Radiation imaging device and imaging condition calculation method

Abstract

To provide a radiation imaging device capable of appropriately adjusting imaging conditions.SOLUTION: A storage unit 70C stores a first imaging condition being an imaging condition that becomes the reference for performing imaging with the radiation in association with each portion of a patient. An imaging control device 55 corrects the first imaging condition corresponding to the imaged portion being the portion to be imaged with the radiation in the patient using a correction coefficient according to the imaging direction in which the patient is imaged with the radiation, and calculates the second imaging condition being the imaging condition for actually imaging the patient with the radiation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a radiation imaging apparatus and an imaging condition calculation method. [Background technology]

[0002] A radiation therapy system and the like are provided with a radiation imaging device that images a subject using radiation such as X-rays. In a radiation imaging device, imaging conditions (such as the radiation dose) suitable for imaging a subject generally change depending on the thickness of the subject through which the radiation passes, and therefore the imaging conditions need to be adjusted depending on the thickness of the subject.

[0003] In response to this, Patent Document 1 discloses a technique for adjusting the dose of radiation irradiated to a subject based on the imaging direction in which the subject is imaged or the imaging part that is the part of the subject that is imaged. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2004-283258 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 only increases the dose when acquiring a radiographic image of the hand compared to when acquiring a radiographic image of the chest, and increases the dose when the patient stands facing perpendicular to the radiation irradiation direction compared to when the patient stands facing the radiation irradiation direction, resulting in a problem that the imaging conditions cannot be finely adjusted.

[0006] For example, in a rotating gantry type device equipped with an imaging system having an X-ray tube and a detector for detecting X-rays, the imaging angle changes according to the gantry angle. Also, if the angle of the couch on which the subject lies can be adjusted, the imaging angle also changes according to the angle of the couch. In such a case, the thickness of the subject through which radiation penetrates changes according to the imaging angle, and as a result, the appropriate value of the imaging condition such as the dose changes. However, it is difficult to appropriately adjust the radiation dose with the technology described in Patent Document 1.

[0007] An object of the present invention is to provide a radiation imaging apparatus and an imaging condition calculation method capable of appropriately adjusting imaging conditions. [Means for solving the problem]

[0008] A radiation imaging device according to one aspect of the present disclosure is a radiation imaging device that images a subject using radiation, and includes a memory unit that stores first imaging conditions, which are standard imaging conditions for performing imaging using radiation, in correspondence with each part of the subject, and an imaging control unit that corrects the first imaging conditions corresponding to imaging parts, which are parts of the subject that are imaged using radiation, with a correction coefficient according to an imaging direction in which the subject is imaged using radiation, to calculate second imaging conditions, which are imaging conditions for imaging the subject using radiation. Effect of the Invention

[0009] According to the present invention, it becomes possible to appropriately adjust the imaging conditions. [Brief description of the drawings]

[0010] [Figure 1] 1 is a diagram showing an overall configuration of a radiation therapy system according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is a diagram for explaining an example of a treatment room in which an imaging system is mounted on a gantry. [Diagram 3] FIG. 1 is a diagram showing an example of a treatment room in which an imaging system is not mounted on a gantry. [Figure 4] FIG. 2 is a diagram showing a configuration of a control block of the control system. [Diagram 5] FIG. 1 is a diagram for explaining an example of a radiation therapy process. [Figure 6] 11 is a flowchart for explaining an example of an imaging condition calculation process. [Figure 7] 13 is a flowchart for explaining another example of the imaging condition calculation process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0012] Fig. 1 is a diagram showing an overall configuration of a radiation therapy system according to an embodiment of the present disclosure. The radiation therapy system shown in Fig. 1 is a particle beam therapy system that irradiates a particle beam as therapeutic radiation to an irradiation target, and includes a therapeutic radiation generator 1, a particle beam transport system 5, a treatment room 9, and a control system 50.

[0013] The therapeutic radiation generating device 1 includes a linac 2 and a circular accelerator 3. The linac 2 is a pre-accelerator that accelerates ions from an ion source (not shown) and inputs the ions into the circular accelerator 3. The circular accelerator 3 further accelerates the ions from the linac 2 and emits them as a particle beam (ion beam), which is radiation for treatment. The circular accelerator 3 is, for example, a synchrotron, a cyclotron, or a synchrocyclotron.

[0014] The particle beam transport system 5 is a transport system that transports the particle beam extracted from the circular accelerator 3 of the therapeutic radiation generator 1 to the treatment room 9, and includes a particle beam path 7 and bending electromagnets 4, 6, and 8. The particle beam path 7 is a path that transmits the particle beam extracted from the circular accelerator 3, and connects the therapeutic radiation generator 1 and the treatment room 9. The bending electromagnets 4, 6, and 8 are provided in the particle beam path 7 and change the traveling direction of the particle beam transmitted through the particle beam path 7. Furthermore, the particle beam path 7 may further include a quadrupole electromagnet for converging the particle beam.

[0015] The treatment room 9 includes an irradiation device 10 , a gantry 11 , X-ray generators 12 and 13 , X-ray detectors 14 and 15 , and a couch 17 .

[0016] The irradiation device 10 irradiates a patient 16, who is an irradiation target, with the particle beam transported by the particle beam transport system 5. The gantry 11 mounts the irradiation device 10 and rotates around the patient 16 to adjust the irradiation angle at which the particle beam is irradiated from the irradiation device 10 to the patient 16.

[0017] The X-ray generators 12 and 13 and the X-ray detectors 14 and 15 constitute a radiation imaging device that images a patient 16 with radiation for imaging. In this embodiment, the radiation for imaging is X-rays, and the radiation imaging device is sometimes called an X-ray imaging device. The X-ray generators 12 and 13 are radiation sources that generate X-rays, which are radiation for imaging, and irradiate the patient 16 with the X-rays. The X-ray detectors 14 and 15 image the patient 16 by detecting the X-rays irradiated from the X-ray generators 12 and 13 through the patient 16.

[0018] The couch 17 is a bed on which the patient 16 rests during particle beam therapy. The couch 17 is movable. In this embodiment, the couch 17 performs translational movement along three mutually different axes and rotational movement around each of the three axes as a rotation axis. Note that the three axes are, for example, perpendicular to each other. In this embodiment, the couch angle, which is the rotation angle of the couch 17 around each rotation axis, is expressed by pitch, roll, and yaw.

[0019] The control system 50 controls each device of the therapeutic radiation generation device 1, the particle beam transport system 5, and the treatment room 9 to perform particle beam therapy on the patient 16. A more detailed description of the control system 50 will be given later with reference to FIG.

[0020] FIG. 2 is a diagram for explaining the internal configuration of a gantry 11 as an example of a treatment room 9 in which an imaging system is mounted on the gantry 11, and shows a vertical cross section of the gantry 11. As shown in FIG.

[0021] As shown in FIG. 2, the gantry 11 has a substantially cylindrical shape, and the irradiation device 10 is installed inside the gantry 11 so as to irradiate a particle beam toward a target 18, which is an affected area in a patient 16 lying on a couch 17. In addition, inside the gantry 11, a plurality of X-ray imaging devices are arranged so as to sandwich the particle beam irradiation port of the irradiation device 10. In the example of FIG. 2, X-ray imaging devices each consisting of a combination of X-ray generators 12 and 13 and X-ray detectors 14 and 15 are arranged on the gantry 11 so that the paths of the X-rays are perpendicular to each other. More specifically, the X-ray generator 12 and the X-ray detector 14 facing each other constitute one X-ray imaging device, and the X-ray generator 13 and the X-ray detector 15 facing each other constitute another X-ray imaging device.

[0022] In order to irradiate the particle beam to the target 18, the patient 16 is placed at a preset position with high accuracy. For example, a user such as a doctor or a radiologist moves the couch 17 while checking an image of the patient 16 captured by the X-ray imaging device (12 to 15), and places the patient 16 at a position preset in the treatment plan.

[0023] Furthermore, if the upper side in the figure is taken as 0 degrees for the gantry angle, gantry 11 can rotate up to 180 degrees clockwise (CW) and up to -180 degrees counterclockwise (CCW) (180 degrees clockwise).

[0024] Furthermore, the radiation therapy system does not necessarily have to include the gantry 11. FIG 3 is a diagram showing an example of a treatment room 9 that does not include the gantry 11.

[0025] In the example of Fig. 3, an irradiation device 10 that emits particle beams toward a target 18 inside a patient 16 lying on a couch 17 is fixedly installed in a treatment room 9. In addition, a plurality of X-ray imaging devices are fixedly installed in the treatment room 9. In the example of Fig. 2, X-ray imaging devices each consisting of a combination of X-ray generators 12 and 13 and X-ray detectors 14 and 15 are arranged in the treatment room 9 so that the paths of the respective X-rays are perpendicular to each other. More specifically, the X-ray generator 12 and the X-ray detector 14 facing each other constitute one X-ray imaging device, and the X-ray generator 13 and the X-ray detector 15 facing each other constitute another X-ray imaging device.

[0026] Fig. 4 is a diagram showing the configuration of control blocks in the control system 50. The control system 50 shown in Fig. 4 includes a central control device 51, an accelerator control device 52, a gantry control device 53, an irradiation control device 54, an imaging control device 55, and a couch control device 56, and is communicatively connected to a radiation therapy information system 60 and a GUI (Graphical User Interface) device 70.

[0027] The radiation therapy information system 60 stores various information related to radiation therapy, such as treatment plan information indicating a treatment plan for the patient 16, and treatment plan images, which are images of the patient 16 used to create the treatment plan information. The treatment plan information indicates, for example, the position of the patient 16 during treatment (such as the gantry angle and couch angle described below) and the dose of particle beams to be irradiated to the patient 16. The treatment plan images are images obtained by imaging the patient in advance in order to create the treatment plan information, and are, for example, X-ray images or CT (Computed Tomography) images.

[0028] The central controller 51 is connected to the accelerator controller 52, the gantry controller 53, the irradiation controller 54, the imaging controller 55, and the couch controller 56, and controls the entire control system 50 by transmitting and receiving necessary information between them. For example, when an irradiation permission signal is turned ON, the central controller 51 controls the therapeutic radiation generator 1 and the irradiation device 10 via the accelerator controller 52 and the irradiation controller 54 to irradiate the target 18 in the patient 16 with particle beams.

[0029] The accelerator controller 52 is connected to and controls the therapeutic radiation generator 1 and the particle beam transport system 5. The gantry controller 53 is connected to the gantry 11 and controls the rotation of the gantry 11. The irradiation controller 54 controls the devices in the irradiation device 10 to irradiate particle beams from the irradiation device 10 to the target 18 of the patient 16 so that a predetermined dose distribution is formed in the patient 16.

[0030] The imaging control device 55 is connected to the two sets of X-ray imaging devices (X-ray generators 12 and 13, and X-ray detectors 14 and 15) and is an imaging control unit that controls these X-ray imaging devices. The couch control device 56 is connected to the couch 17 and controls the movement of the couch 17.

[0031] The imaging control device 55 specifically includes a treatment information control unit 55A, an X-ray control unit 55B, and an image generating unit 55C.

[0032] The treatment information control unit 55A acquires treatment planning information and treatment planning images from the radiation treatment information system 60, and calculates actual imaging conditions (an example of second imaging conditions), which are imaging conditions for actually imaging the patient with X-rays, based on the acquired treatment planning information and treatment planning images.

[0033] The X-ray control unit 55B controls the X-ray generators 12 and 13 so that the patient 16 is imaged under the actual imaging conditions calculated by the treatment information control unit 55A, and causes each of the X-ray generators 12 and 13 to irradiate X-rays onto the patient 16. The irradiated X-rays pass through the target 18 and are detected by the X-ray detectors 14 and 15 facing the X-ray generators 12 and 13, respectively. The X-ray detectors 14 and 15 convert the detected X-rays into electrical signals and transmit them to the image generating unit 55C.

[0034] The image generating unit 55C receives electrical signals from the X-ray detectors 14 and 15, and generates and displays an X-ray image of the patient 16 based on the electrical signals.

[0035] The GUI device 70 is a device for exchanging information with a user, and includes a display unit 70A, an input unit 70B, and a storage unit 70C. The display unit 70A displays various imaging parameters such as actual imaging conditions calculated by the treatment information control unit 55A. The input unit 70B accepts various information from the user. The storage unit 70C stores reference imaging conditions (an example of first imaging conditions) that are imaging conditions serving as a reference for performing imaging using X-rays, in association with each part of the subject. The imaging conditions include, for example, tube current, tube voltage, and imaging time. The subject is a patient 16, and the parts indicate, for example, the head, chest, abdomen, pelvis, etc.

[0036] The reference imaging conditions stored in the storage unit 70C may be directly associated with the part of the subject, or may be associated with part-related information reflecting the part of the subject. There may be a plurality of part-related information for one part. In addition, as the reference imaging conditions, conditions for performing the motion-tracking radiotherapy and conditions for not performing the motion-tracking radiotherapy may be separately prepared for each part of the subject.

[0037] The reference imaging conditions stored in the storage unit 70C can be rewritten according to an instruction received from a user by the input unit 70B. For example, the user can set the reference imaging conditions according to the imaging characteristics (such as a signal-to-noise ratio and contrast) caused by the X-ray imaging device and its device arrangement by inputting an instruction according to the imaging characteristics.

[0038] FIG. 5 is a flowchart for explaining an example of a radiotherapy process performed by the radiotherapy system.

[0039] In the radiotherapy process, the control system 50 first acquires treatment plan information from the radiotherapy information system 60 (step S10), and sets imaging parameters (such as imaging site, gantry angle, and imaging conditions) for imaging by the X-ray imaging device (12-15) based on the treatment plan information and an input from the user (step S20). Then, the control system 50 controls the position (angle) of the gantry 11 and the position of the couch 17 to prepare the treatment device (step S30). The process of setting the imaging conditions in the process of step S20 will be described later with reference to Figs. 6 and 7.

[0040] Thereafter, the patient 16 is fixed in a predetermined position on the couch 17 (S40). This operation is called patient setup. The process of step S40 is not executed by the control system 50, but is manually performed by the user, an assistant worker, or the like. However, the patient may be fixed on the couch 17 using a setup support robot or the like. In this case, the control system 50 may control the setup support robot.

[0041] The imaging control device 55 of the control system 50 uses the imaging parameters set in step S20 to image the patient 16 and obtain an X-ray image for patient positioning as a current image (step S50). The control system 50 obtains a treatment planning image used to create treatment planning information from the radiation therapy information system 60 as a reference image. Then, the control system 50 calculates the amount of deviation between the position of the target 18 in the treatment planning information and the current position of the target 18 based on the amount of deviation between the current image and the reference image, and outputs the amount of deviation to the couch control device 56 (step S60). The couch control device 56 receives the amount of position deviation from the control system 50 and moves the couch 17 so as to eliminate the amount of deviation (step S70).

[0042] The control system 50 moves the couch 17 and the gantry 11 to the treatment position (step S80). In step S80, for example, the rotation angle of the gantry 11 is moved from the setup angle, which is the initial angle, to the irradiation angle (step S80). When preparations for starting treatment are complete, the control system 50 causes the irradiation device 10 to irradiate the patient 16 with therapeutic radiation (S90).

[0043] Next, the imaging condition calculation process for calculating the imaging conditions in step S20 of FIG. 5 will be described.

[0044] The following imaging condition calculation process is mainly executed by the imaging control device 55 (more specifically, the treatment information control unit 55A). In the imaging condition calculation process, the imaging control device 55 acquires reference imaging conditions corresponding to the imaging site of the patient 16, who is the subject of the X-ray imaging device (12 to 14), from the storage unit 70C of the GUI device 70, corrects the reference imaging conditions with a correction coefficient according to the imaging direction for imaging the patient 16, and calculates actual imaging conditions for actually imaging the patient 16.

[0045] 6 is a flowchart for explaining an example of the imaging condition calculation process in more detail. In the example of FIG. 6, the treatment planning image is a CT image of the patient 16. The reference imaging condition stored in the storage unit 70C is associated with the thickness passing through the imaging part of the patient 16 as part-related information, more specifically, with reference subject thickness information to be described later.

[0046] In the imaging condition calculation process, the input unit 70B of the GUI device 70 accepts imaging site information indicating an imaging site of the patient 16 from the user, and outputs the imaging site information to the imaging control device 55. The imaging control device 55 acquires the imaging site information (step S211). The imaging site information may be acquired from the treatment plan information acquired from the radiation therapy information system 60 in step S10 of FIG. 4.

[0047] The imaging control device 55 acquires a CT image of the patient 16, which is an image for treatment planning, from the radiation therapy information system 60. Based on the acquired imaging site information and CT image, the imaging control device 55 calculates reference subject thickness information indicating the subject thickness, which is the thickness of the patient 16 through which the X-rays for imaging pass when the imaging angle at which the patient 16 is imaged by the X-ray imaging device (12 to 15) is a predetermined reference angle (step S212). The subject thickness may be a geometric thickness or a thickness that takes into account the composition in the body, such as a water equivalent thickness. In this embodiment, since there are two sets of X-ray imaging devices, there are two reference angles, for example, 0 degrees (180 degrees) and 90 degrees (270 degrees), or 45 degrees (225 degrees) and 315 degrees (135 degrees).

[0048] The imaging control device 55 acquires the reference imaging conditions corresponding to the reference subject thickness information from the storage unit 70C (step S213).

[0049] The imaging control device 55 also acquires a couch angle, which is a rotation angle of the couch 17 during imaging by the X-ray imaging device (step S221). The imaging control device 55 generates a reconstructed CT image by reconstructing the CT image of the patient 16 by applying the couch angle to the CT image (step S222). The couch angle may be acquired from the treatment plan information acquired from the radiation therapy information system 60 in step S10 of Fig. 4, or may be acquired from the central control device 51 or the couch control device 56.

[0050] The imaging control device 55 also acquires the gantry angle of the gantry 11 during imaging by the X-ray imaging device (step S231). The gantry angle may be acquired from the treatment plan information acquired from the radiation therapy information system 60 in step S10 of FIG. 4, or may be acquired from the central control device 51 or the gantry control device 53.

[0051] Then, the imaging control device 55 calculates an actual imaging angle, which is an actual imaging angle by the X-ray imaging device, based on the gantry angle (step S232). For example, in the example of Fig. 2, the X-ray generators 12 and 13 are located at angles of ±135° from the gantry angle, so the imaging angle is an angle of ±135° from the gantry angle. The imaging control device 55 holds position information indicating the positions (gantry angle) of the X-ray generators 12 and 13 when the gantry angle is a predetermined value (e.g., 0 degrees), and calculates the actual imaging angle from the gantry angle based on the position information.

[0052] Then, the imaging control device 55 calculates subject thickness information indicating the subject thickness, which is the thickness of the patient 16 through which the X-rays for imaging pass when the imaging angle in the X-ray imaging device is the actual imaging angle, based on the actual imaging angle and the reconstructed CT image (step S233). Note that since the couch angle is reflected in the reconstructed CT image, the subject thickness information reflects the imaging direction defined by the actual imaging angle (position information) and the couch angle.

[0053] The imaging control device 55 calculates a correction coefficient for the reference imaging condition from the subject thickness information (step S234). The correction coefficient can be calculated, for example, from a lookup table or a formula indicating the relationship between the subject thickness information and the correction coefficient, and is calculated so that the larger the subject thickness indicated by the subject thickness information, the larger the X-ray dose from the X-ray imaging device. The lookup table or formula is, for example, stored in advance in the imaging control device 55. The correction coefficient may be calculated for all parameters included in the imaging condition, or may be calculated for some parameters included in the imaging condition. For example, the correction coefficient may be calculated only for the tube current.

[0054] Then, the imaging control device 55 calculates the actual imaging conditions from the correction coefficients and the reference imaging conditions (step S235), and ends the process. The imaging control device 55 calculates the actual imaging conditions, for example, by multiplying a parameter included in the reference imaging conditions by a correction coefficient corresponding to the parameter.

[0055] In addition, when the radiation therapy system is configured in a treatment room 9 without a gantry as shown in FIG. 3, the imaging angle is fixed, so that the processing of step S231 is skipped, and in step S232, the imaging control device 55 calculates the fixed imaging angle as the actual imaging angle.

[0056] Fig. 7 is a flow chart for explaining an example of the imaging condition calculation process in more detail. In the example of Fig. 7, the treatment plan image is not used. In addition, the reference imaging condition stored in the storage unit 70C is associated with a subject model image corresponding to the imaging part of the patient described later as part-related information. In each process of Fig. 7, detailed explanations of the same processes as those of Fig. 6 are omitted as appropriate.

[0057] In the imaging condition calculation process, the input unit 70B of the GUI device 70 accepts imaging site information indicating the imaging site of the patient 16 from the user, and outputs the imaging site information to the imaging control device 55. The imaging control device 55 acquires the imaging site information. The imaging control device 55 acquires a subject model image corresponding to the imaging site information (step S241). The subject model image is a CT image of a subject model that is a model of the patient 16, or image data in a similar data format, and is stored in advance in the storage unit 70C of the GUI device 70 for each part of the patient 16. The subject model image may be prepared for each part of the patient 16 and for each body type (gender, age, etc.) of the patient. The subject model is, for example, a homogeneous phantom or a human body phantom.

[0058] The imaging control device 55 acquires the reference imaging conditions corresponding to the subject model image from the storage unit 70C (step S242).

[0059] The imaging control device 55 also acquires a couch angle, which is a rotation angle of the couch 17 during imaging by the X-ray imaging device (step S251). The imaging control device 55 generates a reconstructed model image by reconstructing the subject model image by applying the couch angle to the subject model image (step S252).

[0060] The imaging control device 55 also acquires the gantry angle of the gantry 11 during imaging by the X-ray imaging device (step S261). Then, the imaging control device 55 calculates an actual imaging angle, which is an actual imaging angle by the X-ray imaging device, based on the gantry angle (step S262).

[0061] Then, based on the actual imaging angle and the reconstructed model image, the imaging control device 55 calculates subject thickness information indicating the subject thickness, which is the thickness of the patient 16 through which the imaging X-rays pass when the imaging angle in the X-ray imaging device is the actual imaging angle (step S263).

[0062] The imaging control device 55 calculates a correction coefficient for the reference imaging condition from the subject thickness information (step S264), and then calculates an actual imaging condition from the correction coefficient and the reference imaging condition (step S265), and ends the process.

[0063] The configuration and operation of the radiation therapy system described above are merely examples and are not limited thereto. For example, at least a part of the functions of the GUI device 70 may be provided in the control system 50, and at least a part of the functions of the imaging control device 55 may be provided in the central control device 51.

[0064] The radiation therapy system of the present disclosure is not limited to a particle beam therapy system, but may be one that irradiates an irradiation target with other types of radiation, such as X-rays. The radiation imaging device is not limited to the X-ray imaging device (12 to 15), but may be a CBCT (Cone Beam Computed Tomography) device or the like. In this case, the imaging conditions include, for example, a tube current, a tube voltage, a pulse width, and a frame rate. As the correction coefficient, for example, a correction coefficient corresponding to the direction in which the thickness of the subject is the largest in all directions imaged by the CBCT device is calculated.

[0065] The radiation imaging device may be provided in a device or system other than the radiation therapy system. For example, the radiation imaging device may be provided in a setup room or a simulation device of the radiation therapy system. Note that the setup room and the simulation device are not usually connected to the therapeutic radiation generating device 1.

[0066] As described above, according to this embodiment, the storage unit 70C stores reference imaging conditions, which are imaging conditions serving as a reference for performing imaging using radiation, in association with each part of the patient 16. The imaging control device 55 corrects the reference imaging conditions corresponding to the imaging parts, which are parts of the patient 16 to be imaged using radiation, with a correction coefficient according to the imaging direction in which the patient 16 is imaged using radiation, to calculate actual imaging conditions, which are imaging conditions in which the patient 16 is actually imaged using radiation. This makes it possible to finely adjust the imaging conditions according to the imaging parts and imaging direction, and therefore makes it possible to appropriately adjust the imaging conditions.

[0067] In this embodiment, the imaging control device 55 calculates the correction coefficient based on the imaging direction and the CT image showing the patient 16 or the subject model. In this case, it is possible to calculate a more appropriate correction coefficient.

[0068] In the present embodiment, the imaging control device 55 calculates the subject thickness of the patient 16 based on the imaging direction and the CT image, and calculates the correction coefficient according to the subject thickness. In this case, it is possible to calculate a more appropriate correction coefficient.

[0069] In this embodiment, the subject thickness is a thickness that takes into account the subject's internal body composition, making it possible to calculate a more appropriate correction coefficient.

[0070] In this embodiment, the imaging direction is determined by the positions of the X-ray generators 12 and 13. In addition, when the couch 17 is rotatable, the imaging direction is determined by the positions of the X-ray generators 12 and 13 and the rotation angle of the couch 17. In this case, it is possible to more appropriately set the imaging direction, and therefore it is possible to calculate a more appropriate correction coefficient.

[0071] In addition, in this embodiment, the imaging control device 55 calculates the imaging direction based on the position information and the angle information indicating the rotation angle of the couch 17 on which the patient 16 rests. In this case, it is possible to more appropriately calculate the imaging direction, and therefore it is possible to calculate a more appropriate correction coefficient.

[0072] Furthermore, in this embodiment, the imaging control device 55 rewrites the reference imaging conditions in accordance with an instruction from the user, which makes it possible to more appropriately adjust the imaging conditions.

[0073] The above-described embodiments of the present disclosure are illustrative examples of the present disclosure, and are not intended to limit the scope of the present disclosure to only these embodiments. A person skilled in the art can implement the present disclosure in various other forms without departing from the scope of the present disclosure. [Explanation of symbols]

[0074] 1: Therapeutic radiation generator 2: Linac 3: Circular accelerator 4: Bending magnet 5: Particle beam transport system 6: Bending magnet 7: Particle beam path 9: Treatment room 10: Irradiation device 11: Gantry 12: X-ray generator 13: X-ray generator 14: X-ray detector 15: X-ray detector 16: Patient 17: Couch 18: Target 50: Control system 51: Central control device 52: Accelerator control device 53: Gantry control device 54: Irradiation control device 55: Imaging control device 55A: Treatment information control device 55B: X-ray control device 55C: Image generation unit 56: Couch control device 60: Radiation therapy information system 70: GUI device

Claims

1. A radiation imaging apparatus for imaging a subject with radiation, comprising: a storage unit that stores a first imaging condition, which is a reference imaging condition for performing imaging using radiation, in association with each of the body parts of the subject; and an imaging control unit that calculates a second imaging condition, which is an imaging condition for imaging the subject with radiation, by correcting the first imaging condition corresponding to an imaging part that is a part of the subject to be imaged with radiation, with a correction coefficient according to an imaging direction in which the subject is imaged with radiation.

2. The radiation imaging apparatus according to claim 1 , wherein the imaging control unit calculates the correction coefficient based on the imaging direction and a CT image of the subject or a model of the subject.

3. The radiation imaging apparatus according to claim 2 , wherein the imaging control unit calculates a thickness of the subject through which radiation penetrates, based on the imaging direction and the CT image, and calculates the correction coefficient in accordance with the thickness.

4. The radiation imaging apparatus according to claim 3 , wherein the thickness is determined in consideration of an internal composition of the subject through which the radiation passes.

5. The radiation imaging apparatus according to claim 1 , wherein the imaging direction is defined by a position of a radiation source that emits radiation for imaging the subject.

6. The radiation imaging apparatus according to claim 5 , wherein the imaging direction is defined by a position of the radiation source and a rotation angle of a couch on which the subject is placed.

7. The radiation imaging apparatus according to claim 1 , wherein the imaging control unit rewrites the first imaging condition in accordance with an instruction from a user.

8. 1. A method for calculating imaging conditions by a radiation imaging apparatus that images an object with radiation, comprising: storing a first imaging condition, which is a reference imaging condition for performing imaging using radiation, in association with each of the body parts of the subject; an imaging condition calculation method for calculating a second imaging condition that is an imaging condition for imaging the subject with radiation by correcting the first imaging condition corresponding to an imaging part that is a part of the subject to be imaged with radiation, with a correction coefficient according to an imaging direction in which the subject is imaged with radiation.

Images