JP2020092887A - X-ray ct apparatus - Google Patents

Abstract

To restrict a detector row for outputting data from a stand device for image generation based on the position of the tip of a puncture needle.SOLUTION: An X-ray CT apparatus includes an X-ray tube, an X-ray detector, a detection unit, a specification unit, and an image generation unit. The X-ray tube generates an X-ray with which a subject is to be irradiated. In the X-ray detector, a plurality of detection elements for detecting an X-ray are arranged in a row direction over a first number of rows. The detection unit detects the position of the tip of a puncture needle stuck into the subject. The specification unit specifies a detector row of a second number of rows fewer than the first number of rows based on the detected position of the tip. The image generation unit generates an image based on data output by the specified detector row of the second number of rows.SELECTED DRAWING: Figure 3

Description

Embodiments of the present invention relate to an X-ray CT apparatus.

Recently, an X-ray CT (Computed Tomography) apparatus is sometimes used for CT fluoroscopy. CT fluoroscopy is an imaging method for continuously irradiating a subject with X-rays based on a tube current lower than that in a main scan to generate an image of a region of interest of the subject in real time. For example, a biopsy guide. Used for.

However, CT fluoroscopy requires a large load to generate an image in order to maintain real-time properties. Therefore, for example, an X-ray CT apparatus using an X-ray CT apparatus provided with a so-called two-dimensional array type (multi-slice type) X-ray detector having a plurality of rows (for example, 320 rows) of X-ray detection elements in the slice direction. When fluoroscopy is performed, image generation is performed using data output from X-ray detection elements of some detector rows (for example, four rows) instead of using data output from all X-ray detection elements. .. Therefore, if the image generated by CT fluoroscopy is thin and the speed at which the puncture needle moves in the thickness direction is high, it is difficult to keep capturing the puncture needle in the image. A method of moving the bed is conceivable as a method of continuing to capture the puncture needle in the image, but in this method, the user operation for instructing the movement of the bed is complicated, and the subject is punctured during insertion of the puncture needle. It will be very dangerous because it will move.

JP, 2005-002844, A

The problem to be solved by the present invention is to limit the detector array for outputting data from the gantry device for image generation based on the tip position of the puncture needle.

The X-ray CT apparatus according to the embodiment includes an X-ray tube, an X-ray detector, a detecting unit, a specifying unit, and an image generating unit. The X-ray tube generates X-rays that irradiate the subject. In the X-ray detector, a plurality of detection elements for detecting X-rays are arranged in the column direction for the first number of columns. The detection unit detects the tip position of the puncture needle that is inserted into the subject. The specifying unit specifies a detector row having a second row number smaller than the first row number based on the detected tip position. The image generation unit generates an image based on the data output by the specified second row of detector rows.

The block diagram which shows one structural example of the X-ray CT apparatus which concerns on one Embodiment. The block diagram which shows one structural example of the X-ray detector of a gantry apparatus. The block diagram for explaining the example of the realization function by the processor of the processing circuit of the console device of an X-ray CT apparatus. 9 is a flowchart showing an example of a schematic procedure for restricting a detector array for outputting data from the gantry device for image generation based on the position of the tip of the puncture needle by the processor of the processing circuit of the console device. Explanatory drawing which shows an example of the positional relationship of the position of the front-end|tip of a puncture needle and a specific row from the left side surface of a subject. Explanatory drawing which shows the example at the time of seeing the positional relationship shown in FIG. 5 from the upper surface of a subject. In the example shown in FIG. 6, an explanatory view showing an example in which the X-ray irradiation range and the X-ray irradiation main axis are changed according to the position of a specific row. (A) is explanatory drawing which shows the example of a display of the image produced|generated by the image production function in real time on the display 42, (b) is explanatory drawing which shows another example. 8B is an explanatory diagram showing an example in which an image showing the estimated position of the tip of the puncture needle is further superimposed on the sagittal tomographic image and the coronal tomographic image in the example shown in FIG. 8B.

Hereinafter, an embodiment of an X-ray CT apparatus will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of an X-ray CT apparatus according to an embodiment. As shown in FIG. 1, the X-ray CT apparatus 1 has a gantry device 10, a bed device 30, and a console device 40.

FIG. 2 is a block diagram showing a configuration example of the X-ray detector of the gantry device 10. In addition, FIG. 3 is a block diagram for explaining an example of a function realized by the processor of the processing circuit 45 of the console device 40 of the X-ray CT apparatus 1.

As shown in FIG. 1, in the present embodiment, the longitudinal direction of the rotation axis of the rotary frame 13 or the top plate 33 of the bed apparatus 30 in the non-tilted state is orthogonal to the z-axis direction and the z-axis direction, and is relative to the floor surface. It is assumed that the horizontal axis direction is orthogonal to the x-axis direction and the z-axis direction, and the vertical axis direction to the floor surface is defined as the y-axis direction.

The X-ray CT apparatus 1 includes Rotate/Rotate-Type (third generation CT) in which an X-ray tube and a detector are integrally rotated around the subject, and a large number of X-ray detection elements arranged in a ring shape. There are various types such as Stationary/Rotate-Type (fourth generation CT) in which only the X-ray tube is fixed and rotates around the subject, and any type is applicable to the present embodiment. In the following description, an example in which a third generation Rotate/Rotate-Type is adopted as the X-ray CT apparatus 1 according to the present embodiment will be described.

The gantry device 10 includes an X-ray tube 11, an X-ray detector 12, a rotary frame 13 having an opening 19 in which an imaging region is located, a high-voltage device 14, a controller 15, a wedge 16, a collimator 17, and a data acquisition circuit ( It has a DAS (Data Acquisition System) 18.

The X-ray tube 11 is a vacuum tube that generates X-rays by radiating thermoelectrons from the cathode (filament) to the anode (target) by applying a high voltage from the high voltage device 14.

In addition, in the present embodiment, both a single-tube type X-ray CT apparatus and a so-called multi-tube type X-ray CT apparatus in which a plurality of pairs of an X-ray tube and a detector are mounted on a rotating ring. Applicable. The hardware for generating X-rays is not limited to the X-ray tube 11. For example, instead of the X-ray tube 11, a focus coil that focuses an electron beam generated from an electron gun, a deflection coil that electromagnetically deflects the electron beam, and a deflected electron beam that surrounds a half circumference of the subject P collide with each other to generate X-rays. The X-rays may be generated using the fifth generation method including the target ring to be generated.

The X-ray detector 12 detects the X-rays emitted from the X-ray tube 11 and passing through the subject P, and outputs an electric signal corresponding to the X-ray dose to the DAS 18. The X-ray detector 12 has a plurality of X-ray detection element rows in which a plurality of X-ray detection elements are arranged in the channel direction along one arc centering on the focus of the X-ray tube 11. Further, the X-ray detector 12 has a structure in which a plurality (for example, 320 rows) 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 (column direction, row direction). Have.

Further, the X-ray detector 12 is, for example, an indirect conversion type detector having a grid, a scintillator array, and an optical sensor array. The scintillator array has a plurality of scintillators, and the scintillator has a scintillator crystal that outputs light having a photon amount according to the incident X-ray amount. The grid is arranged on the X-ray incident side surface of the scintillator array and has an X-ray shield having a function of absorbing scattered X-rays. The grid may be called a collimator (one-dimensional collimator or two-dimensional collimator). The photosensor array has a function of converting into an electric signal according to the amount of light from the scintillator, and has, for example, a photosensor such as a photomultiplier tube (photomultiplier: PMT).

The X-ray detector 12 may be a direct conversion type detector having a semiconductor element that converts an incident X-ray into an electric signal.

Further, as shown in FIG. 2, the X-ray detector 12 includes a detection element group 12a including a plurality of X-ray detection elements 121, a switch circuit 12b, and a switch control circuit 12c.

The switch circuit 12b is configured to be able to switch whether to extract data from each X-ray detection element 121 at least for each column in the slice direction. The switch circuit 12b may be a switch element provided in the vicinity of each X-ray detection element 121 like a so-called active matrix method, or may be provided at a position apart from the X-ray detection element 121.

The switch control circuit 12c is controlled by the processing circuit 45 to control the switch circuit 12b so as to switch the X-ray detection element 121 from which data is read. Specifically, the switch control circuit 12c takes out data only from the X-ray detection elements 121 belonging to the row in the slice direction designated by the processing circuit 45, and the X-ray detection elements 121 belonging to the row in the slice direction not designated. The switch circuit 12b is controlled so as not to take out the data from.

The rotating frame 13 is an annular frame that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other, and rotates the X-ray tube 11 and the X-ray detector 12 by a controller 15 described later. In addition to the X-ray tube 11 and the X-ray detector 12, the rotary frame 13 further includes and supports a high voltage device 14 and a DAS 18. The detection data generated by the DAS 18 is provided on a non-rotating portion (for example, a fixed frame, not shown) of the gantry device 10 by optical communication from a transmitter having a light emitting diode (LED) provided on the rotating frame 13. , To a receiver having a photodiode and transferred to the console device 40. The method of transmitting the detection data from the rotating frame 13 to the non-rotating portion of the gantry device 10 is not limited to optical communication, and any method may be adopted as long as it is non-contact type data transmission. A fixed frame (not shown) is a frame that rotatably supports the rotary frame 13.

The high-voltage device 14 has an electric circuit such as a transformer and a rectifier, and has a function of generating a high voltage to be applied to the X-ray tube 11, and an X-ray emitted by the X-ray tube 11. And an X-ray controller for controlling the output voltage according to the line. The high voltage generator may be a transformer type or an inverter type. The high voltage device 14 may be provided on the rotating frame 13 or on the fixed frame side of the gantry device 10.

The control device 15 has a processor provided on a control board, a memory circuit, and a drive mechanism such as a motor and an actuator. The control device 15 has a function of receiving an input signal from an input interface 43 described later attached to the console device 40 or the gantry device 10 and controlling the gantry device 10 and the bed device 30. For example, the control device 15 receives the input signal and rotates the rotating frame 13, tilts the gantry device 10, and controls the bed device 30 and the top plate 33 to operate. The control for tilting the gantry device 10 is performed by the control device 15 based on the tilt angle (tilt angle) information input by the input interface attached to the gantry device 10 so that the control device 15 rotates the rotary frame 13 about an axis parallel to the X-axis direction. It is realized by rotating. The control device 15 may be provided in the gantry device 10 or the console device 40.

The wedge 16 is a filter for adjusting the X-ray dose 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. It is a filter. For example, the wedge 16 (wedge filter, bow-tie filter) is a filter in which aluminum is processed to have a predetermined target angle and a predetermined thickness.

The collimator 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays that have passed through the wedge 16, and a slit is formed by combining a plurality of lead plates and the like. The collimator 17 is an example of an X-ray movable diaphragm.

As shown in FIG. 3, the X-ray tube 11, the wedge 16, and the collimator 17 are held by the holding device 20. The holding device 20 is attached to the rotating frame 13 so that the angles of the X-ray tube 11, the wedge 16, and the collimator 17 with respect to the X-ray detector 12 can be integrally changed. The holding device 20 is controlled by the holding device drive mechanism 21 to change the angle of the tube axis of the X-ray tube 11 with respect to the X-ray detector 12. At this time, the holding device 20 may change the angle of the tube axis of the X-ray tube 11 with respect to the X-ray detector 12 while fixing the SID at a predetermined distance. Further, the holding device 20 may variably hold the relative position or relative angle between the X-ray tube 11 and the collimator 17.

Further, the collimator 17 is controlled by the collimator drive mechanism 22 to change the X-ray irradiation range.

The DAS 18 (Data Acquisition System) is an amplifier that performs an amplification process on the electric signal output from each X-ray detection element 121 of the X-ray detector 12, and an A/D that performs analog-digital conversion (AD conversion) on the electric signal. And a converter to generate detection data. The DAS 18 has a conversion board group including a plurality of signal processing boards (hereinafter referred to as AD conversion boards) including signal processing circuits such as an IV converter and an AD converter that receive data from the X-ray detection element 121. The detection data generated by the DAS 18 is transferred to the console device 40. The DAS 18 is an example of a data collection unit.

The bed device 30 is a device for placing and moving the subject P to be scanned, and includes a base 31, a bed driving device 32, a top plate 33, and a support frame 34.

The base 31 is a housing that supports the support frame 34 so as to be movable in the vertical direction (y direction). The bed driving device 32 is a motor or an actuator that moves the top plate 33 on which the subject P is placed in the long axis direction (z direction) of the top plate 33. The top plate 33 provided on the upper surface of the support frame 34 is a plate on which the subject P is placed.

The bed driving device 32 may move the support frame 34 in the long axis direction (z direction) of the top plate 33 in addition to the top plate 33. Further, the bed driving device 32 may be moved together with the base 31 of the bed device 30. When the present invention can be applied to standing CT, the patient moving mechanism corresponding to the top plate 33 may be moved.

In addition, the scanning system of the gantry device 10 and the top plate 33 are related to the positional relationship between the scanning system of the gantry device 10, such as helical scan imaging, scano imaging for positioning, and so-called wide volume scan imaging in which volume scanning using a multi-row detector is performed at a plurality of positions. When performing imaging with relative change, the relative change of the positional relationship may be performed by driving the top plate 33, or may be performed by traveling of the fixed frame of the gantry device 10. Moreover, it may be performed by a combination thereof.

The console device 40 has a memory 41, a display 42, an input interface 43, a network connection circuit 44, and a processing circuit 45. Although the following description will be made assuming that the console device 40 executes all the functions on a single console, these functions may be executed by a plurality of consoles.

The memory 41 has a configuration including a processor-readable recording medium such as a RAM (Random Access Memory), a semiconductor memory element such as a flash memory, a hard disk, an optical disk, or the like. The memory 41 also stores, for example, projection data, reconstructed image data, volume data of the subject P acquired in advance, and the like. The volume data of the subject P may be imaged and generated by the X-ray CT apparatus 1, or may be generated by another modality and directly from the other modality via a network, an image server, or the like. It may be obtained indirectly through the.

The projection data and the reconstructed image data generated by the X-ray CT apparatus 1 may be stored in the memory 41, or other electronic equipment such as a cloud server connectable to the X-ray CT apparatus 1 via a network. However, it may be stored upon receiving a storage request from the X-ray CT apparatus 1. Similarly, a part or all of data such as programs and tables in the recording medium of the memory 41 may be downloaded by communication via a network, or may be given to the memory 41 via a portable storage medium such as an optical disk. May be

The display 42 displays various information. For example, the display 42 outputs a medical image (CT image) generated by the processing circuit 45, a GUI (Graphical User Interface) for receiving various operations from the user, and the like. For example, the display 42 is a liquid crystal display, a CRT (Cathode Ray Tube) display, an OLED (Organic Light Emitting Diode) display, or the like.

The input interface 43 receives various input operations from the user, converts the received input operations into electric signals, and outputs the electric signals to the processing circuit 45. For example, the input interface 43 receives a collection condition for collecting projection data, a reconstruction condition for reconstructing a CT image, an image processing condition for generating a post-processed image from a CT image, and the like from a user. For example, the input interface 43 uses a trackball, a switch, a button, a mouse, a keyboard, a touch pad for performing an input operation by touching an operation surface, a touch screen in which a display screen and a touch pad are integrated, and an optical sensor. It is realized by a non-contact input circuit, a voice input circuit, and the like.

The network connection circuit 44 implements various information communication protocols according to the form of the network. The network connection circuit 44 connects the X-ray CT apparatus 1 to other devices such as an image server according to these various protocols. For this connection, electrical connection or the like via an electronic network can be applied. Here, the electronic network refers to all information communication networks that use telecommunications technology, such as wireless/wired hospital backbone LAN (Local Area Network) and the Internet network, as well as telephone communication network, optical fiber communication network, and cable. It includes communication networks and satellite communication networks.

The processing circuit 45 reads out and executes the program stored in the memory 41 to execute a process for limiting the detector array that outputs data from the gantry device 10 for image generation based on the position of the tip of the puncture needle. The processor to execute. The processing circuit 45 is also a processor that controls the overall operation of the X-ray CT apparatus 1.

Next, an example of functions implemented by the processor of the processing circuit 45 will be described.

As shown in FIG. 3, the processor of the processing circuit 45 realizes a scan control function 451, a tip position detection function 452, a detector row identification function 453, a tilt control function 454, an aperture control function 455, and an image generation function 456. .. Each of these functions is stored in the memory 41 in the form of a program.

The scan control function 451 controls the gantry device 10 to execute photographing according to the photographing protocol.

The tip position detection function 452 detects the position of the tip 52 of the puncture needle 51 that is inserted into the subject P. The tip position detection function 452 is an example of a detection unit.

The detector row specifying function 453 is based on the position of the tip 52 detected by the tip position detecting function 452 and has a predetermined number of rows (for example, 320 rows) smaller than the number of rows of the X-ray detector 12 in the slice direction (for example, 320 rows). 4 detector rows). Hereinafter, the detector rows specified by the detector row specifying function 453 will be referred to as specific rows 61, and the other detector rows will be referred to as non-target rows 62. The detector row specifying function 453 is an example of a specifying unit.

Further, the detector row specifying function 453 causes the gantry device 10 to transfer to the console device 40 only the output data of the X-ray detection elements 121 of the X-ray detection elements 121 belonging to the specific row 61, and the non-target row 62. It is preferable not to transfer the output data of the belonging X-ray detection element 121. By transferring only the output data of the X-ray detection elements 121 of the X-ray detection elements 121 belonging to the specific column 61 from the gantry device 10 to the console device 40, it is possible to significantly reduce the processing load related to image generation. The real-time property of image generation can be improved.

The tilt control function 454 changes the angle of the X-ray tube 11 with respect to the X-ray detector 12 in accordance with the position of the specific row 61 so that the X-ray irradiation main axis of the X-ray tube 11 faces the specific row 61. The holding device 20 is controlled via the holding device drive mechanism 21. The tilt control function 454 is an example of a tilt control unit.

The diaphragm control function 455 controls the collimator 17 via the collimator drive mechanism 22 according to the position of the specific row 61 so that only the specific row 61 is irradiated with X-rays from the X-ray tube 11. The aperture control function 455 is an example of an aperture control unit.

The image generation function 456 generates an image based on the data output by the X-ray detection element 121 belonging to the specific column 61. Specifically, the image generation function 456 performs imaging while rotating the X-ray tube 11 to perform reconstruction processing based on the data output by the X-ray detection element 121 belonging to the specific column 61, thereby performing the puncture. A tomographic image of the subject P including the tip 52 of the needle 51 is generated and displayed on the display 42. Further, the image generation function 456 generates a projection image based on the data output by the X-ray detection element 121 belonging to the specific column 61 by fixing the X-ray tube 11 and performing imaging, and causes the display 42 to display the projection image. May be. The projected image based on the specific row 61 is useful for confirming the tip 52 of the puncture needle 51, though the image is narrow.

Next, an example of the operation of the X-ray CT apparatus 1 according to this embodiment will be described.

FIG. 4 shows a schematic procedure for limiting the detector array that outputs data from the gantry device 10 for image generation based on the position of the tip 52 of the puncture needle 51 by the processor of the processing circuit 45 of the console device 40. It is a flowchart which shows an example. In FIG. 4, symbols with numbers attached to S indicate each step of the flowchart.

FIG. 5 is an explanatory diagram showing an example of the positional relationship between the position of the tip 52 of the puncture needle 51 and the specific row 61 from the left side surface of the subject P. Further, FIG. 6 is an explanatory diagram showing an example of the positional relationship shown in FIG. 5 viewed from the upper surface of the subject P.

The procedure shown in FIG. 4 starts when the start of CT fluoroscopy is instructed.

First, in step S1, the tip position detection function 452 detects the position of the tip 52 of the puncture needle 51 that is inserted into the subject P (see FIGS. 5 and 6).

As a method for detecting the position of the tip 52 of the puncture needle 51, a method using two optical cameras (see, for example, Japanese Patent Laid-Open No. 2017-0886819), an ultrasonic diagnostic apparatus, and a puncture needle that can be imaged by the ultrasonic diagnostic apparatus are used. Various methods are conventionally known, such as a method, a method of detecting from a CT fluoroscopic image based on a CT value, and a method of using a position sensor such as a magnetic sensor, and any of these methods can be used. .. It is also possible to use a plurality of these methods and use the average position of the results. Further, the tip position detecting function 452 can detect not only the position of the tip 52 of the puncture needle 51 but also the entire position of the puncture needle 51 by these methods. Further, the tip position detecting function 452 can easily obtain the moving direction (insertion angle) and the moving speed of the tip 52 based on the position of the tip 52 at at least two time points.

Next, in step S2, the detector row identification function 453 identifies the detector row corresponding to the position of the tip 52 as the identification row 61 based on the position of the tip 52 detected by the tip position detection function 452. As a result, the non-target row 62, which is a detector row other than the specific row 61, is additionally determined.

For example, the detector row specifying function 453 may set the slice direction detector row that intersects the virtual straight line 71 connecting the focal point of the X-ray tube 11 and the tip 52 as the specific row 61. At this time, the detector row specifying function 453 further sets the detector rows that are continuous on both sides of the particular row 61 as the particular row 61.

At this time, the same number of detector rows may be set in the specific row 61 on both sides. For example, when the predetermined number of rows to be specified as the specific row 61 is 5, there are two rows on the side where the tip 52 moves, two rows on the opposite side, and one row of the detector row intersecting with the virtual straight line 71, that is, five rows in total. Good. Further, in order to secure a large display area by regarding the side where the puncture needle 51 moves as a more dangerous area, the specific row 61 is arranged so that the side where the tip 52 moves becomes larger than the opposite side. You may set it. In this case, for example, if the predetermined number of rows to be specified as the specific row 61 is 8, there are 5 rows on the side where the tip 52 moves, 2 rows on the opposite side, and 1 row of the detector row intersecting with the virtual straight line 71. It is good to have a total of 8 columns.

Next, in step S3, the image generation function 456 generates a tomographic image or a fluoroscopic image including the position of the tip 52 of the puncture needle 51 in real time based on the data output by the X-ray detection element 121 belonging to the specific row 61. , On the display 42.

At this time, the image generation function 456 preferably receives only the data output by the X-ray detection elements 121 belonging to the specific column 61, but does not receive the output data of the X-ray detection elements 121 belonging to the non-target column 62. Therefore, the detector row specifying function 453 causes the gantry device 10 to cause the console device 40 to transfer only the output data of the X-ray detection elements 121 of the X-ray detection elements 121 belonging to the specific row 61 and to the non-target row 62. It is preferable to control the gantry device 10 so that the output data of the belonging X-ray detection element 121 is not transferred.

There are three limiting methods. The first limiting method is a method of limiting the output from the detection element group 12a by controlling the switch control circuit 12c. In the first limiting method, the detector row specifying function 453 takes out only the output data of the X-ray detecting element 121 of the X-ray detecting elements 121 belonging to the specific row 61 via the switch control circuit 12c and the switch circuit 12b. To control.

The second limiting method is a method of operating only the AD conversion substrate corresponding to the specific column 61 of the conversion substrate group forming the DAS 18. Each of the AD conversion boards of the conversion board group is controlled by the detector row specifying function 453 so as to operate in a normal operating state, a standby state, or a stopped state in order to operate between these states. The normal activation state is a state in which an operation of performing an analog-digital conversion (AD conversion) operation on an output signal of the X-ray detection element 121, an operation of outputting a processed signal, and the like are performed. The standby state is a state in which the operation of outputting at least a processed signal is stopped. The sleep state is a state in which power supply is stopped and all operations are stopped. In the second limiting method, the detector row specifying function 453 sets only the AD conversion boards corresponding to the specified row 61 to the normal start-up state, and sets the other AD conversion boards to the standby state or the stop state. If there is an AD conversion board that is used as both the X-ray detection element 121 belonging to the specific column 61 and the X-ray detection element 121 belonging to the non-target row 62, the substrate is the AD conversion board corresponding to the specific column 61. As a normal start state.

The third limiting method is a method in which the first limiting method and the second limiting method are combined. In the third limiting method, the detector row specifying function 453 takes out only the output data of the X-ray detection element 121 of the X-ray detection elements 121 belonging to the specific row 61 via the switch control circuit 12c and the switch circuit 12b. While controlling only the AD conversion boards corresponding to the specific column 61, the other AD conversion boards are put in the standby state or the stopped state.

The image generation function 456 is output by the X-ray detection element 121 belonging to the specific column 61 based on the data given from the gantry device 10 to the image generation function 456 by any one of the first to third limiting methods. A tomographic image or a fluoroscopic image including the position of the tip 52 of the puncture needle 51 is generated in real time based on only the data. Note that when the second limiting method is used and a plurality of X-ray detection elements 121 are assigned to each of the AD conversion boards, the output data of the X-ray detection elements 121 belonging to the non-target column 62 is The image generation function 456 may be provided to the image generation function 456, but in this case as well, the image generation function 456 includes the position of the tip 52 of the puncture needle 51 based on only the data output by the X-ray detection element 121 belonging to the specific row 61. A tomographic image or a fluoroscopic image is generated in real time.

Then, if CT fluoroscopy should be terminated, such as when the user issues an instruction to end CT fluoroscopy via the input interface 43 (YES in step S4), the series of procedures is terminated.

On the other hand, if CT fluoroscopy should be continued (NO in step S4), the process returns to step S1 and the tip position detection function 452 detects the position of the tip 52 of the puncture needle 51 again.

According to the above procedure, the detector array for outputting data from the gantry device 10 for image generation can be restricted based on the position of the tip 52 of the puncture needle 51.

Note that the timing at which the process of FIG. 4 is repeated (the timing at which step S1 from the second time is executed) may be set for each preset frame rate, or the distal end position detection function 452 causes the puncture needle 51 to move. May be detected every time.

The X-ray CT apparatus 1 according to this embodiment can transfer only the minimum necessary data used for real-time image generation in CT fluoroscopy from the gantry apparatus 10 to the console apparatus 40. Therefore, the processing load associated with image generation can be significantly reduced, and the real-time property of image generation can be improved. Also, due to the extremely low communication data amount, it is possible to easily provide the user with an image that flips a tomographic image according to the position of the tip 52 that moves based on volume data that requires a large amount of communication data. can do.

Further, as shown in FIGS. 5 and 6, if the width of the X-ray detector 12 is within the width of the maximum number of rows in the slice direction (for example, 320 rows), the top plate 33 is not moved and the fluoroscopy is performed. The thin tomographic image generated in real time can always include the image of the tip 52 of the puncture needle 51. Therefore, compared to a case in which the tomographic image is made to follow the position of the tip 52 of the puncture needle 51 by moving the top plate 33, the user's operation is unnecessary and the burden on the user can be significantly reduced and the puncture can be performed. It is possible to prevent the risk of moving the subject P while the needle 51 is being inserted.

The X-ray CT apparatus 1 according to the present embodiment has a follow-up mode in which an image is generated so as to follow the position of the tip 52 of the puncture needle 51 as in the procedure of FIG. It may be possible to select which of the two is used. In this case, for example, a soft key for accepting an instruction such as a mode switching button may be displayed on the display 42, and the mode may be switched by an input to this key. In this case, for example, the user operates the puncture needle 51 in the normal mode before starting the procedure, confirms that the tip 52 is in the thin tomographic image, and then changes to the following mode to start the procedure. The procedure of FIG. 4 may be started. Further, in this case, the detector array corresponding to the tomographic image generated in the normal mode may be set by the user via the input interface 43 based on, for example, a wide-range scano image captured in advance.

FIG. 7 is an explanatory diagram showing an example in which the X-ray irradiation range 11a and the X-ray irradiation main axis 11b are changed according to the position of the specific row 61 in the example shown in FIG.

At least one of the X-ray irradiation range 11a and the X-ray irradiation main axis 11b may be changed according to the position of the specific row 61. FIG. 7 shows an example in which both the X-ray irradiation range 11 a and the X-ray irradiation main axis 11 b are changed according to the position of the specific row 61.

As described above, the image generation function 456 according to the present embodiment generates an image based on only the data output by the X-ray detection element 121 belonging to the specific column 61. Therefore, it can be said that the X-rays applied to the non-target row 62 are useless and force the subject P to be exposed to extra radiation. Therefore, the diaphragm control function 455 may control the collimator 17 via the collimator drive mechanism 22 in accordance with the position of the specific row 61 so that only the specific row 61 is irradiated with X-rays from the X-ray tube 11.

The specific row 61 changes as the tip 52 of the puncture needle 51 moves. In general, among the positions of the X-ray detector 12, the distortion of the image is large at a position apart from the front position of the center of the X-ray tube 11 as compared with the position directly facing the center of the focus of the X-ray tube 11. It is known to end up. Therefore, the tilt control function 454 adjusts the angle of the X-ray tube 11 with respect to the X-ray detector 12 according to the position of the specific row 61 so that the X-ray irradiation main axis 11b of the X-ray tube 11 faces the specific row 61. The holding device 20 may be controlled via the holding device drive mechanism 21 so as to be changed. At this time, it is preferable that the X-ray irradiation main axis 11b is directed to the center of the specific row 61. However, if it is difficult due to the limit of the movable range of the holding device 20, the X-ray irradiation main axis 11b is set to the center of the specific row 61. It is advisable to tilt the holding device 20 as close as possible.

FIG. 8A is an explanatory diagram showing a display example of an image generated in real time by the image generation function 456 on the display 42, and FIG. 8B is an explanatory diagram showing another example.

8A and 8B show an example in which the image generation function 456 displays the axial tomographic image 81 of the subject P in real time by the reconstruction process. An image of the tip 52 of the puncture needle 51 is included in the axial tomographic image 81.

When the axial tomographic image 81 of the subject P is displayed in real time, only the axial tomographic image 81 may be displayed as shown in FIG.

Further, as shown in FIG. 8B, an orthogonal three sectional image in which the axial tomographic image 81 is one image may be displayed on the display 42. When displaying the orthogonal three-section image, the image generation function 456 generates the sagittal tomographic image 91 and the coronal tomographic image 92 corresponding to the axial tomographic image 81 based on the volume data of the subject P acquired in advance. The axial tomographic image 81 displayed on the display 42 is updated in real time. On the other hand, the sagittal tomographic image 91 and the coronal tomographic image 92 may be the initial images as they are, or the image generation function 456 uses the volume data so that the images correspond to the axial tomographic image 81 changed according to the movement of the tip 52. May be updated by performing rendering processing again.

FIG. 9 is an explanatory diagram showing an example in which an image 52a showing the estimated position of the tip 52 of the puncture needle 51 is further superimposed on the sagittal tomographic image 91 and the coronal tomographic image 92 in the example shown in FIG. 8B. Is.

The sagittal tomographic image 91 and the coronal tomographic image 92 generated from the volume data of the subject P acquired in advance do not include the images of the puncture needle 51 and its tip 52 (see FIG. 8B). Therefore, the image generation function 456 estimates the position of the tip 52 of the puncture needle 51 in each of the sagittal tomographic image 91 and the coronal tomographic image 92 based on the position of the tip 52 detected by the tip position detection function 452, An image 52a indicating the estimated position of the tip 52 may be superimposed on each of the sagittal tomographic image 91 and the coronal tomographic image 92 (see FIG. 9). When the tip position detection function 452 provides the overall position of the puncture needle 51, the image generation function 456 estimates the overall position of the puncture needle 51 in each of the sagittal tomographic image 91 and the coronal tomographic image 92. The image 51a showing the estimated position of the entire puncture needle 51 may be superimposed on each of the sagittal tomographic image 91 and the coronal tomographic image 92.

According to at least one embodiment described above, it is possible to limit the detector array that outputs data from the gantry device 10 for image generation based on the position of the tip 52 of the puncture needle 51.

In the above embodiment, the word “processor” means, for example, a dedicated or general-purpose CPU (Central Processing Unit), GPU (Graphics Processing Unit), or an application-specific integrated circuit (ASIC), A circuit such as a programmable logic device (for example, Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and FPGA) is meant. The processor realizes various functions by reading and executing a program stored in a storage medium.

Further, in the above embodiment, an example in which a single processor of the processing circuit realizes each function has been described, but a processing circuit is configured by combining a plurality of independent processors, and each processor realizes each function. Good. When a plurality of processors are provided, the storage medium for storing the program may be provided individually for each processor, or one storage medium collectively stores the programs corresponding to the functions of all the processors. Good.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. The embodiments and their modifications are included in the scope of the invention and the scope thereof, and are included in the invention described in the claims and the scope of equivalents thereof.

1 X-ray CT apparatus 11 X-ray tube 11a Irradiation range 11b Irradiation spindle 12 X-ray detector 12a Detection element group 12b Switch circuit 12c Switch control circuit 17 Collimator 20 Holding device 21 Holding device drive mechanism 22 Collimator drive mechanism 42 Display 45 Processing circuit 51 Puncture needle 51a Image showing the entire position of the puncture needle 52 Tip of the puncture needle 52a Image showing the estimated position of the tip of the puncture needle 61 Specific row 62 Non-target row 71 Virtual straight line 81 Axial tomographic image 91 Sagittal tomographic image 92 Coronal slice Image 121 X-ray detection element 452 Tip position detection function 453 Detector row specifying function 454 Tilt control function 455 Aperture control function 456 Image generation function

Claims (8)

An X-ray tube for generating X-rays for irradiating the subject,
An X-ray detector in which a plurality of detection elements for detecting the X-rays are arranged in the column direction over a first number of rows;
A detection unit that detects the tip position of the puncture needle that is inserted into the subject,
A specifying unit that specifies a detector row having a second row number that is smaller than the first row number based on the detected tip position;
An image generation unit that generates an image based on the data output from the specified number of detector rows.
X-ray CT device equipped with. The X-ray detector is
Whether or not to take out the data from the detection element has a switch circuit capable of switching at least for each column,
The specific unit is
Controlling the switch circuit so that data is taken out only from the detection elements belonging to the specified second number of detector rows.
The X-ray CT apparatus according to claim 1. A data collection unit having a plurality of signal processing boards that receive output signals of the plurality of detection elements, perform at least analog-digital conversion processing, and output.
Further equipped with,
The specific unit is
Controlling the data collection unit to operate only the signal processing substrate corresponding to the detection elements belonging to the specified second number of detector rows;
The X-ray CT apparatus according to claim 1 or 2. The X-ray irradiation main axis of the X-ray tube is directed to the specified second number of detector rows so that the X-ray irradiation main axis faces the specified second number of detector rows. A tilt controller for changing the angle of the X-ray tube with respect to the X-ray detector,
The X-ray CT apparatus according to any one of claims 1 to 3, further comprising: An X-ray movable diaphragm for adjusting an irradiation range of X-rays emitted from the X-ray tube,
According to the position of the specified second number of detector rows, the X-ray is irradiated from the X-ray tube only to the specified second number of detector rows. A diaphragm control unit for controlling the movable X-ray diaphragm,
The X-ray CT apparatus according to any one of claims 1 to 4, further comprising: The image generation unit,
A tomographic image of the subject including the tip of the puncture needle is generated by performing reconstruction processing based on the data output by the specified number of detector rows.
The X-ray CT apparatus according to any one of claims 1 to 5. The image generation unit,
Two tomographic images that are orthogonal to the tomographic image are generated based on the volume data of the subject acquired in advance so that three orthogonal cross-sectional images with the tomographic image as one image can be displayed on a display.
The X-ray CT apparatus according to claim 6. The image generation unit,
Based on the detected tip position, the tip position of the puncture needle in each of the two tomographic images orthogonal to the tomographic image is estimated, and an image showing the estimated position is provided in two orthogonal tomographic images. Superimposed on each of the tomographic images,
The X-ray CT apparatus according to claim 7.

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