the target 110 in the 3D image captured by the CT scanner for observation. After recognizing the amount of displacement, radiation irradiation is performed only when the amount of displacement of the target 110 is less than or equal to a predetermined value (steps 306 to 308). This is repeated until the radiation irradiation reaches a predetermined number (step 309). Thereafter, an axial cross-sectional image including the target 110 is generated from the finally acquired 3D image and displayed on the display unit 34 (step 310). Since changes in the target 110 due to respiratory motion and pulse can be recognized based on CT images captured in real time, the target 110 can be irradiated with high accuracy.

  In the fifth modification, the change in the position of the target 110 due to respiratory motion or pulse is detected from the 3D image obtained by the observation CT scanner. However, the displacement of the subject due to respiratory motion or pulse is optically or electrically detected. The amount of displacement in step 206 may be detected using a sensor to detect. Moreover, you may use together these sensors and the detection of the target position using 3D image by CT scanner for observation.

(Second Embodiment)
In the above-described first embodiment and its modifications, the configuration in which the therapeutic radiation source, the scanner X-ray tube, and the X-ray detector rotate on different rotation surfaces that do not interfere with each other has been described. However, the present invention is not necessarily limited to such a configuration. For example, at least the therapeutic rotation mechanism, such as the C-arm as shown in the first embodiment, and the X-ray source rotation mechanism and the detector rotation mechanism are independent and independent. If so, the therapeutic radiation source and the observation X-ray source can be rotated at different speeds, and the image quality of the acquired reconstructed image can be improved.

  That is, for example, as shown in FIG. 9, an X-ray tube 12 and X-ray detection are provided at both ends of an annular therapeutic rotating frame 21 to which a therapeutic radiation irradiation unit 22 is attached and a scanner rotating frame 11 which is a C arm. The rotation plane of the therapeutic radiation irradiating unit 22, the rotation axis of the X-ray tube 12 and the X-ray detector 13 are common, and the rotation for treatment is such that the respective rotation planes are substantially coincident with each other. A frame 21 and a C-arm scanner rotating frame 11 are arranged. At this time, the X-ray tube 12 and the X-ray detector 13 are arranged so as to sandwich the FOV 100.

  Thus, the therapeutic radiation irradiation unit 22, the X-ray tube 12, and the X-ray detector 13 can be rotated by separate independent rotation mechanisms. That is, since the therapeutic radiation irradiation unit 22 is attached to the therapeutic rotation frame 21 independent of the scanner rotation frame 11, the X-ray tube 12 and the X-ray detector 13, the therapeutic radiation irradiation unit 22, Can be rotated at different speeds. More specifically, the therapeutic radiation source is rotated at a speed suitable for radiotherapy such as one rotation per minute, and the X-ray tube 12 and the X-ray detector 13 generate a reconstructed image having a desired image quality. It can be rotated at the speed required to acquire.

  Therefore, it is possible to obtain an isotropic and high-quality reconstructed image with no distortion in the pixels (voxels), and improve the positioning and monitoring accuracy of the subject in radiotherapy.

DESCRIPTION OF SYMBOLS 1 ... Subject, 3 ... Support axis, 10 ... X-ray CT scanner for observation, 11 ... Rotating frame for scanner, 12 ... X-ray tube, 13 ... X-ray detector , 14 ... high voltage generator, 15 ... scanner rotation drive unit, 16 ... scanner control unit, 18 ... X-ray tube rotation frame 18, 19 ... detector rotation frame, 20.・ Radiotherapy device, 21 ... treatment rotary frame, 22 ... treatment radiation irradiation unit, 23 ... high voltage generation unit, 24 ... treatment rotation drive unit, 25 ... treatment control unit , 30 ... control device, 31 ... system control unit, 32 ... image processing unit, 33 ... bed driving unit, 34 ... display unit, 35 ... operation unit, 36 ... Memory

Claims (15)

A therapeutic radiation irradiating unit that is disposed in a therapeutic rotation mechanism and irradiates therapeutic radiation to a target of the subject while rotating around the subject;
An X-ray source that is arranged in an X-ray source rotation mechanism and irradiates the target with X-rays for monitoring while rotating around the subject;
A detector that is disposed in a detector rotation mechanism and detects X-rays that are irradiated from the X-ray source and transmitted through the subject while rotating around the subject in synchronization with the X-ray source rotation mechanism;
The X-ray source and the detector rotate around a common axis of rotation, and the treatment radiation irradiation unit, the X-ray source and the detector have different rotation planes so that they do not interfere with each other. A radiation therapy system in which a rotating mechanism for a motor, the X-ray source rotating mechanism, and the rotating mechanism for the detector are arranged.   The radiotherapy system according to claim 1, wherein at least the therapeutic rotation mechanism, the X-ray source rotation mechanism, and the detector rotation mechanism are separately and independently arranged.   The radiation therapy system according to claim 2, wherein the X-ray source rotation mechanism and the detector rotation mechanism are the same C-arm.   The X-ray source rotation mechanism and the detector rotation mechanism are arranged so that the rotation surface of the X-ray source and the rotation surface of the detector sandwich the rotation surface of the therapeutic radiation irradiation unit. The radiation therapy system described.   The irradiation direction of the therapeutic radiation by the therapeutic radiation irradiation unit and the irradiation direction of the monitoring X-ray by the X-ray source form a predetermined angle with respect to the rotation axis direction of the therapeutic radiation irradiation unit. The radiation therapy system described.   The radiation treatment system according to claim 1, wherein an angle formed by a rotation surface of the therapeutic radiation irradiation unit and a straight line connecting the X-ray source and the detector is variable. The X-ray source rotation mechanism and the detector rotation mechanism are C-arms,
The radiation therapy system according to claim 6, further comprising a mechanism that makes the angle variable by moving the X-ray source and the detector along the C-arm.   The radiation therapy system according to claim 6, wherein the angle is 20 ° to 40 °.   The radiation therapy system according to claim 1, wherein the treatment rotation mechanism, the X-ray source rotation mechanism, and the detector rotation mechanism are separately and independently arranged.   The radiation therapy system according to claim 9, wherein the X-ray source rotation mechanism and the detector rotation mechanism are each a C-arm. A control unit for controlling radiation irradiation timing by the medical radiation irradiation unit and monitoring X-ray irradiation timing by the X-ray source;
2. The radiotherapy system according to claim 1, wherein the control unit controls the irradiation timing of the radiation by the therapeutic radiation irradiation unit and the irradiation timing of the monitoring X-ray by the X-ray source so as not to coincide with each other.   The radiation therapy system according to claim 1, further comprising: an image processing unit configured to reconstruct an image of the subject from an output of the detector and generate an axial cross-sectional image of the subject.   A target recognition unit for recognizing the position of the target from the image of the subject, and a control unit for irradiating the target with radiation from the therapeutic radiation irradiation unit when the target position is within a predetermined range. The radiation therapy system of Claim 12 provided.   The therapeutic radiation irradiation unit is an apparatus that is connected to an external radiation generation apparatus by a vacuum conduit, and irradiates the target by converging a proton beam or a heavy particle beam generated by the radiation generation apparatus with a magnetic field. 2. The radiation therapy system according to 1. A rotation mechanism for treatment;
A therapeutic radiation irradiating unit that is disposed in the therapeutic rotation mechanism and irradiates therapeutic radiation to the target of the subject while rotating around the subject;
A C-arm,
A C-arm rotation mechanism for rotating the C-arm;
An X-ray source disposed at one end of the C-arm and irradiating the target with monitoring X-rays while rotating around the subject;
A radiation therapy system comprising: a detector that is disposed at the other end of the C-arm and detects X-rays that are irradiated from the X-ray source and transmitted through the subject while rotating around the subject.

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