JP4643544B2 - Bed positioning system, radiation therapy system, and particle beam therapy system - Google Patents

Description

The present invention relates to a bed positioning system , a radiation therapy system, and a particle beam therapy system , and in particular, for use in radiation therapy in which various types of radiation such as X-rays or proton beams are irradiated to a diseased part to be treated. The present invention relates to a suitable bed positioning system , a radiation therapy system, and a particle beam therapy system .

  In recent years, radiation therapy aiming at necrosis of cancer cells by irradiating various types of radiation has been widely performed. As the radiation used, not only the most widely used X-rays but also treatments using particle beams such as proton beams are performed.

  One important process of radiation therapy is bed positioning. The bed positioning process will be described below (see Patent Document 1). First, an engineer (or doctor) generally uses a digitally reconstructed radiograph (DRR) image information output from a treatment planning apparatus and a treatment bed (hereinafter referred to as “Dragon”) using an X-ray imaging apparatus before irradiation. X-ray image information obtained by imaging the patient lying on the bed) is compared. Based on this comparison, a deviation amount between the position of the irradiation target (cancer affected part) determined in the treatment plan and the position of the irradiation target of the patient lying on the current bed is calculated. The amount of movement of the bed is obtained using the calculated shift amount so that the two types of images match. The bed positioning is completed by moving the bed based on the amount of movement. Patent Document 2 describes that the amount of bed movement is obtained by pattern matching between DRR image information and X-ray image information.

  The DRR image information is image information simulating X-ray image information, and is generated from CT image information taken at the time of treatment planning. Note that in bed positioning, image information captured using an X-ray simulator or the like may be used as reference image information instead of DRR image information.

  Although the above method is widely used in bed positioning, since X-ray image information mainly shows clear structures such as bones, when cancer cells are present in soft tissues such as organs, It may be difficult to observe the position of the affected area from the image. For this reason, in the bed positioning using the X-ray image information, the positioning is performed on the assumption that the positional relationship between the affected part of cancer, that is, the soft tissue and the bone does not change greatly. However, since the position of the organ in the body changes slightly every day, the organ position in the CT image information at the time of treatment planning may not always match the organ position in the patient on the bed at the time of treatment.

  Recently, three-dimensional radiotherapy that actively avoids giving doses to surrounding organs in the vicinity of an affected area of cancer and concentrates radiation only on the affected area has been actively performed. Examples of such treatment include intensity modulated radiation therapy (IMRT) and radiation therapy using particle beams. In these three-dimensional radiotherapy, it is beginning to be required for more accurate irradiation to grasp the position of the affected part including surrounding organs at the time of positioning and to position based on the organ instead of the bone. In order to respond to such a demand, an attempt has been made to install a CT apparatus near the treatment apparatus (in the treatment room) and perform positioning using CT image information instead of DRR image information. In addition, as part of such an attempt, a device for sharing the bed of the treatment apparatus and the X-ray CT apparatus has also been made (Non-Patent Document 1).

  By using the CT image information as the bed positioning image information, the bed can be positioned while checking the position of the organ. It is desirable to position the bed at the same position as the irradiation device. However, when an X-ray CT apparatus is installed in the treatment room separately from the treatment apparatus, the patient must be transferred from the X-ray CT apparatus to the treatment apparatus (or the bed must be moved). It is necessary to confirm the position of the affected part of the patient and the treatment device on the bed of the treatment device.

  Generally, the radiation irradiation apparatus of a radiotherapy apparatus is attached to a rotating gantry that can rotate 360 degrees around a rotation axis that extends in the longitudinal direction of the bed. An X-ray tube for X-ray imaging and an X-ray image receiving apparatus are also attached to the rotating gantry.

  On the other hand, there is a cone beam method as one of imaging modes for obtaining CT image information. In this cone beam method, X-ray imaging is basically performed around an axis around the entire circumference, and reconstruction processing is performed using X-ray detection signals output from a plurality of radiation detectors to obtain CT image information. Is the way to get. The name of the cone beam method comes from the fact that the X-rays emitted from the X-ray tube become a cone (cone) beam. X-ray imaging performed over the entire circumference of the treatment target while rotating the rotating gantry of the radiotherapy apparatus is the same as imaging by the cone beam method. CT image information can be obtained by reconstructing a plurality of pieces of fluoroscopic image information obtained. A system in which cone beam imaging is performed using an X-ray imaging device attached to a rotating gantry, CT image information is acquired, and used for bed positioning has been put into practical use (Non-Patent Document 2). The advantage of this method is that the coordinate system of the CT image information for positioning coincides with the coordinate system of the treatment apparatus, particularly the irradiation position. This advantage covers the drawbacks of the method of installing the X-ray CT apparatus separately from the treatment apparatus.

  Further, Patent Document 3 describes that a bed positioning method to which a cone beam method is applied is performed by a particle beam therapy apparatus using an ion beam.

JP 2000-510023 JP JP 2004-267250 A JP 2006-239403 A Noriya Yokohama et al., “Outline and examination of patient positioning system using CT-treatment common bed in proton therapy”, Journal of Japanese Society of Radiological Technology, Vol.59, No.11, pp.1432–1436, 2003.

David A. Jaffray, et al., `` A Radiographic and tomographic imaging system integrated into a medical linear accelerator for localization of bone and soft-tissue targets '', Int. J. Radiation Oncology Biol. Phys., Vol. 45, No. 3, 773-789, 1999.

Jinkoo Kim, et al., “Effects of X-ray image enhancements on the robustness and accuracy of a rigid 3D / 2D image registration”, Medical Physics, vol. 32, No. 4, pages 866-873, 2005.

Frederik Maes, et al., “Multimodality image registration by maXimization of mutual information”, IEEE Trans. Med. Image., Vol. 16, No. 2, pp. 187-197, 1997.

Godfrey DJ, et al., “Digital tomosynthesis with an on-board kilovoltage imaging device”, Int J Radiat Oncol Biol Phys. Vol. 65, No. 1, pages 8-15, 2006.

  A bed positioning system that uses CT image information obtained by imaging by a cone beam method using an X-ray imaging device attached to a rotating gantry for positioning a bed is capable of confirming the position of an organ, and a coordinate system for positioning. This has the advantage that the coordinate systems of the irradiating devices match. When this cone beam method is used, the CT image information is reconstructed from the X-ray image information, and the reconstructed CT image information is compared with the CT image information for the treatment plan that has been imaged in advance to determine the irradiation target and the irradiation position. Find the displacement and position the bed. Therefore, the bed positioning method to which the cone beam method is applied requires creation of CT image information by reconstruction processing, compared with the conventional bed positioning method using X-ray image information. It takes longer time to complete. On the other hand, in order to reduce the burden on the patient, it is required to shorten the treatment time from the bed positioning to the end of radiation irradiation as much as possible. However, in the bed positioning method to which the cone beam method is applied, the time required for reconstruction processing for creating CT image information is an obstacle to shortening the treatment time.

An object of the present invention is to provide a bed positioning system , a radiotherapy system, and a particle beam therapy system that can further reduce the time required for radiotherapy .

A feature of the present invention that achieves the above-described object is that X-ray image information is created based on X-ray information output from an X-ray incidence apparatus that makes X-rays incident, and in parallel with the creation of the X-ray image information. The first tomographic image information is created based on the X-ray information, the bed movement amount is obtained based on the X-ray image information and the second tomographic image information used for the treatment plan, and the first tomographic image is obtained based on the bed movement amount. The information is corrected, the bed movement amount, the corrected first tomographic image information, and the second tomographic image information are output to the display device. When the bed movement amount is appropriate, the irradiation target is determined based on the bed movement amount. It is to control the driving device of the supporting bed .

  Since the creation of the X-ray image information and the creation of the first X-ray CT image information can be performed in parallel, the calculation of the bed movement amount using the X-ray image information is performed in parallel with the creation of the first X-ray CT image information. It can be carried out. For this reason, the time required for positioning the bed can be significantly shortened, and the time required for radiation therapy can be further shortened.

  According to the present invention, the time required for radiation therapy can be further shortened.

  Examples of the present invention will be described below.

  A bed positioning system according to Embodiment 1 which is a preferred embodiment of the present invention will be described with reference to FIGS. First, before describing the bed positioning system 2 of the present embodiment, an X-ray treatment system 1 that is a radiation therapy system to which the bed positioning system 2 is applied will be described with reference to FIGS. 1, 2, and 3. . As shown in FIG. 3, the X-ray treatment system 1 includes a bed positioning system 2 and a treatment apparatus 31. The bed positioning system 2 includes an X-ray imaging system 3 and a positioning device 20. The treatment device 31 includes a rotating gantry 32, a support 34, an irradiation head (irradiation nozzle, irradiation device) 35, an X-ray generation device 36, a bed 38, a gantry control device 44, and a gantry console 45. The rotating gantry 32 is rotatably attached to a column 34 installed on the floor surface. The rotating gantry 32 has an arm portion 33 extending in the direction of the rotation center shaft 46, and is driven by a first rotation mechanism (not shown) attached to the column 34 to rotate around the rotation center shaft 46.

  The bed 38 includes a treatment table 40 and a top plate 39 installed at the upper end of the treatment table 40. The treatment table 40 is installed on a turntable (not shown) having a second rotation mechanism (not shown) installed on the floor surface. The top plate 39 is elongated in one direction. The treatment table 40 includes three driving devices (not shown) that move the top board 39 in three directions. The top plate 39 moves 41 in the horizontal direction (referred to as the Y-axis direction) along the rotation center axis 46 by the first driving device. The top plate 39 is moved 42 in the horizontal direction (referred to as the X direction) orthogonal to the rotation center axis 46 by the second driving device. The top plate 39 moves 43 in the height direction (vertical direction) (referred to as the Z direction) by the third driving device. The top plate 39 rotates around the bed rotation shaft 47 by driving the second rotation mechanism. Further, although not shown, the treatment table 40 moves (rolls) the top plate 39 around the rotation center axis 46 and raises and lowers (pitches) the tip of the top plate 39. A fifth drive device is provided. The fourth and fifth driving devices are used for fine adjustment of the positioning of the bed 38, that is, the top plate 39. The state in which the axis extending in the longitudinal direction of the top plate 39 is parallel to the rotation center shaft 46 in the horizontal and vertical directions (the state of the top plate 39 shown in FIGS. 1 and 2) The rotation angle of the bed 38 is defined as zero degrees.

  The irradiation head 35 is installed at a portion extending in the horizontal direction of the rotating gantry 32, that is, at the tip of the arm portion 33 so as to face the top plate 39. The arm portion 33 turns around the top plate 39 as the rotating gantry 32 rotates. An X-ray generator 36 is installed in the arm portion 33. The irradiation head 35 irradiates X-rays incident from the X-ray generator 36 toward an irradiation target (for example, an affected part of cancer existing in a patient). Since the direction of the irradiation head 35 in the circumferential direction is changed by the rotation of the rotating gantry 32, X-rays can be irradiated from any direction within a range of 360 degrees around the rotation center axis 46 to the irradiation target. An arrow 50 (see FIG. 2) is the direction of rotation of the rotating gantry 32. The intersection of the irradiation center line 48 that passes through the axis of the irradiation head 35 and is the direction in which X-rays are irradiated and the rotation center axis 46 is referred to as an irradiation center point (isocenter) 49.

  The gantry console 45 is connected to the gantry control device 44. The gantry console 45 sets the irradiation parameters such as the energy of the X-ray generated by the X-ray generator 36 and the rotation angle of the rotating gantry, and outputs each operation command to the X-ray source generator 36 and the first rotating mechanism. I do. The gantry control device 44 outputs respective control commands for driving the X-ray source generator 36 and the first rotation mechanism based on each irradiation parameter and each operation command.

  The configuration of the bed positioning system 1 will be described. The X-ray imaging system 3 of the bed positioning system 1 includes an X-ray source (X-ray source device) 4, an X-ray receiver (X-ray injector) 5, an imaging control device 6, an imaging console 7, and a reconstruction processing device ( A tomographic image information creation device) 15. The X-ray source 4 and the X-ray receiver 5 are attached to the rotating gantry 32 so as to face each other with the top plate 39 interposed therebetween (see FIG. 2). The X-ray receiver 5 has a plurality of semiconductor radiation detectors (not shown) (hereinafter referred to as semiconductor detectors) which are radiation detectors. A scintillator may be used as the radiation detector. The X-ray receiver 5 used in this embodiment is a flat panel detector (FPD) having a plurality of semiconductor detectors. Any of an FPD having a scintillator and a plurality of photodiodes, an image intensifier, and a CCD can be used for the X-ray receiver 5. The X-ray source 2 and the X-ray receiver 3 are connected to the imaging control device 6.

  As shown in FIG. 4, the imaging console 7 includes a processing device 8, an input device (such as a keyboard and a mouse) 13, and a display device 14. The processing device 8 includes a communication device 9, an imaging processing arithmetic device 10, a main storage device 12, and a storage device 11. An imaging processing arithmetic device 10 is connected to the communication device 9, the main storage device 12, and the storage device 11. The input device 13 and the display device 14 are connected to the communication device 9. The imaging processing arithmetic device 10 has two functions of an X-ray image information creation device (first image information creation device) and a tomographic image creation command device. As the X-ray image information creation device, the imaging processing arithmetic device 10 executes processing of steps 64 and 65 shown in FIG. Further, as the tomographic image creation command device, the imaging processing calculation device 10 executes the processing of steps 67 and 68 shown in FIG. 5 described later, and issues a reconstruction processing start command when the determination in step 67 is “Yes”. The data is output to the reconstruction processing device (second image information creation device) 15. A storage device 11 such as a hard disk stores data and programs. The main storage device 12 temporarily stores programs and data used during arithmetic processing. As illustrated in FIG. 4, the reconstruction processing device 15 includes a communication device 16, a reconstruction calculation device 17, a main storage device 19, and a storage device 18. A reconstruction calculation device 17 is connected to the communication device 16, the main storage device 19, and the storage device 18. A reconstruction calculation processing program used by the reconstruction calculation device 17 is stored in the storage device 18. The main storage device 19 is temporarily loaded with the reconfiguration arithmetic processing program. The X-ray receiver 5, the imaging control device 6, and the reconstruction processing device 15 are connected to the imaging console 7. Specifically, the X-ray receiver 5, the imaging control device 6, and the communication device 16 are connected to the communication device 9.

  The positioning device 20 of the bed positioning system 1 includes a movement amount calculation device 22 and a bed control device 30. As illustrated in FIG. 4, the movement amount calculation device 22 includes a processing device 23, an input device (such as a keyboard and a mouse) 28, and a display device 29. The processing device 23 includes a communication device 24, a movement amount calculation device 25, a main storage device 27, and a storage device 26. A movement amount calculation device 25 is connected to the communication device 24, the main storage device 27, and the storage device 26. The input device 28 and the display device 29 are connected to the communication device 24. The movement amount calculation program used in the movement amount calculation device 25 is stored in the storage device 26 and loaded from the storage device 26 to the main storage device 27 when used in the movement amount calculation device 25. The movement amount calculation device 22 is connected to the imaging console 7 and the bed control device 30. Specifically, the communication device 24 is connected to the communication device 9 and the bed control device 30.

  In radiotherapy, it is necessary to match the irradiation center point 49 with the irradiation target in the patient lying on the top board 39 before the irradiation of the irradiation target. For this reason, positioning of the bed 38, that is, the top plate 39 is performed. The bed positioning method of the present embodiment using the bed positioning system 1 will be described below with reference to FIG.

  First, the bed is moved (step 61). The irradiation target that irradiates X-rays is an affected area of cancer (hereinafter referred to as an affected area) present in a patient that is an irradiation target. After the patient lies on the top board 39, the top board 39 is moved so that the affected part is located near the irradiation center point 49. The movement of the top board 39 is performed when the bed control device 30 inputs a movement command from the input device 28. The bed control device 30 outputs a drive control command based on the movement command input from the imaging console 7 to the first, second, and third drive devices, and drives these drive devices. As a result, movements 41, 42, and 43 with respect to the top board 39 are performed, and the target target reaches near the irradiation center point 49. Note that when the bed control device 30 drives the second rotation mechanism based on the movement command, the top board 39 turns about the bed rotation shaft 47 by a predetermined angle. The top plate 39 is moved near the irradiation center point 49 of the target target using an optical device such as a laser marker as a mark. In some cases, the top plate 39 is moved by using a marker such as a sticker or a crosshair attached to (or drawn on) the surface of the patient without using an optical device.

  X-ray imaging of the irradiation target is executed (step 62). The gantry control device 44 drives the first rotation mechanism based on the rotation command input from the gantry console 45. The rotating gantry 31 rotates around the rotation center axis 34. When the rotation gantry 32 is rotating and the rotation angle of the rotation gantry 32 reaches each preset imaging angle, the imaging control device 6 applies X-rays from the X-ray source 4 in a pulsed manner. Irradiate. X-rays transmitted through the affected area of the patient are detected for each imaging angle set by each semiconductor detector of the X-ray receiver 5 facing the X-ray source 4. A plurality of set shooting angles (or shooting intervals) are stored in advance in the main storage device 12 by an operator input from the input device 13 of the imaging console 7. The imaging processing arithmetic device 10 transmits information on those imaging angles to the imaging control device 6 via the communication device 9. The imaging control device 6 holds information of each imaging angle (or imaging interval) and controls the imaging conditions such as the operation of the X-ray source 4 and the X-ray tube voltage and current of the X-ray source 4. The imaging control device 6 includes a communication device for communicating with the imaging console 7. An X-ray detection signal is input to the imaging console 7 (step 63). The X-ray detection signal output from each semiconductor detector of the X-ray receiver 5 is a voltage signal and is A / D converted in the X-ray receiver 5 to become a digital signal (hereinafter referred to as X-ray data). . X-ray data (X-ray information) is transmitted to the communication device 9 via the imaging control device 6 and input to the imaging processing arithmetic device 10. The imaging processing arithmetic device 10 stores X-ray data in the storage device 11 using a communication program loaded in the main storage device 12 in advance.

  It is determined whether X-ray data of the set angle number has been input (step 67). The imaging processing arithmetic device 10 determines whether or not X-ray data for each imaging angle with respect to the set number of angles has been input. The X-ray data is output to the reconstruction processing device (step 68). When the determination is “Yes”, the imaging processing arithmetic device 10 reconstructs each X-ray data for each imaging angle of the set number of angles by processing based on a program loaded in the main storage device 19. Output to the device 15. These X-ray data are input from the imaging processing arithmetic device 10 to the reconstruction arithmetic device 17 via the communication devices 9 and 16 and stored in the storage device 18. When the X-ray data of each imaging angle with respect to the set number of angles is input based on the above program, that is, when the X-ray imaging is completed, the imaging processing arithmetic device 10 starts the reconstruction processing device 15. Outputs a command. The imaging processing arithmetic device 10 also outputs an X-ray imaging end signal to the movement amount calculation device 22.

  Next, CT image information is created by reconstruction processing (step 69). When a reconstruction processing start command is input, the reconstruction calculation device 17 uses the reconstruction processing program stored in the main storage device 19 and uses these X-ray data to obtain a CT image (hereinafter referred to as a first CT). Reconstruct information (called images). Reconstruction of the first CT image information (first tomographic image information) requires X-ray data for a number of imaging angles. In general, it is said that X-ray data in a range of 180 degrees is required for every 1 degree. For this reason, the determination in the above-described step 67 is performed, and when the result is “Yes”, X-ray data for a large number of imaging angles is input to the reconstruction calculation device 17. The reconstruction calculation device 17 outputs the first CT image information to the imaging console 7 when the reconstruction process is completed.

  In this embodiment, at least the processes of steps 64 to 66 are executed in parallel with the processes of steps 69 and 70. X-ray image information is created (step 64). The imaging processing arithmetic device 10 creates X-ray image information using the X-ray data every time X-ray data for each imaging angle is input. That is, the imaging processing arithmetic device 10 creates X-ray image information from the X-ray data input when the determination processing in step 67 is executed using an image conversion program loaded in advance in the main storage device 12. To do. This X-ray image information is created according to the DICOM format, which is a standard data format in radiology. The created X-ray image information is stored in the storage device 11. The X-ray image information is output to the movement amount calculation device (step 65). Each time X-ray image information for one imaging angle is created, the imaging processing calculation device 10 outputs the X-ray image information read from the storage device 11 to the movement amount calculation device 22 via the communication device 9. The process of whether the X-ray image information is transmitted for each image or collectively is executed by the imaging processing arithmetic device 10 based on operator input information from the input device 13.

  The amount of bed movement is calculated (step 66). The movement amount calculation device 22 is a treatment planning device (not shown) based on information of a treatment planning CT image (hereinafter referred to as a second CT image) stored in a data server (not shown) connected via a network. The information of the DRR image (or the second CT image) generated in (1) is input. The movement amount calculation device 25 of the movement amount calculation device 22 has the DRR image information (or the second CT image information (second tomographic image information)) generated based on the X-ray image information and the second CT image information (second tomographic image information) input in step 65 (or The amount of movement of the top board 39, that is, the amount of movement of the bed is calculated using the second CT image information). Details of the calculation of the bed movement amount will be described later. The operator can specify which of the DRR image information and the second CT image information is used for calculating the bed movement amount from the input device 28 before starting the calculation.

  A specific method for calculating the bed movement amount in step 66 executed by the movement amount calculation device 22 will be described below. The movement amount calculation device 25 reads the second CT image information and one or more pieces of DRR image information generated based on the second CT image information from the data server through the communication device 24, and the main storage device 27 (or the storage device 26). To remember. The movement amount calculation device 25 cannot start calculating the bed movement amount unless the X-ray image information transmission end information is input from the imaging console 7 from the imaging console 7.

  When the initial setting value regarding the image information used for the movement amount calculation by the movement amount calculation device 22 is the second CT image information, or when the operator selects to use the second CT image information for calculating the bed movement amount from the input device 28 First, I will explain. The movement amount calculation device 25 of the movement amount calculation device 22 uses the second CT image information and the DRR image creation program loaded in the main storage device 27 and uses, for example, a high-speed DRR image generation method described in Non-Patent Document 3. Create DRR image information. The method described in Non-Patent Document 3 creates DRR image information using a texture mapping function of graphics hardware. By using this method, a high-speed DRR image can be created.

  For example, the second CT image is coordinate-converted in increments of 0.5 degrees or 1 degree within a range of several degrees (2 to 3 degrees) with respect to the rotation angle of the rotating gantry 32 at a certain angle. The second CT image is translated within a range of several millimeters (2 to 3 millimeters). A combination of a rotation angle and an angle changed in a range of several degrees with respect to a certain rotation angle and a parallel movement amount is set as one parameter (a set of variables). By increasing the rotation angle of the rotating gantry 32 in increments of 1 degree, a set of DRR image information for a combination (change parameter) of the rotation angle and the angle and parallel movement amount changed within a range of several degrees with respect to a certain rotation angle Generate. By such processing, a plurality of pieces of DRR image information with different rotation angles are generated. The DRR image information corresponds to a plurality of pieces of X-ray image information obtained as a result of imaging while rotating the rotating gantry 32. These DRR image information is called a set of DRR image information. By changing the change parameter, a plurality of sets of DRR image information are created. Since the parameters used to create the plurality of sets of DRR image information are known, each DRR image information (a set of DRR image information and DRR image information in the set), and each angle and A change parameter for the amount of translation can be associated. These change parameters represent the movement amount of the second CT image information and the movement amount of the bed. In order to quickly search for the change parameter from the DRR image information, the DRR image information and the information of the change parameter used when creating the same are stored in the main storage device 27 (or the storage device 26) of the movement amount calculation device 22. It is stored in association. The number of DRR image information used for calculating the movement amount of the bed (that is, the step width of the angle and the width of the parallel movement amount) can be changed. For example, more DRR image information can be used, or the number of DRR image information to be compared can be limited to only four. If there is one or more pieces of DRR image information, the amount of bed movement can be calculated.

  The movement amount calculation device 25 obtains the DRR image information that most closely matches the X-ray image information by comparing the created DRR image information with the X-ray image information input from the imaging console 7. The movement amount calculation device 25 acquires the change parameter information for the most consistent DRR image information from the main storage device 27, and how far the irradiation center point 49 is from the irradiation target position based on the acquired change parameter. Ask for. The amount of bed movement in the X-axis direction, the Y-axis direction, and the Z-axis direction necessary to eliminate the difference in the distance between the position of the irradiation target and the irradiation center point 49 can be obtained. The comparison between the DRR image information and the X-ray image information is performed using a mutual information maximization method described in the well-known Non-Patent Document 4. The mutual information maximization method is a method for obtaining the similarity between two images. In this embodiment, the degree of similarity between the DRR image information and the X-ray image information is calculated, and the DRR image information with the highest degree of similarity is set as the most consistent DRR image information.

  An example has been described in which the movement amount calculation device 22 creates DRR image information and compares it with X-ray image information. However, a plurality of DRR image information for a plurality of angles and a plurality of parallel movement amounts created in advance using the second CT image information by an apparatus other than the movement amount calculation apparatus 22 is taken into the movement amount calculation apparatus 22 and It is also possible to calculate the movement amount. This is because the operator inputs a command signal from the input device 28 to the movement amount calculation device 25, and the movement amount calculation device 25 inputs the DRR image information and the X-ray image information created by the imaging processing calculation device 10. Made possible. Creation of DRR image information other than the movement amount calculation device 22 is generally performed using a method described in Non-Patent Document 3 and a method applying the ray tracing method.

  The information of the first CT image is output to the movement amount calculation device (step 71). The movement amount calculation device 25 of the movement amount calculation device 22 uses the first CT image information from the reconstruction processing device 15 via the imaging console 7 after the movement amount is calculated in step 66 (or the movement amount). During calculation) and stored in the main storage device 27 (or storage device 26). The movement amount calculation device 25 performs coordinate conversion of the first CT image information using the calculated movement amount of the bed. For this coordinate conversion, for example, rigid body conversion considering only parallel movement and rotational movement is used.

  Thereafter, the bed movement amount, the first CT image information (hereinafter referred to as corrected CT image information) on which the coordinate conversion has been performed, and the second CT image information are output to the display device (step 72). The movement amount calculation device 25 causes the display device 29 to display the calculated bed movement amount, the corrected CT image information, and the second CT image information input from the data server and stored in the main storage device 27. The operator can determine whether or not the calculated movement amount is appropriate while comparing the two displayed image information. At this time, it is possible to confirm an organ position that is difficult to discriminate with the conventional X-ray image information. Determination information for the calculated movement amount is input (step 73). The operator determines whether the calculated bed movement amount is appropriate by comparing the two displayed CT images. The movement amount calculation device 25 is input from the input device 28 by an operator (physician or radiographer), and “Yes” determination information when the bed movement amount is appropriate, and “No” when it is inappropriate. The determination information is input. The main storage device 27 (or storage device 26) of the movement amount calculation device 22 stores first CT image information, X-ray image information, and DRR image information. The operator determines whether the calculated movement amount of the bed is appropriate by observing the DRR image information, the X-ray image information, the first CT image information, and the second CT image information displayed on the display device 29. For this reason, the movement amount calculation device 22 has a function of switching display of these pieces of image information. Switching of image information to be displayed is performed by a display switching command from the input device 28, for example. There are two ways to display image information: when displaying DRR image information and X-ray image information, and when displaying first CT image information and second CT image information. Since CT image information is generally a set of a large number of pieces of tomographic image information, when displaying each one (called a slice), volume rendering or surface rendering is used as three-dimensional image information. May be displayed.

  If the determination information is “Yes”, the amount of bed movement is output to the bed controller (step 75). The bed movement amount includes movement amounts in the X-axis direction, the Y-axis direction, and the Z-axis direction. The bed control device 30 that receives the bed movement amount from the movement amount calculation device 22 controls the first, second, and third drive devices based on the bed movement amount, and moves the top board 39. As a result, the irradiation target is accurately positioned at the irradiation center point 49. If the determination information is “No”, the amount of bed movement is recalculated (step 74). The movement amount calculation device 25 calculates the bed movement amount based on the first CT image information and the second CT image information. The recalculation is performed by applying the mutual information maximization method described above to the CT image. After the process of step 74, the first CT image information, the second CT image information, and the bed movement amount calculated in step 74 are output to the display device 29 in step 72. When the determination information “Yes” is input in step 73, step 75 is executed. With the above processing, positioning of the top board 39, that is, the bed 38 is completed.

  After the positioning of the bed is completed, the gantry control device 44 performs the X-ray source generation device 36 and the first rotation based on the drive commands of the X-ray source generation device 36 and the first rotation mechanism input from the gantry console 45. The rotation mechanism is driven. The rotary gantry 32 is rotated by driving the first rotating mechanism, and the arm portion 33 is swung around the patient lying on the top board 39. Based on a control command from the gantry control device 44, the X-ray source generator 36 irradiates the patient's affected area with X-rays having a predetermined energy when the rotation angles are set. In this way, the affected area of cancer is irradiated with X-rays.

  In this embodiment, the imaging console 7, that is, the imaging processing arithmetic device 10 creates X-ray image information using X-ray data in parallel with the reconstruction processing of the first CT image information in the reconstruction arithmetic device 17. And transmitted to the movement amount calculation device 22. The format (data format) of the X-ray image information and the first CT image information input to the movement amount calculation device 22 is a dicom format. Other formats such as JPEG images and bitmap images may be used.

  In this embodiment, the creation of X-ray image information by the imaging processing arithmetic device (X-ray image information creation device) 10 is performed in parallel with the creation of the first CT image information by the reconstruction processing device 15. Is completed before that of the first CT image information. As a result, in this embodiment, as shown in FIG. 6A, in parallel with the creation of the first CT image information by the reconstruction processing in the reconstruction calculation device 17, the movement amount calculation device 22 converts the X-ray image information. The amount of movement of the bed used can be calculated. Therefore, this embodiment can significantly reduce the time required for the positioning of the bed 38 after the patient lies on the top board 39. This effect obtained in the present embodiment is more apparent when compared with the conventional bed positioning method shown in FIG. Conventionally, as shown in FIG. 6B, after the reconstruction process for obtaining the first CT image information is completed, the movement amount calculation apparatus inputs the first CT image information, and the bed is based on the first CT image information. The amount of movement was calculated. In this embodiment, since the input of the X-ray image information and the calculation of the movement amount of the bed in the movement amount calculation device 22 are performed in parallel with the creation of the first CT image information by the reconstruction process, the time required until the bed 38 is positioned. Is shortened. Specifically, in this embodiment, the creation of X-ray image information based on the X-ray detection signal from the radiation detector is performed in parallel with the reconstruction process of the first CT image, so that the amount of movement of the bed The calculation can be performed in parallel with the reconstruction process. The significant reduction in the time required for positioning leads to a significant reduction in the time required for patient treatment. According to this embodiment, the number of patients that can be treated per X-ray treatment system per year can be significantly increased. it can.

  In the present embodiment, since the first CT image information is corrected using the calculated amount of movement of the bed, specifically, the coordinate conversion of the first CT image information is performed based on the amount of movement. The first CT image information in a state after moving the bed (specifically, the top board 39) based on the moving amount can be obtained in advance. Therefore, the doctor or the radiologist can accurately and accurately confirm the position of the affected area after moving the bed by viewing the corrected first CT image information.

  In the present embodiment, the corrected first CT image information and the second CT image information are displayed on the display device 29. Therefore, the doctor or the radiographer uses the position of the affected part after the bed movement in the second CT image information used for the treatment plan. It can be easily compared with the position of the affected area. For this reason, it is possible to appropriately determine whether the calculated bed movement amount is appropriate, and it is possible to perform positioning of the bed with higher accuracy.

  If the doctor or radiologist determines “No” for the calculated bed movement amount, the bed movement amount can be calculated using the first CT image information and the second CT image information. A good bed positioning can be performed.

  The imaging console 7, the reconstruction processing device 15, and the movement amount calculation device 22 in this embodiment may be configured with a single computer. The X-ray source 4 and the X-ray receiver 5 are not installed on the rotating gantry 32 but can be installed independently while being separated from the rotating gantry 32.

  A bed positioning system according to embodiment 2, which is another embodiment of the present invention, will be described with reference to FIG. The hardware configuration of the bed positioning system of the present embodiment is the same as the hardware configuration of the bed positioning system of the first embodiment. The bed positioning system of the present embodiment executes the processing procedure shown in FIG. This processing procedure is obtained by changing the processing of step 72 to the processing of step 72A except the processing of step 72 in the processing procedure shown in FIG. 5 executed by the bed positioning system 2 of the first embodiment. The X-ray therapy system to which the bed positioning system of the present embodiment is applied does not perform the process of step 72 in the X-ray therapy system 1 of the first embodiment, but performs the process of step 72A instead of the process of step 72. It is only different in point.

  In step 72A, the bed movement amount calculated in step 66 and the first CT image information and the second CT image information created in the reconstruction process in step 69 are displayed on the display device 29. In step 73, determination information of the doctor or radiologist who has seen this display information is input. The remaining steps shown in FIG. 7 are the same as those in the first embodiment. The present embodiment is suitable when the number of set angles is small and the number of X-ray data acquired for each imaging angle is small, for example, when the range of angle and angle range is limited to 30 degrees or the like. Such an X-ray imaging method is known as digital tomosynthesis (see Non-Patent Document 5).

  The present embodiment can obtain the other effects produced in the first embodiment, except for the effects obtained by correcting the first CT image information using the calculated bed movement amount.

  A bed positioning system applied to a proton beam therapy system (particle beam therapy system) which is a radiation therapy system will be described. First, a schematic configuration of the proton beam treatment system will be described with reference to FIGS. 8 and 9.

  The proton beam treatment system 80 includes a beam generator 82, a rotating gantry 95 (see FIG. 9), a beam irradiation device (irradiation device) 87, a bed 88, and the bed positioning system 2. The proton beam treatment system 80 is a cancer treatment device. The beam generator 82 includes an ion source (not shown), a pre-accelerator 81, and a synchrotron 83. Ions (for example, positive ions or carbon ions) generated in the ion source are accelerated by the pre-accelerator 81. This ion beam (for example, proton beam) is incident on the synchrotron 83 from the front stage accelerator 81. The ion beam is accelerated by the synchrotron 83, raised to the set energy, and then emitted from the extraction deflector 84.

  The ion beam emitted from the synchrotron 83 reaches the beam irradiation device 87 which is a device for irradiating the patient with the ion beam through the beam transport system 85. The beam irradiation device 87 and the inverted U-shaped beam transport device 86 which is a part of the beam transport system 85 are installed in the rotating gantry 95 and rotate together with the rotating gantry 95. The ion beam is applied to the affected area of the patient 101 lying on the top plate 89 of the bed 88 from the beam irradiation device 87 through the beam transport device 86.

  As shown in FIG. 9, the rotating gantry 95 includes a cylindrical rotating drum (rotating body) 96 having a front ring 97 and a rear ring 100. A front ring 97 provided at one end of the rotating drum 96 is supported by a plurality of rotatable support rollers 98A. The support roller 98A is attached to a support device 99A installed on the building foundation. The rear ring 100 provided at the other end of the rotary drum 96 is also supported by a plurality of support rollers 98B attached to the support device 99B. A motor 108 is coupled to one of the plurality of support rollers 18B. The rotation angle of the rotating gantry 95 is measured by an angle detector 109 connected to one rotating shaft of the plurality of support rollers 98A. An irradiation chamber 106 for particle beam therapy is provided in the rotary drum 96.

  The bed 88 includes a treatment table 90 and a top plate 89. Further, the bed 88 includes an X-axis direction drive mechanism 91, a Y-axis direction drive mechanism 93, a Z-axis direction drive mechanism 92, and a rotation drive mechanism 94. The X-axis direction drive mechanism 91 is installed on the building foundation. The Z-axis direction drive mechanism 92 is installed on the X-axis direction drive mechanism 91, and the Y-axis direction drive mechanism 93 is installed on the Z-axis direction drive mechanism 92. The top plate 89 is installed on a rotation drive mechanism 94 installed on the Y-axis direction drive mechanism 93. The Y-axis direction coincides with the direction in which the rotation axis of the rotating gantry 95 extends. The X-axis direction is a direction perpendicular to the Y-axis direction in the horizontal direction. The Z-axis direction is the vertical direction. The top plate 89 is inserted into the irradiation chamber 106 for particle beam therapy in the rotary drum 96.

  The X-ray source (X-ray source device) 4 of the bed positioning system 2 is installed in the beam irradiation device 87 and is movable in a direction orthogonal to the beam path in the beam irradiation device 87. That is, the X-ray source 4 moves between a first position on the central axis of the beam path and a second position away from the beam path. The X-ray receiver 5 of the bed positioning system 2 is disposed in the irradiation chamber 106 and attached to the receiver moving device 104. The receiver moving device 104 passes through the partition wall 107 of the irradiation chamber 106, and one end thereof is installed on one surface of the guide member 105 attached to the support member 110. The X-ray receiver 5 is disposed so as to face the X-ray source 4 with the rotation axis of the rotary cylinder 12 interposed therebetween when positioned on the extension line of the beam path. The X-ray source 4 can also be installed on the outer surface of the beam irradiation device 87. As long as the X-ray source 4 is arranged in the irradiation device 106, it may be installed not in the beam irradiation device 87 but in the rotating drum 96.

  A bed positioning method in the proton beam therapy system 80 will be described below. Also in this method, the processing procedure shown in FIG. 5 performed in the first embodiment is executed. In particular, steps 61 and 62 different from the first embodiment will be described. In step 61, the top plate 89 is moved to a predetermined position in the treatment room 106 by driving the X-axis direction drive mechanism 91, the Y-axis direction drive mechanism 93, the Z-axis direction drive mechanism 92, and the rotation drive mechanism 94. In this movement, an operator (for example, a radiographer) in the irradiation chamber 106 displays an approximate treatment target position of the patient 14 (a position of an affected part to which an ion beam is irradiated) on a pendant (not shown) display device (not shown). ) Based on the treatment plan information displayed in (). Based on the treatment plan information, the operator inputs a bed movement command to the bed control device 30 using a pendant input device held in the hand. The bed control device 62 controls each of the drive mechanisms described above based on the movement command. By these driving operations, the affected part of the patient 101 is positioned in the vicinity of the irradiation center point 49 on the rotation axis of the rotating gantry 95 in the vicinity of the extension of the beam path in the beam irradiation device 87. The pendant is also connected to the receiver moving device 104 and the X-ray source 4.

  In step 61, the receiver 5 is also moved. Based on the control command from the pendant, the receiver moving device 104 is driven, and the X-ray receiver 5 is positioned on the extension line of the beam path. A control command from the pendant is also input to the X-ray source 4. The X-ray source 4 is moved from the second position to the first position.

  In step 62, the gantry control device 44 drives the motor 108 based on the rotation command input from the gantry console 45. The rotating gantry 95 rotates around the rotation axis. The imaging control device 6 causes the X-ray source 4 to irradiate the irradiation target in a pulsed manner from the X-ray source 4 when the rotation angle of the rotation gantry 95 reaches the respective imaging angles set in advance. This X-ray passes through the patient 101 and is detected by the X-ray receiver 5.

  Thereafter, the processes of steps 63 to 75 are sequentially performed. The bed control device 30 controls the above moving mechanisms and positions the bed 88 based on the amount of bed movement when the determination information input in step 73 is “Yes”.

  After the positioning of the bed 88 is completed, the ion beam emitted from the synchrotron 83 reaches the beam irradiation device 87 through the beam transport system 85. The beam path of the beam irradiation device 87 is set in advance so as to face a predetermined angle with respect to the affected part of the patient 101 by the rotation of the rotating gantry 95. The ion beam is irradiated to the affected part of the patient 101 on the top plate 89 through the beam path in the beam irradiation apparatus 87.

  In the present embodiment, the effects produced in the first embodiment can be obtained.

  In the bed positioning system 2 of the proton beam treatment system 80, the processing procedure shown in FIG. 7 can be used instead of the processing procedure shown in FIG. However, the processing of steps 61 and 62 is the same as the processing contents of those steps in the third embodiment.

1 is a configuration diagram of an X-ray treatment system to which a bed positioning system according to a first embodiment which is a preferred embodiment of the present invention is applied. FIG. It is a front view of the treatment apparatus shown in FIG. It is explanatory drawing which shows the structure of each subsystem contained in the X-ray therapy system shown in FIG. FIG. 2 is a detailed configuration diagram of each of an imaging console, a reconstruction processing device, and a movement amount calculation device illustrated in FIG. 1. It is explanatory drawing which shows the procedure of the bed positioning method performed with the bed positioning system in Example 1. FIG. It is explanatory drawing which shows the effect in Example 1. FIG. It is explanatory drawing which shows the procedure of the bed positioning method performed with the bed positioning system of Example 2 which is another Example of this invention. It is a block diagram of the proton beam treatment system to which the bed positioning system of Example 1 which is one preferred embodiment of the present invention is applied. It is a detailed block diagram in the rotation gantry of the proton beam therapy system shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... X-ray therapy system, 2 ... Bed positioning system, 3 ... X-ray imaging system, 4 ... X-ray source, 5 ... X-ray receiver, 6 ... Imaging control apparatus, 7 ... Imaging console, 10 ... Imaging process calculation Device ... 14, 29 ... Display device, 15 ... Reconstruction processing device, 17 ... Reconfiguration arithmetic device, 20 ... Positioning device, 22 ... Movement amount calculation device, 25 ... Movement amount arithmetic device, 30 ... Bed control device, 31 ... Treatment device, 32, 95 ... Rotating gantry, 35 ... Irradiation head, 36 ... X-ray generator, 38, 88 ... Bed, 39, 89 ... Top plate, 40, 90 ... Treatment table, 80 ... Proton treatment system, 82 DESCRIPTION OF SYMBOLS ... Beam generator, 83 ... Synchrotron, 85 ... Beam transport system, 87 ... Beam irradiation apparatus, 96 ... Rotary drum, 97 ... Front ring, 100 ... Rear ring, 106 ... Irradiation chamber.

Claims (10)

An X-ray source device that emits X-rays, an X-ray incident device that emits X-rays and outputs X-ray information corresponding to the X-rays, and X-ray image information based on the input X-ray information. A first image information creation device to create, and a second image information creation to create first tomographic image information using the X-ray information in parallel with the creation of the X-ray image information in the first image information creation device a device, a display device, obtains a bed movement amount based on the second tomographic image information used in the treatment planning and the X-ray image information, and correct the first tomographic image information on the basis of the bed moving amount, the bed Based on the bed movement amount when the bed movement amount is appropriate, and a bed movement amount calculation device that outputs the corrected first tomographic image information and the second tomographic image information to the display device. The bed drive that supports the irradiation target Couch positioning system characterized by comprising a couch controller for controlling. A tomographic image creation command device that inputs the X-ray information and outputs a creation start command of the first tomographic image information to the second image information creation device;
The second image information creation device, after inputting the creation start command , creates the first tomographic image information in parallel with the creation of the X-ray image information in the first image information creation device. The bed positioning system according to 1. The bed movement amount calculation device obtains the bed movement amount again based on the first tomographic image information and the second tomographic image information when the information indicating that the bed movement amount is inappropriate is input,
The bed positioning system according to claim 1 or 2, wherein the bed control device controls the driving device based on the bed movement amount obtained again . A bed for supporting an irradiation target; a rotating gantry; a radiation generator installed in the rotating gantry for emitting radiation; an irradiation device provided in the rotating gantry for irradiating the irradiation target; and X-rays X-ray source device that emits X-rays, an X-ray incidence device that inputs X-rays and outputs X-ray information corresponding to the X-rays, and generates X-ray image information based on the input X-ray information A first image information creation device; and a second image information creation device that creates first tomographic image information using the X-ray information in parallel with the creation of the X-ray image information in the first image information creation device; The bed movement amount is obtained based on the display device, the X-ray image information and the second tomographic image information used for the treatment plan, the first tomographic image information is corrected based on the bed movement amount, and the bed movement amount. The modified A bed movement amount calculation device that outputs the first tomographic image information and the second tomographic image information to the display device, and supports an irradiation target based on the bed movement amount when the bed movement amount is appropriate. A radiation therapy system comprising a bed control device for controlling a bed driving device . The radiotherapy system according to claim 4, wherein the X-ray source device and the X-ray incidence device are provided on the rotating gantry so as to face each other . A tomographic image creation command device that inputs the X-ray information and outputs a creation start command of the first tomographic image information to the second image information creation device;
The second image information creation device, after inputting the creation start command, creates the first tomographic image information in parallel with the creation of the X-ray image information in the first image information creation device. The radiation therapy system of Claim 6 or Claim 7 . The bed movement amount calculation device obtains the bed movement amount again based on the first tomographic image information and the second tomographic image information when the information indicating that the bed movement amount is inappropriate is input,
The radiotherapy system according to any one of claims 4 to 6 , wherein the bed control device controls the driving device based on the bed movement amount obtained again . An ion beam generating device that generates an ion beam, a rotating gantry, an irradiation device that is installed in the rotating gantry and irradiates the irradiation target with the ion beam, a bed that supports the irradiation target, and a rotating gantry An X-ray source device that emits X-rays, an X-ray incidence device that is provided in the rotating gantry and that receives the X-rays and outputs X-ray information corresponding to the X-rays, and the input X-ray information A first image information creating apparatus for creating X-ray image information based on the first tomographic image information using the X-ray information in parallel with the creation of the X-ray image information in the first image information creating apparatus A second image information creation device for creating the image, a display device, a bed movement amount based on the X-ray image information and the second tomographic image information used for the treatment plan, and the first disconnection based on the bed movement amount. A bed movement amount calculation device that corrects image information and outputs the bed movement amount, the corrected first tomographic image information, and the second tomographic image information to the display device, and the bed movement amount are appropriate. A particle beam therapy system comprising: a bed control device that controls a bed drive device that supports an irradiation object based on the bed movement amount . A tomographic image creation command device that inputs the X-ray information and outputs a creation start command of the first tomographic image information to the second image information creation device;
The second image information creation device, after inputting the creation start command, creates the first tomographic image information in parallel with the creation of the X-ray image information in the first image information creation device. 8. The particle beam therapy system according to 8 . The bed movement amount calculation device obtains the bed movement amount again based on the first tomographic image information and the second tomographic image information when the information indicating that the bed movement amount is inappropriate is input,
The particle beam therapy system according to claim 8 or 9 , wherein the bed control device controls the driving device based on the bed movement amount obtained again .

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