JP7199958B2 - Angio CT device - Google Patents

Description

An embodiment of the present invention relates to an angio-CT (Computed Tomography) apparatus.

There is an angio-CT apparatus in which an angio-gantry and a CT gantry are installed in one room. This type of angio-CT apparatus can switch between angio-imaging and CT imaging, and employs one of two placement methods. The first placement method is used, for example, when scanning the whole body of a subject who has been involved in a traffic accident. It is a method to evacuate. The second arrangement method is used, for example, when scanning a part of the subject, and is a method in which the table on which the subject is placed is moved with respect to the fixed position angiogantry and CT gantry. Compared with the first arrangement method, the second arrangement method has the advantage of being able to quickly switch between shootings. Therefore, the following description is based on the second arrangement method.

In the second arrangement method, the angio-CT apparatus can switch between angio-imaging and CT imaging by moving the tabletop along the longitudinal direction. In this case, the angio-CT apparatus is used, for example, in liver intervention to determine whether embolization therapy should be applied to liver cancer cells. Angio imaging is used when a catheter is manipulated and inserted into an artery, and CT imaging is used when diagnosing whether embolization therapy should be performed. For example, in two contrast-enhanced CT scans, if cancer cells are hardly imaged by portal vein imaging and cancer cells are clearly imaged by artery imaging, embolization therapy is recommended by doctors. be judged. Thus, under X-ray fluoroscopy imaging by an angiographic gantry, embolization is performed on feeding blood vessels to cancer cells. Even if the feeding vessel is embolized, normal cells are hardly damaged because the blood flow from the portal vein is not stopped. In addition, blood flow from arteries is blocked by embolization of feeding vessels, so cancer cells are damaged. This is the outline of transcatheter arterial embolization (TAE).

Normally, there is no particular problem with the angio-CT apparatus as described above. There is room for improvement in terms of wanting to reduce the difference. That is, when angio imaging and CT imaging are performed by moving the tabletop, the bending of the tabletop differs between the imaging position of the angio image and the imaging position of the CT image. occurs. Along with this, a deviation occurs between the obtained angio image and the CT image. Therefore, from the viewpoint of reducing such a shift between images, it is preferable to reduce the difference in inclination of the tabletop between the imaging position of the angio image and the imaging position of the CT image.

Japanese Patent Application Laid-Open No. 2014-330

The problem to be solved by the present invention is to reduce the difference in inclination of the tabletop when the tabletop is moved to alternately perform angiographic imaging and CT imaging.

An angio-CT apparatus according to an embodiment includes an acquisition unit and a tabletop control unit.
The acquisition unit is obtained by imaging the subject with a CT gantry having an opening into which the top board pulled out from a support frame that movably supports the top board on which the subject is placed and moved is inserted. Based on the CT image, information about the deflection of the tabletop at the imaging position of the CT image is obtained.
When moving the tabletop from the CT image capturing position to place the subject at an angioimage capturing position by an angiogantry placed near the support frame, the tabletop controller controls the information based on, the top plate is tilted so as to reproduce the inclination due to the deflection of the top plate.

FIG. 1 is a block diagram showing the configuration of an angio-CT apparatus according to the first embodiment. FIG. 2 is a perspective view showing the appearance of the angio-CT apparatus according to the first embodiment. FIG. 3 is a schematic diagram for explaining an example of a CT image according to the first embodiment. FIG. 4 is a schematic diagram for explaining an example of a patient load table according to the first embodiment. FIG. 5 is a flow chart for explaining the operation in the first embodiment. FIG. 6 is a schematic diagram for explaining the operation of step ST2 in the first embodiment. FIG. 7 is a schematic diagram for explaining the operations of steps ST5 and ST6 in the first embodiment. FIG. 8 is a flow chart for explaining the operation in the first embodiment. FIG. 9 is a schematic diagram for explaining the operation of step ST12 in the first embodiment. FIG. 10 is a schematic diagram for explaining the operation of step ST14 in the first embodiment. FIG. 11 is a schematic diagram for explaining the operation of step ST16 in the first embodiment. FIG. 12 is a schematic diagram for explaining a tilt sensor according to a first modification of the first embodiment; FIG. 13 is a schematic diagram for explaining a correction table according to the first modification of the first embodiment; FIG. 14 is a schematic diagram for explaining the operation in the second modified example of the first embodiment. FIG. 15 is a plan view for explaining the angio-CT apparatus according to the second embodiment. FIG. 16 is a flowchart for explaining operations in the second embodiment. FIG. 17 is a schematic diagram for explaining an interference region according to the second embodiment. FIG. 18 is a schematic diagram for explaining a default interference region according to the second embodiment. FIG. 19 is a flowchart for explaining operations in the third embodiment. FIG. 20 is a schematic diagram for explaining the operation of step ST7b-1 in the third embodiment. FIG. 21 is a flowchart for explaining operations in the fourth embodiment. FIG. 22 is a schematic diagram for explaining the operation of step ST4c-2 in the fourth embodiment.

Hereinafter, an angio-CT apparatus according to each embodiment will be described with reference to the drawings.

<First embodiment>
FIG. 1 is a block diagram showing the configuration of the angio-CT apparatus according to the first embodiment, and FIG. 2 is a perspective view showing the appearance of the angio-CT apparatus. The angio-CT apparatus 1 includes an angio-gantry 10 , a CT gantry 30 , a bed device 50 and a console device 70 . The angiogantry 10 includes a high voltage generator 11 , an X-ray generator 12 , an X-ray detector 13 , a C-arm 14 , a state detector 141 and a C-arm driver 142 .

The high voltage generator 11 generates a high voltage to be applied between the anode and the cathode in order to accelerate thermal electrons generated from the cathode of the X-ray tube, and outputs the high voltage to the X-ray tube.

The X-ray generator 12 includes an X-ray tube that irradiates the subject P with X-rays, and an ROI (Region Of Interest) filter and X-ray diaphragm that have a function of attenuating or reducing the amount of irradiated X-rays.

X-ray tubes generate X-rays. Specifically, an X-ray tube is a vacuum tube that holds a cathode that generates thermoelectrons and an anode that receives thermoelectrons flying from the cathode and generates X-rays. For example, there is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermal electrons. The X-ray tube is connected to a high voltage generator 11 via a high voltage cable. A tube voltage is applied between the cathode and the anode by a high voltage generator 11 . Thermal electrons fly from the cathode to the anode by applying a tube voltage. A tube current flows due to thermal electrons flying from the cathode to the anode. By applying a high voltage and supplying a filament current from the high voltage generator 11, thermal electrons fly from the cathode toward the anode, and the thermal electrons collide with the anode to generate X-rays.

The ROI filter is positioned between the X-ray tube and the X-ray diaphragm, and is composed of a metal plate such as copper or aluminum. The ROI filter has an open area in at least a portion, for example a central portion, and attenuates X-rays outside the open area. Therefore, the ROI filter fully transmits X-rays in the X-ray passing area of the opening area, and attenuates and transmits X-rays in other areas. The ROI filter is driven by a driving device (not shown) according to the region of interest input by the operator through the input interface 73 .

The X-ray diaphragm is positioned between the X-ray tube and the X-ray detector 13 and is composed of a lead plate as a metal plate. The X-ray diaphragm narrows down the X-rays generated by the X-ray tube so that only the region of interest of the subject P is irradiated by shielding the X-rays outside the aperture region. For example, the X-ray diaphragm has four diaphragm blades, and by sliding these diaphragm blades, the X-ray shielded area can be adjusted to any size. The diaphragm blades of the X-ray diaphragm are driven by a driving device (not shown) according to the region of interest input by the operator through the input interface 73 .

The X-ray detector 13 detects X-rays that have passed through the subject P. FIG. As such an X-ray detector 13, it is possible to use one that converts X-rays directly into charges, and one that converts X-rays into charges after converting them into light. It doesn't matter if it is. That is, the X-ray detector 13 includes, for example, a planar FPD (Flat Panel Detector) that converts X-rays that have passed through the subject P into charges and accumulates them, and a drive for reading out the charges accumulated in this FPD. and a gate driver for generating pulses. FPD sizes are typically 8 to 12 inches. The FPD is configured by two-dimensionally arranging minute detection elements in the column direction and the line direction. Each detection element senses X-rays and includes a photoelectric film that generates charges according to the amount of incident X-rays, a charge storage capacitor that stores the charges generated in the photoelectric film, and a predetermined charge stored in the charge storage capacitor. It has a TFT (thin film transistor) that outputs at the timing of . Accumulated charges are sequentially read out by drive pulses supplied by the gate driver.

A projection data generation circuit and a projection data storage circuit (not shown) are provided at the stage subsequent to the X-ray detector 13 . The projection data generation circuit includes a charge-to-voltage converter that converts the charge read out in parallel from the FPD in units of rows or columns into a voltage, and an A/D that converts the output of the charge-to-voltage converter into a digital signal. It has a converter and a parallel/serial converter that converts the digitally converted parallel signal into a time-series serial signal. The projection data generation circuit supplies this serial signal as time-series projection data to the projection data storage circuit. The projection data storage circuit sequentially stores the time-series projection data supplied from the projection data generation circuit to generate two-dimensional projection data. This two-dimensional projection data is stored in the memory 71 .

The C-arm 14 holds the X-ray generator 12 and the X-ray detector 13 so as to face each other with the subject P and the top plate 53 interposed therebetween, thereby performing X-ray imaging of the subject P on the top plate 53 . have a configuration that can be done.

Specifically, as shown in FIG. 2, the C-arm 14 can move under a plurality of rails r2 provided on the ceiling along the long axis direction or the short axis direction of the top plate 53. It is possible to move between the rails r2 along the long axis direction and the short axis direction of the top plate 53 by a moving mechanism that does not move. Also, the C-arm 14 is supported by a support arm 14b via a holding portion 14a. The support arm 14b has a substantially arcuate shape and has a proximal end attached to a movement mechanism for the rail r2. The C-arm 14 is held by the holding portion 14a so as to be rotatable about an X-direction axis orthogonal to both the Y-direction perpendicular to the top plate 53 and the Z-direction along the longitudinal direction of the top plate 53. there is The C-arm 14 has a substantially circular arc shape centered on the Z-direction axis, and is held by the holding portion 14a so as to be slidable along the substantially circular arc shape. That is, the C-arm 14 can perform a sliding motion about the Y-direction axis. In addition, the C-arm 14 can rotate around the X-direction axis around the holding portion 14a (hereinafter referred to as "main rotation operation"). It makes it possible to observe an X-ray image from an angular direction. Furthermore, the C-arm 14 can also rotate about the Z-direction axis, so that, for example, the rotation center axis of the sliding operation described above can be the X-direction. The imaging axis passing through the X-ray focal point of the X-ray generator 12 and the center of the detection surface of the X-ray detector 13 intersects the rotation center axis of the slide movement and the rotation center axis of the main rotation movement at one point. is designed to The intersection point is generally called the isocenter. The isocenter is not displaced even when the C-arm 14 performs the above-described sliding motion and main rotating motion. Therefore, when the site of interest is positioned at the isocenter, the site of interest can be easily observed in the moving image of the medical image obtained by the sliding motion or the main rotating motion of the C-arm 14 .

Returning to FIG. 1, the C-arm 14 is provided with a support arm 14b under the rail r2, and a plurality of power sources for realizing movements related to the X-axis, Y-axis and Z-axis. provided for. These power sources constitute the C-arm drive device 142 . The C-arm drive device 142 reads drive signals from the drive control function 742 and causes the C-arm 14 to slide, rotate, and linearly move. Furthermore, each C-arm 14 is provided with a state detector 141 for detecting information on its angle, posture, and position. The state detector 141 is composed of, for example, a potentiometer that detects a rotation angle and a movement amount, an encoder that is a position detection sensor, and the like. As the encoder, a so-called absolute encoder such as a magnetic system, a brush system, or a photoelectric system can be used. As the state detector 141, various types of position detection mechanisms can be appropriately used, such as a rotary encoder that outputs rotational displacement as a digital signal or a linear encoder that outputs linear displacement as a digital signal.

CT gantry 30 has X-ray tube 31 , X-ray detector 32 , rotating frame 33 , X-ray high voltage device 34 , CT controller 35 , wedge 36 , collimator 37 and DAS 38 . Although a plurality of CT gantrys 30 are shown in FIG. 1 from the viewpoint of showing the relationship with the bed apparatus 50, only one CT gantry 30 is used in this embodiment.

The X-ray tube 31 generates X-rays. Specifically, the X-ray tube 31 is a vacuum tube that holds a cathode that generates thermoelectrons and an anode that receives thermoelectrons flying from the cathode and generates X-rays. For example, the X-ray tube 31 is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermal electrons. The X-ray tube 31 is connected to an X-ray high voltage device 34 via a high voltage cable. An X-ray high voltage device 34 applies a tube voltage between the cathode and the anode. Thermal electrons fly from the cathode to the anode by applying a tube voltage. A tube current flows due to thermal electrons flying from the cathode to the anode. By applying a high voltage and supplying a filament current from the X-ray high-voltage device 34, thermal electrons fly from the cathode toward the anode, and the thermal electrons collide with the anode to generate X-rays.

The X-ray detector 32 detects X-rays emitted from the X-ray tube 31 and passing through the subject P, and outputs an electrical signal corresponding to the X-ray dose to the DAS 38 . The X-ray detector 32 has, for example, a plurality of X-ray detection element arrays in which a plurality of X-ray detection elements are arranged in the channel direction along one circular arc centered on the focal point of the X-ray tube. The X-ray detector 32 has, for example, a structure in which a plurality of X-ray detection element arrays each having a plurality of X-ray detection elements arranged in the channel direction are arranged in the slice direction (column direction, row direction). Also, the X-ray detector 32 is, for example, an indirect conversion type detector having a grid, a scintillator array, and a photosensor array.

The scintillator array has a plurality of scintillators, and each scintillator has a scintillator crystal that outputs a photon amount of light corresponding to the amount of incident X-rays.

The grid has an X-ray shielding plate arranged on the surface of the scintillator array on the X-ray incident side and having a function of absorbing scattered X-rays. Note that the grid may also be called a collimator (one-dimensional collimator or two-dimensional collimator).

The photosensor array has a function of converting the amount of light from the scintillator into an electrical signal, and includes photosensors such as photomultiplier tubes (PMTs).

Note that the X-ray detector 32 may be a direct conversion detector having a semiconductor element that converts incident X-rays into electrical signals. Also, the X-ray detector 32 is an example of an X-ray detection unit.

The rotating frame 33 is an annular frame that rotatably supports the X-ray tube 31 and the X-ray detector 32 around the rotation axis Z. As shown in FIG. Specifically, the rotating frame 33 is housed in the CT gantry 30 and supports the X-ray tube 31 and the X-ray detector 32 arranged to face each other through the opening 30a. The rotating frame 33 is rotatably supported around the rotation axis Z by a fixed frame (not shown). The X-ray tube 31 and the X-ray detector 32 are rotated about the rotation axis Z by rotating the rotation frame 33 about the rotation axis Z by the CT control device 35 . The rotating frame 33 receives power from the drive mechanism of the CT control device 35 and rotates around the rotation axis Z at a constant angular velocity. An image field of view (FOV) is set in the opening of the rotating frame 33 .

In this embodiment, the rotation axis of the rotating frame 33 in the non-tilt state or the longitudinal direction of the top board 53 of the bed device 50 is the Z-axis direction, and the axial direction perpendicular to the Z-axis direction and horizontal to the floor surface is is defined as the X-axis direction, and the axial direction perpendicular to the Z-axis direction and perpendicular to the floor surface is defined as the Y-axis direction.

The X-ray high voltage device 34 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 31 and a filament current to be supplied to the X-ray tube 31. , and an X-ray control device for controlling the output voltage according to the X-rays emitted by the X-ray tube 31 . The high voltage generator may be of a transformer type or an inverter type. The X-ray high voltage device 34 may be provided on the rotating frame 33 within the CT gantry 30 or may be provided on a fixed frame (not shown) within the CT gantry 30 .

The CT control device 35 controls the X-ray high-voltage device 34 and the DAS 38 to perform X-ray CT imaging according to the imaging control function 733 of the processing circuit 74 of the console device 70 . The CT control device 35 has a processing circuit having a CPU and the like, and drive mechanisms such as motors and actuators. The processing circuit has, as hardware resources, processors such as CPU and MPU, and memories such as ROM and RAM. Also, the CT control device 35 may be realized by ASIC, FPGA, CPLD, or SPLD.

The CT control device 35 has a function of receiving an input signal from an input interface 73 attached to the console device 70 or the CT gantry 30 and controlling the operation of the CT gantry 30 and the bed device 50 . For example, the CT control device 35 receives an input signal and performs control to rotate the rotating frame 33 , control to tilt the CT gantry 30 , and control to operate the bed device 50 and the tabletop 53 . The control for tilting the CT gantry 30 is performed by rotating the CT controller 35 about an axis parallel to the X-axis direction according to tilt angle (tilt angle) information input by the input interface 73 attached to the CT gantry 30. It is realized by rotating the frame 33 . Note that the CT control device 35 may be provided in the CT gantry 30 or may be provided in the console device 70 .

The wedge 36 adjusts the dose of X-rays with which the subject P is irradiated. Specifically, the wedge 36 attenuates the X-rays so that the dose of the X-rays emitted from the X-ray tube 31 to the subject P has a predetermined distribution. For example, as the wedge 36, a metal plate such as aluminum is used for a wedge filter, a bow-tie filter, or the like.

A collimator 37 limits the irradiation range of X-rays transmitted through the wedge 36 . The collimator 37 slidably supports a plurality of lead plates that shield X-rays, and adjusts the form of slits formed by the plurality of lead plates.

A DAS 38 (Data Acquisition System) receives information about the incident channel output from the X-ray detector 32 for each view period, and collects detection data having a digital value corresponding to the dose of X-rays over the view period. do. The DAS 38 is realized, for example, by an ASIC equipped with circuit elements capable of generating detection data. The detected data is transmitted to the console device 70 via a contactless data transmission device or the like.

The CT gantry 30 is a Rotate/Rotate-Type (third-generation CT) in which the X-ray generator and the X-ray detector are integrally rotated around the subject, and a large number of X-ray detectors arrayed in a ring shape. There are various types such as Stationary/Rotate-Type (4th generation CT) in which the element is fixed and only the X-ray generator rotates around the subject, and any type is applicable to one embodiment.

The bed device 50 is a device for placing and moving the subject P, and includes a base 51 , a bed driving device 52 , a top plate 53 and a support frame 54 .

The base 51 is a housing that is installed on the floor and supports the support frame 54 so as to be movable in the vertical direction (Y direction).

The bed driving device 52 is housed in the housing of the bed device 50 and includes a motor or actuator that moves the table 53 on which the subject P is placed in the longitudinal direction (Z direction) of the table 53 . The bed drive device 52 reads the drive signal from the drive control function 742 and moves the tabletop 53 horizontally or vertically with respect to the floor surface. Similarly, the bed drive device 52 reads the drive signal from the drive control function 742 and tilts the tabletop 53 about the minor axis direction of the tabletop 53 . The bed drive device 52 may tilt the top plate 53 by tilting the support frame 54 . As the C-arm 14 or the top plate 53 moves, the positional relationship of the imaging axis with respect to the subject P changes. Note that the bed drive device 52 may move the support frame 54 in the longitudinal direction of the top plate 53 in addition to the top plate 53 .

The top plate 53 is a plate provided on the upper surface of the support frame 54 and on which the subject P is placed.

The support frame 54 movably supports the top plate 53 on which the subject P is placed. Specifically, the support frame 54 is provided above the base 51 and supports the top plate 53 so as to be slidable along its longitudinal direction.

The console device 70 has a memory 71 , a display 72 , an input interface 73 and a processing circuit 74 .

The memory 71 includes a memory main body such as an HDD (Hard Disk Drive) for recording electrical information, and peripheral circuits such as a memory controller and a memory interface attached to the memory main body. The memory 71 stores, for example, programs to be executed by the processing circuit 74, detection data received from the DAS 38, medical images generated by the processing circuit 74, data used for processing by the processing circuit 74, various tables, and data during processing. and processed data, etc. are stored. Medical images include, for example, CT images, 3D-CT images, 3D angio images, 2D angio images, superimposed images, and processed images. In the CT image g1 shown in FIG. 3, the subject placed on the tabletop 53 is imaged in a direction Lt inclined by an angle θ from the horizontal direction Lh with respect to the floor surface. This angle θ is information about the deflection of the tabletop 53 pulled out from the support frame 54 and tends to increase according to the moving amount (pulling amount) of the tabletop 53 and the weight of the subject P. This angle .theta. may be appropriately called by any desired name, such as "tilt angle related to deflection" or "top sagging angle". As various tables, there is a patient load table 71a as shown in FIG. The patient load table 71a describes the tilt angle of the tabletop 53 in association with the movement amount (pull-out amount) of the tabletop 53 and the weight of the subject P described above. The patient load table 71a may include the height of the subject P in addition to the body weight of the subject.

The display 72 is composed of a display body that displays various information such as medical images, an internal circuit that supplies display signals to the display body, and peripheral circuits such as connectors and cables that connect the display body and the internal circuits. there is The internal circuit superimposes incidental information such as subject information and projection data generation conditions on image data supplied from the image processing function 744 of the processing circuit 74 to generate display data, and D/D for the obtained display data. A conversion and TV format conversion are performed and displayed on the display main body. For example, the display 72 outputs a medical image generated by the processing circuit 74, a GUI (Graphical User Interface) for accepting various operations from the operator, and the like. For example, the display 72 is a liquid crystal display or a CRT (Cathode Ray Tube) display. Also, the display 72 is an example of a display unit. The display 72 may also be provided on the CT gantry 30 . The display 72 may be of a desktop type, or may be configured by a tablet terminal or the like capable of wireless communication with the main body of the console device 70 .

The input interface 73 is used for inputting subject information, setting X-ray conditions, and inputting various command signals. The subject information includes, for example, subject ID, subject name, date of birth, age, weight, sex, examination site, and the like. Note that the subject information may include the height of the subject. The input interface 73 includes, for example, a trackball for instructing movement of the C-arm 14, setting a region of interest (ROI), a switch button, a mouse, a keyboard, a touch pad for performing input operations by touching the operation surface, and It is realized by a touch panel display or the like in which a display screen and a touch pad are integrated. The input interface 73 is connected to the processing circuit 74 , converts an input operation received from the operator into an electrical signal, and outputs the electrical signal to the processing circuit 74 . Note that the input interface 73 may be provided in the CT gantry 30 . Also, the input interface 73 may be composed of a tablet terminal or the like capable of wireless communication with the main body of the console device 70 . Also, in this specification, the input interface 73 is not limited to having physical operation parts such as a mouse and a keyboard. For example, the input interface 73 also includes an electrical signal processing circuit that receives an electrical signal corresponding to an input operation from an external input device provided separately from the device and outputs the electrical signal to the processing circuit 74. .

The processing circuit 74 is a processor that implements a system control function 741, a drive control function 742, an imaging control function 743, an image processing function 744, and a display control function 746 corresponding to the programs by calling and executing the programs in the memory 71. be. 1, the system control function 741, the drive control function 742, the imaging control function 743, the image processing function 744, the acquisition function 745, and the display control function 746 are realized by the single processing circuit 74. However, a processing circuit may be configured by combining a plurality of independent processors, and each function may be realized by each processor executing a program. A system control function 741, a drive control function 742, an imaging control function 743, an image processing function 744, an acquisition function 745, and a display control function 746 are respectively a system control circuit, a drive control circuit, an imaging control circuit, an image processing circuit, and an acquisition control circuit. They may also be referred to as circuits and display control circuits, and may be implemented as separate hardware circuits.

The system control function 741 , for example, temporarily stores information such as a command signal by an operator input from the input interface 73 and various initial setting conditions, and then transmits this information to each processing function of the processing circuit 74 .

The drive control function 742 controls the CT control device 35, the C-arm drive device 142, and the bed drive device 52 using, for example, information regarding the drive of the CT gantry 30, the C-arm 14, and the tabletop 53 input from the input interface 73. control. For example, the drive control function 742 controls movement and rotation of the angiogantry 10, movement, rotation and tilt of the CT gantry 30, movement and tilt of the bed apparatus 50, and the like. Further, for example, the drive control function 742 may move the top plate 53 from the CT image capturing position and place the subject P at the angio image capturing position by the angiogantry 10 disposed near the support frame 54. . In this case, the drive control function 742 tilts the tabletop 53 so as to reproduce the inclination due to the deflection of the tabletop 53 based on the information about the deflection of the tabletop 53 at the CT image capturing position. The drive control function 742 may change the height of the top plate 53 in addition to tilting the top plate 53 . The tilt and height changes of the top plate 53 may be performed in parallel or in series. As an opposite case, the drive control function 742 may move the tabletop 53 from the imaging position of the angio image to place the subject P at the imaging position of the CT image. In this case, the top 53 is tilted so that the top 53 is in a horizontal state based on the information about the deflection of the top 53 based on the amount of movement of the top 53 and the weight of the subject P. Similarly, the drive control function 742 may change the height of the top plate 53 in addition to tilting the top plate 53 . The tilt and height changes of the top plate 53 may be performed in parallel or in series. Further, the drive control function 742 performs interference control so as to avoid contact between the angiogantry 10 and the subject P based on the set interference area. The drive control function 742 is an example of a tabletop controller.

The imaging control function 743 , for example, reads information from the system control function 741 and controls X-ray conditions such as tube voltage, tube current, and irradiation time in the high voltage generator 11 . X-ray conditions may include the product of tube current and irradiation time (mAs).

For CT imaging, for example, the image processing function 744 performs preprocessing such as logarithmic conversion processing, offset correction processing, inter-channel sensitivity correction processing, and beam hardening correction on the detected data in the memory 71, and then converts the data into data. Generate. Data before preprocessing (detection data) and data after preprocessing may be collectively referred to as projection data. The image processing function 744 also performs reconstruction processing using the filtered back projection method, the iterative reconstruction method, or the like on the projection data generated by the preprocessing to generate CT image data. In addition, the image processing function 744 converts the generated CT image data 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 operator via the input interface 73. do. That is, the image processing function 744 generates two-dimensional CT image data based on projection data indicating the intensity distribution of X-rays transmitted through the subject P, and converts the two-dimensional CT image data into a three-dimensional medical image. Convert to CT image data or tomogram data. As well-known methods, for example, volume rendering, surface volume rendering, pixel value projection processing, MPR (Multi-Planer Reconstruction) processing, and CPR (Curved MPR) processing can be used as appropriate. The image processing function 744 can also generate CT localization images based on the detected data.

On the other hand, for angio imaging, the image processing function 744 performs image processing such as filtering on the projection data in the memory 71 to generate angio image data, and stores the angio image data in the memory 71 . Furthermore, the image processing function 744 performs synthesis processing, subtraction processing, etc. on the obtained plural angio image data, and stores the obtained angio image data in the memory 71 .

On the other hand, the image processing function 744 can also perform fusion processing, processing, and the like based on CT images and angio images.

The acquisition function 745 captures the CT image based on the CT image obtained by imaging the subject P with the CT gantry 30 having the opening 30a into which the top plate 53 that has been pulled out and moved from the support frame 54 is inserted. Obtain information about the deflection of the top plate 53 at the position. For example, the acquisition function 745 determines the angle between the direction of a straight line fitted to the surface (not shown) of the tabletop 53 in the CT image or the contour of the tabletop side of the subject P and the horizontal direction. It may be acquired as information about the deflection of the tabletop 53 at the imaging position of the CT image. In addition, the acquisition function 745 is pulled out from the support frame 54 from the imaging position of the angio image by the angio gantry 10 arranged near the support frame 54 that movably supports the table 53 on which the subject P is placed. Based on the amount of movement of the top plate to the CT image imaging position by the CT gantry 30 having the opening 30a into which the top plate 53 moved by the movement of the body is inserted, and the weight of the subject P, the top plate at the CT image imaging position Obtain information about the deflection of 53 . Acquisition function 745 is an example of an acquisition unit.

For example, the display control function 746 reads a signal from the system control function 741, acquires desired medical image data from the memory 71, and performs control such as displaying the data on the display 72. FIG.

Next, the operation of the angio-CT apparatus configured as described above will be described with reference to the flow charts of FIGS. 5 and 8 and the schematic diagrams of FIGS. In the following description, the operation in the case of imaging an angio image after imaging a CT image will be described with reference to FIGS. 5 to 7. FIG. Next, as an opposite case, the operation of capturing a CT image after capturing an angio image will be described with reference to FIGS. 8 to 11. FIG.

[When taking an angio image after taking a CT image: ST1 to ST8]
In step ST1, the processing circuit 74 of the angio-CT apparatus 1 controls the CT gantry 30 and the angio-gantry 10 to move along the rails r1 and r2 in accordance with the operation of the input interface 73 by the operator. As a result, the angiogantry 10 is placed in the vicinity of the support frame 54 of the couch apparatus 50, as shown in FIG. The CT gantry 30 is arranged at a position where the top plate 53 pulled out from the support frame 54 can be inserted into the opening 30a.

After step ST1 is finished, in step ST2, the processing circuit 74 draws out the table 53 on which the subject is placed from the support frame 54 and moves it to the CT image capturing position, as shown in FIG. Place P. At this time, gravity causes the top plate 53 to bend, and the tip of the top plate 53 is lowered. Along with this, the subject P tilts in the direction in which the head is lowered.

After step ST2, in step ST3, the processing circuit 74 controls the CT gantry 30 to perform a positioning scan and then CT imaging. As a result, a CT image of the tilted subject is obtained as shown in FIG.

After step ST3, in step ST4, the processing circuit 74 acquires information on the deflection of the tabletop 53 at the imaging position of the CT image based on the CT image.

After step ST4, in step ST5, the processing circuit 74 moves the top plate 53 from the CT image capturing position, and the angiogantry 10 placed near the support frame 54 performs the The subject P is arranged at the imaging position of the angio image. Note that when only step ST5 is executed, as shown in FIG. 7B, the tabletop 53 and the subject P are in a horizontal state because the tabletop 53 is not flexed at the imaging position of the angio image.

After step ST5, in step ST6, the processing circuit 74 reproduces the tilt due to the deflection of the tabletop 53 as shown in FIG. The top plate 53 is tilted so as to Note that steps ST5 and ST6 may be executed in parallel or in series. At this time, the processing circuit 74 may change the height of the top plate 53 in addition to tilting the top plate 53 . In any case, the subject P inclines in the direction in which the head is lowered.

After step ST6, in step ST7, the processing circuitry 74 controls the angiogantry 10 to perform angio-imaging. As a result, an angio image of the tilted subject is obtained.

After step ST7, in step ST8, the processing circuit 74 uses the CT image and the angio image of the subject P tilted at the same angle to each other to perform image fusion or image processing.

[When taking a CT image after taking an angio image: ST11 to ST18]
In step ST11, the processing circuit 74 of the angio-CT apparatus 1 arranges the angio-CT gantry 10 and the CT gantry 30 as shown in FIG. 2, similarly to step ST1 described above.

After the end of step ST11, in step ST12, the processing circuit 74 moves the table 53 on which the subject P is placed, and places the subject P at the imaging position of the angio image, as shown in FIG. At this time, the top plate 53 is supported by the support frame 54 and becomes horizontal. Similarly, the subject P on the top board 53 is also in a horizontal state.

After step ST12, in step ST13, the processing circuitry 74 controls the angio gantry 10 to perform angio imaging. As a result, an angio image of the object P in the horizontal state is obtained.

After the end of step ST13, in step ST14, the processing circuit 74 pulls out the table 53 on which the subject P is placed from the support frame 54 and moves it to the CT image capturing position, as shown in FIG. A specimen P is placed. At this time, gravity causes the top plate 53 to bend, and the tip of the top plate 53 is lowered. Along with this, the subject P tilts in the direction in which the head is lowered.

After step ST14, in step ST15, the processing circuit 74 determines the imaging position of the CT image based on the weight of the subject P and the amount of movement of the tabletop 53 from the imaging position of the angio image to the imaging position of the CT image. acquires information about the deflection of the top plate 53 at . Specifically, the processing circuit 74 reads the tilt angle of the deflection of the tabletop 53 from the patient load table 71 a in the memory 71 based on the amount of movement of the tabletop 53 and the weight of the subject P. FIG. Note that this tilt angle may also be referred to as the angle of top board sag.

After step ST15, in step ST16, the processing circuit 74 moves the top plate 53 so that it is in a horizontal state as shown in FIG. 53 is tilted. The processing circuit 74 may change the height of the top plate 53 in addition to tilting the top plate 53 . In any case, the subject P will be in a horizontal state.

After step ST16, in step ST17, the processing circuit 74 controls the CT gantry 30 to perform positioning scanning and then CT imaging. As a result, a CT image of the subject P in the horizontal state is obtained.

After step ST17, in step ST18, the processing circuit 74 performs image fusion or image processing using the CT image and the angio image of the subject P tilted at the same angle. Here, the image fusion may be, for example, a process of aligning and superimposing an angio image and a CT image. Also, as image processing, for example, a process of aligning an angio image and a CT image and performing some processing can be applied. As some kind of processing, for example, the difference between both aligned images may be detected, and a specific region may be deleted or reduced from the detection result. The specific region may be, for example, a bone region or some noise. Noise may be an artifact.

As described above, according to the first embodiment, a CT gantry having an opening into which the top board that has been pulled out from the support frame that movably supports the top board on which the subject is placed and moved is inserted is placed on the subject. is acquired based on the CT image obtained by imaging . In addition, when moving the tabletop from the imaging position of the CT image and arranging the subject at the imaging position of the angio image by the angiogantry placed near the support frame, based on the information, the bending of the tabletop Tilt the top plate to reproduce the tilt. Therefore, when the table is moved to alternately perform angiographic imaging and CT imaging, the difference in inclination of the table can be reduced. Supplementally, it is possible to reduce the difference in inclination of the tabletop based on the inclination of the tabletop during CT imaging.

In addition, by reducing the difference in the tilt of the tabletop, when image fusion or image processing is performed using angiographic images and CT images, differences in the position and blood flow of parts such as organs occur due to the influence of gravity. Therefore, the shift between images can be reduced. Supplementally, if the tilt of the tabletop differs between the CT image and the angiographic image, the positions of the organs will differ between the two images due to the influence of gravity. Even if you create an image, there will still be a gap between the images. On the other hand, in the first embodiment, by reducing the difference in inclination of the tabletop, it is possible to reduce the displacement between images, as described above.

Further, according to the first embodiment, in addition to tilting the top plate, the height of the top plate may be changed. In this case, the center of rotation of the deflection of the tabletop and the center of rotation of the tabletop tilt can be matched to prevent or reduce the deviation between the enlargement ratio of the CT image and the enlargement ratio of the angio image.

Further, according to the first embodiment, the angio-image imaging position by the angiogantry arranged near the support frame that movably supports the tabletop on which the subject is placed is pulled out from the support frame. Based on the amount of movement of the tabletop to the imaging position of the CT image by a CT gantry having an opening into which the moved tabletop is inserted, and the weight of the subject, information on the deflection of the tabletop at the imaging position of the CT image is obtained. get. Further, when the table is moved from the imaging position of the angio image to place the subject at the imaging position of the CT image, the table is tilted so as to be horizontal based on the information. Therefore, when the table is moved to alternately perform angiographic imaging and CT imaging, the difference in inclination of the table can be reduced. Supplementally, it is possible to reduce the difference in inclination of the tabletop with reference to the inclination of the tabletop during angio imaging. In addition, this makes it possible to reduce the difference in inclination of the tabletop during both CT imaging and angio imaging.

(First modification)
Next, an angio-CT apparatus according to a first modified example of the first embodiment will be described. In the following description, the same reference numerals are assigned to the same parts as in the above-described drawings, and detailed description thereof will be omitted, and mainly different parts will be described. This is the same for each modification and each embodiment described below.

The first modified example is intended to reduce errors in the information regarding the deflection of the top plate 53, and as shown in FIG.

Here, the tilt sensor 54a is used to adjust the support frame 54 to the absolute horizontal level and measures the difference between the tilt of the support frame 54 and the absolute horizontal level.

The memory 71 stores a correction table 71b as shown in FIG. 13 instead of the patient load table 71a. The correction table 71b describes the amount of movement of the top plate 53 and information about the deflection of the top plate in association with each other. In the example shown in FIG. 13, the information about the deflection of the top plate is the tilt angle due to the deflection of the top plate 53 . The tilt angle due to the deflection of the top plate 53 may be called the tilt angle of the top plate 53 or the top plate sagging angle. Also, the amount of movement of the top plate may be called the horizontal movement position of the top plate. That is, the movement amount of the tabletop may be represented by the horizontal movement position of the tabletop.

Other configurations are similar to those of the first embodiment.

Next, the operation of the angio-CT apparatus according to the first modification will be described. Steps ST1 to ST8 for performing angiographic imaging after CT imaging are as described above.

On the other hand, the operations of steps ST11 to ST18 for performing CT imaging after angio imaging are slightly different. That is, after steps ST11 to ST14 similar to those described above, in step ST15, the processing circuit 74 acquires the tilt angle due to the deflection of the top plate 53 from the correction table 71b in the memory 71 based on the amount of movement of the top plate 53. .

After step ST15, in step ST16, the processing circuit 74 aligns the tilt angle of the tabletop 53 with the absolute horizontal level based on the measurement value of the tilt sensor 54a. Thereafter, the processing circuit 74 tilts the top plate 53 so that the top plate 53 is in a horizontal state based on the inclination angle of the top plate 53 at the CT image capturing position. The processing circuit 74 may change the height of the top plate 53 in addition to tilting the top plate 53 . In any case, the subject P will be in a horizontal state.

Thereafter, steps ST17 to ST18 are executed in the same manner as described above.

According to the first modification of the first embodiment as described above, the tilt sensor for measuring the absolute horizontal level is provided on the support frame, and the tabletop is tilted based on the measured value of the tilt sensor. You can tilt the tabletop to a more precise angle than without it.

(Second modification)
The second modified example is a specific example of image fusion or image processing executed by the processing circuit 74 in step ST8 or ST18. An example of image fusion is the registration and fusion of a 3D-CT image and a 3D-angio image.

Another example of image fusion is the registration and fusion of a 2D-CT image with a 2D-angio image. In this case, for example, as shown in FIG. 14, a corresponding 2D-CT image g11 is cut out from the 3D-CT image g10 at a certain cut-out angle, and the 2D-CT image g11 is aligned with the 2D-angioscopic image g20. superimposed to create a superimposed image g31. Here, the cut-out angle is based on angle information of the C-arm 14 .

As an example of image processing, a process of aligning an angio image and a CT image and performing some processing can be applied. For example, the 2D-CT image g11 described above is aligned with the 2D-angioscopic image g20, the difference between the two images is detected, and processing is performed to eliminate the bone region from the detection result, thereby creating a processed image g32. A specific area such as noise may be erased or reduced instead of the process of erasing the bone area. Noise may be an artifact.

According to the second modification of the first embodiment as described above, a 2D-CT image cut out from a 3D-CT image based on the angle information of the C-arm 14 and a 2D-angio image may be used. . In this case, in addition to the effects of the first embodiment, it is possible to reduce image deviation when performing image fusion or image processing. Also, image artifacts can be reduced.

<Second embodiment>
Next, an angio-CT apparatus according to a second embodiment will be described.

The second embodiment is a modification of the first embodiment, and as shown in FIG. 15, has a configuration in which an interference region is set based on a CT image when angiographic imaging is performed.

Along with this, the image processing function 744 of the processing circuit 74 generates three-dimensional image data representing the surface shape of the subject P based on the CT image of the subject captured by the CT gantry 30 in addition to the functions described above. do. Image processing function 744 is an example of a generator.

In addition to the functions described above, the drive control function 742 sets an interference region for avoiding contact between the angiogantry 10 and the subject P based on the three-dimensional image data. The set interference area is used for interference control in the same manner as described above. The drive control function 742 is an example of an area setting section. Note that the image processing function 744 may be used as an example of the area setting unit instead of the drive control function 742 .

Other configurations are similar to those of the first embodiment.

Next, the operation of the angio-CT apparatus configured as described above will be described with reference to the flow chart of FIG. 16 and the schematic diagrams of FIGS.

It is now assumed that steps ST1 to ST6 are executed in the same manner as described above, and that the tabletop 53 is tilted so as to reproduce the tilt due to the bending of the tabletop 53 based on the CT image at the imaging position of the angio image.

After step ST6, steps ST7-1 to ST7-3 are sequentially executed instead of step ST7. That is, in step ST7-1, the processing circuit 74 generates three-dimensional image data g2 representing the surface shape of the subject P based on the CT image, as shown in FIG.

After step ST7-1, in step ST7-2, the processing circuit 74 sets an interference area A1 for avoiding contact between the angiogantry 10 and the subject P based on the three-dimensional image data g2. In FIG. 17, the interference area A1 is an area corresponding to the surface shape of the subject P, but is not limited to this, and may be an area in the vicinity of the subject that wraps the surface shape of the subject P. FIG. The processing circuitry 74 may also set the interference area A1 to overwrite the initially set interference area A0, as shown in FIG. At this time, the processing circuit 74 may or may not compare the interference area A1 created from the three-dimensional image data g2 and the initially set interference area A0. In the case of comparison, if the created interference area A1 is larger than the initially set interference area A0, the processing circuit 74 may overwrite the interference area A1. If no comparison is made, the processing circuit 74 may uniformly overwrite and set the newly created interference area A1. In any case, the processing circuit 74 sets the interference area A1 in the memory 71 based on the three-dimensional image data g2 or g3.

After step ST7-2, in step ST7-3, the processing circuit 74 controls the angio gantry 10 while performing interference control based on the set interference area A1 to perform angio imaging. As a result, an angio image of the tilted subject is obtained.

After step ST7-3, step ST8 is executed in the same manner as described above.

According to the second embodiment as described above, three-dimensional image data representing the surface shape of the subject is generated based on the CT image. Also, based on the three-dimensional image data, an interference region for avoiding contact between the angiogantry and the subject is set. Therefore, in addition to the effects of the first embodiment, the X-ray detector at the tip of the C-arm can be arranged at a position closer to the surface of the subject, and a safer angio-CT apparatus can be provided.

<Third Embodiment>
Next, an angio-CT apparatus according to a third embodiment will be described.

The third embodiment is a modification of the first or second embodiment, and is configured to set conditions for angiographic imaging based on information at the time of CT imaging.

Along with this, the imaging control function 743 of the processing circuit 74 sets the X-ray conditions for imaging an angio image based on the CT image in addition to the functions described above.

For example, the imaging control function 743 performs rotational DSA imaging according to an operator's operation while a plurality of MPR (Multi-Planar Reformat) images generated from CT volume data forming a three-dimensional CT image are being displayed on the display 72. The center point (isocenter) of the region of interest in is specified, and the positional information of the isocenter is embedded in the CT volume data. The CT volume data is data having CT value distribution information in a three-dimensional space. Also, the operator refers to a plurality of MPR images or three-dimensional CT images and embeds region information of a target region (region of interest) for rotational DSA imaging into CT volume data. Note that the isocenter position information and the region of interest position information are embedded as, for example, header information of the CT volume data. DSA is an abbreviation for Digital Subtraction Angiography.

In addition, the imaging control function 743 arranges the CT volume data at the position (coordinates) at which the projection image similar to the angio image generated in the position information of the top plate 53 and the C-arm 14 is generated, thereby performing position alignment. do For example, registration is performed by placing the CT volume data based on the feature points of a particular organ (liver, heart, brain, etc.) in the region of interest. The imaging control function 743 also controls the desired imaging based on the amount of deviation between the desired isocenter (the point where the isocenter embedded in the CT volume data is projected onto the simulated X-ray image) and the isocenter of the angiogantry 10. The position of the subject P is adjusted by adjusting the positions of the top plate 53 and the C-arm 14 so that the coordinates of the isocenter and the isocenter of the angiogantry 10 match.

Then, the imaging control function 743 transfers each CT value of the CT volume data aligned with the angio imaging coordinate system from the X-ray generator 12 at the imaging position to the X-ray detector 13 position (x , y, z), and further corrects the replaced X-ray absorption value based on the set X-ray conditions. Then, the imaging control function 743 integrates the corrected X-ray absorption values to obtain X-ray image information when the CT volume data is projected at the position (x, y, z) of the X-ray detector 13. Calculate Simulated X-ray image data is generated by performing this for all the coordinates of the detection surface of the X-ray detector 13 . In addition, the imaging control function 743 reads out the position information of the table top 53 and the C-arm 14 and the set X-ray conditions, and simulates each rotational imaging angle (for example, every 10°) at which rotational imaging is performed. Generate X-ray image data. After that, the imaging control function 743 adjusts the dose of X-rays emitted from the X-ray generation unit 12 so that each of the generated simulated X-ray images for each rotational imaging angle is displayed with appropriate brightness on the display 72. A "tube voltage (unit: kV)" and a "product of tube current and X-ray irradiation time (unit: mAs)" for correction are calculated. That is, the imaging control function 743, after FOV (Field of View) and SID (Source Image Distance) are set, again generates simulated X-ray image data for each rotational imaging angle for one rotation every 10°. , the brightness gain is calculated so that the brightness of the imaging range (region of interest) is appropriate in the simulated X-ray image on the display 72 . Further, the imaging control function 743 calculates and sets X-ray conditions for realizing each calculated luminance gain. Note that the imaging control function 743 is not limited to this, and performs arithmetic processing on the position and body shape information of the subject P at the imaging position of the angio image from the X-ray conditions and bed position information at the imaging position of the CT image, and performs CT imaging. may be used as information for converting the X-ray conditions of to the X-ray conditions of angio imaging. The imaging control function 743 is an example of a condition setting section.

Other configurations are similar to those of the first or second embodiment.

Next, the operation of the angio-CT apparatus configured as described above will be described with reference to the flow chart of FIG. 19 and the schematic diagram of FIG.

It is now assumed that steps ST1 to ST6 are executed in the same manner as described above, and that the tabletop 53 is tilted so as to reproduce the tilt due to the bending of the tabletop 53 based on the CT image at the imaging position of the angio image.

After step ST6, steps ST7b-1 and ST7b-2 are sequentially executed instead of step ST7 or steps ST7-1 to ST7-3 described above. That is, in step ST7b-1, the processing circuit 74 sets X-ray conditions for capturing an angio image based on the CT image. For example, the processing circuit 74 outputs X-ray image information when the CT volume data aligned with the coordinate system for angio imaging is projected at the position (x, y, z) of the X-ray detector 13. Calculate Simulated X-ray image data is generated by performing this for all the coordinates of the detection surface of the X-ray detector 13 . The imaging control function 743 also reads the position information of the table top 53 and the C-arm 14 and the set X-ray conditions, and generates simulated X-ray image data for each rotational imaging angle at which rotational imaging is performed. . After that, the imaging control function 743 sets the X-ray conditions “tube voltage” and “tube current and X-ray intensity” so that the generated simulated X-ray images for each rotational imaging angle are displayed with appropriate brightness on the display 72 . Calculate the product of the number of seconds of irradiation. For example, as shown in FIG. 20, the processing circuit 74 determines that the X-ray conditions for realizing an appropriate "luminance gain: 1.0" of "RAO/LAO" are "80 kV, 100 mAs" and "RAO" The X-ray conditions for all simulated X-ray images are calculated such that the X-ray conditions for realizing an appropriate "brightness gain: 0.8" are "80 kV, 80 mAs". Further, the processing circuit 74 sets the X-ray conditions for each rotational imaging angle. "RAO" is an abbreviation for "right anterior oblique". "LAO" is an abbreviation for "left anterior oblique".

After step ST7b-1, in step ST7b-2, the processing circuit 74 controls the angiogantry 10 based on the set X-ray conditions to perform angioimaging. For example, when the processing circuit 74 receives a request to start rotational DSA imaging from the operator via the input interface 73, the processing circuit 74 moves the C-arm 14 adjusted to an appropriate position to the top plate 53 adjusted to an appropriate angle. The subject P is rotated around the upper subject P, and X-rays are emitted from the X-ray generation unit 12 based on the X-ray conditions for each set rotation imaging angle to execute rotation DSA imaging. Note that the angiographic imaging is not limited to this, and X-ray fluoroscopic imaging or other methods may be used. In any case, angio-imaging is performed based on the set X-ray conditions.

After step ST7b-2, step ST8 is executed in the same manner as described above.

According to the third embodiment as described above, the X-ray conditions for capturing an angio image are set based on the X-ray conditions and the CT image when the CT image was captured. Therefore, in addition to the effects of the first or second embodiment, this eliminates the need for test exposure for setting X-ray conditions when switching from CT imaging to angio imaging, thereby reducing exposure. can be done. In addition, since test exposure is unnecessary, inspection efficiency can be improved.

<Fourth Embodiment>
Next, an angio-CT apparatus according to a fourth embodiment will be described.

The fourth embodiment is a modified example of each of the first to third embodiments, and has a configuration in which a CT image is corrected and displayed so that the subject is in a horizontal state.

Along with this, the image processing function 744 of the processing circuit 74 corrects the CT image based on the CT image so that the subject P in the CT image is in a horizontal state, in addition to the functions described above. Specifically, for example, the image processing function 744 is based on the angle between the direction of the straight line fitted to the surface of the tabletop 53 in the CT image or the contour of the tabletop side of the subject P and the horizontal direction. , the CT image should be rotated so that the straight line is horizontal. The center of rotation when rotating the CT image may be the imaging position of the angio image separated from the imaging position of the CT image by the distance between the CT gantry 30 and the angiogantry 10, or may be an arbitrary point in the CT image. good. In addition, the image processing function 744 creates a superimposed image by superimposing the corrected CT image on the angio image based on the movement amount of the tabletop from the imaging position of the CT image to the imaging position of the angio image. may The angio image used by the image processing function 744 (that is, the angio image obtained by imaging the subject P with the angio gantry 10) is stored in the memory 71. FIG. The image processing function 744 is an example of an image correction unit and an image superimposition unit. The memory 71 is an example of a storage unit.

The display control function 746 displays the corrected CT image on the display 72 in addition to the functions described above. Also, the display control function 746 may cause the display 72 to display the superimposed image. The display control function 746 is an example of a display control unit.

Other configurations are the same as those of the first to third embodiments.

Next, the operation of the angio-CT apparatus configured as described above will be described with reference to the flow chart of FIG. 21 and the schematic diagram of FIG. Note that the following description will be given by taking the case of applying to the first embodiment as an example, but it can be similarly applied to the second or third embodiment.

Assume that steps ST1 to ST3 have been executed in the same manner as described above, and CT imaging has been performed at the CT image imaging position. Suppose that a CT image g4 obtained by photographing the tilted subject P as shown in the upper part of FIG. 22 is obtained. In order to facilitate understanding, the horizontal direction Lh1 and the direction Lt inclined by an angle θ from the horizontal direction Lh1 due to the deflection of the table top 53 are illustrated. and tilted direction Lt are not superimposed.

After step ST3, steps ST4c-1 and ST4c-2 are sequentially executed instead of step ST4. That is, in step ST4c-1, the processing circuit 74 acquires information on the deflection of the tabletop 53 at the imaging position of the CT image g4 based on the CT image g4.

After step ST4c-1, in step ST4c-2, the processing circuit 74 corrects the CT image g4 based on the CT image g4 so that the subject P in the CT image g4 is horizontal. As a result, a corrected CT image g4c as shown in the lower part of FIG. 22 is obtained. Although horizontal directions Lh1 and Lh2 are illustrated for ease of understanding, these horizontal directions Lh1 and Lh2 are not superimposed on the actual CT image g4c. The processing circuit 74 also causes the display 72 to display the corrected CT image g4c.

After step 4c-2, steps ST5 to ST7 are executed in the same manner as described above to obtain an angio image of the subject P imaged at the angio imaging position.

After step ST7, steps ST8c-1 and ST8c-2 are sequentially executed instead of step ST8. That is, in step ST8c-1, the processing circuit 74 superimposes the corrected CT image g4c on the angio image based on the amount of movement of the tabletop 53 from the imaging position of the CT image g4c to the imaging position of the angio image. to create a superimposed image.

After step ST8c-1, the processing circuit 74 causes the display 72 to display the superimposed image in step ST8c-2.

As described above, according to the fourth embodiment, the CT image is corrected so that the subject in the CT image is in a horizontal state based on the information about the deflection of the tabletop, and the corrected CT image is displayed. display on the display. As a result, it is possible to automatically display the displayed CT image always in a horizontal state.

Further, according to the fourth embodiment, the CT image is corrected to a horizontal state so that the subject in the CT image is horizontal based on the information about the bending of the tabletop. An angio image obtained by imaging a subject with an angio gantry is stored. A superimposed image is created by superimposing the corrected CT image on the angio image based on the movement amount of the tabletop from the imaging position of the angio image to the imaging position of the CT image. The superimposed image is displayed on the display unit.

Therefore, since the horizontal state of the CT image is maintained, a shift correction operation for superimposing a CT image and an angio image for fusion display and a pixel shift operation for correcting image artifacts due to shift can be performed simply by X , and the coordinates in the Y direction. Therefore, in the fourth embodiment, operability can be improved. On the other hand, in a state where the CT image is tilted due to table sagging, coordinate conversion in the X and Y directions becomes complicated during misalignment correction operation for fusion display and pixel shift operation, and simple adjustment is performed. I can't.

According to at least one of the embodiments described above, a CT gantry having an opening into which a top board that is pulled out from a support frame that movably supports a top board on which the subject is placed is inserted. Based on the CT image obtained by imaging, information about the deflection of the tabletop at the imaging position of the CT image is acquired. In addition, when moving the tabletop from the imaging position of the CT image and arranging the subject at the imaging position of the angio image by the angiogantry placed near the support frame, based on the information, the bending of the tabletop Tilt the top plate to reproduce the tilt. Therefore, when the table is moved to alternately perform angiographic imaging and CT imaging, the difference in inclination of the table can be reduced.

The term "processor" used in the above description is, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC), a programmable logic device (e.g., Circuits such as Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), Field Programmable Gate Array (FPGA), etc. A processor is a memory circuit. The function is realized by reading and executing the program stored in.In addition, instead of storing the program in the memory circuit, it may be configured so that the program is directly incorporated in the circuit of the processor.In this case, the processor The function is realized by reading and executing the program embedded in the circuit.In addition, each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may be configured as a plurality of independent circuits. 1 or 16 may be integrated into one processor to realize its function. .

It should be noted that although several embodiments of the invention 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, and modifications 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 angio-CT apparatus 10 angiogantry 11 high-voltage generator 12 X-ray generator 13, 32 X-ray detector 14 C-arm 14a holder 14b support arm 141 state detector 142 C-arm drive 30 CT gantry 30a opening 31 X-ray Tube 33 Rotating frame 34 X-ray high voltage device 35 CT controller 36 Wedge 37 Collimator 38 DAS
50 bed device 51 base 52 bed drive device 53 top plate 54 support frame 54a tilt sensor 70 console device 71 memory 71a patient load table 71b correction table 72 display 73 input interface 74 processing circuit 741 system control function 742 drive control function 743 imaging control Function 744 Image processing function 745 Acquisition function 746 Display control function A1, A0 Interference area g1, g4 CT image g2, g3 Three-dimensional image data Lh, Lh1, Lh2 Horizontal direction Lt Tilted direction r1, r2 Rail

Claims (7)

Based on a CT image obtained by imaging the subject with a CT gantry having an opening into which the top board pulled out from a support frame that movably supports the top board on which the subject is placed and moved is inserted. , an acquisition unit that acquires information about the deflection of the top board at the imaging position of the CT image;
When the table is moved from the CT image capturing position and the subject is positioned at the angio image capturing position by an angiogantry placed near the support frame, the table is positioned on the basis of the information. an angio-CT apparatus comprising: a top plate control unit that tilts the top plate so as to reproduce the inclination due to the deflection of the top plate. 2. The angio-CT apparatus according to claim 1, wherein said tabletop controller changes the height of said tabletop in addition to tilting said tabletop. a generation unit that generates three-dimensional image data representing the surface shape of the subject based on the CT image;
3. The angio-CT apparatus according to claim 1, further comprising: an area setting unit that sets an interference area for avoiding contact between the angiogantry and the subject based on the three-dimensional image data. 4. The angio-CT apparatus according to any one of claims 1 to 3, further comprising a condition setting unit that sets X-ray conditions for capturing the angio-image based on the CT image. Equipped with an image correction unit and a display control unit,
The image correction unit corrects the CT image based on the CT image so that the subject in the CT image is in a horizontal state,
2. The angio-CT apparatus according to claim 1, wherein said display control unit causes a display unit to display said corrected CT image. An image correction unit, a storage unit, an image superimposition unit and a display control unit,
The image correction unit corrects the CT image to a horizontal state based on the CT image so that the subject in the CT image is horizontal;
The storage unit stores an angio image obtained by imaging the subject with the angio gantry,
The image superimposing unit superimposes the corrected CT image on the angio image based on the amount of movement of the tabletop from the imaging position of the CT image to the imaging position of the angio image. make,
2. The angio-CT apparatus according to claim 1, wherein said display control unit causes a display unit to display said superimposed image. The acquisition unit obtains the table top at the CT image imaging position based on the amount of movement of the tabletop from the angiographic image imaging position to the CT image imaging position and the body weight of the subject. Get information about the deflection of the plate,
The table control unit moves the table from the imaging position of the angio image to arrange the subject at the imaging position of the CT image, the table control unit obtains the Based on the information, tilting the top plate so that the top plate is in a horizontal state ;
The angio-CT apparatus according to any one of claims 1 to 6 .

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