JP7813554B2 - Medical image diagnostic device, X-ray CT device, and control method - Google Patents

Description

The embodiments disclosed in this specification and drawings relate to a medical image diagnostic device, an X-ray CT device, and a control method.

Generally, in medical imaging diagnostic equipment equipped with a gantry and a bed, the gantry has a mechanism for imaging the 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 their posture while moving to the gantry (e.g., lifting their head or bending their knees), and depending on their posture, they may collide with the gantry around the opening and be injured. Therefore, a system is needed to prevent collisions between the subject and the gantry during movement.

To prevent collisions, one method is to detect 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 if the subject is located in the camera's blind spot, such as near the opening of the gantry. In light of this situation, there is a particular need for a system that can detect or estimate the posture of the subject without relying on optical equipment such as a camera, and prevent collisions between the subject and the gantry while it is moving.

International Publication No. 2010/143487

One of the problems that the embodiments disclosed in this specification and drawings attempt to solve is preventing collisions between a moving subject and a gantry. However, the problems that the embodiments disclosed in this specification and drawings attempt to solve are not limited to the above problem. Problems corresponding to the effects of each configuration shown in the embodiments described below can also be positioned as other problems.

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 tabletop 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 the 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.

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

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

Figure 1 is a block diagram showing an example configuration of an X-ray CT device 1 according to an embodiment. The X-ray CT device 1 is an example of a medical imaging diagnostic device equipped with a gantry device and a bed device. Other examples of such medical imaging diagnostic devices include magnetic resonance imaging (MRI) devices and radioisotope (RI) devices (e.g., single photon emission computed tomography (SPECT) devices and positron emission tomography (PET) devices).

The X-ray CT system 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 wired or wireless communication so that they can communicate with each other.

(mounting device)
The gantry 10 is a scanning device having a mechanism for performing X-ray CT imaging of a subject P. The gantry 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).

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.

The X-ray tube 11 is a vacuum tube that generates X-rays by applying high voltage from the X-ray high-voltage device 14 and supplying filament current, causing thermions to collide from the cathode (filament) toward the anode (target). 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 via the collimator 17 and then irradiated onto the subject P.

The detector 12 detects X-rays that have passed 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 array in which multiple 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 array structure in which multiple X-ray detection element arrays in the channel direction are arranged in the slice direction (row direction; Z-axis direction).

The rotating frame 13 is an annular frame that supports the X-ray tube 11 and detector 12 facing each other and rotatably around 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 at a constant angular velocity around the rotation axis Z.

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

The X-ray high-voltage device 14 has electrical circuits such as a transformer and rectifier, and includes a high-voltage generator that generates the high voltage applied to the X-ray tube 11 and the filament current supplied to the X-ray tube 11, and an X-ray control device that controls the output voltage according to the X-rays emitted by the X-ray tube 11. The high-voltage generator may be 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.

The control device 15 has a processing circuit and drive mechanisms such as motors and actuators. The processing circuit has hardware resources such as a processor such as a CPU (Central Processing Unit) or MPU (Micro Processing Unit), and memory such as ROM (Read Only Memory) or RAM (Random Access Memory). The control device 15 can 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, X-ray high-voltage device 14, DAS 18, etc. in accordance with commands from the console device 40.

In this embodiment, the control device 15 receives input signals from the 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 input signals 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 achieved 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 via 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.

The wedge 16 is a filter that adjusts the amount of X-rays emitted from the X-ray tube 11. Specifically, the wedge 16 transmits and attenuates the X-rays emitted 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 thickness.

The collimator 17 is a lead plate or the like that narrows the irradiation range of the X-rays that have passed through the wedge 16. The collimator 17 has a slit formed by combining multiple lead plates or the like.

When the detector 12 is an integral detector, the DAS 18 reads out electrical signals from the detector 12 and generates digital data (i.e., imaging data) relating to the X-ray dose detected by the detector 12 based on the read electrical signals. 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 column number, the view number indicating the acquired view (projection angle), and the integrated value of the detected X-ray dose.

When the detector 12 is a photon-counting detector, the DAS 18 generates imaging data indicating the count values of X-ray photons detected by the detector 12 for each of multiple energy bands. In this case, the imaging data is a set of data indicating the 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.

(bed device)
The bed device 30 is a device that moves the subject P in any axial direction (X-axis, Y-axis, Z-axis) on which the subject P is placed. 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.

The base 31 is a structure that mounts and supports the bed drive mechanism 32, tabletop 33, and support frame 34. Specifically, the bed drive mechanism 32 is mounted on top of the base 31, the support frame 34 is mounted on top of the bed drive mechanism 32, and the tabletop 33 is mounted on 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.

The bed drive 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 drive mechanism 32 generates power by driving at a rotational speed that corresponds to the duty ratio, etc., of the drive signal supplied from the control device 15, and uses the generated power to move the tabletop 33. The bed drive mechanism 32 includes motors such as direct drive motors and servo motors for generating the power. Furthermore, the bed drive mechanism 32 includes an X-shaped structure (X-link) that supports the support frame 34 so that it can move in the vertical direction (Y-axis direction).

In this embodiment, the bed driving mechanism 32 moves the top plate 33 in each axial direction so that the body axis of the subject P placed on the top plate 33 coincides with the central axis of the opening 19 in the rotating frame 13. The bed driving mechanism 32 also moves the top plate 33 in the longitudinal direction (Z-axis direction) in conjunction with X-ray CT imaging performed by the gantry device 10. The bed driving mechanism 32 may also move the support frame 34 in each axial direction in addition to the top plate 33.

The top plate 33 is a flat structure on which the subject P rests. The top plate 33 may be made of an elastic material such as urethane.

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.

(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. At least a part of the components may be included in the gantry device 10 or the bed device 30.

Memory 41 is a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or integrated circuit storage device that stores various information. Memory 41 stores, for example, imaging data and reconstructed image data. In addition to an HDD or SSD, memory 41 may also be a drive device that reads and writes various information to portable storage media such as CDs (Compact Discs), DVDs (Digital Versatile Discs), and flash memory, or semiconductor memory elements such as RAM. The storage area of memory 41 may be located within the X-ray CT device 1, or in an external storage device connected to the X-ray CT device 1 via a network. For example, memory 41 stores various control programs in addition to image data such as CT images and display images.

The display 42 displays various information. For example, the display 42 displays medical images (CT images) generated by the processing circuitry 44 and a GUI (Graphical User Interface) for accepting 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 (OELD), 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.

The input interface 43 accepts various input operations from the user, converts the accepted input operations into electrical signals, and outputs them to the processing circuitry 44. For example, the input interface 43 accepts acquisition conditions when acquiring imaging data, reconstruction conditions when reconstructing CT images, and image processing conditions when 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 device 1 and outputs the electrical signals to the processing circuitry 44. The input interface 43 may be provided in the gantry device 10 or the bed device 30 instead of the console device 40. The input interface 43 may also be a tablet terminal or the like that is capable of wireless communication with the console device 40.

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

The system control function 441 controls each function of the processing circuitry 44. Specifically, the system control function 441 reads the control program stored in the memory 41, expands it into the memory within the processing circuitry 44, and controls the X-ray CT device 1 in accordance with the expanded control program.

The pre-processing function 442 generates corrected imaging data by performing 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.

The reconstruction processing function 443 generates CT image data by performing reconstruction processing using filtered back projection (FBP) or iterative reconstruction methods on the corrected imaging data generated by the preprocessing function 442.

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

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 the 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.

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

Figure 2 is a side view showing an example configuration of an X-ray CT system 1 according to an embodiment. Specifically, the external appearance of the X-ray CT system 1 is shown when the subject P is placed supine on the tabletop 33 and before the tabletop 33 begins to move. For ease 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 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 of the subject P (the base of the feet).

At least one force sensor 500 capable of detecting the center of gravity of the subject P in real time is installed on the bed device 30. 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 transmits the output electrical signal to the console device 40, so it need only be connected to the console device 40 via wired or wireless communication. 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 that make up the bed drive mechanism 32 and inside the support frame 34.

Figure 3 is a diagram showing a first modified example regarding the installation location of the force sensors 500. In the example shown in Figure 3, two force sensors 500 are installed between the floor surface and the base 31, near the end of the base 31. Since the load of the bed device 30 as well as the load of the subject P is applied to each force sensor 500, it is expected that the output of the force sensors 500 will increase compared to the example in Figure 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 device 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.

Figure 4 shows a second modified example regarding the installation location of the force sensors 500. In the example shown in Figure 4, multiple force sensors 500 (seven in this figure) are installed inside the tabletop 33. Specifically, multiple 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, using a load cell containing metal as the force sensor 500 may result in artifacts in the captured image. Therefore, when installing the force sensor 500 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 such force sensors 500 are not limited to being installed inside the tabletop 33, but may also be installed on the top or bottom surface of the tabletop 33.

Figure 5 is a flow diagram showing an example of the operation of the X-ray CT device 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 that the tabletop 33 has not been moved. In other words, it is assumed that the subject P is placed in the state shown in Figures 2 to 4.

In step S1, the X-ray CT device 1 accepts input of a scan plan. A "scan plan" refers to an imaging plan for X-ray CT imaging of the 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 area). The scan plan can be input by the user of the X-ray CT device 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.

"Placement direction" is information indicating the direction in which the subject P is placed toward the gantry 10. In typical X-ray CT imaging, the subject P may be placed with their feet facing the gantry 10 (foot-first), or with their head facing the gantry 10 (head-first). Typically, when the subject P is placed feet-first, the gantry 10 will image the subject P from their toes to below their neck. On the other hand, when the subject P is placed head-first, the gantry 10 will image, for example, the subject P's head. "Foot-first" is information indicating that the subject is placed with their feet facing the gantry 10, and "head-first" is information indicating that the subject is placed with their head facing the gantry 10. In the examples of Figures 2 to 4, the subject P is placed in both feet-first positions.

The "imaging region" is information indicating the region of the subject P that will be imaged by the gantry device 10. The imaging region can be any anatomical region of the subject P (e.g., head, neck, chest, abdomen, lower back, 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 position is, for example, any anatomical region ranging from the toes to below the neck. On the other hand, the imaging region of a subject P placed in a head-first position is, for example, the head.

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

In step S3, the X-ray CT device 1 moves the top plate 33. Specifically, the X-ray CT device 1 moves the top plate 33, on which the subject P is placed, toward the gantry device 10. At this time, the X-ray CT device 1 may move the top plate 33 by any desired distance (e.g., X cm). The distance the top plate 33 moves may be the same or different each time this step is performed. Note that it is expected that the subject P will consciously or unconsciously change their posture while this step is being performed. It is expected that the position of the center of gravity of the subject P will also change as the posture of the subject P changes.

In step S4, the X-ray CT device 1 determines whether the top 33 has been moved to a predetermined position. For example, the X-ray CT device 1 determines whether the top 33 has been moved until the imaging area of the subject P is within the imaging space of the gantry device 10. If the X-ray CT device 1 has moved the top 33 to the predetermined position (Yes in step S4), the process ends. Following the end of the process, the X-ray CT device 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 device 1 has not moved the top 33 to the predetermined position (No in step S4), the process proceeds to step S5.

In step S5, the X-ray CT system 1 detects the position of the center of gravity of the subject P on the table 33 after the subject P has been moved. Specifically, the X-ray CT system 1 detects the position of the center of gravity of the subject P after the table 33 on which the subject P is placed has moved toward the gantry 10 (i.e., after step S3 has been executed). At this time, the X-ray CT system 1 detects the position of the center of gravity of the subject P after the movement based on the output from the force sensor 500 installed on the bed 30. According to the examples in Figures 6 to 9 described below, 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).

In step S6, the X-ray CT device 1 calculates the change in the center of gravity of the subject P. Specifically, the X-ray CT device 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, we will show how to calculate the change in the center of gravity position according to various postures when the subject P is placed.

Figure 6 shows an example of the first posture of subject P and a change in the center of gravity. Specifically, it shows the appearance of the X-ray CT scanner 1 after the tabletop 33 has moved a predetermined distance in the direction toward the gantry 10 (direction D1; Z-axis direction). Subject P is placed with his feet facing the gantry 10 (foot-first), and his right leg is extended and his left knee is bent. Here, the height from the tabletop 33 to the apex of subject P's left knee exceeds the height from the tabletop 33 to the top edge of the opening 19. Therefore, if the tabletop 33 is moved further in the direction D1, there is a risk that subject P's left knee 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 subject P is at position "G2A."

First, the X-ray CT device 1 estimates the center of gravity position "G1'" of the subject P after the top 33 has been moved, assuming that the subject P's posture has not changed. For example, the X-ray CT device 1 estimates the position of "G1'" by adding the center of gravity position "G1" of the subject P before the top 33 was moved, detected in step S2, to the amount of movement of the top 33 moved in step S3. G1' is illustrated by a white dot located near the center of the subject P (the base of the feet).

Next, the X-ray CT system 1 calculates the difference between the center of gravity positions "G1'" and "G2A". Because the subject P has bent his left knee in a direction away from the gantry device 10, it is assumed that "G2A" has moved further backward than "G1'" (change in center of gravity position: G1' → G2A). In other words, the movement direction of the subject P's center of gravity is calculated to be "backward". The X-ray CT system 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.

Figure 7 shows an example of the second posture of subject P and a change in the center of gravity position. 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 subject P's head 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 subject P is at position "G3A."

Using a method similar to the example in Figure 6, the X-ray CT system 1 estimates the position of "G1'". Next, the X-ray CT system 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" has moved forward compared to "G1'" (change in center of gravity position: G1' → G3A). In other words, the movement direction of the subject P's center of gravity is calculated to be "forward". The X-ray CT system 1 considers the calculated difference to be the change in the center of gravity position of the subject P before and after the movement of the tabletop 33.

Figure 8 shows an example of a third posture of subject P and a change in the center of gravity. 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 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 subject P is at position "G2B."

Using a method similar to the example in Figure 6, the X-ray CT system 1 estimates the position of "G1'". Next, the X-ray CT system 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 subject P's center of gravity is calculated to be "forward". The X-ray CT system 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.

Figure 9 shows an example of the fourth posture of subject P and a change in the center of gravity. Subject P is placed with his head facing the gantry 10 (head first), and his legs are stretched and his head raised. Here, the height from the tabletop 33 to the top of 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 moved further in the D1 direction, there is a risk that 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 subject P is at position "G3B."

Using a method similar to the example in Figure 6, the X-ray CT system 1 estimates the position of "G1'". Next, the X-ray CT system 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" has moved further backward than "G1'" (change in center of gravity position: G1' → G3B). In other words, the movement direction of the subject P's center of gravity is calculated to be "backward". The X-ray CT system 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.

In step S7, the X-ray CT device 1 determines whether the center of gravity of the subject P has changed. For example, the X-ray CT device 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 device 1 considers 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 device 1 considers 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 above threshold may be set to the amount of change in the center of gravity when the risk of the subject P colliding with the gantry device 10 first occurs. In other words, if the subject P changes its center of gravity until it reaches this threshold, the subject P will collide with the gantry device 10.

In step S8, the X-ray CT device 1 references the scan plan. Specifically, the X-ray CT device 1 references the scan plan received in step S1. For example, the X-ray CT device 1 references the "placement direction" and "area to be imaged" included in the scan plan.

In step S9, the X-ray CT device 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 device 1 determines whether the subject P is placed head-first or feet-first, based on the information regarding the "placement direction" referenced in step S8. At the same time, the X-ray CT device 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.

In other words, in step S9, the X-ray CT device 1 estimates changes 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 direction in which the center of gravity of the subject P is moving. Furthermore, the X-ray CT device 1 determines the risk of the subject P colliding with the gantry device 10 based on the estimated changes in the posture of the subject P.

Figure 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 the 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.

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

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

Thirdly, assume that the scan plan is "head first" and the center of gravity is moving "forward" (as in Figure 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 that at least one knee is bent. In this case, the X-ray CT device 1 determines that there is no risk of collision.

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

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

Instead of step S10, the X-ray CT device 1 may stop moving 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 device 1 may stop moving the top 33 at the same time as issuing the above-mentioned alert.

The above describes the X-ray CT system 1 according to an embodiment. With this configuration, even if the subject P is located in a blind spot that may occur near the opening 19 of the gantry 10, the X-ray CT system 1 can detect or estimate a change in the subject P's posture based on the scan plan and changes in the center of gravity of the subject P. Furthermore, the X-ray CT system 1 can determine the risk of the subject P colliding with the gantry 10 based on the estimated change in the subject P's posture. Furthermore, if such a risk exists, the X-ray CT system 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 system 1 can stop the movement of the top 33. Therefore, the X-ray CT system 1 can prevent the subject P from colliding with the gantry 10 without impairing usability.

(Other modified examples)
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.

First, assume that the change in the center of gravity of subject P is in the direction away from the gantry 10 (rearward), that the subject is placed feet-first, and that the imaging region includes the subject P's knees (as in Figure 6). Based on this information, the X-ray CT scanner 1 estimates that 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 scanner 1 estimates that the subject P's knees will collide with the gantry 10 when the subject P is carried into the gantry 10. Therefore, the X-ray CT scanner 1 determines that there is a collision risk. Conversely, if the imaging region does not include the subject P's knees under the above conditions, the X-ray CT scanner 1 determines that there is no collision risk. For example, if the imaging region is closer to the gantry 10 than the subject P's knees (e.g., the feet), the X-ray CT scanner 1 determines that there is no collision risk.

Secondly, assume that the change in the center of gravity of subject P is in the direction (forward) approaching the gantry 10, that the subject is placed head-first, and that the imaging region includes the subject's knees (as in Figure 8). Based on this information, the X-ray CT system 1 estimates that subject P is placed with his 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 system 1 estimates that the subject's knees will collide with the gantry 10 when the subject P is being carried into the gantry 10. Therefore, the X-ray CT system 1 determines that there is a collision risk. Conversely, if the imaging region does not include the subject's knees under the above conditions, the X-ray CT system 1 determines that there is no collision risk. For example, if the imaging region is a region (e.g., head, neck, chest, abdomen, waist, thigh) closer to the gantry device 10 than the knees of the subject P, the X-ray CT device 1 determines that there is no risk of collision.

An X-ray CT apparatus 1 according to another modification may calculate the change in 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 can be trained using training data in which, for example, the change in output from the force sensor 500 when various subjects P with different physiques change posture is used as input data, and the change in center of gravity position corresponding to the above cases is used as correct answer data. The machine learning model can be, for example, a deep learning-based model. The X-ray CT apparatus 1 can calculate the change in center of gravity position for various subjects P by using a trained machine learning model.

In yet another modified example, the X-ray CT system 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. Specific conditions include, for example, when the X-ray CT system 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, so if the above function is "on," there is a concern that unnecessary alerts may be issued or the subject P's movement may be halted. Therefore, the X-ray CT system 1 can avoid the above unnecessary actions by setting the function to "off." Additionally, the X-ray CT system 1 may set the function to "off" even when imaging the subject P using restraints that limit changes in the subject P's posture. The X-ray CT system 1 may also display on the display 42 whether the function is "on" or "off."

At least one of the embodiments described above can prevent collisions between a moving subject and the gantry.

While several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments may be embodied in a variety of other forms, and various omissions, substitutions, modifications, and combinations of embodiments may be made without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

REFERENCE SIGNS LIST 1 X-ray CT device 10 gantry device 11 X-ray tube 12 detector 13 rotating frame 14 X-ray high voltage device 15 control device 16 wedge 17 collimator 18 DAS
19 Opening 30 Bed device 31 Base 32 Bed driving mechanism 33 Top plate 34 Support frame 40 Console device 41 Memory 42 Display 43 Input interface 44 Processing circuit 100 Table 441 System control function 442 Preprocessing function 443 Reconstruction processing function 444 Display control function 445 Acquisition function 446 Calculation function 447 Determination function 448 Output function 449 Movement control function 500 Force sensor

Claims (16)

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: 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: 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, placement direction information indicating the direction of the subject placed toward the gantry, and imaging region information indicating the region of the subject that is imaged by the gantry;
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: 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, placement direction information indicating the direction of the subject placed toward the gantry, and imaging region information indicating the region of the subject that is imaged by the gantry;
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: 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. 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 . 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. 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 . 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 . 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 . 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 . 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 . 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 . 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 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: 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: 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.