JP2011072457A - Radiotherapy system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance positioning accuracy using soft tissue information such as organs in positioning a radiotherapy bed. <P>SOLUTION: The radiotherapy system is equipped with a bed for putting a subject on the same, a bed positioning unit for positioning the bed in radiotherapy, and an X-ray imaging unit having an X-ray generating unit for generating X-ray and an X-ray receiver receiving the X-ray from the X-ray generating unit. The bed positioning unit generates bed positioning data based on the first X-ray transparent image data imaged in the X-ray imaging unit and soft tissue transparent data generated from X-ray CT image data obtained when planning treatment, thereby the problem can be solved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a radiotherapy system for treating an affected area by irradiation with various types of radiation such as X-rays or particle beams (charged particle beams such as proton beams and heavy particle beams), and in particular, a bed positioning system for radiotherapy. A radiation therapy system comprising:

  In recent years, radiation therapy aiming at necrosis of tumor cells by irradiating various types of radiation has been widely performed. As the radiation used, treatment using not only the most widely used X-ray but also a particle beam such as a proton beam is performed.

  One important process of radiation therapy is bed positioning. Bed positioning is generally a DRR (Digital Reconstructed Radiograph) image output from a treatment planning device and an X-ray imaging device before radiation irradiation, and the patient is laid on a treatment bed (hereinafter abbreviated as a bed). By comparing an X-ray image (DR image, Digital Radiograph image) taken in a state with an engineer or doctor, the difference between the position of the irradiation target determined in the treatment plan and the position of the irradiation target on the current bed is calculated. In this process, the amount of movement of the bed is determined so that the two types of images match, and the bed is moved.

  The DRR image is a two-dimensional image that simulates an X-ray image, and is generated from a CT image that is a three-dimensional image taken during treatment planning. In the bed positioning, an image captured using an X-ray simulator or the like may be used as a reference image instead of the DRR image.

  The above method is widely used in bed positioning. In bed positioning using DR and DRR images (hereinafter referred to as DR-DRR bed positioning), it is possible to accurately detect 3 degrees of freedom of translation and 2 degrees of freedom of rotation (in-plane rotation) about the imaging direction. It is known that it is difficult to automatically detect rotation around the axis (rotation outside the plane) perpendicular to the imaging direction (Non-Patent Document 1), and it is difficult to realize more accurate bed alignment.

  A method using CT images and DR images in a bed positioning system (hereinafter referred to as CT-DR bed positioning) is known as a positioning method capable of automatically detecting six degrees of freedom with the same equipment as conventional DR-DRR bed positioning. (Non-Patent Document 2). In DR-DRR bed positioning, the pixel values of the DRR image generated only at the treatment plan position and the DR image are compared to calculate the movement amount, whereas in CT-DR bed positioning, the treatment plan CT image is displayed at various angles. The movement amount is calculated by creating a DRR image and comparing the pixel value with the DR image. Since it is possible to create an omnidirectional DRR image from the treatment plan CT image, 6 degrees of freedom can be detected.

J. Hanley, et al. “The Effects Of Out-Of-Plane Rotations On Two On Two Dimensional Portal Image Registration In Conformal Radiotherapy Of Prostate”, Int. J. Radiat. Oncol. Biol. Phys. 33 (5), 1331 -43, 1995. J. Kim et al., "Effects of x-ray and CT image enhancements on the robustness and accuracy of a rigid 3D / 2D image registration", Med. Phys. 32 (4), April, 2005. : Shigeru Muraki et al. “Survey on Medical Application of 3D Image Analysis and Graphics Technology” IEICE Transactions D-II Vol. J97-D-II No.10 pp.1887-1920 2004. 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, 2005. Frederik Maes, et al., `` Multimodality image registration by maximization of mutual information '', IEEE Trans. Med. Image., Vol. 16, No. 2, 1997.

  Since X-ray images (DR images) and DRR images mainly show structures such as bones with a high X-ray absorption rate, when a tumor region is present in a soft tissue such as an organ, the tumor position is directly observed from the image. In some cases, the contour and area of the organ itself become unclear. This is because the X-ray image (DR image) is data obtained by projecting the three-dimensional structure of the human body onto a two-dimensional surface, and the X-ray absorption coefficient of soft tissue is lower than that of bone, and there is a difference in coefficient values between organs. Since it is small, it may be difficult to distinguish the boundary when a plurality of soft tissues overlap in the projection direction. For this reason, in bed positioning using an X-ray image (DR image), it is assumed that the positional relationship between a tumor region, that is, a soft tissue and a bone, does not change significantly, and bed positioning is performed. However, in reality, the position of the organ in the body changes slightly every day, so the organ position in the CT image at the time of treatment planning may not always match the organ position on the bed at the time of treatment.

  The bed positioning device using a DR image acquired by an orthogonal X-ray device and a DRR image in an arbitrary direction created from a CT image for treatment planning has the advantage of being able to detect six degrees of freedom of translation and rotation. Have.

  When this method is used, the DR image obtained from the X-ray imaging apparatus and the DRR image obtained from the CT image for treatment planning both clearly show structures such as bones with a high absorption rate, and borders of soft tissues such as affected areas and organs. Is unclear. Therefore, even if 6 degrees of freedom for bed positioning can be detected by comparing the pixel values of the DR image and the DRR image, the morphological information of the soft tissue is not sufficiently utilized, and the position of the soft tissue such as an organ is the same as that at the time of treatment planning The bed is positioned assuming that it will not change.

  On the other hand, recently, three-dimensional radiation therapy in which radiation is concentrated on a tumor region (affected site) while avoiding giving a dose to surrounding organs in the vicinity of the tumor region as much as possible has become popular. For example, IMRT (Intensity Modulated Radiation Therapy) or radiation therapy using particle beams. In these three-dimensional treatments, 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 such high-accuracy three-dimensional radiotherapy, it is necessary to avoid dose administration to normal tissues as much as possible.

  The problem to be solved by the present invention is that, in bed positioning using a DR image acquired by an X-ray imaging apparatus used in a radiotherapy apparatus and a treatment plan CT image, in addition to a conventional structure such as bone, soft tissue such as an organ This information is used to improve the bed positioning accuracy.

  The feature of the present invention that solves the above-described problems is that a bed on which a patient is placed, a bed positioning device that positions the bed in radiotherapy, an X-ray generator that generates X-rays, and an X-ray from the X-ray generator X-ray imaging apparatus having an X-ray receiver for receiving a line, and this bed positioning apparatus uses first X-ray fluoroscopic image data imaged by the X-ray imaging apparatus and an X-ray CT image acquired at the time of treatment planning The bed positioning data is generated based on the soft tissue projection image data generated from the data.

  According to the present invention, since bed positioning using bone or soft tissue is possible, bed positioning with higher accuracy is possible.

It is a block diagram (side surface) of the radiotherapy system for implementing this invention. In the treatment plan apparatus of a present Example, it is a flowchart figure which shows the flow until it extracts a soft tissue from an X-ray CT image. It is a flowchart figure which shows the flow of bed positioning of the radiotherapy system of a present Example. It is a figure which shows the outline | summary of soft tissue characteristic shape data preparation. It is a figure which shows arrangement | positioning on the monitor of the image for bed positioning. It is a figure which shows the outline | summary of the bed positioning using soft tissue characteristic shape data. It is a block diagram of the X-ray imaging system 115 of the radiotherapy system of an Example.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  As shown in FIG. 1, the radiotherapy system 1 according to the present embodiment includes a treatment planning apparatus 101, an image data server 110, an X-ray imaging system 115, a bed positioning apparatus 116, and a radiation irradiation system 127.

  The treatment planning apparatus 101 includes a monitor 102 that is a display device, an input unit 103, and a treatment plan calculation device 104. The treatment plan calculation device 104 is a calculation device for calculating a treatment plan prior to treatment by radiation irradiation. The monitor 102 displays the calculation result of the treatment plan calculation processing device 107. The input unit 103 is an input unit for giving an instruction to the treatment plan calculation device 107 through a user interface displayed on the monitor 102, and is generally a keyboard or a mouse. As a user interface, a graphical user interface (GUI) is often used. Further, the treatment plan calculation device 107 is connected to the network 126 for communication, the communication device 105 for communication, the storage result 106 for storing data such as calculation results and CT images, and the treatment plan program, and the calculation processing of the treatment plan program. And a treatment plan calculation processing device 107 for controlling the treatment plan device 101, and a treatment plan program stored in the storage device 106 and necessary for the processing when the treatment plan calculation processing device 107 calculates the treatment plan program. A main storage device 108 is provided for temporarily storing data.

  The image data server 110 is connected to the network 126 and controls the communication device 111 for exchanging data with other devices, the storage device 112 for storing data, and the internal devices of the image data server to control the data. For example, a data arithmetic processing device 113 that performs arithmetic operations such as compression of data capacity, and a main storage device 114 that temporarily stores processing programs used by the data arithmetic processing device 113 and processing target data are provided.

  The treatment plan calculation device 104 acquires a treatment plan CT image from the image data server 110 via the network 126 and uses the soft tissue extraction program stored in the storage device 106 and the main storage device 108 for the treatment plan. A soft tissue extraction processing unit 109 for extracting soft tissue from CT is provided.

  The bed positioning device 116 includes a monitor 117 which is a display device, an input unit 118, and a bed positioning calculation device 119. The bed positioning calculation device 119 is a calculation device for performing positioning calculation of the bed 128 in radiotherapy. The monitor 117 has a function of displaying a result calculated by the bed positioning calculation device 119 and a function of displaying a user interface. The input unit 118 is an input unit for inputting an instruction to the bed positioning calculation device 119 and the bed control device 125 through a user interface displayed on the monitor 117. As the input means 118, a keyboard, a mouse, or the like is used. Furthermore, the bed positioning calculation device 119 includes a communication device 120 for transmitting input data and calculation results, a storage device 121 for storing data and a bed positioning calculation program, and a bed positioning calculation process for executing bed positioning calculation. The apparatus 122 includes a main storage device 123 for temporarily storing an arithmetic program, input data, and the like for use in the bed positioning arithmetic processing unit 122. The bed positioning calculation device 119 includes a soft tissue feature shape creation calculation process 124 for acquiring a soft tissue extracted image from the image data server 110 via the network 126 and calculating a soft tissue feature shape. Details of the soft tissue feature shape creation processing will be described later.

  Although the bed control device 125 is shown in a simplified manner, the bed control device 125 is a control device for controlling the bed 128 on which an irradiation target for irradiating radiation is placed. The bed control device 125 has a function of receiving the movement amount (bed positioning data) of the bed 128 calculated by the bed positioning device 116 by calculation and sending a movement command to the drive mechanism included in the bed 128. Although the bed 128 and the bed control device 125 are not described in detail in this specification, they constitute part of the radiation irradiation system 127. The radiation irradiation system 127 includes an irradiation head (irradiation nozzle) 129 that emits radiation, a gantry 130 that includes and holds the irradiation head, a treatment device control unit 131 that controls the irradiation head 129 and the gantry 130, and a treatment device control unit. A treatment apparatus console 132 for giving an instruction to 131 is provided. The gantry 129 generally includes a rotation mechanism, and the rotation direction of the rotation gantry 129 can arbitrarily change the irradiation direction of the therapeutic radiation. Here, an X-ray imaging apparatus including an irradiation head 129 that emits therapeutic radiation, a bed 128 on which a patient is placed, an X-ray source 134, and an X-ray image receiving apparatus 135 is installed in the treatment irradiation room. .

  As shown in FIG. 7, the X-ray imaging system 115 includes an X-ray imaging apparatus and an X-ray imaging apparatus control console 133. The X-ray imaging apparatus includes an X-ray generator (X-ray source) 134 and an X-ray image receiver 135 disposed at a position facing the X-ray source 134. The bed 128 is located between the X-ray source 134 and the X-ray image receiver 135, and the irradiation target exists on the bed. The X-ray imaging apparatus is used for imaging an irradiation target on the bed 128. Further, the X-ray image receiving apparatus 135 uses a flat panel detector, an image intensifier, or the like. The X-ray imaging apparatus control console 133 has a function for setting imaging conditions necessary for imaging, such as the voltage of the X-ray source 134 and imaging time, for the imaging, and the X-ray imaging apparatus. It has a function of transmitting to the photographing apparatus control unit 136. The X-ray imaging apparatus control unit 136 transmits the received instruction from the console to the X-ray source 134 and the image receiving apparatus 135. Further, it has a function of receiving an X-ray image captured by the X-ray image capturing apparatus from the X-ray image capturing apparatus and transmitting it to the image data server 110.

  The treatment planning apparatus 101, the image data server 110, the bed positioning apparatus 116, the X-ray imaging system 115, and the bed control apparatus 125 are connected via a network 126, and can transmit and receive data via the network.

  The flow of the bed positioning process in the system shown in FIG. 1 will be described with reference to FIGS. The image data is generated by the treatment planning apparatus 101 and the X-ray imaging system 115, stored in the image data server 110, and used by the bed positioning apparatus 116. Below, the flow of a bed positioning process is demonstrated in detail.

  First, the treatment planning apparatus 101 reads X-ray CT image data acquired prior to treatment for treatment planning from the image data server 110 via the network 125 (step 201), and stores the X-ray CT image in a storage device. 106 and the main storage device 108 (step 202). The treatment planning apparatus 101 has a function of setting which region to irradiate the irradiation target. This is called irradiation region setting, and the set region is called an irradiation region. In addition, the treatment planning apparatus 101 has a function (irradiation planning function) for calculating from which direction and how to irradiate radiation to a set irradiation region based on an instruction from the operator. In this way, the treatment planning apparatus 101 makes a treatment plan (step 203). This is the general treatment planning procedure.

  The treatment planning apparatus 10 of the present embodiment includes a soft tissue extraction calculation processing device 109. When this soft tissue extraction calculation processing device 109 reads (receives) an X-ray CT image (treatment plan CT image) stored in the main storage device 108, it is used as a bed positioning target based on this treatment plan CT image. A target soft tissue (organ) is extracted (step 204). Examples of the soft tissue automatic extraction method include the Region Growing method described in Non-Patent Document 4 and a method using a shape model. The soft tissue extraction calculation processing device 109 outputs the extraction result to the monitor 117. On the monitor 117, the target soft tissue is displayed as a fill or polygon. Based on the display of the target soft tissue displayed on the monitor 117, a medical worker (such as a doctor or a diagnostic radiographer) determines whether the soft tissue region is correct (step 205). When it is determined that the extraction accuracy is sufficient, the medical worker inputs an extraction completion signal from the input unit 118. When the extraction completion signal is input, the bed positioning calculation device 119 transmits this extracted soft tissue image to the image data server 110 (step 206). If it is determined that the extraction accuracy is insufficient, the medical staff inputs an extraction start signal from the input means 118. The soft tissue extraction calculation processing device 109 that has received this extraction start signal executes the soft tissue extraction process again. Instead of inputting this extraction start signal, the medical staff can also make corrections manually via the user interface. Further, instead of the soft tissue extraction process performed again by the soft tissue extraction calculation processing device 109, a medical worker can perform a series of soft tissue extraction processes using the input unit 118. All the organ extraction processes may be performed manually using the input means 118, such as filling the target soft tissue or specifying the polygon shape to extract the region. The image data server 109 stores the received extracted soft tissue image in the storage device 112 (step 206).

  In the radiation therapy, it is necessary to match the irradiation target set to the tumor in the patient with the irradiation center point before the irradiation target is irradiated with the radiation, and the bed positioning is performed in order to match them. The bed positioning apparatus and method provided by this embodiment will be described.

  The bed positioning flow provided by this embodiment is shown in FIG. 3 and will be described along this flow. After the irradiation target is placed on the bed 127, the medical staff first moves the bed using an optical device such as a laser marker so that the irradiation target is close to the irradiation center point (step 301). In step 301, the bed may be moved by eye measurement using a marker such as a sticker or a cross line attached or drawn on the irradiation target without using an optical device.

  Next, in the X-ray imaging system 115, X-ray emission from the X-ray source 134 is started in order to take an X-ray fluoroscopic image of the patient fixed to the bed 128 for radiation irradiation. X-rays emitted from an X-ray source 134 installed in the treatment room pass through the patient and are received by the X-ray image receiving device 135. The X-ray image receiving apparatus 135 transmits the obtained X-ray data to the X-ray imaging apparatus console 133 (step 302).

  X-ray data is converted into DR image data at the X-ray imaging apparatus console 133 (step 303), and the converted DR image data is transmitted to the image data server 110. The image data server 110 that has received the DR image data from the X-ray imaging system 115 stores the DR image data in the storage device 112. Here, it is assumed that the DR image data is in a DICOM format generally used in the field of the bed positioning device 116.

  Further, the generated image data is transmitted from the X-ray imaging apparatus console 133 via the network 126 to the communication device 120 of the positioning operation device 119 (step 304). In the positioning arithmetic unit 119, when the image data is received by the communication device (step 305), the program that constantly monitors the arrival of the data loaded in the main storage device 108 takes in the image data into the main storage device 108. It is executed and further stored in the storage device 106.

  The positioning calculation performed by the bed positioning device 116 will be described. An operator (healthcare professional) who operates the bed positioning device 116 positions the CT image data used in the treatment plan from the data server and one or more DRR images generated from the CT image data used in the treatment plan in advance. Are stored in the main storage device 123 or the storage device 121 (step 306). Further, the positioning calculation cannot be started unless the DR image transmission end notification is notified from the X-ray imaging apparatus console 133 to the positioning apparatus 116.

  The bed positioning calculation device 119 of the bed positioning device 116 uses the CT image data and program loaded in the main storage device 128 and uses, for example, a high-speed DRR image generation method as described in Non-Patent Document 4 to perform positioning calculation processing. An operation is performed by the device 122 to generate an omnidirectional DRR image. The technique of Non-Patent Document 4 generates a DRR image by using a texture mapping function of graphics hardware. By using this method, a high-speed DRR image can be generated.

  For example, in a treatment plan CT image, the CT image is rotated by 0.5 degrees or 1 degree in all directions, and the CT image is translated within a range of several millimeters (2 to 3 millimeters). And A set of DRR images corresponding to the same parameter is generated by increasing the gantry angle by 1 degree (step 307). A plurality of DRR images having different gantry angles with the same parameters are generated. Since the parameters used to generate the plurality of DRR images are known, each DRR image (a set of DRR images and a DRR image in the set) is associated with parameters related to each angle and parallel movement amount when the DRR images are generated. be able to. These parameters represent the moving amount of the CT image and the moving amount of the bed. In order to quickly search for a parameter from the DRR image, the DRR image and the parameter used to generate the DRR image are stored in association with each other in the main storage device 123 or the storage device 121 of the positioning calculation device 119.

  It should be noted that the number of DRRs used for the positioning calculation (that is, the step size and numerical range of the angle and movement amount) can be changed. For example, more DRR images can be used, or the number of DRR images to be compared can be limited to only four. If there is one or more images, positioning calculation is possible.

  The most consistent DRR image can be obtained by comparing the generated DRR image with the DR image data transmitted from the console 111 of the X-ray imaging apparatus. Since the DRR image and the parameter used for image generation are stored in association with each other, the parameter used for generating the DRR image can be acquired. If the parameter can be acquired, it is possible to know how far the irradiation target position is from the irradiation center point, and the bed movement amount necessary to eliminate it (step 309).

  For comparison between the DRR image data and the X-ray image data (step 308), a mutual information maximization method described in Non-Patent Document 5 which is widely known is used. The mutual information maximization method is a method for obtaining the similarity between two images. In the present invention, the similarity between the DRR image and the DR image is calculated, and the image with the maximum similarity is determined as the most consistent image. .

  In the bed positioning device 116, an operator who operates the bed positioning device 116 receives soft tissue extraction image data created in advance during treatment planning from the data server (step 310), and the storage device 121 and the main storage device of the bed positioning calculation device 119. 123.

  The soft tissue feature shape data creation computation device 124 of the bed positioning computation device 119 creates soft tissue feature shape data from the soft tissue extracted image data (step 312). The procedure by which the soft tissue feature shape data creation calculation device 124 creates soft tissue feature shape data will be described with reference to FIG. A soft tissue projection image is created from the soft tissue extraction image using the optimum parameters obtained by comparing the DR image data and the DRR image data and the DRR creation program stored in the storage device 121. Using the DRR image and the soft tissue projection image, soft tissue feature shape data having points, lines, regions and the like representing the feature shape of the target soft tissue in the projection image is created. For example, a part where the boundary line (edge) of the soft tissue projection image and the edge appearing on the DRR image can be confirmed in both images can be used as soft tissue feature shape data. FIG. 4 shows a case where the soft tissue is rectangular in order to simplify the description. Even if the soft tissue is composed of actual curves and phases, the contents of the process are not changed at all. Assume that imaging objects are arranged in a state where three rectangular objects are slightly shifted vertically and horizontally, and the target soft tissue is sandwiched between two separate tissues. The DRR image obtained by projecting this image data from the direction of the arrow in FIG. 4 has a shape in which three rectangles are overlapped and shifted. On the other hand, when the image extracted from the organ is projected, it becomes a rectangular shape. Since the DRR image and the organ extraction image are perfectly aligned, it is possible to recognize the position of the projected shape of the target soft tissue on the DRR image. Since three rectangles overlap on the DRR image, it is impossible to recognize all the contours of the target soft tissue. However, since all the contours and regions can be recognized from the projected image of the soft tissue extraction image, the target on the DRR Portions that are points, lines, and regions that are characteristic shapes of soft tissue are identified and used as soft tissue characteristic shape data.

  The DR image, DRR image, and soft tissue feature shape data are displayed on the monitor 117 of the bed positioning device 116 (step 313). An example of the image arrangement on the monitor 117 is shown in FIG. An X-ray image, a DRR image, and soft tissue feature shape data are displayed in the display regions 501, 502, and 503, and the operator of the bed positioning device 116 moves the image in the region 504 where the DR image and soft tissue feature shape data are fusion-displayed. Confirm. Further, the operator corrects the image misalignment on the operation panel 505.

  A method in which the operator performs alignment using soft tissue feature shape data and an X-ray image will be described with reference to FIG. FIG. 6 shows the state of the imaging target during treatment. Although the imaging target is the same as that in FIG. 4, it is assumed that the position of the target soft tissue is shifted from the dotted line portion as illustrated in FIG. For example, it is not possible to recognize all contours of soft tissue on an X-ray image, but if there are some feature shapes such as points, lines, and regions, the feature shapes are compared with soft tissue feature shape data and aligned by the operator. can do. It is also possible to perform automatic alignment by comparing the pixel value distribution representing the shape in the soft tissue feature shape data with the pixel value distribution of the X-ray image (step 316).

  The operator of the bed positioning device inputs the confirmation of the movement amount from the input means (step 315), converts the image alignment movement amount of the DR image and the DRR line image into the movement amount of the bed, and transmits it to the bed control device 124. (Step 317) Thus, the bed positioning is completed.

  As described above, with the bed positioning system and method provided by this embodiment, the accuracy of bed positioning can be improved using information on soft tissues such as organs.

  In the conventional bed positioning using the DR image acquired by the orthogonal X-ray apparatus and the treatment plan CT image, the main factor that hinders the positioning using the position information of the soft tissue such as the affected part or the organ is the soft tissue on the DR image and the DRR image. It is conceivable that it is difficult to discriminate the region and contour. This is because each image is a two-dimensional projection image, and depending on the projection direction, the soft tissue region and the contour information on the image are ambiguous or lost. Therefore, in this embodiment, not only the bed positioning is performed using the bone tissue mainly drawn in the DR image and the DRR image, but also the target region / organ is extracted from the treatment plan CT image, and its contour and region are extracted. The corresponding contours and regions on the DR image and the DRR image are specified using the information, and the bed is positioned using the information. Specifically, a target region / organ (soft tissue) is extracted based on the treatment plan CT image. Also, a DRR image is created from the treatment plan CT image. An image in which the extracted soft tissue region and outline are projected is created, and data representing feature points, contour lines, and regions that can be the shape of the soft tissue on the projection image is obtained based on these images. The DR image and the DRR image are aligned using the DR image, the DRR image, and the shape feature data projected from the soft tissue at the time of actual bed positioning. As a result, bed positioning using a soft tissue shape is possible, and the accuracy of bed positioning is improved.

  According to the present embodiment, a soft tissue (organ) serving as a reference for calculating a bed positioning parameter in a treatment plan CT image is extracted, and a target soft tissue extraction image is created. Using the DRR image created from the treatment plan CT image and the soft tissue projection image obtained by projecting the target soft tissue extracted image in the same direction as the DRR image, soft tissue feature shape data having the target organ feature shape on the projection image is created. . Bed positioning using soft tissue information is performed by comparing X-ray images, DRR images, and soft tissue feature shape data captured during treatment. As described above, according to the present embodiment, in bed positioning for radiotherapy, particularly in high-accuracy three-dimensional radiotherapy, in addition to conventional alignment using mainly a bone structure, bed positioning using a soft tissue structure is used. Therefore, it is possible to position the bed with higher accuracy than before. As a result, the radiation dose for treatment can be concentrated on the affected area, and high-accuracy radiotherapy can be performed.

  The present embodiment can be applied to configurations other than those described in the present embodiment without impairing the function. First, in the present embodiment, the treatment planning device 101, the bed positioning device 116, the X-ray imaging device console 133, and the treatment device console 132 are described as independent devices, but all of them may be a single device. Or some of these may be a single device.

  In the present embodiment, the Dicom format is used for the DR image data transmitted from the console 133 to the positioning device 116 and the CT image data from the image data server 110 and the format (data format) of the organ extraction image. Of course, other formats such as JPEG images and bitmap images may be used.

  Although the configuration is such that the data file is stored in the image data server 110, the treatment planning apparatus 101 and the bed positioning apparatus 116 may directly communicate to exchange data files. Further, the DR image file may be supplemented to the storage device 121 of the bed positioning calculation processing device 119 without being stored in the image data server 110. Furthermore, the treatment planning device 101 and the bed positioning calculation device 119 may be a single device. Further, although a mode using communication of a data file or the like via the network 126 has been described, other storage media such as a floppy (registered trademark) disk or a CD-R may be used as a data file exchange means. .

  In the present embodiment, the case where the irradiation target is placed on the bed of the radiotherapy system has been described. However, the present invention is also applied to the case where the bed positioning is performed in a room having the same bed and the X-ray imaging system as the radiotherapy system. it can.

  In the present embodiment, the X-ray therapy apparatus is described. However, the particle beam therapy apparatus using a particle beam other than X-rays also includes a rotating gantry including an irradiation head, and the present invention can be applied as it is.

DESCRIPTION OF SYMBOLS 1 Radiation treatment system 101 Treatment plan apparatus 102,117 Monitor 103,118 Input means 104 Treatment plan calculation apparatus 105,111,120 Communication apparatus 106,112,121 Storage apparatus 107 Treatment plan calculation processing apparatus 108,114,123 Main storage apparatus 109 Soft tissue extraction arithmetic processing unit 110 Image data server 113 Data arithmetic processing unit 115 X-ray imaging system 116 Bed positioning unit 119 Bed positioning arithmetic unit 122 Bed positioning arithmetic processing unit 124 Soft tissue feature shape data creation arithmetic unit 125 Bed control unit 126 Network 127 Radiation therapy system 126
128 Bed 129 Irradiation head 130 Gantry 131 Treatment device controller 132 Treatment device console 133 X-ray imaging device console 134 X-ray source 135 Image receiving device 136 X-ray imaging device controller 501 DR image display area 502 DRR line image display area 503 Soft tissue feature shape data display area 504 Fusion image display area 505 Operation panel

Claims (6)

A bed on which the patient is placed;
A bed positioning device for positioning the bed in radiation therapy;
An X-ray imaging apparatus having an X-ray generator for generating X-rays and an X-ray receiver for receiving the X-rays from the X-ray generator;
The bed positioning device includes:
Bed positioning data is generated based on first X-ray fluoroscopic image data imaged by the X-ray imaging apparatus and soft tissue projection image data generated from X-ray CT image data acquired at the time of treatment planning. Radiotherapy system. The bed positioning device includes:
Based on the soft tissue projection image data received from the treatment planning apparatus, soft tissue feature shape data is generated by extracting the soft tissue feature shape, and the generated soft tissue feature shape data is compared with the first X-ray fluoroscopic image data. The radiotherapy system according to claim 1, wherein the bed positioning data is generated. The bed positioning device includes:
Based on the soft tissue image data received from the treatment planning device, generate soft tissue feature shape data obtained by extracting the soft tissue feature shape,
The radiotherapy system according to claim 1, wherein the bed positioning data is generated by comparing feature shape data of a soft tissue image included in the first X-ray fluoroscopic image data and the soft tissue feature shape data. .   The radiotherapy system according to any one of claims 1 to 3, further comprising a display device that displays a composite image of the soft tissue characteristic shape image and the first X-ray fluoroscopic image.   A radiotherapy system comprising a bed control device that moves and controls positioning of the bed based on the bed positioning data.   6. The treatment planning apparatus according to claim 1, further comprising a treatment planning apparatus that extracts soft tissue included in the X-ray CT image data and creates the soft tissue projection image data created by simulating imaging by X-rays. 7. Radiation therapy system.

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