Medical image diagnostic device, X-ray CT device, and control method

Abstract

To prevent a collision between a moving subject and a rack device.SOLUTION: A medical image diagnostic apparatus according to an embodiment comprises: an acquisition unit; a calculation unit; a determination unit; and an output unit. The acquisition unit acquires gravity center position information indicating the gravity center position of a subject at time points before and after movement of a top plate mounted with the subject toward a rack device and mounting direction information indicating the direction of the subject mounted toward the rack device. The calculation unit calculates a positional change about the gravity center position of the subject on the basis of the gravity center position information. The determination unit determines such a risk that the subject collides with the rack device on the basis of the positional change and the mounting direction information. The output unit outputs an alert to notify that the risk exists when it is determined that the risk exists.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The embodiments disclosed in this specification and the drawings relate to a medical image diagnostic apparatus, an X-ray CT apparatus, and a control method. [Background technology]

[0002] In general, in a medical imaging diagnostic device equipped with a gantry and a bed, the gantry has a mechanism for imaging a subject, and the bed has a mechanism for moving the subject to an opening (also called a "bore") that forms the imaging space of the gantry. The subject may change posture (e.g., raise their head or bend their knees) while being moved to the gantry, and depending on their posture, they may collide with the gantry around the opening and be injured. Therefore, a system is desired that prevents collisions between the subject and the gantry during movement.

[0003] To prevent collisions, there is a method of detecting the posture of the subject using a camera installed in a position where the subject can be photographed (e.g., on the ceiling of the room where the gantry is installed, or on the front cover of the gantry). However, this method makes it difficult to detect the posture of the subject when the subject is located in a blind spot of the camera, such as near an opening in the gantry. In view of this situation, a system that detects or estimates the posture of the subject without relying on optical equipment such as a camera and that prevents collisions between the subject and the gantry during movement is particularly desirable. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2010 / 143487 Summary of the Invention [Problem to be solved by the invention]

[0005] One of the problems to be solved by the embodiments disclosed in this specification and the drawings is to prevent a collision between a moving subject and a gantry. However, the problems to be solved by the embodiments disclosed in this specification and the drawings are not limited to the above problem. Problems corresponding to the effects of the configurations shown in the embodiments described below can also be positioned as other problems. [Means for solving the problem]

[0006] A medical image diagnostic apparatus according to an embodiment includes an acquisition unit, a calculation unit, a determination unit, and an output unit. The acquisition unit acquires center of gravity position information indicating the center of gravity of the subject before and after a top plate on which the subject is placed moves toward a gantry, and placement direction information indicating the direction of the subject placed toward the gantry. The calculation unit calculates a position change related to the center of gravity of the subject based on the center of gravity position information. The determination unit determines a risk of the subject colliding with the gantry based on the position change and the placement direction information. If it is determined that the risk exists, the output unit outputs an alert notifying the user of the risk. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of an X-ray CT apparatus according to an embodiment. [Figure 2] FIG. 2 is a side view showing an example of the configuration of the X-ray CT apparatus according to the embodiment. [Figure 3] FIG. 3 is a diagram showing a first modified example of the installation location of the force sensor. [Figure 4] FIG. 4 is a diagram showing a second modified example of the installation location of the force sensor. [Figure 5] FIG. 5 is a flowchart showing an example of the operation of the X-ray CT apparatus according to the embodiment. [Figure 6] FIG. 6 is a diagram showing an example of the first posture of the subject and a change in the center of gravity position. [Figure 7] FIG. 7 is a diagram showing an example of the second posture of the subject and a change in the center of gravity position. [Figure 8]FIG. 8 is a diagram showing an example of the third posture of the subject and a change in the center of gravity position. [Figure 9] FIG. 9 is a diagram showing an example of the fourth posture of the subject and a change in the center of gravity position. [Figure 10] FIG. 10 is a diagram showing an example of a table related to collision risk determination. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, a medical image diagnostic apparatus, an X-ray CT apparatus, and a control method according to the embodiments will be described with reference to the drawings. In the following embodiments, parts with the same reference numerals perform similar operations, and redundant explanations will be omitted as appropriate.

[0009] 1 is a block diagram showing an example of the configuration of an X-ray CT apparatus 1 according to an embodiment. The X-ray CT apparatus 1 is an example of a medical image diagnostic apparatus including a gantry device and a bed device. Other examples of the medical image diagnostic apparatus include a magnetic resonance imaging (MRI) apparatus and a radioisotope (RI) apparatus (e.g., a single photon emission computed tomography (SPECT) apparatus and a positron emission tomography (PET) apparatus).

[0010] The X-ray CT apparatus 1 includes a gantry 10, a bed 30, and a console 40. For example, the gantry 10 and the bed 30 are installed in a CT examination room, while the console 40 is installed in a control room adjacent to the CT examination room. Of course, the gantry 10, the bed 30, and the console 40 may all be installed in the same room. The gantry 10, the bed 30, and the console 40 are connected to each other via wire or wirelessly so that they can communicate with each other.

[0011] (mounting device) The gantry device 10 is a scanning device having a mechanism for performing X-ray CT imaging of a subject P. The gantry device 10 includes, as its components, an X-ray tube 11, a detector 12, a rotating frame 13, an X-ray high voltage device 14, a control device 15, a wedge 16, a collimator 17, and a DAS 18. Each component is housed in a housing (not shown) having an opening 19 that forms an imaging space. The opening 19 substantially coincides with the field of view (FOV). The opening 19 is also called a "bore." Hereinafter, the subject P is assumed to be a patient (i.e., a human being).

[0012] In this embodiment, the direction parallel to the rotation axis of the rotating frame 13 in the non-tilted state is defined as the "Z-axis direction." Meanwhile, the axis direction perpendicular to the Z-axis direction and horizontal to the floor surface is defined as the "X-axis direction," and the axis direction perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the "Y-axis direction." The mutually orthogonal X-axis, Y-axis, and Z-axis form a three-dimensional Cartesian coordinate system. The central axis of the opening 19 coincides with the rotation axis (Z-axis) of the rotating frame 13.

[0013] The X-ray tube 11 is a vacuum tube that generates X-rays by irradiating thermions from a cathode (filament) toward an anode (target) and causing them to collide with each other when a high voltage is applied from the X-ray high voltage device 14 and a filament current is supplied. The X-ray tube 11 is, for example, a rotating anode type X-ray tube that irradiates thermions onto a rotating anode. The X-rays generated by the X-ray tube 11 are shaped into a cone beam by a collimator 17 and then irradiated onto the subject P.

[0014] The detector 12 detects X-rays transmitted through the subject P and outputs an electrical signal corresponding to the X-ray dose to the DAS 18. The detector 12 has an X-ray detection element row in which a plurality of X-ray detection elements are arranged in the channel direction (column direction; X-axis direction) along an arc centered on the focal point of the X-ray tube 11. However, the detector 12 may have a two-dimensional row structure in which a plurality of X-ray detection element rows in which a plurality of X-ray detection elements are arranged in the channel direction are arranged in the slice direction (row direction; Z-axis direction).

[0015] The rotating frame 13 is an annular frame that supports the X-ray tube 11 and the detector 12 so that they face each other and are rotatable about the rotation axis Z. For example, the rotating frame 13 is rotatably supported on a fixed frame (not shown) made of a metal such as aluminum. Specifically, the rotating frame 13 is connected to the edge of the fixed frame via bearings. The rotating frame 13 receives power from the control device 15 and rotates about the rotation axis Z at a constant angular velocity.

[0016] In this embodiment, the rotating frame 13 supports not only the X-ray tube 11 and the detector 12, but also the X-ray high-voltage generator 14 and the DAS 18. The imaging data generated by the DAS 18 is transmitted by optical communication from a transmitter (not shown) having, for example, a light-emitting diode (LED) to a receiver (not shown) having a photodiode provided in a non-rotating portion (i.e., a fixed frame) of the gantry 10, and then transferred to the console device 40. Note that the method of transmitting the imaging data from the rotating frame 13 to the non-rotating portion of the gantry 10 is not limited to optical communication, and any non-contact data transmission method such as a capacitive coupling method or an electromagnetic wave method may be used. Furthermore, a contact data transmission method using a slip ring and an electrode brush may also be used as the transmission method.

[0017] The X-ray high voltage device 14 has electrical circuits such as a transformer and a rectifier, and includes a high voltage generator that generates a high voltage to be applied to the X-ray tube 11 and a filament current to be supplied to the X-ray tube 11, and an X-ray controller that controls the output voltage according to the X-rays irradiated by the X-ray tube 11. The high voltage generator may be of a transformer type or an inverter type. The X-ray high voltage device 14 may be provided on the fixed frame of the gantry device 10 instead of the rotating frame 13.

[0018] The control device 15 includes a processing circuit and drive mechanisms such as motors and actuators. The processing circuit includes hardware resources such as a processor, such as a central processing unit (CPU) or a microprocessing unit (MPU), and memories, such as read-only memory (ROM) or random-access memory (RAM). The control device 15 may be implemented using an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a complex programmable logic device (CPLD), or a simple programmable logic device (SPLD). The control device 15 controls the rotating frame 13, the X-ray high-voltage generator 14, the DAS 18, and other components in accordance with commands from the console device 40.

[0019] In this embodiment, the control device 15 receives an input signal from an input interface 43 installed in the console device 40 and controls the operation of the gantry device 10 and the bed device 30. For example, the control device 15 receives the input signal and controls the tilting of the gantry device 10, the rotation of the rotating frame 13, and the operation of the bed device 30. The control of tilting the gantry device 10 is realized by the control device 15 rotating the rotating frame 13 around an axis parallel to the X-axis direction based on inclination angle (tilt angle) information input through the input interface 43 attached to the gantry device 10. The control device 15 may be provided in the console device 40 instead of the gantry device 10.

[0020] The wedge 16 is a filter that adjusts the amount of X-rays irradiated from the X-ray tube 11. Specifically, the wedge 16 transmits and attenuates the X-rays irradiated from the X-ray tube 11 so that the X-rays irradiated from the X-ray tube 11 to the subject P have a predetermined distribution. For example, the wedge 16 (wedge filter, bow-tie filter) is a filter made of processed aluminum that is adapted to a predetermined target angle and a predetermined thickness.

[0021] The collimator 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 16. The collimator 17 has a slit formed by combining a plurality of lead plates or the like.

[0022] When the detector 12 is an integral detector, the DAS 18 reads out electrical signals from the detector 12 and generates, based on the read out electrical signals, digital data (i.e., imaging data) relating to the dose of X-rays detected by the detector 12. In this case, the imaging data is a set of data indicating the channel number of the X-ray detection element that generated the data, the row number, the view number indicating the acquired view (projection angle), and the integral value of the dose of X-rays detected.

[0023] When the detector 12 is a photon-counting detector, the DAS 18 generates imaging data indicating count values ​​of X-ray photons detected by the detector 12 for each of a plurality of energy bands. In this case, the imaging data is a set of data indicating count values ​​of X-ray photons identified by the channel number of the X-ray detection element that generated the imaging data, the column number, the view number indicating the collected view (projection angle), and the energy bin number. The DAS 18 is realized, for example, by an ASIC equipped with circuit elements capable of generating imaging data. DAS 18 is an abbreviation for Data Acquisition System.

[0024] (bed device) The bed device 30 is a device on which the subject P is placed and which moves in any of the axial directions (X-axis, Y-axis, Z-axis). The bed device 30 includes a base 31, a bed driving mechanism 32, a top plate 33, and a support frame 34. The bed device 30 is installed opposite the gantry device 10.

[0025] The base 31 is a structure that mounts and supports the bed driving mechanism 32, the tabletop 33, and the support frame 34. Specifically, the bed driving mechanism 32 is mounted on the top of the base 31, the support frame 34 is mounted on the top of the bed driving mechanism 32, and the tabletop 33 is mounted on the top of the support frame 34. The base 31 is installed on the floor. The base 31 can be made of a rigid body such as metal.

[0026] The bed driving mechanism 32 is a mechanism that moves the tabletop 33 under the control of the control device 15 or the console device 40. Specifically, the bed driving mechanism 32 generates power by driving at a rotational speed according to the duty ratio, etc., of a drive signal supplied from the control device 15, and moves the tabletop 33 using the generated power. The bed driving mechanism 32 includes motors such as a direct drive motor and a servo motor for generating the power. Furthermore, the bed driving mechanism 32 includes an X-shaped structure (X link) that supports the support frame 34 movably in the vertical direction (Y-axis direction).

[0027] In this embodiment, the bed driving mechanism 32 moves the top 33 in each axial direction so that the body axis of the subject P placed on the top 33 coincides with the central axis of the opening 19 of the rotating frame 13. The bed driving mechanism 32 also moves the top 33 in the longitudinal direction (Z-axis direction) in conjunction with X-ray CT imaging by the gantry device 10. Note that the bed driving mechanism 32 may move not only the top 33 but also the support frame 34 in each axial direction.

[0028] The top board 33 is a flat structure on which the subject P is placed. The top board 33 can be made of an elastic material such as urethane.

[0029] The support frame 34 is a structure that supports the top plate 33. The support frame 34 can be made of a rigid material such as metal.

[0030] (Console device) The console device 40 is a device that controls the overall operation of the X-ray CT apparatus 1. The console device 40 includes, as its components, a memory 41, a display 42, an input interface 43, and a processing circuit 44. Data communication between the components is performed via a bus (BUS). At least a part of the components may be included in the gantry device 10 or the bed device 30.

[0031] The memory 41 is a storage device such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), or an integrated circuit storage device that stores various types of information. The memory 41 stores, for example, imaging data and reconstructed image data. In addition to an HDD or an SSD, the memory 41 may be a portable storage medium such as a CD (Compact Disc), a DVD (Digital Versatile Disc), or a flash memory, or a drive device that reads and writes various types of information from and to a semiconductor memory element such as a RAM. The storage area of ​​the memory 41 may be located within the X-ray CT apparatus 1 or in an external storage device connected to the X-ray CT apparatus 1 via a network. For example, the memory 41 stores various control programs in addition to image data such as CT images and display images.

[0032] The display 42 displays various information. For example, the display 42 displays medical images (CT images) generated by the processing circuitry 44 and a graphical user interface (GUI) for receiving various operations from the user. Examples of the display 42 include a liquid crystal display (LCD), a cathode ray tube (CRT) display, an organic electroluminescence display (OLED), and a plasma display. The display 42 may be provided on the gantry 10 or the bed 30 instead of the console device 40. The display 42 may be a desktop type, or may be a tablet terminal or the like capable of wireless communication with the console device 40.

[0033] The input interface 43 accepts various input operations from a user, converts the accepted input operations into electrical signals, and outputs the electrical signals to the processing circuitry 44. For example, the input interface 43 accepts acquisition conditions for acquiring imaging data, reconstruction conditions for reconstructing CT images, and image processing conditions for generating post-processed images from CT images. Examples of the input interface 43 include a mouse, keyboard, trackball, switch, button, joystick, touchpad, and touch panel display. Alternatively, the input interface 43 may be a device that receives electrical signals corresponding to input operations from an external input device provided separately from the X-ray CT apparatus 1 and outputs the electrical signals to the processing circuitry 44. The input interface 43 may be provided in the gantry 10 or the bed 30 instead of the console device 40. The input interface 43 may be a tablet terminal or the like that is capable of wireless communication with the console device 40.

[0034] The processing circuitry 44 controls the overall operation of the X-ray CT apparatus 1, depending or independent of the electrical signals of the input operation output from the input interface 43. For example, the processing circuitry 44 has a processor such as a CPU, MPU, or GPU, and memories such as a ROM and RAM as hardware resources. The processing circuitry 44 executes each function (e.g., a system control function 441, a preprocessing function 442, a reconstruction processing function 443, a display control function 444, an acquisition function 445, a calculation function 446, a determination function 447, an output function 448, and a movement control function 449) by a processor that executes a program expanded in the memory. Each function can be realized by at least one processor.

[0035] The system control function 441 controls each function of the processing circuitry 44. Specifically, the system control function 441 reads out a control program stored in the memory 41, expands it on the memory in the processing circuitry 44, and controls the X-ray CT apparatus 1 in accordance with the expanded control program.

[0036] The pre-processing function 442 performs pre-processing such as logarithmic conversion, offset correction, inter-channel sensitivity correction, and beam hardening correction on the imaging data output from the DAS 18 to generate corrected imaging data.

[0037] The reconstruction processing function 443 generates CT image data by performing reconstruction processing using the filtered back projection method (FBP method), iterative reconstruction method, etc. on the corrected imaging data generated by the preprocessing function 442.

[0038] The display control function 444 controls the display 42 to display information on the progress or results of each function or process of the processing circuit 44.

[0039] The acquisition function 445 acquires center of gravity position information indicating the center of gravity of the subject P before and after the top 33 on which the subject P is placed moves toward the gantry 10, and placement direction information indicating the direction of the subject P placed toward the gantry 10. The calculation function 446 calculates a change in the center of gravity of the subject P based on the center of gravity position information. The determination function 447 determines the risk of the subject P colliding with the gantry 10 based on the change in the center of gravity of the subject P and the placement direction information. If it is determined that there is a risk of the subject P colliding with the gantry 10, the output function 448 outputs an alert notifying the user of the risk. If it is determined that there is a risk of the subject P colliding with the gantry 10, the movement control function 449 stops the movement of the top 33.

[0040] The processing circuitry 44 also performs scan control processing and image processing. The scan control processing is processing for controlling various operations related to X-ray scanning, such as supplying high voltage to the X-ray high voltage device 14 and irradiating X-rays to the X-ray tube 11. The image processing is processing for converting CT image data generated by the reconstruction processing function 443 into tomographic image data or three-dimensional image data of an arbitrary cross section using a known method, based on input operations received from a user via the input interface 43. The processing circuitry 44 may be included in an integrated server that collectively processes data acquired from multiple medical image diagnostic devices, instead of the console device 40.

[0041] FIG. 2 is a side view showing an example of the configuration of the X-ray CT apparatus 1 according to the embodiment. Specifically, the figure shows the appearance of the X-ray CT apparatus 1 when the subject P is placed supine on the tabletop 33 and before the tabletop 33 starts to move. For convenience of explanation, the direction in which the tabletop 33 is carried into the gantry 10 is defined as "forward," and the direction in which the tabletop 33 is carried out of the gantry 10 is defined as "rearward." In other words, the direction in which the tabletop 33 approaches the gantry 10 corresponds to "forward," and the direction in which the tabletop 33 moves away from the gantry 10 corresponds to "rearward." In this case, the position of the center of gravity of the subject P on the tabletop 33 is represented as "G1." G1 is illustrated by a black dot located near the center (groin) of the subject P.

[0042] The bed device 30 is provided with at least one force sensor 500 capable of detecting the center of gravity of the subject P in real time. The force sensor 500 detects forces (mass, torque) in multiple directions and outputs an electrical signal corresponding to the detected force. The force sensor 500 may be connected to the console device 40 via wired or wireless communication to transmit the output electrical signal to the console device 40. The console device 40 detects or estimates the center of gravity of the subject P based on the transmitted electrical signal. The force sensor 500 may be, for example, a load cell, a piezoelectric element, or a displacement sensor. Note that any number of force sensors 500 may be installed at any location as long as they are capable of detecting the center of gravity of the subject P. In the example shown in FIG. 2, two force sensors 500 are installed near the end points of the X-links constituting the bed driving mechanism 32 and inside the support frame 34.

[0043] 3 is a diagram showing a first modified example of the installation location of the force sensor 500. In the example shown in FIG. 3, two force sensors 500 are installed between the floor surface and the base 31 and near the end of the base 31. Since the load of the bed apparatus 30 as well as the load of the subject P is applied to each force sensor 500, it is considered that the output of the force sensor 500 increases compared to the example in FIG. 2. In this case, the net output of the force sensor 500 based on the load of the subject P can be derived by subtracting the output of the force sensor 500 based on the load of the bed apparatus 30 from the increased output of the force sensor 500. The console device 40 may detect or estimate the position of the center of gravity of the subject P based on the net output of the force sensor 500.

[0044] FIG. 4 is a diagram showing a second modified example of the installation location of the force sensors 500. In the example shown in FIG. 4, a large number of force sensors 500 (seven in this figure) are installed inside the tabletop 33. Specifically, a large number of force sensors 500 are installed over an area encompassing the entire body of the subject P. Here, since the tabletop 33 is carried into the opening 19 of the gantry device 10, if a load cell containing metal or the like is used as the force sensor 500, artifacts may occur in the captured image. Therefore, when the force sensor 500 is installed inside the tabletop 33, an air tube containing no metal may be installed as the force sensor 500. The console device 40 may detect or estimate the center of gravity of the subject P based on changes in air pressure in the air tube or distortion of the air tube itself. Note that the force sensor 500 is not limited to being installed inside the tabletop 33, but may also be installed on the upper or lower surface of the tabletop 33.

[0045] 5 is a flow diagram showing an example of the operation of the X-ray CT apparatus 1 according to the embodiment. Before the first step S1 in this example of operation is performed, it is assumed that the subject P is already placed on the tabletop 33 and the tabletop 33 has not been moved. In other words, it is assumed that the subject P is placed in the state shown in FIGS. 2 to 4.

[0046] In step S1, the X-ray CT apparatus 1 accepts input of a scan plan. A "scan plan" refers to an imaging plan for X-ray CT imaging of a subject P, and specifically consists of various imaging conditions (e.g., tube voltage value, tube current value, slice thickness, pitch, scan time, total scan time, placement direction, and imaging region). The scan plan can be input by the user of the X-ray CT apparatus 1 via the input interface 43. Alternatively, the user may select a desired scan plan from multiple scan plans stored as presets in the memory 41.

[0047] The "placing direction" is information indicating the direction of the subject P placed toward the gantry 10. In general X-ray CT imaging, the subject P is assumed to be placed with his / her feet facing the gantry 10 (foot-first) or with his / her head facing the gantry 10 (head-first). Usually, when the subject P is placed in the feet-first manner, the gantry 10 will image the subject P from his / her toes to below the neck. On the other hand, when the subject P is placed in the head-first manner, the gantry 10 will image, for example, the head of the subject P. The feet-first manner is information indicating that the subject is placed with his / her feet facing the gantry 10, and the head-first manner is information indicating that the subject P is placed with his / her head facing the gantry 10. According to the examples of FIGS. 2 to 4, the subject P is placed in both the feet-first manner.

[0048] The "imaging region" is information indicating the region of the subject P that is to be imaged by the gantry device 10. The imaging region may be any anatomical region of the subject P (e.g., head, neck, chest, abdomen, waist, thighs, knees, lower legs, feet). The imaging region may also be a combination of these exemplified regions. The imaging region of a subject P placed in a feet-first manner is, for example, any anatomical region in the range from the toes to below the neck. On the other hand, the imaging region of a subject P placed in a head-first manner is, for example, the head.

[0049] In step S2, the X-ray CT apparatus 1 detects the position of the center of gravity of the subject P on the table 33 before the subject P is moved. Specifically, the X-ray CT apparatus 1 detects the position of the center of gravity of the subject P before the table 33 on which the subject P is placed is moved toward the gantry device 10. At this time, the X-ray CT apparatus 1 detects the position of the center of gravity of the subject P before the movement based on the output from the force sensor 500 installed on the bed device 30. According to the examples of FIGS. 2 to 4, the position of the center of gravity detected by executing this step corresponds to "G1."

[0050] In step S3, the X-ray CT apparatus 1 moves the top 33. Specifically, the X-ray CT apparatus 1 moves the top 33 on which the subject P is placed toward the gantry device 10. At this time, the X-ray CT apparatus 1 may move the top 33 by any amount (e.g., X cm). The amount of movement of the top 33 may be the same or different each time this step is executed. Note that it is assumed that the subject P will consciously or unconsciously change his / her posture while this step is being executed. It is assumed that the position of the center of gravity of the subject P will also change as the posture of the subject P changes.

[0051] In step S4, the X-ray CT apparatus 1 determines whether the tabletop 33 has been moved to a predetermined position. For example, the X-ray CT apparatus 1 determines whether the tabletop 33 has been moved so that the imaging area of ​​the subject P is within the imaging space of the gantry device 10. If the X-ray CT apparatus 1 has moved the tabletop 33 to the predetermined position (Yes in step S4), the process ends. Following the end of the process, the X-ray CT apparatus 1 may start imaging the subject P in accordance with the scan plan received in step S1. On the other hand, if the X-ray CT apparatus 1 has not moved the tabletop 33 to the predetermined position (No in step S4), the process proceeds to step S5.

[0052] In step S5, the X-ray CT apparatus 1 detects the position of the center of gravity of the object P on the table 33 after the object P has been moved. Specifically, the X-ray CT apparatus 1 detects the position of the center of gravity of the object P at the time after the table 33 on which the object P is placed has moved toward the gantry device 10 (i.e., the time after step S3 has been executed). At this time, the X-ray CT apparatus 1 detects the position of the center of gravity of the object P after the movement based on the output from the force sensor 500 installed on the bed device 30. According to the examples of Figs. 6 to 9 described later, the position of the center of gravity detected by executing this step corresponds to "G2" (a collective term for G2A and G2B) or "G3" (a collective term for G3A and G3B).

[0053] In step S6, the X-ray CT apparatus 1 calculates the change in the center of gravity of the subject P. Specifically, the X-ray CT apparatus 1 calculates the change in the center of gravity of the subject P based on the center of gravity position "G1" of the subject P before movement detected in step S2 and the center of gravity position "G2" or "G3" of the subject P after movement detected in step S5. At this time, the amount and direction of change in the center of gravity of the subject P can be calculated. Below, a method for calculating the change in the center of gravity position according to various postures when the subject P is placed will be described.

[0054] FIG. 6 is a diagram showing an example of a first posture of the subject P and a change in the center of gravity position. Specifically, the figure shows the appearance of the X-ray CT apparatus 1 after the tabletop 33 has moved a predetermined distance in the direction toward the gantry 10 (direction D1; Z-axis direction). The subject P is placed with his feet facing the gantry 10 (feet first), and is in a posture with his right leg extended and his left knee bent. Here, the height from the tabletop 33 to the top of the subject P's left knee exceeds the height from the tabletop 33 to the top end of the opening 19. Therefore, if the tabletop 33 is further moved in the direction D1, there is a risk that the left knee of the subject P will collide with the gantry 10 around the opening 19. Furthermore, the output of the force sensor 500 detects that the center of gravity of the subject P is at position "G2A."

[0055] First, the X-ray CT apparatus 1 estimates the position "G1'" of the center of gravity of the subject P after the movement of the tabletop 33 when the posture of the subject P has not changed. For example, the X-ray CT apparatus 1 estimates the position "G1'" by adding the amount of movement of the tabletop 33 moved in step S3 to the position "G1" of the center of gravity of the subject P before the movement of the tabletop 33 detected in step S2. G1' is illustrated by a white dot located near the center of the subject P (the base of the feet).

[0056] Next, the X-ray CT device 1 calculates the difference between the center of gravity positions "G1'" and "G2A". Because the subject P bends his left knee in a direction away from the gantry device 10, it is assumed that "G2A" moves backward compared to "G1'" (change in center of gravity position: G1' → G2A). In other words, the movement direction of the center of gravity of the subject P is calculated to be "backward". The X-ray CT device 1 regards the calculated difference as the change in the center of gravity position of the subject P before and after the movement of the tabletop 33.

[0057] 7 is a diagram showing an example of the second posture of the subject P and a change in the center of gravity position. The subject P is placed with his feet facing the gantry device 10 (feet first), and is in a posture with both legs extended and his head raised. Here, the height from the tabletop 33 to the top of the subject P's head exceeds the height from the tabletop 33 to the top end of the opening 19. Furthermore, the output of the force sensor 500 detects that the center of gravity of the subject P is at position "G3A."

[0058] Using a method similar to the example in FIG. 6, the X-ray CT device 1 estimates the position of "G1'". Next, the X-ray CT device 1 calculates the difference between the center of gravity positions "G1'" and "G3A". Because the subject P has raised his head in a direction approaching the gantry device 10, it is assumed that "G3A" moves forward compared to "G1'" (change in center of gravity position: G1' → G3A). In other words, the movement direction of the center of gravity of the subject P is calculated to be "forward". The X-ray CT device 1 regards the calculated difference as the change in the center of gravity position of the subject P before and after the movement of the tabletop 33.

[0059] 8 is a diagram showing an example of a third posture of the subject P and a change in the center of gravity position. The subject P is placed with his head facing the gantry device 10 (head first), and assumes a posture with his left leg extended and his right knee bent. Here, the height from the tabletop 33 to the top of the subject P's right knee exceeds the height from the tabletop 33 to the top edge of the opening 19. Furthermore, the output of the force sensor 500 detects that the center of gravity of the subject P is at the position "G2B."

[0060] Using a method similar to the example in FIG. 6, the X-ray CT device 1 estimates the position of "G1'". Next, the X-ray CT device 1 calculates the difference between the center of gravity positions "G1'" and "G2B". Because the subject P has raised his right knee in a direction approaching the gantry device 10, it is assumed that "G2B" moves forward compared to "G1'" (change in center of gravity position: G1' → G2B). In other words, the movement direction of the center of gravity of the subject P is calculated to be "forward". The X-ray CT device 1 regards the calculated difference as the change in the center of gravity position of the subject P before and after the movement of the tabletop 33.

[0061] 9 is a diagram showing an example of the fourth posture of the subject P and a change in the center of gravity position. The subject P is placed with his head facing the gantry 10 (head first), and is in a posture with his legs stretched and his head raised. Here, the height from the tabletop 33 to the top of the subject P's head exceeds the height from the tabletop 33 to the top edge of the opening 19. Therefore, if the tabletop 33 is further moved in the direction D1, there is a risk that the subject P's head will collide with the gantry 10 around the opening 19. Furthermore, the output of the force sensor 500 detects that the center of gravity of the subject P is at the position "G3B."

[0062] Using a method similar to the example in FIG. 6, the X-ray CT device 1 estimates the position of "G1'". Next, the X-ray CT device 1 calculates the difference between the center of gravity positions "G1'" and "G3B". Because the subject P has raised his head in a direction away from the gantry device 10, it is assumed that "G3B" moves backward compared to "G1'" (change in center of gravity position: G1' → G3B). In other words, the movement direction of the center of gravity of the subject P is calculated to be "backward". The X-ray CT device 1 regards the calculated difference as the change in the center of gravity position of the subject P before and after the movement of the tabletop 33.

[0063] In step S7, the X-ray CT apparatus 1 determines whether the center of gravity of the subject P has changed. For example, the X-ray CT apparatus 1 determines whether the change in the center of gravity of the subject P calculated in step S6 is equal to or greater than a predetermined threshold. If the change in the center of gravity is equal to or greater than the threshold, the X-ray CT apparatus 1 determines that the center of gravity of the subject P has changed. On the other hand, if the change in the center of gravity is less than the threshold, the X-ray CT apparatus 1 determines that the center of gravity of the subject P has not changed. If the center of gravity of the subject P has changed (Yes in step S7), the process proceeds to step S8. On the other hand, if the center of gravity of the subject P has not changed (No in step S7), the process returns to step S3. The change in the center of gravity may be the amount of change in the center of gravity. Furthermore, the threshold may be set to the amount of change in the center of gravity when a risk of the subject P colliding with the gantry 10 first occurs. In other words, if the center of gravity of the subject P changes until it reaches the threshold, the subject P will collide with the gantry 10.

[0064] In step S8, the X-ray CT apparatus 1 refers to the scan plan. Specifically, the X-ray CT apparatus 1 refers to the scan plan received in step S1. For example, the X-ray CT apparatus 1 refers to the "placing direction" and "imaged region" included in the scan plan.

[0065] In step S9, the X-ray CT apparatus 1 determines whether the subject P is placed head-first or feet-first and the center of gravity has moved backward. Specifically, the X-ray CT apparatus 1 determines whether the subject P is placed head-first or feet-first, based on the information about the "placement direction" referenced in step S8. At the same time, the X-ray CT apparatus 1 determines whether the subject P's center of gravity has moved backward, based on the change in the subject P's center of gravity calculated in step S6. If this determination condition is met (Yes in step S9), the process proceeds to step S10. On the other hand, if this determination condition is not met (No in step S9), the process returns to step S3.

[0066] In other words, in step S9, the X-ray CT apparatus 1 estimates a change in the posture of the subject P (i.e., whether the head is raised or not, whether the knees are bent or not) based on the placement direction information indicating the direction in which the subject P is placed and the movement direction of the center of gravity of the subject P. Furthermore, the X-ray CT apparatus 1 determines the risk of the subject P colliding with the gantry device 10 based on the estimated change in the posture of the subject P.

[0067] 10 is a diagram showing an example of a table 100 related to collision risk determination. The X-ray CT apparatus 1 may determine the collision risk by referring to the table 100. The table 100 shows the posture of the subject P estimated according to various combinations of placement direction information (foot first or head first) included in the scan plan and the calculated movement direction of the center of gravity of the subject P (forward or backward). Furthermore, the table 100 is associated with the presence or absence of a collision risk (yes or no) according to the posture of the subject P. The table 100 may be stored in the memory 41.

[0068] First, assume that the scan plan is "feet first" and the direction of movement of the center of gravity is "backward" (as in FIG. 6). Based on this information, the X-ray CT device 1 estimates that the subject P is placed with his feet facing the gantry device 10 and that at least one knee is bent. In this case, the X-ray CT device 1 determines that there is a collision risk.

[0069] Secondly, assume that the scan plan is "feet first" and the direction of movement of the center of gravity is "forward" (as in FIG. 7). Based on this information, the X-ray CT device 1 estimates that the subject P is placed with his feet facing the gantry device 10 and has raised his head. In this case, the X-ray CT device 1 determines that there is no risk of collision. Since the subject P can visually confirm that the gantry device 10 is approaching him as the tabletop 33 moves, it is assumed that the subject P can avoid a collision by his own judgment.

[0070] Thirdly, assume that the scan plan is "head first" and the direction of movement of the center of gravity is "forward" (as in FIG. 8). Based on this information, the X-ray CT device 1 estimates that the subject P is placed with his head facing the gantry device 10 and has at least one knee bent. In this case, the X-ray CT device 1 determines that there is no risk of collision.

[0071] Fourth, assume that the scan plan is "head first" and the direction of movement of the center of gravity is "backward" (as in FIG. 9). Based on this information, the X-ray CT device 1 estimates that the subject P is placed with his / her head facing the gantry device 10 and has raised his / her head. In this case, the X-ray CT device 1 determines that there is a collision risk.

[0072] In step S10, the X-ray CT apparatus 1 outputs an alert. Specifically, if it is determined in step S9 that there is a risk of the subject P colliding with the gantry device 10, the X-ray CT apparatus 1 outputs an alert notifying that the risk exists. The alert may be displayed on the display 42. At this time, the X-ray CT apparatus 1 may also issue a warning sound at the same time as the alert is displayed. After step S10 is executed, the processing returns to step S3.

[0073] Instead of step S10, the X-ray CT apparatus 1 may stop the movement of the top 33. In this case, the process does not need to return to step S3 and may end. Of course, the X-ray CT apparatus 1 may stop the movement of the top 33 at the same time as issuing the above-mentioned alert.

[0074] The X-ray CT apparatus 1 according to the embodiment has been described above. The X-ray CT apparatus 1 having such a configuration can detect or estimate a change in the posture of the subject P based on the scan plan and a change in the center of gravity of the subject P, even if the subject P is located in a blind spot that may occur near the opening 19 of the gantry 10. Furthermore, the X-ray CT apparatus 1 can determine the risk of the subject P colliding with the gantry 10 based on the estimated change in the posture of the subject P. Furthermore, if such a risk exists, the X-ray CT apparatus 1 can issue an alert or halt the loading of the subject P onto the gantry 10. In response to the issued alert, the user of the X-ray CT apparatus 1 can stop the movement of the top 33. Therefore, the X-ray CT apparatus 1 can prevent the subject P from colliding with the gantry 10 without impairing usability for the user.

[0075] (Other variations) The X-ray CT apparatus 1 according to the modified example may determine the collision risk further based on information relating to the imaging region (imaging region information). In other words, the X-ray CT apparatus 1 may determine the collision risk based on a change in the center of gravity position of the subject P, placement direction information, and imaging region information. By further referring to the imaging region information, the X-ray CT apparatus 1 can determine the risk of the subject P colliding with the gantry device 10 in more detail.

[0076] First, assume that the change in the center of gravity position of the subject P is a change in the direction away from the gantry 10 (backward), the placement direction is feet-first, and the imaging region includes the knees of the subject P (as in FIG. 6 ). Based on this information, the X-ray CT apparatus 1 estimates that the subject P is placed with his feet facing the gantry 10 and that at least one knee is bent. Furthermore, because the knees are included in the imaging region, the X-ray CT apparatus 1 estimates that the knees of the subject P will collide with the gantry 10 when the subject P is carried into the gantry 10. Therefore, the X-ray CT apparatus 1 determines that there is a collision risk. Conversely, if the imaging region does not include the knees of the subject P under the above conditions, the X-ray CT apparatus 1 determines that there is no collision risk. For example, if the imaging region is a region (e.g., a foot) closer to the gantry 10 than the knees of the subject P, the X-ray CT apparatus 1 determines that there is no collision risk.

[0077] Secondly, assume that the change in the center of gravity position of the subject P is a change in the direction (forward) approaching the gantry 10, the subject is placed in a head-first orientation, and the imaging region includes the knees of the subject P (as in FIG. 8 ). Based on this information, the X-ray CT apparatus 1 estimates that the subject P is placed with his / her head facing the gantry 10 and that at least one knee is bent. Furthermore, because the knees are included in the imaging region, the X-ray CT apparatus 1 estimates that the knees of the subject P will collide with the gantry 10 when the subject P is carried into the gantry 10. Therefore, the X-ray CT apparatus 1 determines that there is a collision risk. Conversely, if the imaging region does not include the knees of the subject P under the above conditions, the X-ray CT apparatus 1 determines that there is no collision risk. For example, if the imaging region is a region (such as the head, neck, chest, abdomen, waist, or thigh) closer to the gantry device 10 than the knees of the subject P, the X-ray CT apparatus 1 determines that there is no collision risk.

[0078] The X-ray CT apparatus 1 according to another modification may calculate the change in the center of gravity position before and after the movement of the subject P using a machine learning model (related to step S6). Such a machine learning model may be trained using training data in which, for example, the change in the output of the force sensor 500 when various subjects P with different physiques change their posture is used as input data, and the change in the center of gravity position corresponding to the above cases is used as correct answer data. The machine learning model may be, for example, a deep learning-based model. The X-ray CT apparatus 1 can calculate the change in the center of gravity position for various subjects P by using the trained machine learning model.

[0079] In yet another modified example, the X-ray CT apparatus 1 may set the function for detecting the center of gravity of the subject P to "off" by switching the force sensor 500 from an active state to an inactive state under specific conditions. The specific conditions include, for example, a case where the X-ray CT apparatus 1 is imaging the dynamics of the subject P's knee joint, etc. In this case, the subject P is expected to repeatedly bend his knee. Therefore, if the function is "on," there is a concern that unnecessary alerts may be issued or the subject P's movement may be stopped. Therefore, the X-ray CT apparatus 1 can avoid the above-mentioned unnecessary actions by setting the function to "off." Additionally, the X-ray CT apparatus 1 may set the function to "off" even when imaging the subject P using a restraint device that restricts the subject P from changing his / her posture. The X-ray CT apparatus 1 may also display on the display 42 whether the function is "on" or "off."

[0080] According to at least one of the embodiments described above, it is possible to prevent a collision between a moving subject and a gantry device.

[0081] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, modifications, and combinations of embodiments can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0082] 1 X-ray CT device 10 Mounting device 11 X-ray tube 12 Detectors 13 Rotating Frame 14 X-ray high voltage device 15 Control device 16 Wedge 17 Collimator 18 DAS 19 Aperture 30 Bed Device 31 Foundation 32 Bed drive mechanism 33 Top plate 34 Support frame 40 Console device 41 memory 42 Display 43 Input Interface 44 Processing circuit 100 tables 441 System Control Functions 442 Pre-processing function 443 Reconstruction Processing Function 444 Display Control Function 445 Acquisition Function 446 Calculation Function 447 Judgment Function 448 Output Function 449 Movement Control Function 500 Force Sensor

Claims

1. an acquisition unit that acquires center-of-gravity position information indicating the center-of-gravity position of the subject before and after a top board on which the subject is placed moves toward a gantry device, and placement direction information indicating the direction of the subject placed toward the gantry device; a calculation unit that calculates a position change related to the center of gravity of the subject based on the center of gravity position information; a determination unit that determines a risk of the subject colliding with the gantry device based on the position change and the placement direction information; an output unit that, when it is determined that the risk exists, outputs an alert notifying that the risk exists; A medical image diagnostic device comprising:

2. an acquisition unit that acquires center-of-gravity position information indicating the center-of-gravity position of the subject before and after a top board on which the subject is placed moves toward a gantry device, and placement direction information indicating the direction of the subject placed toward the gantry device; a calculation unit that calculates a position change related to the center of gravity of the subject based on the center of gravity position information; a determination unit that determines a risk of the subject colliding with the gantry device based on the position change and the placement direction information; a movement control unit that stops the movement of the tabletop when it is determined that the risk exists; A medical image diagnostic device comprising:

3. An acquisition unit that acquires center of gravity position information indicating the center of gravity position of the subject at each point before and after the top plate on which the subject is placed moves toward the gantry device, placement direction information indicating the direction of the subject placed toward the gantry device, and imaging part information indicating the part of the subject that will be imaged by the gantry device; a calculation unit that calculates a position change related to the center of gravity of the subject based on the center of gravity position information; a determination unit that determines a risk of the subject colliding with the gantry device based on the position change, the placement direction information, and the imaging region information; an output unit that, when it is determined that the risk exists, outputs an alert notifying that the risk exists; A medical image diagnostic device comprising:

4. An acquisition unit that acquires center of gravity position information indicating the center of gravity position of the subject at each point before and after the top plate on which the subject is placed moves toward the gantry device, placement direction information indicating the direction of the subject placed toward the gantry device, and imaging part information indicating the part of the subject that will be imaged by the gantry device; a calculation unit that calculates a position change related to the center of gravity of the subject based on the center of gravity position information; a determination unit that determines a risk of the subject colliding with the gantry device based on the position change, the placement direction information, and the imaging region information; a movement control unit that stops the movement of the tabletop when it is determined that the risk exists; A medical image diagnostic device comprising:

5. the determination unit determines that the risk exists when the position change is a change in a direction away from the gantry device and the placement direction information is information indicating that the subject is placed with the head or feet facing the gantry device. The medical image diagnostic apparatus according to any one of claims 1 to 4.

6. the determination unit determines that the risk does not exist when the position change is a change in a direction approaching the gantry device and the placement direction information is information indicating that the subject is placed with the head or feet facing the gantry device. The medical image diagnostic apparatus according to any one of claims 1 to 5.

7. the acquisition unit acquires imaging region information indicating a region of the subject to be imaged by the gantry device; the determination unit determines the risk based on the position change, the placement direction information, and the imaging region information.

3. The medical image diagnostic apparatus according to claim 1.

8. the determination unit determines that the risk exists when the position change is a change in a direction away from the gantry, the placement direction information is information indicating that the subject is placed with the feet facing the gantry, and the imaging region information includes the knees of the subject.

8. The medical image diagnostic apparatus according to claim 3, claim 4 or claim 7.

9. the determination unit determines that the risk does not exist when the position change is a change in a direction away from the gantry device, the placement direction information is information indicating that the subject is placed with the feet facing the gantry device, and the imaging region information does not include the knees of the subject.

9. The medical image diagnostic apparatus according to claim 3, claim 4, claim 7 or claim 8.

10. the determination unit determines that the risk exists when the position change is a change in a direction approaching the gantry device, the placement direction information is information indicating that the subject is placed with the head facing the gantry device, and the imaging region information includes the knee of the subject.

10. The medical image diagnostic apparatus according to claim 3, claim 4, claim 7, claim 8 or claim 9.

11. the determination unit determines that the risk does not exist when the position change is a change in a direction approaching the gantry device, the placement direction information is information indicating that the subject is placed with the head facing the gantry device, and the imaging region information does not include the knees of the subject.

11. The medical image diagnostic apparatus according to claim 3, 4, 7, 8, 9 or 10.

12. the center-of-gravity position information is acquired by at least one sensor installed in a bed device including the tabletop; The medical image diagnostic apparatus according to any one of claims 1 to 11.

13. The sensor is a load cell, a piezoelectric element, a displacement sensor, or an air tube. The medical image diagnostic apparatus according to claim 12.

14. An acquisition unit that acquires center of gravity position information indicating the center of gravity position of the subject at each point before and after the top plate on which the subject is placed moves toward the gantry device, and placement direction information indicating the direction of the subject placed toward the gantry device; a calculation unit that calculates a moving direction of the center of gravity of the subject based on the center of gravity position information; determining that there is a risk that the subject will collide with the gantry when it is estimated that a part of the subject that is close to the gantry has risen based on the placement orientation information and the movement direction; a determination unit that determines that the risk does not exist when it is estimated that a part of the subject farthest from the gantry device has risen based on the placement orientation information and the movement direction; If it is determined that the risk exists, the movement of the top plate is stopped, a movement control unit that continues the movement of the tabletop when it is determined that the risk does not exist; A medical image diagnostic device comprising:

15. an acquisition unit that acquires center-of-gravity position information indicating the center-of-gravity position of the subject before and after a top board on which the subject is placed moves toward a gantry device, and placement direction information indicating the direction of the subject placed toward the gantry device; a calculation unit that calculates a position change related to the center of gravity of the subject based on the center of gravity position information; a determination unit that determines a risk of the subject colliding with the gantry device based on the position change and the placement direction information; an output unit that, when it is determined that the risk exists, outputs an alert notifying that the risk exists; An X-ray CT device comprising:

16. acquire center-of-gravity position information indicating the center-of-gravity position of the subject before and after the top board on which the subject is placed moves toward a gantry device, and placement direction information indicating the direction of the subject placed toward the gantry device; calculating a position change related to the center of gravity of the subject based on the center of gravity position information; determining a risk of the subject colliding with the gantry device based on the position change and the placement direction information; If it is determined that the risk exists, an alert is output to notify the user that the risk exists. Control method.

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