JP7236239B2 - X-ray CT system and CT scan execution program - Google Patents

Description

Embodiments of the present invention relate to an X-ray CT (Computed Tomography) system and a CT scan execution program.

2. Description of the Related Art There are medical image diagnostic apparatuses that generate medical image data in which internal tissue of a subject is imaged. Examples of medical image diagnostic apparatuses include X-ray CT systems and MRI (Magnetic Resonance Imaging) systems. The X-ray CT system irradiates the subject with X-rays and generates CT image data and volume data of the subject's axial tomography based on electrical signals based on the X-rays detected by the X-ray detector.

Conventionally, an X-ray CT system employs an imaging method called dynamic scanning. Dynamic scanning is a method of continuously scanning for a predetermined period of time according to the velocity of the contrast medium flowing through the subject after administration of the contrast medium. An X-ray CT system generates non-contrast image data of a subject in a non-contrast state, sets a region of interest (ROI) and a threshold based on the non-contrast image data, and starts injection of a contrast medium. . Then, the X-ray CT system starts Real Prep after starting the injection of the contrast agent. Realprep detects the start timing (trigger) of a main scan before a main scan such as a dynamic scan, and starts the main scan when the CT value in the ROI exceeds a threshold value.

JP 2015-213749 A

The problem to be solved by the present invention is to improve the efficiency of contrast imaging examination.

An X-ray CT system according to an embodiment has a scanning unit, an image generating unit, and an analyzing unit. The scanning unit performs a first scan including irradiation and detection of X-rays. The image generation unit generates a plurality of images corresponding to a plurality of time phases based on a plurality of detection data sets corresponding to a plurality of time phases collected by the first scan. The analysis unit divides at least a portion of each of the plurality of images into a plurality of sections, extracts at least one region by integrating the sections having the same or similar temporal changes in pixel values, and extracts information indicating characteristics of the region. and reference information. The scanning unit performs a second scan including irradiation and detection of X-rays according to the result of the comparison.

1 is a schematic diagram showing the configuration of an X-ray CT system according to an embodiment; FIG. FIG. 2 is a block diagram showing the configuration and functions of the X-ray CT system according to the embodiment; FIG. 3 is a diagram showing, as a flowchart, the operation of the X-ray CT system according to the embodiment; FIG. 4 is a diagram showing, as a flowchart, the operation of the X-ray CT system according to the embodiment; FIG. 5 is a diagram showing sections dividing a segmentation target region in contrast-enhanced image data of the abdomen generated by the X-ray CT system according to the embodiment; FIG. 6 is a diagram showing sections dividing a segmentation target region in contrast-enhanced image data of the head generated by the X-ray CT system according to the embodiment; FIG. 7 is a diagram showing a first example of integrated regions generated by the X-ray CT system according to the embodiment; FIG. 8 is a diagram showing a second example of integrated regions generated by the X-ray CT system according to the embodiment; FIG. 9 is a diagram showing an example of TDC in the X-ray CT system according to the embodiment;

Hereinafter, embodiments of an X-ray CT system and a CT scan execution program will be described in detail with reference to the drawings.

The X-ray CT system data acquisition methods include a rotation/rotation (RR) method in which the X-ray source and the X-ray detector rotate around the subject as a unit, and a ring-shaped method. There are various schemes such as the Stationary/Rotate (SR) scheme in which a large number of detector elements are arrayed in the X-ray tube and only the X-ray tube rotates around the subject. The present invention can be applied to any method. In the following, the X-ray CT system according to the embodiment will be described by taking as an example a case where the rotation/rotation method of the third generation, which is currently the mainstream, is adopted.

1. Embodiment FIG. 1 is a schematic diagram showing the configuration of an X-ray CT system according to an embodiment. FIG. 2 is a block diagram showing the configuration and functions of the X-ray CT system according to the embodiment.

FIG. 1 shows an X-ray CT system 1 . The X-ray CT system 1 includes a gantry device 10, a bed device 30, and a medical image processing device according to the first embodiment, that is, a console device 40. FIG. The gantry device 10 and the bed device 30 are installed in an examination room. The gantry device 10 acquires X-ray detection data (also called “pure raw data”) regarding a subject (for example, a patient) P placed on the couch device 30 . The console device 40 generates raw data by performing preprocessing on detection data for a plurality of views, and reconstructs and displays CT image data by performing reconstruction processing on the raw data.

In FIG. 1, for convenience of explanation, a plurality of gantry devices 10 are drawn on the upper and lower sides of the left side, but there is only one gantry device 10 as an actual configuration.

The gantry device 10 includes an X-ray source (for example, an X-ray tube) 11, an X-ray detector 12, a rotating section (for example, a rotating frame) 13, an X-ray high voltage device 14, a control device 15, a wedge 16, a collimator 17, A data acquisition circuit (DAS: Data Acquisition System) 18 is provided. Note that the gantry device 10 is an example of a gantry.

The X-ray tube 11 is provided on a rotating frame 13 . The X-ray tube 11 is a vacuum tube that generates X-rays by applying a high voltage from an X-ray high-voltage device 14 and irradiating thermal electrons from a cathode (filament) toward an anode (target). For example, the X-ray tube 11 is a rotating anode type X-ray tube that generates X-rays by irradiating a rotating anode with thermal electrons.

In addition, in the embodiment, both the single-tube type X-ray CT system and the so-called multi-tube type X-ray CT system in which a plurality of pairs of X-ray tubes and X-ray detectors are mounted on a rotating ring. Applicable. Also, the X-ray source that generates X-rays is not limited to the X-ray tube 11 . For example, instead of the X-ray tube 11, a focus coil for converging the electron beam generated from the electron gun, a deflection coil for electromagnetic deflection, and a target surrounding half the circumference of the patient P and generating X-rays by collision of the deflected electron beam. X-rays may be generated by a fifth generation system that includes a ring. Note that the X-ray tube 11 is an example of an X-ray irradiation unit.

The X-ray detector 12 is provided on the rotating frame 13 so as to face the X-ray tube 11 . The X-ray detector 12 detects X-rays emitted from the X-ray tube 11 and outputs detection data corresponding to the X-ray dose to the DAS 18 as electrical signals. The X-ray detector 12 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 around the focal point of the X-ray tube. The X-ray detector 12 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 12 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).

The X-ray detector 12 may be a direct conversion type detector having a semiconductor element that converts incident X-rays into electrical signals. Also, the X-ray detector 12 is an example of an X-ray detection unit.

The rotating frame 13 supports the X-ray tube 11 and the X-ray detector 12 so as to face each other. The rotating frame 13 is an annular frame that rotates the X-ray tube 11 and the X-ray detector 12 together under the control of a control device 15, which will be described later. In addition to the X-ray tube 11 and the X-ray detector 12, the rotating frame 13 may further include an X-ray high-voltage device 14 and a DAS 18 to support them. Also, the rotating frame 13 is an example of a rotating portion.

In this way, the X-ray CT system 1 rotates around the patient P the rotating frame 13 that supports the X-ray tube 11 and the X-ray detector 12 so as to face each other. 360° worth of detection data is collected. Note that the CT image data reconstruction method is not limited to the full-scan reconstruction method using detection data for 360°. For example, the X-ray CT system 1 may employ a half-reconstruction method for reconstructing CT image data based on detection data for a half rotation (180°) plus the fan angle.

The X-ray high-voltage device 14 is provided on the rotating frame 13 or a non-rotating portion (for example, a fixed frame not shown) that rotatably supports the rotating frame 13 . The X-ray high voltage device 14 has electric circuits such as a transformer and a rectifier. The X-ray high voltage device 14 is controlled by a high voltage generator (not shown) having a function of generating a high voltage to be applied to the X-ray tube 11 under the control of the control device 15, which will be described later, and the control device 15, which will be described later. , there is an X-ray control device (not shown) for controlling the output voltage according to the X-rays emitted by the X-ray tube 11 . The high voltage generator may be of a transformer type or an inverter type. In FIG. 1, for convenience of explanation, the X-ray high-voltage device 14 is arranged at a position in the positive direction of the x-axis with respect to the X-ray tube 11. It may be placed in the position of the direction.

The controller 15 has processing circuitry and memory, and drive mechanisms such as motors and actuators. The configuration of the processing circuit and memory is the same as that of the processing circuit 44 and memory 41 of the console device 40, which will be described later, and therefore the description thereof is omitted.

The control device 15 has a function of receiving an input signal from an input interface (described later) attached to the console device 40 or the gantry device 10 and controlling the operations of the gantry device 10 and the bed device 30 . For example, the control device 15 receives an input signal and performs control to rotate the rotating frame 13 , control to tilt the gantry device 10 , and control to operate the bed device 30 and the tabletop 33 . Note that the control for tilting the gantry device 10 is performed by the control device 15 based on the tilt angle (tilt angle) information input through the input interface attached to the gantry device 10, so as to rotate the rotating frame 13 about an axis parallel to the X-axis direction. This is achieved by rotating the Note that the control device 15 may be provided in the gantry device 10 or may be provided in the console device 40 . Note that the control device 15 is an example of a control unit.

In addition, the control device 15 controls the rotation angle of the X-ray tube 11, the rotation angle of the wedge 16 and the collimator 17, which will be described later, based on imaging conditions input from an input interface, which will be described later, attached to the console device 40 and the gantry device 10. control behavior.

A wedge 16 is provided on the rotating frame 13 so as to be arranged on the X-ray emission side of the X-ray tube 11 . Wedge 16 is a filter for adjusting the dose of X-rays emitted from X-ray tube 11 under the control of controller 15 . Specifically, the wedge 16 is a filter that 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 patient P have a predetermined distribution. is. For example, the wedge 16 (wedge filter, bow-tie filter) is a filter made of aluminum so as to have a predetermined target angle and a predetermined thickness.

The collimator 17 , also called an X-ray diaphragm or slit, is provided on the rotating frame 13 so as to be arranged on the X-ray exit side of the X-ray tube 11 . The collimator 17 is a lead plate or the like for narrowing down the irradiation range of the X-rays transmitted through the wedge 16 under the control of the control device 15. A combination of a plurality of lead plates or the like forms an X-ray irradiation aperture.

A DAS 18 is provided on the rotating frame 13 . Under the control of the controller 15, the DAS 18 includes an amplifier that amplifies the electrical signal output from each X-ray detection element of the X-ray detector 12, and converts the electrical signal into a digital signal under the control of the controller 15. It has an A/D (Analog to Digital) converter for converting into a signal, and generates detection data after amplification and digital conversion. The multiple views of detection data generated by the DAS 18 are transferred to the console device 40 .

Here, the detection data generated by the DAS 18 is transmitted by optical communication from a transmitter having a light emitting diode (LED) provided on the rotating frame 13 to a receiver having a photodiode provided on the fixed frame of the gantry 10. and transferred to the console device 40 . The method of transmitting the detection data from the rotating frame 13 to the fixed frame of the gantry device 10 is not limited to the above-described optical communication, and any method of non-contact data transmission may be adopted. Also, the rotating frame 13 is an example of a rotating portion.

The bed device 30 includes a base 31 , a bed driving device 32 , a top plate 33 and a support frame 34 . The bed device 30 is a device on which the patient P to be scanned is placed and which is moved under the control of the control device 15 .

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

Note that the bed drive device 32 may move the support frame 34 in addition to the top plate 33 in the long axis direction (z-axis direction) of the top plate 33 . Further, the bed drive device 32 may move the base 31 of the bed device 30 together. When the present invention is applied to standing CT, a method of moving a patient moving mechanism corresponding to the top plate 33 may be used. Further, when performing imaging that involves a relative change in the positional relationship between the imaging system of the gantry device 10 and the table top 33, such as helical scanning or scano imaging for positioning, the relative change in the positional relationship is It may be carried out by driving the top plate 33, may be carried out by running the fixed part of the gantry device 10, or may be carried out by combining them.

In the embodiment, the longitudinal direction of the rotation axis of the rotating frame 13 or the top plate 33 of the bed device 30 in the non-tilt state is the z-axis direction, and the axial direction perpendicular to the z-axis direction and horizontal to the floor surface is the z-axis direction. An axial direction perpendicular to the x-axis direction and the z-axis direction and perpendicular to the floor surface is defined as a y-axis direction.

The console device 40 has a configuration as a computer, and includes a memory 41 , a display 42 , an input interface 43 and a processing circuit 44 . Although the console device 40 is described as being separate from the gantry device 10 , the console device 40 or a part of each component of the console device 40 may be included in the gantry device 10 . Also, in the following description, the console device 40 is assumed to execute all functions with a single console, but these functions may be executed by a plurality of consoles. Note that the console device 40 is an example of a medical image processing device.

The memory 41 is composed of, for example, a RAM (Random Access Memory), a semiconductor memory device such as a flash memory, a hard disk, an optical disk, or the like. The memory 41 may be configured by portable media such as USB (Universal Serial Bus) memory and DVD (Digital Video Disk). The memory 41 stores various processing programs (including not only application programs but also an OS (Operating System) and the like) used in the processing circuit 44 and data necessary for executing the programs. Also, the OS may include a GUI (Graphic User Interface) that uses graphics extensively to display information on the display 42 for the operator and allows basic operations to be performed through the input interface 43 .

The memory 41 stores, for example, detection data before preprocessing, raw data after preprocessing and before reconstruction, and CT image data after reconstruction based on the raw data. Pre-processing means at least one of logarithmic transformation processing, offset correction processing, inter-channel sensitivity correction processing, beam hardening processing, etc., on the detected data. Also, a cloud server connectable to the X-ray CT system 1 via a communication network such as the Internet receives a storage request from the X-ray CT system 1 and stores detected data, raw data, or CT image data. may be

The memory 41 also includes an image storage area for storing CT image data as medical image data, an evaluation value storage area for storing an evaluation value to be described later, and a sensitivity parameter for storing a sensitivity parameter to be described later. and a storage area (shown in FIG. 2). Note that the memory 41 is an example of a storage unit.

The display 42 displays various information. For example, the display 42 outputs CT image data generated by the processing circuit 44, a GUI (Graphical User Interface) for accepting 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. Also, the display 42 may be provided on the gantry device 10 . The display 42 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 40 . Note that the display 42 is an example of a display unit.

The input interface 43 includes an input device that can be operated by an operator such as a technician, and an input circuit that inputs signals from the input device. Input devices include mice, keyboards, trackballs, switches, buttons, joysticks, touchpads that perform input operations by touching the operation surface, touchscreens that integrate the display screen and touchpad, and non-optical sensors. It is implemented by a contact input circuit, a voice input circuit, or the like. When the input device receives an input operation from the operator, the input circuit generates an electrical signal according to the input operation and outputs it to the processing circuit 44 . Also, the input interface 43 may be provided in the gantry device 10 . Also, the input interface 43 may be composed of a tablet terminal or the like capable of wireless communication with the main body of the console device 40 . Note that the input interface 43 is an example of an input unit.

Note that the console device 40 may also include a network interface (not shown). The network interface is composed of connectors conforming to parallel connection specifications and serial connection specifications. When the X-ray CT system 1 is installed on a medical imaging system, the network interface transmits and receives information to and from external devices on the network. For example, under the control of the processing circuit 44, the network interface receives an examination order for a CT examination from an external device, and also receives detection data acquired by the X-ray CT system 1, raw data generated, or CT images. Send data to an external device.

A processing circuit 44 controls the overall operation of the X-ray CT system 1 . The processing circuit 44 means a processor such as a dedicated or general-purpose CPU (Central Processing Unit), MPU (Micro Processor Unit), or GPU (Graphics Processing Unit), as well as an ASIC, a programmable logic device, and the like. Examples of programmable logic devices include simple programmable logic devices (SPLDs), complex programmable logic devices (CPLDs), and field programmable gate arrays (FPGAs). mentioned.

Moreover, the processing circuit 44 may be configured by a single circuit, or may be configured by a combination of a plurality of independent processing circuit elements. In the latter case, a separate memory may be provided for each processing circuit element, or a single memory may store programs corresponding to functions of a plurality of processing circuit elements.

The processing circuit 44 implements a scanning function 441, an image generating function 442, an analyzing function 443, a combining function 444, and a display control function 445 as shown in FIG. 2 by executing programs stored in the memory 41. . It should be noted that all or part of the functions 441 to 445 are not limited to being realized by executing the program of the console device 40, but may be provided as a circuit such as an ASIC in the console device 40. . Also, all or part of the functions 441 to 445 may be realized by the control device 15 as well as the console device 40 .

The scanning function 441 controls the gantry device 10, the bed device 30, and the like via the control device 15 according to preset scanning conditions, thereby executing a CT scan including irradiation and detection of X-rays. Includes a function to collect detection data for multiple views. Also, for example, the scan conditions include tube current mA, tube voltage kV, X-ray intensity control conditions (X-ray modulation conditions), rotation speed of the X-ray tube 11 (or rotating frame 13), etc., related to irradiated X-rays. .

Here, the CT scan in the embodiment includes prescan, realprep scan, main scan, and the like. Note that the scanning function is an example of a scanning unit. Also, the real prep scan is an example of the first scan, and the main scan is an example of the second scan.

The image generation function 442 performs preprocessing on the detection data for multiple views collected by scanning by the scanning function 441, thereby collecting raw data for multiple views, and collecting raw data for multiple views after preprocessing. and a function of generating a plurality of CT image data corresponding to a plurality of time phases by image reconstruction processing on the raw data. In addition, the image generation function 441 has a function of storing each CT image data in the memory 41, a function of displaying each CT image data as a CT image on the display 42, and a function of displaying each CT image data via a network interface (not shown). may also include the ability to send to an external device via Note that the image generation function 441 is an example of an image generation unit.

The analysis function 443 divides at least a portion of each of the plurality of CT image data stored in the memory 41 (hereinafter referred to as “fragmentation target regions”) into a plurality of sections, each of which has the same or similar temporal change in pixel value. It includes a function of extracting at least one area (hereinafter referred to as "integrated area") by integrating the partitions. In addition, the analysis function 443 includes a function of comparing information indicating characteristics of integrated regions and reference information.

Here, the analysis function 443 uses the entire image of the CT image data as a segmentation target region, and extracts the integrated region by segmenting the entire image. Alternatively, the analysis function 443 sets a region of interest (ROI) in an image of CT image data as a segmentation target region, and extracts an integrated region by segmenting the ROI. When the inside of the ROI is segmented, it is not affected by the pixel values outside the ROI, so the accuracy of the subsequent integration processing is improved. Hereinafter, unless otherwise specified, the case where the analysis function 443 sets the ROI as the segmentation target region and segments the inside of the ROI will be described.

Further, the information indicating the characteristics of the integrated region includes at least one of information on pixel values (for example, CT values) of pixels included in the integrated region, information on the size of the integrated region, and information on the shape of the integrated region. include. The reference information includes at least one of blood vessel pixel value information, blood vessel size information, and blood vessel shape information. The analysis function 443 compares information about the size of the integrated region and information about the size of the blood vessel. For example, in the case of the ascending aorta, the blood vessel size is a little less than 3 [cm] in the abdomen and a little less than 1 [cm] in the neck. The analysis function 443 also compares the information about the size of the integrated region with the information about the size of the blood vessel, and compares the information about the shape of the integrated region with the information about the shape of the blood vessel. Note that the analysis function 443 is an example of an analysis unit.

Then, the scan function 441 executes a main scan including irradiation and detection of X-rays according to the result of comparison by the analysis function 443 . That is, the scanning function 441 determines that the accuracy of the information on the size of the integrated region obtained from the CT image data with respect to the information on the size of the blood vessel is equal to or higher than a preset threshold value, or the threshold value is exceeded by the analysis by the analysis function 443. When it is determined that it exceeds, the start timing of the main scan is detected. When the scan function 441 detects the start timing of the main scan, the scan function 441 executes the main scan by controlling the gantry device 10, the bed device 30, etc. via the control device 15 according to preset scan conditions.

The synthesizing function 444 includes a function of synthesizing at least one piece of CT image data generated by the image generating function 442 with the integrated region extracted by the analyzing function 443 to generate synthesized image data. Note that the synthesizing function 444 is an example of a synthesizing unit.

The display control function 445 includes a function of displaying the synthesized image data generated by the synthesizing function 444 on the display 42 . Note that the display control function 445 is an example of a display control unit.

The operations of the functions 441-445 will be described later with reference to FIGS. 3-9.

3 and 4 are flowcharts showing the operation of the X-ray CT system 1. FIG. In FIGS. 3 and 4, each step of the code flow chart is shown with a numeral attached to "ST".

First, FIG. 3 will be described. The scanning function 441 controls the gantry device 10, the bed device 30, and the like via the control device 15 according to preset scanning conditions before the real prep scan and the main scan, thereby prescanning the patient P without contrast enhancement. Execute (step ST1).

The image generation function 442 generates non-contrast image data based on the data acquired by the gantry device 10 through prescanning (step ST2). The non-contrast image data generated in step ST2 is displayed on the display 42 and/or stored in the memory 41 as a non-contrast image.

The analysis function 443 sets a ROI as a segmentation target region so as to include the blood vessel region based on the non-contrast image data generated in step ST2 (step ST3). For example, in step ST3, the analysis function 443 displays the non-contrast image data on the display 42, and based on the input signal input by the operator via the input interface 43 while viewing the non-contrast image data displayed on the display 42, to set the ROI.

The analysis function 443 sets the size or number of partitions dividing the ROI (step ST4). For example, in step ST4, the analysis function 443 sets the size or number of partitions dividing the ROI based on the input signal input by the operator via the input interface 43 . Setting the partition size in the ROI determines the number of partitions, and setting the number of partitions in the ROI also determines the partition size.

Note that the analysis function 443 may set a value preset for each imaging site by using the size or number of sections divided within the ROI, and/or the ROI set in step ST3. can be set according to the size of Also, the minimum unit of the partition size is a pixel.

The partition size (or the number of partitions) is set so that accuracy can be secured according to the blood vessel size to be detected. For example, if the detected blood vessel size is relatively large, the partition size is set large (or the number of partitions is small). are set).

The scanning function 441 starts injection of a contrast medium (step ST5), and controls the gantry device 10, the bed device 30, and the like via the control device 15 according to preset scanning conditions, thereby performing a prep scan on the patient P. start (step ST6). For example, in step ST5, the scan function 441 starts contrast agent injection based on an input signal input by the operator via the input interface 43. FIG.

The image generation function 442 generates contrast image data by real-time reconstruction based on the data collected by the gantry device 10 by the prep scan (step ST7). The image generation function 442 displays the contrast-enhanced image data generated in step ST7 on the display 42 as a contrast-enhanced image, and stores it in the memory 41 (step ST8).

Moving on to the description of FIG. 4, the analysis function 443 performs analysis within the ROI of the latest frame of contrast image data generated in step ST7 and within the ROI of the past (for example, immediately preceding frame) contrast image data stored in the memory 41. are divided into a plurality of sections in accordance with the settings in step ST4 (step ST9).

FIG. 5 is a diagram showing divisions into which the segmentation target regions are divided in the contrast-enhanced image data of the abdomen. FIG. 5A is a diagram showing ROIs set in the contrast image data. FIG. 5(B) is a diagram showing partitions divided within the ROI of FIG. 5(A). FIG. 5(C) is a diagram showing divisions into which the entire image of contrast-enhanced image data is segmented.

FIG. 6 is a diagram showing divisions into which division target regions are divided in contrast-enhanced image data of the neck. FIG. 6A is a diagram showing ROIs set in the contrast image data. FIG. 6(B) is a diagram showing partitions divided within the ROI of FIG. 6(A). FIG. 6(C) is a diagram showing divisions into which the entire image of contrast-enhanced image data is segmented.

Once the number or size of the partitions is set, the partitions are placed within the ROI as shown in FIGS. 5B and 6B. Also, when the number or size of the sections is set when the ROI is not set, the sections are arranged within the entire image of the contrast image data as shown in FIGS. 5(C) and 6(C). It should be noted that the sizes of the end partitions of the plurality of partitions within the region are adjusted as appropriate.

Returning to the explanation of FIG. 4, the analysis function 443 measures the time change of the representative pixel value (for example, average pixel value) of the pixel group existing in each section within the ROI (step ST10). Examples of the representative pixel value include the average pixel value that is the average value of the pixel values indicated by the pixel group, the maximum pixel value that is the maximum value of the pixel values indicated by the pixel group, and the minimum value of the pixel values indicated by the pixel group. A certain minimum pixel value and the like can be mentioned. An example in which the representative pixel value is the average pixel value will be described below. In step ST10, the analysis function 443 measures the time change of the average pixel value of the pixel group existing in each section within the ROI by performing difference processing between the contrast image data of the latest frame and the contrast image data of the past frame. .

Note that when the segmentation target region is the entire image and the entire image is segmented into a plurality of segments, the analysis function 443 performs difference processing between the contrast image data of the latest frame and the contrast image data of the past frames. Also, it is preferable to correct the positional deviation between the two image data. For example, the analysis function 443 corrects the positional deviation between the two image data by linearly transforming the image so that the local regions of each image data are aligned. The analysis function 443 corrects the positional deviation between both image data, and divides the entire corrected image into a plurality of sections.

The analysis function 443 integrates (groups) sections having the same or similar temporal changes in pixel values to generate an integrated area (step ST11). In step ST11, the analysis function 443, for example, sets a boundary threshold for classifying each partition into one of a plurality of levels, and determines which level each partition is included in. Note that the boundary threshold value may be a fixed value, or may be changed according to the elapsed time from the start of injection of the contrast medium. In addition, the analysis function 443 preliminarily sets a predetermined range of time change of the average pixel value considering the elapsed time from the start of injection of the contrast agent, and only the sections having the average pixel value within that range are the targets of integration. can be As a result, the load of integration processing can be reduced.

FIG. 7 is a diagram showing a first example of integrated regions. FIG. 7(A) is a diagram showing an integrated region within an ROI in contrast-enhanced image data of the neck. FIG. 7B is a diagram showing an integrated region of the entire image in the contrast-enhanced image data of the neck. FIG. 7C is for comparison with FIGS. 7A and 7B, and is a reference diagram showing an integrated region of the entire image in the non-contrast image data of the neck.

FIG. 7A shows an integrated region L1 resulting from a contrast agent, which is an integrated region when the segmentation target region is the ROI. The integrated region L1 is a set of multiple partitions having an average pixel value between the lower threshold and the upper threshold within the ROI. On the other hand, FIG. 7B shows an integrated area L2 including an integrated area L1 caused by a contrast medium, which is an integrated area when the segmentation target area is the entire image. The integrated region L2 is a set of a plurality of sections having an average pixel value between the lower threshold and the upper threshold in the entire image. These integrated areas L1 and L2 are generated for each frame (for each thinned frame).

Comparing FIGS. 7(A) and (B), FIG. 7(A), in which the segmentation target region is set as the ROI, is the integration outside the ROI caused by the body movement of the patient P shown in FIG. 7(B). It is advantageous in that it can eliminate regions.

Returning to the description of FIG. 4, the synthesizing function 444 synthesizes the integrated region (illustrated in FIGS. 7A and 7B) generated in step ST11 with the contrast-enhanced image data generated in step ST7 in FIG. to generate composite image data (step ST12). The display control function 445 causes the display 42 to display the synthesized image data generated in step ST12 as a synthesized image (step ST13). In step ST13, the display control function 445 can also cause the display 42 to display in color the integrated area portion of the synthesized image data (illustrated in FIGS. 7A and 7B). Note that the display control function 445 may cause the display 42 to independently display the integrated area generated in step ST11. In that case, the display control function 445 can also cause the display 42 to display the combined area (illustrated in FIGS. 7A and 7B) alone in color.

The analysis function 443 compares the information indicating the characteristics of the integrated area generated in step ST11 with the reference information (step ST14). In step ST14, for example, the analysis function 443 obtains the blood vessel-likeness of the information indicating the characteristics of the integrated region, that is, the accuracy of the information indicating the characteristics of the integrated region with respect to blood vessels, and compares the accuracy with a threshold.

In step ST14, the analysis function 443 performs a process of generating the accuracy of the information indicating the feature of the integrated region with respect to the blood vessel based on the information indicating the feature of the integrated region. This processing may be performed, for example, by automatic recognition such as matching with an atlas (standard organ) image, or by CNN (convolutional neural network) or convolutional deep belief network (CDBN: Convolutional Deep Belief Network). , may be performed by deep learning using a multi-layered neural network.

As a result of the comparison in step ST14, the analysis function 443 determines whether or not the accuracy of the information indicating the feature of the integrated region with respect to the blood vessel is equal to or greater than the threshold (or exceeds the threshold) (step ST15). If the determination in step ST15 is NO, that is, if it is determined that the accuracy of the information indicating the characteristics of the integrated region with respect to blood vessels is less than the threshold (or equal to or less than the threshold), contrast image data is generated for the next frame. (Step ST7 in FIG. 3).

On the other hand, if the determination in step ST15 is YES, that is, if it is determined that the accuracy of the information indicating the characteristics of the integrated region with respect to the blood vessel is equal to or greater than the threshold (or exceeds the threshold), the scan function 441 By controlling the gantry device 10, the bed device 30, etc. via the control device 15 in accordance with the scanning conditions, the main scanning for the patient P is started (step ST16). The multiple contrast image data generated by the prep scan and the image data generated based on the detection data set collected by the main scan are classified as separate series according to DICOM (Digital Imaging and COmmunications in Medicine). It is preferably stored in memory 41 . That is, the X-ray CT system 1 can manage a plurality of contrast-enhanced image data generated by prep scanning and image data generated by main scanning as separate series.

Note that when the analysis function 443 generates a plurality of integrated regions with different levels of differences in average pixel values, it is determined that the accuracy of the information indicating the feature of one of the plurality of integrated regions is equal to or greater than the threshold. Sometimes it is necessary to shift to the main scan.

FIG. 8 is a diagram showing a second example of the integrated area. FIG. 8(A) is a diagram showing an integrated region within an ROI in contrast-enhanced image data of the neck. FIG. 8B is a diagram showing an integrated region of the entire image in the contrast-enhanced image data of the neck. FIG. 8(C) is for comparison with FIGS. 8(A) and 8(B), and is a reference diagram showing an integrated region of the entire image in the non-contrast image data of the neck.

FIG. 8A shows integrated regions when the segmentation target regions are ROIs, and shows a plurality of integrated regions Ls1 caused by the contrast agent. On the other hand, FIG. 8B shows an integrated area when the segmentation target area is the entire image, and shows a plurality of integrated areas Ls2 including a plurality of integrated areas Ls1 caused by the contrast agent. These integrated regions Ls1 and Ls2 are generated for each frame (for each thinned frame).

In step ST12 in FIG. 4, the synthesizing function 444 synthesizes the integrated regions shown in FIGS. 8A and 8B with the contrast image data to generate synthesized image data. In step ST13, the synthesized image data may be displayed on the display 42 as a synthesized image. In that case, the display control function 445 causes the display 42 to color-display the integrated area portion of the synthesized image data (illustrated in FIGS. 8A and 8B), and according to the magnitude of the average pixel value difference, Colors (either hue, saturation, or lightness) can also be changed. Note that the display control function 445 may cause the display 42 to display the integrated area alone. In that case, the display control function 445 causes the integrated region (shown in FIGS. 8A and 8B) to be displayed in color on the display 42 alone, and the color (hue, Saturation and/or lightness) can also be changed.

Returning to the description of FIG. 4, the analysis function 443 performs the fractional When the temporal change of the average pixel value in the target region shows a high value, it may be determined that the patient P has made a body motion, and the determination in step ST16 may be NO.

As described above, the X-ray CT system 1 uses the information (pixel values, etc.) representing the characteristics of the integrated region in the segmentation target region (for example, ROI) as the reference information (ideal blood vessel shape when the contrast medium flows). (pixel value, etc.) is configured to shift to the main scan when the accuracy is high. According to this configuration, it is possible to detect an increase in the pixel value due to the contrast agent even when the patient P moves. In addition, even when it is difficult to set an ROI with an appropriate size at an appropriate position on the image of non-contrast image data, such as when imaging the neck, an appropriate By performing such processing, the timing to shift to the main scan can be measured, so the load of ROI operation can be reduced.

2. Modifications So far, the analysis function 443 has explained the case of measuring the time change of the average pixel value of the pixel group existing in each section in the image data between two frames, but it is not limited to this case. . The analysis function 443 may measure temporal changes in average pixel values of pixel groups existing in each section in image data for three or more frames. The analysis function 443 can use a TDC (Time-Density Curve) as a temporal change in the average pixel value of a group of pixels existing in each section in image data for three or more frames. For example, the analysis function 443 generates a TDC for each frame based on the average pixel value of a group of pixels existing in each section within the ROI as the segmentation target area, and the difference between the TDC and the ideal TDC is Merge identical or similar partitions.

FIG. 9 is a diagram showing an example of TDC. FIG. 9(A) shows the TDC in a certain compartment. FIG. 9(B) shows an ideal TDC in the vascular region.

The analysis function 443 compares the TDC shown in FIG. 9A with the portion corresponding to the frame of the ideal TDC shown in FIG. You can find the difference.

According to the configuration of the modification of the X-ray CT system 1, the same effects as those of the above-described X-ray CT system 1 can be obtained from three or more frames of image data.

Note that the scanning function 441 is an example of a scanning unit. The image generation function 442 is an example of an image generator. The analysis function 443 is an example of an analysis unit. Compositing function 444 is an example of a compositing unit. The display control function 445 is an example of a display control unit.

According to at least one embodiment described above, it is possible to improve the efficiency of an imaging examination.

While several embodiments of the invention have been described, these embodiments have been presented 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.

1 X-ray CT system 40 console device (medical image processing device)
44 processing circuit 441 scan function 442 image generation function 443 analysis function 444 synthesis function 445 display control function

Claims (14)

a scanning unit that performs a first scan including irradiation and detection of X-rays;
an image generation unit that generates a plurality of images corresponding to the plurality of time phases based on the plurality of detection data sets corresponding to the plurality of time phases collected by the first scan;
At least one region is extracted by dividing the entirety of each of the plurality of images into a plurality of sections, and integrating the sections having the same or similar temporal changes in pixel values, and referring to information indicating the characteristics of the region. an analysis unit that compares information;
with
The scanning unit performs a second scan including irradiation and detection of X-rays according to the result of the comparison.
X-ray CT system. The information indicating the features of the region includes at least one of information on pixel values of pixels included in the region, information on the size of the region, and information on the shape of the region.
An X-ray CT system according to claim 1. The analysis unit corrects the positional deviation of the plurality of images, divides the entirety of each of the plurality of images after correction into a plurality of sections , and extracts the regions.
3. The X-ray CT system according to claim 1 or 2. a synthesizing unit that synthesizes at least one of the plurality of images and the region to generate a synthesized image;
a display control unit for displaying the composite image on a display unit;
4. An X-ray CT system according to any one of claims 1 to 3 , comprising: Images generated based on the plurality of images and the detection data set collected by the second scan are managed as separate series;
X-ray CT system according to any one of claims 1 to 4 . The analysis unit presets a predetermined range of temporal changes in pixel values, and only blocks having pixel values within that range are subject to integration.
X-ray CT system according to any one of claims 1 to 5 . The analysis unit sets the partition size or the number of partitions according to the imaging part , and sets the plurality of partitions according to the set size of partitions or the number of partitions.
X-ray CT system according to any one of claims 1 to 6 . a scanning unit that performs a first scan including irradiation and detection of X-rays;
an image generation unit that generates a plurality of images corresponding to the plurality of time phases based on the plurality of detection data sets corresponding to the plurality of time phases collected by the first scan;
At least one region is formed by correcting the positional deviation of the plurality of images, dividing the entirety of each of the plurality of images after correction into a plurality of sections, and integrating the sections having the same or similar temporal changes in pixel values. an analysis unit that extracts and compares information indicating the characteristics of the region with reference information;
with
The scanning unit performs a second scan including irradiation and detection of X-rays according to the result of the comparison.
X-ray CT system. The analysis unit sets the partition size or the number of partitions according to the imaging part , and sets the plurality of partitions according to the set size of partitions or the number of partitions.
An X-ray CT system according to claim 8 . a scanning unit that performs a first scan including irradiation and detection of X-rays;
an image generation unit that generates a plurality of images corresponding to the plurality of time phases based on the plurality of detection data sets corresponding to the plurality of time phases collected by the first scan;
At least one region is extracted by dividing at least a part of each of the plurality of images into a plurality of sections, and integrating the sections with the same or similar temporal changes in pixel values, and information indicating the characteristics of the region. and an analysis unit that compares reference information with
with
The analysis unit sets the partition size or the number of partitions according to the imaging part, sets the plurality of partitions according to the set partition size or the number of partitions,
The scanning unit performs a second scan including irradiation and detection of X-rays according to the result of the comparison.
X-ray CT system. The analysis unit divides a region of interest in each image of the plurality of images into a plurality of sections and extracts the regions.
X-ray CT system according to claim 10 . on the computer of the console device ,
a function of controlling the gantry to perform a first scan including irradiation and detection of X-rays;
A function of generating a plurality of images corresponding to the plurality of phases based on the plurality of detection data sets corresponding to the plurality of phases collected by the first scan;
At least one region is extracted by dividing the entirety of each of the plurality of images into a plurality of sections, and integrating the sections having the same or similar temporal changes in pixel values, and referring to information indicating the characteristics of the region. the ability to compare information;
a function of controlling the gantry to perform a second scan including irradiation and detection of X-rays according to the result of the comparison;
A CT scan execution program that realizes on the computer of the console device ,
a function of controlling the gantry to perform a first scan including irradiation and detection of X-rays;
A function of generating a plurality of images corresponding to the plurality of phases based on the plurality of detection data sets corresponding to the plurality of phases collected by the first scan;
At least one region is formed by correcting the positional deviation of the plurality of images, dividing the whole of each of the plurality of images after correction into a plurality of sections, and integrating the sections having the same or similar temporal changes in pixel values. a function of extracting and comparing the information indicating the characteristics of the region with the reference information;
a function of controlling the gantry to perform a second scan including irradiation and detection of X-rays according to the result of the comparison;
A CT scan execution program that realizes on the computer of the console device ,
a function of controlling the gantry to perform a first scan including irradiation and detection of X-rays;
A function of generating a plurality of images corresponding to the plurality of phases based on the plurality of detection data sets corresponding to the plurality of phases collected by the first scan;
At least one region is extracted by dividing at least a part of each of the plurality of images into a plurality of sections, and integrating the sections having the same or similar temporal changes in pixel values, and information and reference indicating characteristics of the region. an analysis function that compares information;
a function of controlling the gantry to perform a second scan including irradiation and detection of X-rays according to the result of the comparison;
to realize
The analysis function includes a function of setting the partition size or the number of partitions according to the imaging part, and setting the plurality of partitions according to the set partition size or number of partitions,
CT scan executive program.

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