JP2008302129A - Radiation therapy system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radiation therapy system which can accurately check the location of a tumor under irradiation with a therapeutic radiation beam, raises the safety and certainty of radiation therapy by this, and can ease a patient. <P>SOLUTION: A control system 11 irradiates the human body 1 with the therapeutic radiation beam 9 when integrally rotating a therapeutic radiation beam emitter 7 and human imaging devices 13 and 17 centering around the human body 1 by a rotation mechanism, forms the two or more perspective images of the inside of the human body 1 by irradiating the human body 1 with an imaging radiation beam 15 from various directions during the emission of the radiation beam 9, and composes a CT image of the inside of the human body 1 based on the two or more generated perspective images. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a radiation therapy system that performs treatment of a treatment target portion by irradiating the treatment target portion in a human body, and in particular, accurately confirms the position of a tumor during irradiation of the treatment radiation beam. The present invention relates to a radiotherapy system that can increase safety and reliability of radiotherapy and can relieve a patient.

  2. Description of the Related Art Various types of radiation treatment systems for treating a treatment target portion in a human body, specifically, for example, a treatment of a tumor by irradiating the tumor with a radiation beam have been known (for example, (See Patent Document 1).

  In a conventional radiotherapy system, a bed for placing a human body and a so-called donut-shaped rotating gantry mechanism provided around the bed are arranged. Here, when the human body is placed on the bed, the human body is positioned along the central axis of the rotating gantry mechanism. The rotating gantry mechanism rotates around the human body arranged at such a position.

  A radiation beam irradiator for irradiating a human body placed on a bed with a radiation beam (for example, an X-ray beam) is attached to the rotating gantry mechanism. When a treatment is performed on the human body, the rotating gantry mechanism always rotates around the human body, so that various directions (360 ° of 360 ° from the radiation beam irradiator attached to the rotating gantry mechanism to the human body). Radiation beam is irradiated from (direction). By irradiating the human body with the radiation beam from various directions as described above, the normal tissue of the human body can be protected.

JP 2006-51064 A

  When performing radiotherapy in the radiotherapy system as described above, it is necessary to absorb a high-dose radiation beam to a tumor in the human body. However, the position of a tumor in the prostate, for example, changes day by day, and the position of a lung tumor changes periodically with the breathing of the human body. The fluctuation range of the position of such a tumor may exceed 2-3 cm. For this reason, when performing radiotherapy, after confirming the position of the tumor before the treatment, the irradiation range of the radiation beam is positioned, and then the radiation beam is irradiated onto the tumor.

  A conventional method for confirming the tumor position will be described below. Before or after irradiating a tumor with a therapeutic radiation beam, the human body is irradiated with a radiation beam (X-ray beam) from various directions, and this radiation beam transmitted through the human body is detected. A plurality of fluoroscopic images (two-dimensional images) are generated, and a cone beam CT image is constructed based on the generated fluoroscopic images. Here, the cone beam CT image is a high-resolution three-dimensional image in which a tumor is clearly depicted and its position can be confirmed with high accuracy. However, in such a method, the position of the tumor is confirmed before or after the therapeutic radiation beam is irradiated on the tumor. In the conventional method of confirming the tumor position, radiation treatment is performed from the tumor position confirmed before and after the radiation treatment. It was only to estimate the location of the tumor during the period.

  In recent years, as a part of information disclosure in radiation therapy, there is a case where it is required for a patient to indicate with an image that a therapeutic radiation beam is accurately irradiated on a tumor. In general, it is necessary to perform 20 to 30 radiation treatments normally because a single radiation treatment cannot obtain a sufficient absorbed dose of the radiation beam for the tumor. If a CT image showing the position is obtained, this CT image can improve the treatment plan when the human body is irradiated with the radiation beam in the next radiation treatment.

  The present invention has been made in consideration of the above points, and a CT image showing the position of a tumor during radiation therapy while a therapeutic radiation beam is being irradiated on the human body. Therefore, it is possible to accurately confirm the position of the tumor during the irradiation of the therapeutic radiation beam, thereby improving the safety and reliability of the radiation therapy and relieving the patient. The purpose is to provide a system.

  The present invention relates to a radiation treatment system for treating a treatment target portion by irradiating the treatment target portion in a human body with the radiation beam for treatment, which irradiates the human body with the treatment radiation beam. A human body imaging device that generates a fluoroscopic image inside the human body by irradiating the human body with an imaging radiation beam so as to be orthogonal to the therapeutic radiation beam irradiated from the therapeutic radiation beam irradiation device, and the treatment A rotation mechanism for integrally rotating a radiation beam irradiation apparatus for a human body and the human body imaging apparatus around a human body, and a control apparatus for controlling the therapeutic radiation beam irradiation apparatus, the human body imaging apparatus, and the rotation mechanism. Then, the therapeutic radiation beam irradiation device and the human body imaging device are integrally rotated around the human body by the rotation mechanism. The human body imaging device while the human body is irradiated with the therapeutic radiation beam by the rotating therapeutic radiation beam irradiation device and the human body is irradiated with the therapeutic radiation beam by the therapeutic radiation beam irradiation device The human body is irradiated with an imaging radiation beam from various directions to generate a plurality of fluoroscopic images inside the human body, and control is performed so as to obtain a CT image inside the human body based on the generated fluoroscopic images. A radiotherapy system comprising a control device.

  According to such a radiation therapy system, when the therapeutic radiation beam irradiation device and the human body imaging device are integrally rotated around the human body by the rotation mechanism, the human body is irradiated with the therapeutic radiation beam, During irradiation of the therapeutic radiation beam, the human body is irradiated with an imaging radiation beam from various directions to generate a plurality of fluoroscopic images inside the human body, and based on the generated fluoroscopic images, CT images (for example, cone beam CT images) can be obtained. Thus, while the therapeutic radiation beam is being applied to the human body, a CT image showing the position of a treatment target portion such as a tumor (hereinafter referred to as a tumor as an example) during radiotherapy is obtained. Therefore, the position of the tumor during irradiation with the therapeutic radiation beam can be confirmed with high accuracy. This can increase the safety and certainty of radiation therapy and reassure the patient. In the above-described radiation therapy system, the human body is simultaneously irradiated with the therapeutic radiation beam and the imaging radiation beam. However, these radiation beams interfere with each other and affect the other radiation beam. rare. This is because the doses of the therapeutic radiation beam and the imaging radiation beam are greatly different, and the irradiation direction of the therapeutic radiation beam and the irradiation direction of the imaging radiation beam are orthogonal to each other. Is minimized.

  In the radiotherapy system of the present invention, the radiotherapy system further includes a display mechanism for displaying a CT image inside the human body, and the control device is provided inside the human body obtained based on a plurality of fluoroscopic images generated by the human body imaging device. It is preferable to control the display mechanism so that the CT image is displayed on the display mechanism. This makes it possible to display a CT image inside the human body on the display mechanism, so that the position of the tumor during irradiation of the therapeutic radiation beam can also be displayed on this display mechanism. The person can confirm the position of the tumor more reliably.

  In the radiotherapy system of the present invention, the control device superimposes the irradiation range of the therapeutic radiation beam irradiated by the therapeutic radiation beam irradiation device on the CT image inside the human body and causes the display mechanism to display the superimposed image. It is preferable to perform such control. As a result, the operator can easily and quickly confirm whether or not the therapeutic radiation beam is accurately applied to the tumor by simply viewing the CT image.

  In the radiotherapy system of the present invention, it is preferable that the therapeutic radiation beam irradiation apparatus has a collimator, and the collimator changes the irradiation range of the therapeutic radiation beam. In particular, the collimator is preferably a multi-leaf collimator.

  In the radiotherapy system of the present invention, the control device rotates the therapeutic radiation beam irradiation device and the human body imaging device one or more times around the human body by the rotation mechanism in one radiotherapy step, While the therapeutic radiation beam is irradiated on the human body by the therapeutic radiation beam irradiation device, the human body imaging device irradiates the human body with the imaging radiation beam from various directions of 360 °, and the inside of the human body. It is preferable to perform control such that a plurality of fluoroscopic images are generated and a CT image inside the human body is obtained based on the generated fluoroscopic images. In this case, since a plurality of fluoroscopic images inside the human body are generated by irradiating the human body with imaging radiation beams from various directions of 360 °, the position of the tumor is surely and accurately determined in the finally obtained CT image. I will be able to show you well.

  In the radiotherapy system of the present invention, the control device includes a CT image at the time of treatment planning that is generated in advance before the therapeutic radiation beam is irradiated onto the human body by the therapeutic radiation beam irradiation device, and the human body. It is preferable that the amount of positional deviation between the CT image obtained based on a plurality of fluoroscopic images generated by the imaging device is calculated. As a result, the operator can quantitatively determine whether or not a tumor misalignment has occurred during the irradiation of the therapeutic radiation beam.

  In the radiotherapy system of the present invention, the control device performs control to irradiate the human body with a therapeutic radiation beam based on a treatment plan, and the positional deviation amount is larger than a preset value. It is preferable that the treatment plan for irradiating the human body with the therapeutic radiation beam in the next radiation treatment is changed based on the positional deviation amount. Therefore, even when the tumor is misaligned when the therapeutic radiation beam is applied to the tumor and the tumor cannot be irradiated with a desired dose of the therapeutic radiation beam, the next radiation It becomes possible to irradiate the tumor with a therapeutic radiation beam while correcting this at the time of treatment.

  In the radiotherapy system of the present invention, the control device superimposes the dose distribution of the therapeutic radiation beam irradiated by the therapeutic radiation beam irradiation device on the CT image inside the human body and causes the display mechanism to display it. It is preferable to perform such control. As a result, the operator can directly confirm on the image how much therapeutic radiation beam has been applied to the tumor.

  At this time, a therapeutic radiation beam detector for detecting a therapeutic radiation beam emitted from the therapeutic radiation beam irradiation apparatus is installed, and a dose distribution of the therapeutic radiation beam is determined by the therapeutic radiation. It is recalculated from the boundary coordinates of the therapeutic radiation beam detected by the beam detector. Alternatively, the control device may include a CT image for treatment planning that is generated in advance before the therapeutic radiation beam is applied to the human body by the therapeutic radiation beam irradiation device, and a plurality of images that are generated by the human body imaging device. The amount of misalignment with the CT image obtained based on the fluoroscopic image of the treatment is calculated, and the dose distribution of the therapeutic radiation beam changes the incidence condition of the therapeutic radiation beam on the human body using the misregistration amount. It has been recalculated. Alternatively, the control device may include a CT image for treatment planning that is generated in advance before the therapeutic radiation beam is applied to the human body by the therapeutic radiation beam irradiation device, and a plurality of images that are generated by the human body imaging device. The amount of positional deviation between the CT image obtained based on the fluoroscopic image of the treatment is calculated, and the dose distribution of the therapeutic radiation beam is changed by changing the position of the CT image during treatment planning according to the amount of positional deviation. It has been recalculated.

  According to the radiotherapy system of the present invention, the position of the tumor during the irradiation of the therapeutic radiation beam can be confirmed with high accuracy, thereby improving the safety and certainty of the radiotherapy and relieving the patient. it can.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 6 are views showing an embodiment of a radiation therapy system according to the present invention.
Among these, FIG. 1 is a schematic perspective view showing a configuration of a radiotherapy system according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of the radiotherapy system shown in FIG. FIG. 3 is a schematic configuration diagram of a multi-leaf collimator in the radiotherapy system shown in FIG. 4 is a flowchart showing one control content in the control apparatus of the radiotherapy system shown in FIGS. 1 to 3, and FIG. 5 shows another control content in the control apparatus of the radiotherapy system shown in FIGS. It is a flowchart which shows the control content. FIGS. 6A to 6D are cone beam CT images obtained in the radiation therapy system shown in FIGS.

  The radiation treatment system according to the present embodiment performs treatment of a tumor 3 by irradiating a treatment target portion inside the human body 1, specifically, a tumor 3 such as a lung tumor with a radiation beam. is there. As shown in FIG. 1 and FIG. 2, especially FIG. 2, the radiation therapy system includes an imaging radiation beam irradiator 13 that irradiates a human body 1 with an imaging radiation beam 15, and a human body irradiated with the imaging radiation beam irradiator 13. An imaging radiation beam detector 17 that receives the imaging radiation beam 15 that has passed through 1 and generates a fluoroscopic image from the received imaging radiation beam 15 and a treatment that irradiates the human body 1 with the therapeutic radiation beam 9 And a therapeutic radiation beam detector 34 that receives the therapeutic radiation beam 9 irradiated from the therapeutic radiation beam irradiator 7 and transmitted through the human body 1. Further, a control device 11 for controlling the imaging radiation beam irradiator 13 and the therapeutic radiation beam irradiator 7 is installed in the radiation therapy system. Here, the imaging radiation beam irradiator 13 and the imaging radiation beam detector 17 constitute a human body imaging device for imaging in the human body 1.

  Each component of such a radiation therapy system will be described in detail below with reference to FIGS.

  The therapeutic radiation beam irradiator 7 irradiates the tumor 3 in the human body 1 with the therapeutic radiation beam 9 as described above. Here, as the therapeutic radiation beam 9, for example, an X-ray beam having an energy in the range of 4 MV to 10 MV (1 MV is 1 million volts) is used. In particular, the therapeutic radiation beam irradiator 7 accelerates electrons by an electron accelerating portion provided therein, and generates a high energy X-ray beam by colliding the accelerated high energy electrons with a metal target. It is preferable to irradiate the human body 1 with this high-energy X-ray beam as a therapeutic radiation beam 9. The therapeutic radiation beam 9 irradiated from the therapeutic radiation beam irradiator 7 and transmitted through the human body 1 is received and detected by the therapeutic radiation beam detector 34 formed of, for example, a flat panel type semiconductor two-dimensional array detector. It has become.

  As shown in FIG. 2, a multi-leaf collimator 33 for narrowing the irradiation range of the therapeutic radiation beam 9 emitted from the therapeutic radiation beam irradiator 7 is provided in the vicinity of the therapeutic radiation beam irradiator 7. is set up. The multileaf collimator 33 is communicatively connected to the control device 11 via a cable 43. The multi-leaf collimator 33 can change the irradiation range of the therapeutic radiation beam 9 irradiated from the therapeutic radiation beam irradiator 7 over time based on the control signal from the control device 11. Yes.

  The multi-leaf collimator 33 will be specifically described with reference to FIG. As shown in FIG. 3, the multi-leaf collimator 33 has a number of shielding plates 33s made of tungsten. Each shielding plate (also referred to as a leaf) 33s has a size in the range of 5 mm to 1 cm in the vertical direction in FIG. 3 and a thickness in the depth direction in FIG. 3 of about 8 cm. Each shielding plate 33s can be moved in a one-dimensional direction, that is, in the left-right direction in FIG. 3, independently from the other shielding plate 33s by an actuator (not shown). In FIG. 3, when the multi-leaf collimator 33 is in the form of the upper multi-leaf collimator 33a, the therapeutic radiation beam 9 emitted from the therapeutic radiation beam irradiator 7 is completely blocked, and the human body 1 is not irradiated with the therapeutic radiation beam 9. Here, when the shielding plate 33s is opened to the left and right, an opening (blacked portion in FIG. 3) is formed as shown in the middle multi-leaf collimator 33b, and the therapeutic radiation beam 9 passes through this opening. To come. Further, when the irradiation range of the therapeutic radiation beam 9 on the human body 1 is changed, the pair of left and right shielding plates 33s move in the direction of the arrow in the multi-leaf collimator 33b in the middle stage of FIG. In this way, the opening changes as shown in the lower multi-leaf collimator 33c in FIG. Thus, by changing the mode of the multi-leaf collimator 33 according to the movement of the tumor 3, specifically, each shielding plate 33 s is appropriately moved, so that the irradiation range of the therapeutic radiation beam 9 on the human body 1 is reduced. Can be varied. Here, such control of the multi-leaf collimator 33 is performed based on a control signal from the control device 11.

  When the tumor 3 in the human body 1 is small, the shape thereof is almost spherical, so that the irradiation range of the therapeutic radiation beam 9 can be fixed regardless of the irradiation direction of the therapeutic radiation beam 9. However, when the tumor 3 is large, the tumor 3 has a complicated shape. As a result, when the rotating gantry mechanism 35 is rotated, the shape of the tumor 3 as viewed from the irradiation direction of the therapeutic radiation beam 9 changes. To do. Therefore, during the rotation of the rotating gantry mechanism 35, for example, by moving each shielding plate 33s from the state of the middle multi-leaf collimator 33b in FIG. 3 to the state of the lower multi-leaf collimator 33c in FIG. The entire tumor 3 can be irradiated with the therapeutic radiation beam 9 and the normal tissue around the tumor 3 can be prevented from being irradiated with the therapeutic radiation beam 9. Note that the irradiation method of the therapeutic radiation beam 9 that moves the shielding plates 33s of the multi-leaf collimator 33 during the rotation of the rotating gantry mechanism 35 is called a dynamic irradiation method, but is limited to such a dynamic irradiation method. It is also possible to use a rotational irradiation method in which the irradiation field of the therapeutic radiation beam 9 is kept constant during the rotation of the rotating gantry mechanism 35.

  The imaging radiation beam irradiator 13 irradiates the human body 1 with the imaging radiation beam 15. Specifically, the imaging radiation beam irradiator 13 irradiates the imaging radiation beam 15 so that the irradiation range includes the tumor 3 in the human body 1. Here, the imaging radiation beam irradiator 13 accelerates electrons with a voltage of about 100 kV by an X-ray tube provided inside, and generates an X-ray beam by colliding the accelerated electrons with a metal target. The human body 1 is preferably irradiated with this X-ray beam as an imaging radiation beam 15.

  The imaging radiation beam detector 17 receives the imaging radiation beam 15 irradiated from the imaging radiation beam irradiator 13 and transmitted through the human body. For example, the flat panel type semiconductor two-dimensional array detector having amorphous silicon is used. Consists of. The imaging radiation beam detector 17 generates a fluoroscopic image from the received imaging radiation beam 15.

  As shown in FIG. 1, the therapeutic radiation beam irradiator 7, the imaging radiation beam irradiator 13, the imaging radiation beam detector 17, and the therapeutic radiation beam detector 34 are attached to a so-called donut-shaped rotating gantry mechanism 35. It has been. Further, the human body 1 is positioned along the central axis of the rotating gantry mechanism 35 when performing treatment, and the rotating gantry mechanism 35 is centered on the human body 1 disposed at such a position. It rotates in the direction of the arrow 1. Here, the treatment for the rotating gantry mechanism 35 is performed so that the therapeutic radiation beam 9 emitted from the therapeutic radiation beam irradiator 7 and the imaging radiation beam 15 emitted from the imaging radiation beam irradiator 13 are substantially orthogonal to each other. The mounting positions of the radiation beam irradiator 7 and the imaging radiation beam irradiator 13 are set (that is, the positions of the therapeutic radiation beam irradiator 7 and the imaging radiation beam irradiator 13 with respect to the central axis of the rotating gantry mechanism 35). The phase difference is about 90 °). The therapeutic radiation beam detector 34 is attached to the rotating gantry mechanism 35 so as to be opposite to the therapeutic radiation beam irradiator 7 with respect to the central axis of the rotating gantry mechanism 35. Similarly, the mounting position of the imaging radiation beam detector 17 with respect to the rotating gantry mechanism 35 is set so as to be opposite to the imaging radiation beam irradiator 13 with respect to the central axis of the rotating gantry mechanism 35.

  Here, as shown in FIGS. 1 and 2, a movable bed 39 for placing the human body 1 is provided in the vicinity of the rotating gantry mechanism 35. When the human body 1 is treated, the bed 39 on which the human body 1 is placed is moved in advance to position the human body 1 along the central axis of the rotating gantry mechanism 35. The position of the bed 39 is controlled by a control device 11 (described later). A display device 37 for displaying various treatment parameters is provided in the vicinity of the rotating gantry mechanism 35. The display device 37 displays various treatment parameters transmitted from the control device 11 (described later).

  Furthermore, the control apparatus 11 is provided in the radiotherapy system. The control device 11 includes a therapeutic radiation beam irradiator 7, an imaging radiation beam irradiator 13, an imaging radiation beam detector 17, and a therapeutic radiation via cables 19, 23, 21, 44, 43 and 45, respectively. The beam detector 34, the multi-leaf collimator 33, and the movable bed 39 are communicatively connected. Details of control contents in the control device 11 will be described later.

  Next, operation | movement of the radiotherapy system which consists of such a structure is demonstrated below using the flowchart of FIG. The operation of the radiation therapy system as shown in the flowchart of FIG. 4 is performed by controlling the imaging radiation beam irradiator 13, the therapeutic radiation beam irradiator 7, and the like by the control device 11.

  First, a treatment plan is created before performing radiation treatment of the human body 1. Specifically, a CT image inside the human body 1 (hereinafter referred to as a CT image during treatment planning) is generated by a CT system different from the radiotherapy system as shown in FIGS. Based on the CT image at the time of treatment planning, a plan for the irradiation direction, irradiation range, irradiation dose, etc. of the therapeutic radiation beam 9 to the tumor 3 of the human body 1 in radiation therapy is created in advance.

  Next, the human body 1 is placed on the bed 39, and a cone beam CT image for alignment is generated before radiation treatment. Specifically, as shown in Step 1 of FIG. 4, the rotating gantry mechanism 35 is rotated once, while the imaging radiation beam irradiator 13 continues to irradiate the imaging body with the imaging radiation beam 15 and passes through the body 1. The imaging radiation beam 15 received is received by the imaging radiation beam detector 17, thereby generating fluoroscopic images (two-dimensional images) inside the human body 1 from various directions. Then, a cone beam CT image is constructed based on the generated plurality of fluoroscopic images. The cone beam CT image for alignment obtained in this way is as shown in FIG. Here, the cone beam CT image is a high-resolution three-dimensional image in which the tumor 3 is clearly depicted and its position can be confirmed with high accuracy. In FIG. 6A, the intersection of the white cross lines indicates the center of the irradiation range of the therapeutic radiation beam 9 to be irradiated from the therapeutic radiation beam irradiator 7.

  Next, as shown in Step 2 of FIG. 4, the irradiation range of the therapeutic radiation beam 9 is adjusted to the position of the tumor 3 in the cone beam CT image by moving the bed 39 by the control device 11. Specifically, in the cone beam CT image shown in FIG. 6A, the tumor 3 is located above the intersection of the white cross lines, but the tumor 3 is moved by moving the bed 39. Match the intersection of the white cross lines. FIG. 6B shows a cone beam CT image before irradiation of the therapeutic radiation beam 9 when the position of the tumor 3 is adjusted to the irradiation range of the therapeutic radiation beam 9.

  Then, as shown in Step 3 of FIG. 4, the rotating gantry mechanism 35 is rotated once around the human body 1, and the therapeutic radiation beam 9 is applied to the human body 1 from various directions by the rotating therapeutic radiation beam irradiator 7. Irradiate. At this time, any one of the above-described rotational irradiation method or dynamic irradiation method is used. While the human body 1 is irradiated with the therapeutic radiation beam 9, the imaging radiation beam irradiator 13 continues to irradiate the human body 1 with the imaging radiation beam 15 and passes through the human body 1. 15 is received by the imaging radiation beam detector 17, and thereby generates fluoroscopic images (two-dimensional images) inside the human body 1 from various directions. Then, a cone beam CT image is constructed based on the generated plurality of fluoroscopic images. The cone beam CT image under treatment obtained in this way is as shown in FIG.

  In Step 3 in FIG. 4, the human body 1 is irradiated with the therapeutic radiation beam 9 and the imaging radiation beam 15 at the same time. However, these radiation beams 9 and 15 interfere with each other to form a counterpart radiation beam. There is little impact. This is because the doses of the therapeutic radiation beam 9 and the imaging radiation beam 15 are greatly different as described above, and the irradiation direction of the therapeutic radiation beam 9 and the irradiation direction of the imaging radiation beam 15 are as shown in FIG. This is because the degree of interference with the counterpart radiation beam is minimized because they are orthogonal.

  When the rotating gantry mechanism 35 finishes rotating, the irradiation of the therapeutic radiation beam 9 and the imaging radiation beam 15 on the human body 1 is terminated. The cone beam CT image inside the human body 1 after the end of the radiotherapy is as shown in FIG. Under the control of the control device 11, the cone beam CT image inside the human body 1 after treatment is displayed on the display device 37 before treatment, during treatment, and after treatment. That is, the cone beam CT images shown in FIGS. 6A to 6D are displayed on the display device 37 at a time. As a result, the operator can confirm the position of the tumor 3 in the human body 1 more reliably by visual recognition.

  Further, when the cone beam CT image inside the human body 1 during irradiation of the therapeutic radiation beam 9 is displayed on the display device 37, the irradiation range of the therapeutic radiation beam 9 is displayed superimposed on the cone beam CT image. May be. FIG. 7 is an image when the irradiation range of the therapeutic radiation beam 9 is superimposed on the cone beam CT image inside the human body 1 during the irradiation of the therapeutic radiation beam 9. As a result, the operator can visually confirm that the therapeutic radiation beam 9 has been accurately applied to the tumor 3. Here, the boundary line of the irradiation range of the therapeutic radiation beam 9 in FIG. 7 is 50% intensity of the peripheral portion of the therapeutic radiation beam 9 detected by the therapeutic radiation beam detector 34 that receives the therapeutic radiation beam 9. By extracting the contour, it can be uniquely determined. Note that the cone beam CT image shown in FIG. 6 is a planar image passing through the center of the therapeutic radiation beam 9, and therefore, by considering the projection onto the planar image, as shown in FIG. The boundary surface of the therapeutic radiation beam 9 is converted into two boundary lines. In FIG. 7, this boundary line is displayed only in two opposing directions.

  FIG. 8 is a cone beam CT image along a cross section inside the human body 1 during irradiation of the therapeutic radiation beam 9. In such an image, since it is possible to display at 360 ° rotation by the rotating gantry mechanism 35, it is possible to display the boundary surfaces of all the therapeutic radiation beams 9 being rotated 360 ° by the rotating gantry mechanism 35. it can. In FIG. 8, the boundary surface of the therapeutic radiation beam 9 is displayed in only two directions for easy viewing of the image.

Thereafter, as shown in Step 4 of FIG. 4, the tumor of the cone beam CT image as shown in FIG. 6C obtained based on the position of the tumor 3 of the CT image at the time of the above-described treatment planning and a plurality of fluoroscopic images. 3 positions are compared, and the amount of positional deviation between them is calculated. Here, as the amount of positional deviation, the deviation values in the three coordinates of the X direction, the Y direction, and the Z direction along the X axis, the Y axis, and the Z axis, respectively, and the X axis, the Y axis, and the Z axis, A total of six values of the deviation values in the three rotation directions are calculated.
As a result, the operator can quantitatively determine whether or not the tumor 3 is displaced during the irradiation of the therapeutic radiation beam 9. The calculated positional deviation amount can be stored in the control device 11 or an external storage medium attached to the radiation therapy system.
Thus, one radiotherapy process by the radiotherapy system is completed. Actually, the radiotherapy process as shown in Step 1 to Step 4 of FIG. 4 is performed about 20 to 30 times a day.

  Next, another operation of the radiation therapy system will be described below using the flowchart of FIG. The operation of the radiotherapy system as shown in the flowchart of FIG. 5 is performed by controlling the imaging radiation beam irradiator 13, the therapeutic radiation beam irradiator 7, and the like by the control device 11.

  In other operations of the radiotherapy system as shown in the flowchart of FIG. 5, the operations from Step 1 to Step 4 are substantially the same as the operations from Step 1 to Step 4 in the flowchart of FIG. 4 as described above. The operation shown in the flowchart of FIG. 5 is different from the operation shown in the flowchart of FIG. 4 in that the operation of Step 5 is added after Step 4.

  That is, in Step 4 of FIG. 5, the amount of positional deviation between the position of the tumor 3 in the CT image at the time of treatment planning and the position of the tumor 3 in the cone beam CT image is calculated. In Step 5 of FIG. If the calculated positional deviation amount is larger than a preset value, a treatment plan for irradiating the human body 1 with the therapeutic radiation beam 9 in the next and subsequent radiotherapy is based on the positional deviation amount. change.

  Specifically, when the amount of displacement calculated in Step 4 of FIG. 5 exceeds the set value, the therapeutic radiation beam 9 of the originally planned dose is not irradiated to the tumor 3. It is necessary to correct this at the next irradiation time of the therapeutic radiation beam 9. In general, when the therapeutic radiation beam 9 is irradiated with the tumor 3 being displaced, a sufficient dose of the therapeutic radiation beam 9 is not applied to a part (or all) of the tumor 3, and the tumor 3 A very uneven dose distribution of the therapeutic radiation beam 9 is generated inside. Here, since the dose distribution of the therapeutic radiation beam 9 can be calculated by the control device 11 by quantifying the positional deviation amount of the tumor 3, in the next irradiation of the therapeutic radiation beam 9, The therapeutic radiation beam 9 having a dose distribution that corrects the previous dose distribution in the non-uniform tumor 3 can be provided to the tumor 3. That is, the irradiation range of the therapeutic radiation beam 9 can be corrected so that the total dose distribution of the previous dose distribution and the current dose distribution is uniform.

  As described above, according to the radiation therapy system of the present embodiment as shown in FIGS. 1 to 3, the therapeutic radiant beam irradiation unit 7 and the imaging radiation beam irradiator 13 centering on the human body 1 by the rotating gantry mechanism 35. When the imaging radiation beam detector 17 is rotated integrally, the human body 1 is irradiated with the therapeutic radiation beam 9 and the human body 1 is irradiated with the imaging radiation beam 15 during the irradiation of the therapeutic radiation beam 9. Can be irradiated from various directions to generate a plurality of fluoroscopic images inside the human body 1, and a cone beam CT image inside the human body 1 can be obtained based on the generated fluoroscopic images. In this way, while the therapeutic radiation beam 9 is being applied to the human body 1, a cone beam CT image showing the position of the tumor 3 during the radiotherapy can be obtained. The position of the tumor 3 during the irradiation of the beam 9 can be confirmed with high accuracy. This can increase the safety and certainty of radiation therapy and reassure the patient.

  In addition, the radiotherapy system by this Embodiment is not limited to said aspect, A various change can be added.

  For example, in the above-described embodiment, the rotating gantry mechanism 35 is rotated once with respect to the human body 1 when the therapeutic radiation beam 9 is applied to the tumor 3 of the human body 1. The number of rotations 35 is not particularly limited as long as it is one rotation or more. Furthermore, if a cone beam CT image can be constructed from a plurality of fluoroscopic images generated by the imaging radiation beam 15, the rotational speed of the rotating gantry mechanism 35 can be set to a half rotation, for example, less than one rotation. .

  Further, as a CT image composed of a plurality of fluoroscopic images generated by the imaging radiation beam 15, a cone beam CT image is desirable, but other types of CT images can be obtained by a human body imaging device. Also good.

  As another modification, when the cone beam CT image is displayed on the display device 37, as shown in FIG. 9, the cone beam CT image along the cross section inside the human body 1 as shown in FIG. The dose distribution of the therapeutic radiation beam 9 may be superimposed and displayed. Although the dose distribution of the image shown in FIG. 9 is composed of triple frame lines, the dose lines are 100%, 90%, and 80% isodose lines in order from the frame line closer to the center. As shown in the flowchart of FIG. 10, such a dose distribution of the therapeutic radiation beam 9 is recalculated from the boundary coordinates of the therapeutic radiation beam 9 detected by the therapeutic radiation beam detector 34. (Step 1). In this way, by displaying the dose distribution of the therapeutic radiation beam 9 superimposed on the cone beam CT image (Step 2), the operator directly determines how much the therapeutic radiation beam 9 has been irradiated on the tumor 3. Can be confirmed with images.

Here, a method for recalculating the dose distribution from the boundary coordinates of the therapeutic radiation beam 9 detected by the therapeutic radiation beam detector 34 will be described below.
As shown in the CT images of FIGS. 7 and 8, when the boundary line of the therapeutic radiation beam 9 is superimposed on the cone beam CT image inside the human body 1 during the irradiation of the therapeutic radiation beam 9, 7 or 8, the in-vivo dose is recalculated with respect to the incident position of the therapeutic radiation beam 9 in the CT image as shown in FIG. 7 and FIG. 8, and thus the dose distribution as shown in FIG. 9 is recalculated. In this case, the dose distribution is recalculated using a CT image at the time of treatment planning, but the dose distribution may be calculated using a cone beam CT image.

  Further, as another recalculation method of the dose distribution of the therapeutic radiation beam 9, as shown in the flowchart of FIG. 11, the position of the therapeutic radiation beam 9 is calculated using the positional deviation amount calculated in Step 4 of FIG. 4 or FIG. 5. There is also a method of recalculating the dose distribution by changing the incident condition on the human body 1. In this case, dose calculation is performed in an image coordinate system in which a CT image at the time of treatment planning is fixed.

  Further, as still another recalculation method of the dose distribution of the therapeutic radiation beam 9, as shown in the flowchart of FIG. 12, the incident beam coordinates of the therapeutic radiation beam 9 are not changed, and the above-mentioned positional deviation amount is adjusted. There is also a method of recalculating the dose distribution by changing the position of the CT image at the time of treatment planning.

  In any of the recalculation methods, it is verified whether or not the dose of the therapeutic radiation beam 9 can be concentrated at an accurate position by superimposing the dose distribution of the therapeutic radiation beam 9 on the cone beam CT image. Will do.

It is a schematic perspective view which shows the structure of the radiotherapy system in one embodiment of this invention. It is a schematic block diagram of the radiotherapy system shown in FIG. It is a schematic block diagram of the multileaf collimator in the radiotherapy system shown in FIG. It is a flowchart which shows one control content in the control apparatus of the radiotherapy system shown in FIG. 1 thru | or FIG. It is a flowchart which shows the other control content in the control apparatus of the radiotherapy system shown in FIG. (A)-(d) is a radiograph obtained in the radiotherapy system shown in FIG. 1 thru | or FIG. It is an X-ray photograph when the irradiation range of the therapeutic radiation beam is superimposed on the cone beam CT image inside the human body during the irradiation of the therapeutic radiation beam. It is an X-ray photograph when the irradiation range of the therapeutic radiation beam is superimposed on the cone beam CT image along the cross section inside the human body during the irradiation of the therapeutic radiation beam. FIG. 9 is an X-ray photograph in which a dose distribution of a therapeutic radiation beam is superimposed and displayed on a cone beam CT image along a cross section inside a human body as shown in FIG. It is a flowchart when superimposing and displaying the dose distribution of a therapeutic radiation beam on a cone beam CT image. It is another flowchart when displaying the dose distribution of the therapeutic radiation beam superimposed on the cone beam CT image. It is another flowchart when the dose distribution of a therapeutic radiation beam is superimposed and displayed on a cone beam CT image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Human body 3 Tumor 7 Treatment radiation beam irradiator 9 Treatment radiation beam 11 Control device 13 Imaging radiation beam irradiator 15 Imaging radiation beam 17 Imaging radiation beam detector 19, 21, 23 Cable 33 Multi-leaf collimator 33s Shielding Board (leaf)
34 Treatment Radiation Beam Detector 35 Rotating Gantry Mechanism 37 Display Device 39 Beds 43, 44, 45 Cable

Claims (12)

A radiation treatment system for treating a treatment target portion by irradiating the treatment target portion in a human body with a radiation beam,
A therapeutic radiation beam irradiation apparatus for irradiating the human body with a therapeutic radiation beam; and
A human body imaging device that generates a fluoroscopic image inside the human body by irradiating the human body with the imaging radiation beam so as to be orthogonal to the therapeutic radiation beam irradiated from the therapeutic radiation beam irradiation device;
A rotation mechanism that integrally rotates the therapeutic radiation beam irradiation apparatus and the human body imaging apparatus around the human body;
A control device for controlling the therapeutic radiation beam irradiation device, the human body imaging device, and the rotation mechanism, wherein the therapeutic radiation beam irradiation device and the human body imaging device are integrated with the rotation mechanism as a center. The human body is irradiated with the therapeutic radiation beam by the rotating therapeutic radiation beam irradiation apparatus, and the human body is irradiated with the therapeutic radiation beam by the therapeutic radiation beam irradiation apparatus. An in-vivo imaging device irradiates a human body with imaging radiation beams from various directions to generate a plurality of fluoroscopic images inside the human body, and obtains a CT image inside the human body based on the generated fluoroscopic images. A control device for performing the control;
A radiation therapy system comprising: A display mechanism for displaying a CT image inside the human body;
The control device controls the display mechanism so that a CT image inside a human body obtained based on a plurality of fluoroscopic images generated by the human body imaging device is displayed on the display mechanism. Item 2. The radiation therapy system according to Item 1.   The control device performs control so as to superimpose an irradiation range of the therapeutic radiation beam irradiated by the therapeutic radiation beam irradiation device on a CT image inside the human body and display it on the display mechanism. The radiation therapy system according to claim 2.   The radiation according to any one of claims 1 to 3, wherein the therapeutic radiation beam irradiation apparatus includes a collimator, and the collimator varies the irradiation range of the therapeutic radiation beam. Treatment system.   The radiation therapy system according to claim 4, wherein the collimator is a multi-leaf collimator.   The control device rotates the therapeutic radiation beam irradiation device and the human body imaging device one or more times around the human body by the rotation mechanism in one radiation treatment step, and the human body is rotated by the therapeutic radiation beam irradiation device. While the therapeutic radiation beam is being irradiated, the human body imaging device irradiates the human body with the imaging radiation beam from various directions of 360 ° to generate a plurality of fluoroscopic images inside the human body. 6. The radiotherapy system according to claim 1, wherein control is performed so as to obtain a CT image inside the human body based on a plurality of fluoroscopic images.   The control device includes a CT image for treatment planning that is generated in advance before the therapeutic radiation beam is applied to the human body by the therapeutic radiation beam irradiation device, and a plurality of fluoroscopic images generated by the human body imaging device. The radiotherapy system according to claim 6, wherein a displacement amount between the CT image obtained based on the image is calculated.   The control device performs control to irradiate the human body with a therapeutic radiation beam based on a treatment plan, and when the amount of positional deviation is larger than a preset value, the human body is subjected to subsequent radiotherapy. 8. The radiation treatment system according to claim 7, wherein a treatment plan for irradiating the treatment radiation beam is changed based on the amount of positional deviation.   The control device performs control so as to superimpose a dose distribution of a therapeutic radiation beam irradiated by the therapeutic radiation beam irradiation device on a CT image inside a human body and display it on the display mechanism. The radiation therapy system according to claim 2. A therapeutic radiation beam detector for detecting a therapeutic radiation beam irradiated from the therapeutic radiation beam irradiation apparatus is installed;
10. The radiation treatment system according to claim 9, wherein the dose distribution of the treatment radiation beam is recalculated from boundary coordinates of the treatment radiation beam detected by the treatment radiation beam detector. The control device includes a CT image for treatment planning that is generated in advance before the therapeutic radiation beam is applied to the human body by the therapeutic radiation beam irradiation device, and a plurality of fluoroscopic images generated by the human body imaging device. Calculating the amount of misalignment with the CT image obtained based on the image;
10. The radiation therapy according to claim 9, wherein the dose distribution of the therapeutic radiation beam is recalculated by changing the incidence condition of the therapeutic radiation beam on the human body using the misregistration amount. system. The control device includes a CT image for treatment planning that is generated in advance before the therapeutic radiation beam is applied to the human body by the therapeutic radiation beam irradiation device, and a plurality of fluoroscopic images generated by the human body imaging device. Calculating the amount of misalignment with the CT image obtained based on the image;
10. The radiation therapy system according to claim 9, wherein the dose distribution of the therapeutic radiation beam is recalculated by changing the position of the CT image at the time of treatment planning in accordance with the amount of positional deviation.