JP2023067495A - Medical image diagnostic apparatus, x-ray ct apparatus and control method - Google Patents

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

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

In general, in a medical image diagnostic apparatus provided with a gantry and a couch, the gantry has a mechanism for imaging an object, and the couch has an opening (also called a "bore") forming an imaging space of the gantry. has a mechanism for moving Subjects may change their posture (e.g., raise their head, bend their knees) while moving to the gantry, and depending on their posture, they may collide with the gantry around the opening and be injured. be. Therefore, a system that prevents collision between a moving subject and a gantry is desired.

In order to prevent collisions, there is a method in which the posture of the subject is detected by a camera installed at a position where the subject can be imaged (eg, on the ceiling of the room where the gantry is installed, or on the front cover of the gantry). However, with this method, it is difficult to detect the posture of the subject when the subject is positioned in the blind spot of the camera, such as near the opening of the gantry. In view of such circumstances, a system that detects or estimates the posture of a subject without relying on an optical device such as a camera and prevents collision between the moving subject and the gantry is especially desired.

International Publication No. 2010/143487

One of the problems to be solved by the embodiments disclosed in this specification and drawings is to prevent collisions between a moving subject and a gantry. However, the problems to be solved by the embodiments disclosed in this specification and drawings are not limited to the above problems. A problem corresponding to each effect of each configuration shown in the embodiments described later can be positioned as another problem.

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 obtains center-of-gravity position information indicating the center-of-gravity position of the subject before and after the table on which the subject is placed moves toward the gantry, and the subject placed toward the gantry. Placement direction information indicating the direction of the sample is acquired. The calculator calculates a positional change related to the center-of-gravity position of the subject based on the center-of-gravity position information. The determination unit determines a risk of the subject colliding with the gantry device based on the positional change and the placement direction information. The output unit outputs an alert notifying that the risk exists when it is determined that the risk exists.

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

A medical image diagnostic apparatus, an X-ray CT apparatus, and a control method according to embodiments will be described below with reference to the drawings. In the following embodiments, it is assumed that parts with the same reference numerals perform the same operations, and overlapping descriptions will be omitted as appropriate.

FIG. 1 is a block diagram showing a configuration example 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. Examples of the medical image diagnostic apparatus include magnetic resonance imaging (MRI) apparatus, radioisotope (RI) apparatus (e.g., single photon emission computed tomography (SPECT) ) devices, including Positron Emission Tomography (PET) devices.

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

(mounting device)
The gantry device 10 is a scanning device having a mechanism for X-ray CT imaging of the subject P. As shown in FIG. The gantry 10 includes 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 as components. Each configuration is accommodated in a housing (not shown) in which an opening 19 forming an imaging space is formed. The aperture 19 substantially matches the viewing angle (FOV: Field Of View). The opening 19 is also called "bore". In the following, it is assumed that subject P is a patient (ie, human).

In this embodiment, the direction parallel to the rotation axis of the rotating frame 13 in the non-tilt state is defined as the "Z-axis direction". On the other hand, the axial direction orthogonal to the Z-axis direction and horizontal to the floor surface is defined as the “X-axis direction”, and the axial direction orthogonal to the Z-axis direction and vertical to the floor surface is defined as the “Y-axis direction”. do. The X-axis, Y-axis and Z-axis orthogonal to each other form a three-dimensional orthogonal coordinate system. Note that the central axis of the opening 19 coincides with the rotation axis (Z-axis) of the rotation frame 13 .

The X-ray tube 11 generates X-rays by irradiating thermoelectrons from the cathode (filament) to the anode (target) and colliding them with high voltage and filament current from the X-ray high voltage device 14 . It is a vacuum tube that The X-ray tube 11 is, for example, a rotating anode type X-ray tube that irradiates a rotating anode with thermoelectrons. The X-rays generated by the X-ray tube 11 are shaped into a cone beam through a collimator 17 and then irradiated onto the subject P. FIG.

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, for example, an X-ray detection element array 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 . Not limited to this, the detector 12 is a two-dimensional array 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). column structure.

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

In this embodiment, the rotating frame 13 further comprises and supports the X-ray tube 11 and the detector 12 as well as the X-ray high voltage device 14 and the DAS 18 . The photographing data generated by the DAS 18 is transmitted from a transmitter (not shown) having, for example, a light emitting diode (LED) to a photodiode provided in a non-rotating portion (that is, a fixed frame) of the gantry 10 by optical communication. , and transferred to the console device 40 . The method of transmitting image data from the rotatable 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 radio wave method may be used. In addition, a contact type data transmission method using a slip ring and an electrode brush may be adopted as the transmission method.

The X-ray high voltage device 14 has electric circuits such as a transformer and a rectifier, and is 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 control device for controlling the output voltage according to the X-rays emitted by the X-ray tube 11 . The high voltage generator may be of transformer type or 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 controller 15 has a processing circuit and drive mechanisms such as motors and actuators. The processing circuit has, as hardware resources, processors such as a CPU (Central Processing Unit) and MPU (Micro Processing Unit), and memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The control device 15 may be an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a complex programmable logic device (CPLD), or a simple It can be realized by a programmable logic device (SPLD: Simple Programmable Logic Device). The control device 15 controls the rotating frame 13, the X-ray high-voltage device 14, the DAS 18, etc. according to commands from the console device 40. FIG.

In this embodiment, the control device 15 receives an input signal from the input interface 43 installed in the console device 40 and controls the operations of the gantry device 10 and the bed device 30 . For example, the control device 15 receives an input signal and performs control to tilt the gantry device 10 , control to rotate the rotating frame 13 , and control to operate the bed device 30 . Control for tilting the gantry 10 is performed by the control device 15 controlling the rotation frame 13 about an axis parallel to the X-axis direction based on tilt angle (tilt angle) information input by the input interface 43 attached to the gantry 10 . This is achieved by rotating 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 dose 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 emitted 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 machined from aluminum to fit a given target angle and thickness.

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 . A slit is formed in the collimator 17 by combining a plurality of lead plates or the like.

If the detector 12 is an integrating detector, the DAS 18 reads an electrical signal from the detector 12, and based on the read electrical signal, digital data (i.e., imaging) regarding the dose of X-rays detected by the detector 12. data). In this case, the imaging data is a set of data indicating the channel number and row number of the X-ray detection element that is the source of the generation, the view number indicating the acquired view (projection angle), and the integral value of the detected X-ray dose. be.

If the detector 12 is a photon-counting detector, the DAS 18 generates imaging data representing count values of X-ray photons detected by the detector 12 for each of a plurality of energy bands. In this case, the radiographic data is data indicating the X-ray photon count value identified by the channel number, row number, view number indicating the acquired view (projection angle), and energy bin number of the X-ray detection element that is the source of generation. is a set of The DAS 18 is implemented, 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 on which the subject P is placed and moves in arbitrary axial directions (X-axis, Y-axis, Z-axis). The bed device 30 includes a base 31, a bed drive mechanism 32, a top board 33, and a support frame 34 as components. The bed device 30 is installed facing the gantry device 10 .

The base 31 is a structure that mounts and supports the bed drive mechanism 32, the top plate 33, and the support frame 34. As shown in FIG. Specifically, a bed drive mechanism 32 is mounted on the base 31 , a support frame 34 is mounted on the bed drive mechanism 32 , and a top board 33 is mounted on the support frame 34 . The base 31 is installed on the floor. Note that the base 31 may be formed of a rigid body such as metal.

The bed drive mechanism 32 is a mechanism that moves the table top 33 under the control of the control device 15 or the console device 40 . Specifically, the bed drive mechanism 32 is driven at a rotational speed corresponding to the duty ratio of the drive signal supplied from the control device 15 to generate power, and the tabletop 33 is moved by the generated power. The bed drive mechanism 32 includes motors such as direct drive motors and servo motors for generating the power. Further, the bed drive mechanism 32 includes an X-shaped structure (X link) that supports the support frame 34 so as to be movable in the vertical direction (Y-axis direction).

In this embodiment, the bed driving mechanism 32 moves the table 33 in each axial direction so that the body axis of the subject P placed on the table 33 is aligned with the central axis of the opening 19 of the rotating frame 13 . . Further, the bed drive mechanism 32 moves the tabletop 33 in the longitudinal direction (Z-axis direction) as the gantry 10 performs X-ray CT imaging. The bed drive mechanism 32 may move not only the top plate 33 but also the support frame 34 in each axial direction.

The top plate 33 is a flat structure on which the subject P is placed. 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 may be made of a rigid body such as metal.

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

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 information. The memory 41 stores, for example, photographed data and reconstructed image data. The memory 41 reads and writes various information from and to portable storage media such as CDs (Compact Discs), DVDs (Digital Versatile Discs), flash memories, semiconductor memory devices such as RAMs, etc., in addition to HDDs and SSDs. It may be a driving device that Moreover, the storage area of the memory 41 may be in 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.

The display 42 displays various information. For example, the display 42 displays a medical image (CT image) generated by the processing circuit 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 CRT (Cathode Ray Tube) display, an organic EL display (OELD: Organic Electro Luminescence Display), and a plasma display. The display 42 may be provided on the gantry device 10 or the bed device 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 receives various input operations from the user, converts the received input operations into electrical signals, and outputs the electrical signals to the processing circuit 44 . For example, the input interface 43 receives acquisition conditions for acquiring imaging data, reconstruction conditions for reconstructing CT images, image processing conditions for generating post-processed images from CT images, and the like. Examples of input interfaces 43 include mice, keyboards, trackballs, switches, buttons, joysticks, touchpads and touch panel displays. Not limited to this, the input interface 43 may be a device that receives an electric signal corresponding to an input operation from an external input device provided separately from the X-ray CT apparatus 1 and outputs the electric signal to the processing circuit 44. good. 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 be a tablet terminal or the like capable of wireless communication with the console device 40 .

The processing circuit 44 controls the operation of the entire X-ray CT apparatus 1 dependently or independently on the electric signal of the input operation output from the input interface 43 . For example, the processing circuit 44 has processors such as CPU, MPU, and GPU, and memories such as ROM and RAM as hardware resources. The processing circuit 44 executes each function (eg, 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, movement control function 449). Each function can be implemented by at least one processor.

A system control function 441 controls each function of the processing circuit 44 . Specifically, the system control function 441 reads the control program stored in the memory 41, develops it on the memory in the processing circuit 44, and controls the X-ray CT apparatus 1 according to the developed control program.

The preprocessing function 442 generates corrected imaging data by performing preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the imaging data output from the DAS 18. .

A reconstruction processing function 443 performs reconstruction processing using a filtered back projection (FBP) method, an iterative reconstruction method, or the like on the corrected imaging data generated by the preprocessing function 442. to generate CT image data.

The display control function 444 controls the display 42 so as to display information on the progress or result 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 position of the subject P before and after the table 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 thereon is acquired. The calculation function 446 calculates a position change regarding the center-of-gravity position 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 position of the center of gravity of the subject P and the placing direction information. When it is determined that there is a risk that the subject P will collide with the gantry device 10, the output function 448 outputs an alert notifying that the risk exists. The movement control function 449 stops movement of the tabletop 33 when it is determined that there is a risk that the subject P will collide with the gantry device 10 .

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

FIG. 2 is a side view showing a configuration example of the X-ray CT apparatus 1 according to the embodiment. Specifically, the external appearance of the X-ray CT apparatus 1 is shown when the subject P is placed face up on the table 33 and before the table 33 starts to move. For convenience of explanation, the direction in which the top plate 33 is carried into the gantry device 10 is defined as "forward", and the direction in which the top plate 33 is carried out from the gantry device 10 is defined as "rearward". In other words, the direction in which the top plate 33 approaches the gantry device 10 corresponds to "forward", and the direction in which the top plate 33 separates from the gantry device 10 corresponds to "rearward". At this time, the position of the center of gravity of the subject P on the top board 33 is represented as "G1". G1 is illustrated by a black dot located near the center of subject P (groin).

At least one force sensor 500 capable of detecting the position of the center of gravity of the subject P in real time is installed on the bed device 30 . The force sensor 500 is a sensor that detects forces (mass, torque) in multiple directions, and outputs electrical signals corresponding to the detected forces. The force sensor 500 may be connected to the console device 40 in a wired or wireless manner so as to transfer the output electrical signal to the console device 40 . The console device 40 detects or estimates the center-of-gravity position of the subject P based on the transferred electrical signals. Force sensor 500 is, for example, a load cell, a piezoelectric element or a displacement sensor. As long as the force sensor 500 can detect the center-of-gravity position of the subject P, any number of force sensors 500 may be installed at any location. According to the example shown in FIG. 2, two force sensors 500 are installed near the end points of the X-links that constitute the bed drive mechanism 32 and inside the support frame 34 .

FIG. 3 is a diagram showing a first modification regarding the installation location of the force sensor 500. As shown in FIG. According to 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 not only the load of the subject P but also the load of the bed device 30 is applied to any of the force sensors 500, the output of the force sensor 500 is considered to increase compared to the example of FIG. 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 couch device 30 from the increased output of the force sensor 500 . The console device 40 may detect or estimate the center-of-gravity position of the subject P based on the net output of the force sensor 500 .

FIG. 4 is a diagram showing a second modification regarding the installation location of the force sensor 500. As shown in FIG. According to the example shown in FIG. 4, a large number of force sensors 500 (seven in this figure) are installed inside the top plate 33 . Specifically, a large number of force sensors 500 are installed over a range that includes the subject P's whole body. Here, since the top plate 33 is carried into the opening 19 of the gantry 10, if a load cell or the like containing metal is used as the force sensor 500, artifacts may occur in the captured image. Therefore, when installing the force sensor 500 inside the top plate 33 , an air tube containing no metal can be installed as the force sensor 500 . The console device 40 may detect or estimate the center-of-gravity position of the subject P based on changes in air pressure inside the air tube or distortion of the air tube itself. Note that the force sensor 500 may be installed not only inside the top plate 33 but also on the upper surface or the lower surface of the top plate 33 .

FIG. 5 is a flowchart showing an operation example of the X-ray CT apparatus 1 according to the embodiment. It is assumed that the subject P has already been placed on the tabletop 33 and the tabletop 33 has not been moved before the first step S1 according to this operation example is executed. That is, it is assumed that the subject P is placed in the state shown in FIGS. 2 to 4. FIG.

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

The “placement direction” is information indicating the direction of the subject P placed facing the gantry device 10 . In general X-ray CT imaging, when the subject P is placed with the feet facing the gantry device 10 side (foot first), and when the subject P is placed with the head facing the gantry device 10 side ( head first) is assumed. Normally, when the subject P is placed in the foot-first manner, the gantry device 10 images the subject P from the toes to the neck. On the other hand, when the subject P is placed in the head first mode, the gantry device 10 images the head of the subject P, for example. Foot first is information indicating that the feet of the subject are placed facing the gantry device 10, and head first indicates that the head of the subject P is placed facing the gantry device 10. Information. According to the examples of FIGS. 2 to 4, the subject P is placed in a foot-first manner.

The “imaging site” is information indicating the site of the subject P to be imaged by the gantry device 10 . The imaged part can be any anatomical part of the subject P (eg, head, neck, chest, abdomen, waist, thigh, knee, lower leg, foot). The imaged region may be a combination of these exemplified regions. The imaging part of the subject P placed in the foot-first mode is, for example, any anatomical part in the range from the toe to the neck. On the other hand, the part to be imaged of the subject P placed in the head-first mode is, for example, the head.

In step S2, the X-ray CT apparatus 1 detects the position of the center of gravity of the subject P on the top board 33 before movement. 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 moves toward the gantry 10 . At this time, the X-ray CT apparatus 1 detects the center-of-gravity position of the subject P before movement based on the output from the force sensor 500 installed on the bed apparatus 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".

In step S<b>3 , the X-ray CT apparatus 1 moves the top plate 33 . Specifically, the X-ray CT apparatus 1 moves the table 33 on which the subject P is placed toward the gantry 10 . At this time, the X-ray CT apparatus 1 may move the top plate 33 by an arbitrary amount of movement (eg, X cm). The amount of movement of the top plate 33 may be the same or different each time this step is executed. Note that it is assumed that the subject P changes its posture consciously or unconsciously during execution of this step. It is assumed that the position of the center of gravity of the subject P changes as the posture of the subject P changes.

In step S4, the X-ray CT apparatus 1 determines whether or not the tabletop 33 has been moved to a predetermined position. For example, the X-ray CT apparatus 1 determines whether or not the imaging region of the subject P has moved on the top plate 33 to the imaging space of the gantry device 10 . If the X-ray CT apparatus 1 has moved the top plate 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 according to the scan plan accepted in step S1. On the other hand, if the X-ray CT apparatus 1 has not moved the top plate 33 to the predetermined position (No in step S4), the process proceeds to step S5.

In step S5, the X-ray CT apparatus 1 detects the center-of-gravity position of the subject P on the tabletop 33 after movement. Specifically, the X-ray CT apparatus 1 determines 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 (that is, after step S3 is executed). to detect. At this time, the X-ray CT apparatus 1 detects the center-of-gravity position of the subject P after movement based on the output from the force sensor 500 installed on the bed apparatus 30 . 6 to 9, which will be described later, the position of the center of gravity detected by executing this step corresponds to "G2" (generic term for G2A and G2B) or "G3" (generic term for G3A and G3B).

In step S6, the X-ray CT apparatus 1 calculates changes in the position of the center of gravity of the subject P. FIG. Specifically, the X-ray CT apparatus 1 uses the center-of-gravity position “G1” of the subject P before movement detected in step S2 and the center-of-gravity position “G2” of the subject P after movement detected in step S5 or Based on "G3", the change in the position of the center of gravity of the subject P is calculated. At this time, the amount of change and the direction of change in the center-of-gravity position of the subject P can be calculated. A method of calculating the change in the position of the center of gravity according to various postures when the subject P is placed will be described below.

FIG. 6 is a diagram showing an example of the first posture of the subject P and changes in the position of the center of gravity. Specifically, the appearance of the X-ray CT apparatus 1 after the top plate 33 has moved by a predetermined amount in the direction toward the gantry 10 (D1 direction; Z-axis direction) is shown. The subject P is placed with the feet facing the gantry device 10 (foot first), and is in a posture with the right leg extended and the left knee bent. Here, the height from the top plate 33 to the top of the left knee of the subject P exceeds the height from the top plate 33 to the upper end of the opening 19 . Therefore, if the tabletop 33 is further carried in in the D1 direction, there is a risk that the left knee of the subject P will collide with the gantry device 10 around the opening 19 . Also, from the output of the force sensor 500, it is detected that the position of the center of gravity of the subject P is at the position "G2A".

First, the X-ray CT apparatus 1 estimates the center-of-gravity position "G1'" of the subject P after the table 33 is moved when the posture of the subject P does not change. For example, the X-ray CT apparatus 1 adds the movement amount of the table 33 moved in step S3 to the center-of-gravity position "G1" of the subject P detected in step S2 before the table 33 is moved, thereby obtaining "G1'. ” is estimated. G1' is illustrated by a white dot located near the center of subject P (groin).

Subsequently, the X-ray CT apparatus 1 calculates the difference between the center-of-gravity positions "G1'" and "G2A". Since the left knee of the subject P is bent in the direction of detaching from the gantry device 10, it is assumed that "G2A" moves backward compared to "G1'" (change in the position of the center of gravity: G1'→G2A). That is, the moving direction of the center of gravity of the subject P is calculated to be "backward". The X-ray CT apparatus 1 regards the calculated difference as the change in the position of the center of gravity of the subject P before and after the table 33 is moved.

FIG. 7 is a diagram showing an example of the second posture of the subject P and changes in the position of the center of gravity. The subject P is placed with the feet facing the gantry device 10 (foot first), and takes a posture with both legs extended and the head raised. Here, the height from the top plate 33 to the top of the head of the subject P exceeds the height from the top plate 33 to the upper end of the opening 19 . Also, from the output of the force sensor 500, it is detected that the position of the center of gravity of the subject P is at the position "G3A".

The X-ray CT apparatus 1 estimates the position of "G1'" in the same manner as in the example of FIG. Subsequently, the X-ray CT apparatus 1 calculates the difference between the center-of-gravity positions "G1'" and "G3A". Since the subject P raises the head in the direction to approach the gantry device 10, it is assumed that "G3A" moves forward compared to "G1'" (change in the position of the center of gravity: G1'→G3A). That is, the movement direction of the center of gravity of the subject P is calculated as "forward". The X-ray CT apparatus 1 regards the calculated difference as the change in the position of the center of gravity of the subject P before and after the table 33 is moved.

FIG. 8 is a diagram showing an example of the third posture of the subject P and changes in the position of the center of gravity. The subject P is placed with the head facing the gantry device 10 (head first), and takes a posture with the left leg extended and the right knee bent. Here, the height from the top plate 33 to the top of the right knee of the subject P exceeds the height from the top plate 33 to the upper end of the opening 19 . Also, from the output of the force sensor 500, it is detected that the position of the center of gravity of the subject P is at the position "G2B".

The X-ray CT apparatus 1 estimates the position of "G1'" in the same manner as in the example of FIG. Subsequently, the X-ray CT apparatus 1 calculates the difference between the center-of-gravity positions "G1'" and "G2B". Since the subject P raises the right knee toward the gantry device 10, it is assumed that "G2B" moves forward compared to "G1'" (change in the position of the center of gravity: G1'→G2B). That is, the movement direction of the center of gravity of the subject P is calculated as "forward". The X-ray CT apparatus 1 regards the calculated difference as the change in the position of the center of gravity of the subject P before and after the table 33 is moved.

FIG. 9 is a diagram showing an example of the fourth posture of the subject P and changes in the position of the center of gravity. The subject P is placed with the head facing the gantry device 10 (head first), and takes a posture with both legs extended and the head raised. Here, the height from the top plate 33 to the top of the head of the subject P exceeds the height from the top plate 33 to the upper end of the opening 19 . Therefore, if the tabletop 33 is further carried in in the D1 direction, the head of the subject P may collide with the gantry device 10 around the opening 19 . Also, from the output of the force sensor 500, it is detected that the position of the center of gravity of the subject P is at the position "G3B".

The X-ray CT apparatus 1 estimates the position of "G1'" in the same manner as in the example of FIG. Subsequently, the X-ray CT apparatus 1 calculates the difference between the center-of-gravity positions "G1'" and "G3B". Since the subject P raises the head in the direction away from the gantry device 10, it is assumed that "G3B" moves backward compared to "G1'" (change in the position of the center of gravity: G1'→G3B). That is, the moving direction of the center of gravity of the subject P is calculated to be "backward". The X-ray CT apparatus 1 regards the calculated difference as the change in the position of the center of gravity of the subject P before and after the table 33 is moved.

In step S7, the X-ray CT apparatus 1 determines whether or not the position of the center of gravity of the subject P has changed. For example, the X-ray CT apparatus 1 determines whether or not the change in the center-of-gravity position of the subject P calculated in step S6 is greater than or equal to a predetermined threshold. The X-ray CT apparatus 1 considers that the center-of-gravity position of the subject P has changed when the change in the center-of-gravity position is equal to or greater than the threshold. On the other hand, the X-ray CT apparatus 1 considers that the center-of-gravity position of the subject P has not changed when the change in the center-of-gravity position is less than the threshold. If the position of 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 position of 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 position of the center of gravity may be the amount of change in the position of the center of gravity. Furthermore, the above threshold may be set to the amount of change in the position of the center of gravity when the risk of the subject P colliding with the gantry device 10 first occurs. In other words, the subject P collides with the gantry device 10 when the center-of-gravity position of the subject P is changed up to the threshold value.

At 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 accepted in step S1. For example, the X-ray CT apparatus 1 refers to the "placement direction" and "imaging site" included in the scan plan.

In step S9, the X-ray CT apparatus 1 determines whether or not the head-first or foot-first and center-of-gravity position has moved rearward. Specifically, the X-ray CT apparatus 1 determines whether the mode in which the subject P is placed is head-first or foot-first, based on the information on the "placement direction" referred to in step S8. At the same time, the X-ray CT apparatus 1 determines whether the position of the center of gravity of the subject P has moved backward based on the change in the position of the center of gravity of the subject P calculated in step S6. If this determination condition is satisfied (Yes in step S9), the process proceeds to step S10. On the other hand, if this determination condition is not satisfied (No in step S9), the process returns to step S3.

In other words, in step S9, the X-ray CT apparatus 1 changes the posture of the subject P 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 position of the subject P. (i.e., whether the head is raised, whether the knee is bent) is estimated. Furthermore, the X-ray CT apparatus 1 determines the risk of the subject P colliding with the gantry device 10 based on the estimated posture change of the subject P. FIG.

FIG. 10 is a diagram showing an example of a table 100 relating to collision risk determination. The X-ray CT apparatus 1 may refer to the table 100 to determine the collision risk. In the table 100, the estimated placement direction information (foot first or head first) included in the scan plan and the calculated moving direction (forward or backward) of the center of gravity of the subject P are estimated according to various combinations. , the posture of the subject P is shown. Further, the table 100 is associated with the presence or absence (presence or absence) of a collision risk according to the posture of the subject P. FIG. Table 100 may be stored in memory 41 .

First, it is assumed that the scan plan is "foot first" and the moving direction of the center of gravity is "backward" (in the case of FIG. 6). Based on these pieces of information, the X-ray CT apparatus 1 estimates that the subject P is placed with the foot toward the gantry 10 and that at least one knee is bent. In this case, the X-ray CT apparatus 1 determines that there is a collision risk.

Secondly, it is assumed that the scan plan is "foot first" and the moving direction of the center of gravity is "forward" (in the case of FIG. 7). Based on these pieces of information, the X-ray CT apparatus 1 estimates that the subject P is placed with the feet facing the gantry 10 and that the head is raised. In this case, the X-ray CT apparatus 1 determines that there is no collision risk. Since the subject P can visually recognize that the gantry device 10 is approaching him/herself as the top board 33 moves, it is assumed that the subject P can avoid the collision based on his or her own judgment.

Third, it is assumed that the scan plan is "head first" and the moving direction of the center of gravity is "forward" (in the case of FIG. 8). Based on these pieces of information, the X-ray CT apparatus 1 estimates that the subject P is placed with the head facing the gantry 10 and that at least one knee is bent. In this case, the X-ray CT apparatus 1 determines that there is no collision risk.

Fourthly, it is assumed that the scan plan is "head first" and the moving direction of the center of gravity is "backward" (case of FIG. 9). Based on this information, the X-ray CT apparatus 1 estimates that the subject P is placed with the head facing the gantry 10 and that the head is raised. In this case, the X-ray CT apparatus 1 determines that there is a collision risk.

At step S10, the X-ray CT apparatus 1 outputs an alert. Specifically, when it is determined in step S9 that there is a risk that the subject P will collide with the gantry 10, the X-ray CT apparatus 1 outputs an alert notifying that the risk exists. Alerts may be displayed on display 42 . At this time, the X-ray CT apparatus 1 may generate a warning sound at the same time as the alert is displayed. After execution of step S10, the process returns to step S3.

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

The X-ray CT apparatus 1 according to the embodiment has been described above. According to the X-ray CT apparatus 1 having such a configuration, even if the subject P is positioned in a blind spot that can occur near the opening 19 of the gantry device 10, the scan plan and the position of the center of gravity of the subject P can be changed. Based on this, the posture change of the subject P can be detected or estimated. Furthermore, the X-ray CT apparatus 1 can determine the risk of the subject P colliding with the gantry device 10 based on the estimated posture change of the subject P. FIG. Furthermore, when the risk exists, the X-ray CT apparatus 1 can issue an alert or stop carrying the subject P into the gantry apparatus 10 . The user of the X-ray CT apparatus 1 can stop moving the tabletop 33 in response to the issued alert. Therefore, the X-ray CT apparatus 1 can prevent the subject P from colliding with the gantry 10 without impairing usability for the user.

(Other modifications)
The X-ray CT apparatus 1 according to the modified example may further determine the collision risk based on the information (imaging part information) on the part to be imaged. In other words, the X-ray CT apparatus 1 may determine the collision risk based on the change in the position of the center of gravity of the subject P, the placement direction information, and the radiographed region information. The X-ray CT apparatus 1 can determine the risk of the subject P colliding with the gantry 10 in more detail by further referring to the imaging region information.

First, the change in the position of the center of gravity of the subject P is a change in the direction (backward) away from the gantry device 10, the placement direction is foot first, and the imaging region includes the knee of the subject P. A case (case of FIG. 6) is assumed. Based on these pieces of information, the X-ray CT apparatus 1 estimates that the subject P is placed with the foot toward the gantry 10 and that at least one knee is bent. Furthermore, since the X-ray CT apparatus 1 includes a knee as an imaging region, it is estimated that the knee of the subject P collides 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 knee of the subject P under the above conditions, the X-ray CT apparatus 1 determines that there is no collision risk. For example, when the part to be imaged is a part closer to the gantry device 10 than the knee of the subject P (eg, foot), the X-ray CT apparatus 1 determines that there is no collision risk.

Second, the change in the position of the center of gravity of the subject P is a change in the direction (forward) approaching the gantry device 10, the mounting direction is head first, and the imaging region includes the knee of the subject P. A case (the case of FIG. 8) is assumed. Based on these pieces of information, the X-ray CT apparatus 1 estimates that the subject P is placed with the head facing the gantry 10 and that at least one knee is bent. Furthermore, since the X-ray CT apparatus 1 includes a knee as an imaging region, it is estimated that the knee of the subject P collides 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 knee of the subject P under the above conditions, the X-ray CT apparatus 1 determines that there is no collision risk. For example, when the imaging part is closer to the gantry device 10 than the knees of the subject P (eg, head, neck, chest, abdomen, waist, thighs), the X-ray CT apparatus 1 has a collision risk. does not exist.

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

Furthermore, the X-ray CT apparatus 1 according to another modification switches the force sensor 500 from the active state to the inactive state under specific conditions, thereby setting the function of detecting the center-of-gravity position of the subject P to "OFF". You may The specific condition includes, for example, the case where the X-ray CT apparatus 1 captures the dynamics of the subject P's knee joint or the like. At this time, since it is assumed that the subject P will repeatedly bend the knee, there is a concern that unnecessary alerts may be issued or movement of the subject P may be stopped if the above function is in the "on" state. . Therefore, the X-ray CT apparatus 1 can avoid the unnecessary operation by setting the function to "OFF". In addition, the X-ray CT apparatus 1 may set the function to "OFF" even when the subject P is imaged using a restraint device that restricts the posture change of the subject P. FIG. Also, the X-ray CT apparatus 1 may display on the display 42 that the function is "on" or "off."

According to at least one embodiment described above, it is possible to prevent a collision between the subject and the gantry during movement.

While several embodiments have been described, these embodiments are provided by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, changes, and combinations of embodiments can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

Reference Signs List 1 X-ray CT device 10 Mounting 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 drive 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 (13)

Center-of-gravity position information indicating the center-of-gravity position of the subject before and after the table on which the subject is placed moves toward the gantry, and the direction of the subject placed toward the gantry. an acquisition unit for acquiring placement direction information indicating
a calculation unit that calculates a positional change related to the center-of-gravity position 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 outputs an alert notifying that the risk exists when it is determined that the risk exists;
A medical image diagnostic apparatus comprising: Center-of-gravity position information indicating the center-of-gravity position of the subject before and after the table on which the subject is placed moves toward the gantry, and the direction of the subject placed toward the gantry. an acquisition unit for acquiring placement direction information indicating
a calculation unit that calculates a positional change related to the center-of-gravity position 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 movement of the tabletop when it is determined that the risk exists;
A medical image diagnostic apparatus comprising: The determination unit determines that the positional change is a change in a direction in which the subject is separated from the gantry device, and the placement direction information indicates that the subject's head or foot is placed toward the gantry device. If the information indicates that, it is determined that the risk exists,
The medical image diagnostic apparatus according to claim 1 or 2. The determination unit determines that the positional change is a change in a direction toward the gantry device, and the placement direction information indicates that the subject's head or foot is placed toward the gantry device. If the information indicates that the risk does not exist,
The medical image diagnostic apparatus according to any one of claims 1 to 3. 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 part information.
The medical image diagnostic apparatus according to any one of claims 1 to 4. The determination unit determines that the change in position is a change in a direction away from the gantry device, and the placement direction information indicates that the foot of the subject is placed toward the gantry device. information, and when the imaging region information includes the knee of the subject, determining that the risk exists;
The medical image diagnostic apparatus according to claim 5. The determination unit determines that the change in position is a change in a direction away from the gantry device, and the placement direction information indicates that the foot of the subject is placed toward the gantry device. information and the imaging region information does not include the knee of the subject, determining that the risk does not exist;
The medical image diagnostic apparatus according to claim 5 or 6. The determining unit determines that the change in position is a change in a direction toward the gantry device, and the placement direction information indicates that the head of the subject is placed toward the gantry device. information, and when the imaging region information includes the knee of the subject, determining that the risk exists;
The medical image diagnostic apparatus according to any one of claims 5 to 7. The determining unit determines that the change in position is a change in a direction toward the gantry device, and the placement direction information indicates that the head of the subject is placed toward the gantry device. information and the imaging region information does not include the knee of the subject, determining that the risk does not exist;
The medical image diagnostic apparatus according to any one of claims 5 to 8. The center-of-gravity position information is acquired by at least one sensor installed in a couch device including the top board.
The medical image diagnostic apparatus according to any one of claims 1 to 9. wherein the sensor is a load cell, piezoelectric element, displacement sensor or air tube;
The medical image diagnostic apparatus according to claim 10. Center-of-gravity position information indicating the center-of-gravity position of the subject before and after the table on which the subject is placed moves toward the gantry, and the direction of the subject placed toward the gantry. an acquisition unit for acquiring placement direction information indicating
a calculation unit that calculates a positional change related to the center-of-gravity position 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 outputs an alert notifying that the risk exists when it is determined that the risk exists;
An X-ray CT apparatus comprising: Center-of-gravity position information indicating the center-of-gravity position of the subject before and after the table on which the subject is placed moves toward the gantry, and the direction of the subject placed toward the gantry. Acquire the placement direction information shown and
calculating a positional change related to the center-of-gravity position 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, output an alert notifying that the risk exists;
control method.

Images