JP2016119975A - Medical image processor, image data display method in medical image processor, and x-ray ct apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medical image processor capable of observing the whole of a predetermined region in captured image data at a time, an image data display method in a medical image processor, and an X-ray CT apparatus.SOLUTION: A medical image processor includes a region extraction part for extracting a predetermined three-dimensional region from volume data of a subject, a region center setting part for setting a center point in the extracted predetermined three-dimensional region, a viewpoint setting part for setting a plurality of viewpoints on a plurality of lines extending radially from the center point in a three-dimensional direction respectively, and a rendering processing part for performing ray-casting from the plurality of viewpoints toward the center point and performing volume-rendering.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to a medical image processing apparatus, an image data display method in the medical image processing apparatus, and an X-ray CT (Computerized Tomography) apparatus.

  As current medical technology, for example, a subject is imaged using an imaging device such as an X-ray CT apparatus or a magnetic resonance imaging apparatus, and medical practices such as diagnosis / treatment of diseases and surgical planning are performed based on the captured image of the subject. Has been done.

  For example, in an imaging apparatus such as an X-ray CT apparatus or a magnetic resonance imaging apparatus, a predetermined region such as a heart or a brain is imaged, and image data is generated in these imaging apparatus or medical image processing apparatus. Then, the operator visually confirms these image data.

  Here, in the case of examining the heart, a technique is disclosed in which a reference cross section in the heart is positioned in a simple and short time, and an imaging region of the heart is imaged through the reference cross section (for example, Patent Document 1). .

JP 2012-110688 A

  By the way, when a heart, a brain, or the like is imaged, an X-ray CT image generally displays an image captured by a 3D (3 Dimension) rendering image. In this case, a line of sight is set in parallel from a specific direction, and a 3D rendering image is generated based on the line of sight.

  In the conventional rendered image, the line of sight is set from a specific direction, and therefore, the 3D rendered image viewed from the specific direction cannot see an image other than the specific direction. That is, for example, when the heart is imaged, the 3D rendering image on the front side of the heart can be viewed, but the back side of the heart cannot be observed at a time unless the 3D rendering image is rotated.

  Therefore, there has been a demand for a medical image processing apparatus, an image data display method in the medical image processing apparatus, and an X-ray CT apparatus capable of observing the entire predetermined region at once in the captured image data.

  In order to solve the above-described problem, the medical image processing apparatus according to the present embodiment includes a region extraction unit that extracts a predetermined three-dimensional region from the volume data of a subject, and a central point in the extracted three-dimensional region. A region center setting unit for setting a plurality of viewpoints on a plurality of lines extending radially from the center point in a three-dimensional direction, and ray casting from the plurality of viewpoints toward the center point. And a rendering processing unit for performing volume rendering.

The hardware block diagram which shows the X-ray CT apparatus which concerns on this embodiment. The block diagram which shows the function of the X-ray CT apparatus which concerns on this embodiment. The flowchart which shows operation | movement of the X-ray CT apparatus which concerns on this embodiment. Explanatory drawing which shows the concept in case an area | region center setting part calculates the center axis | shaft in a left ventricle area | region, and sets a center point. Explanatory drawing which shows the concept in case a viewpoint setting part sets a some viewpoint to a three-dimensional direction from the center point of a left ventricle area | region, and sets a center point as a drawing point. Explanatory drawing which shows the concept which sets a several viewpoint in a three-dimensional direction at the time of seeing a left ventricle area | region from the direction perpendicular | vertical to a sagittal cross section. Explanatory drawing which shows the concept which sets a several viewpoint in a three-dimensional direction at the time of seeing a left ventricle area | region from the direction perpendicular | vertical to an axial cross section. Explanatory drawing in the case of displaying the total value of the density of each voxel as a rendering image. The image figure which showed an example of the conventional 3D rendering image. The image figure which looked at the conventional 3D rendering image from right above. FIG. 11 is an image diagram of a rendering image when ray casting is performed from a plurality of viewpoints from the three-dimensional direction and volume rendering is performed from a plurality of viewpoints with respect to the 3D rendering image of FIG. 10 in the present embodiment.

  Hereinafter, an image processing apparatus and an X-ray CT apparatus according to the present embodiment will be described with reference to the accompanying drawings.

  The X-ray CT apparatus of this embodiment includes a rotation / rotation (ROTATE / ROTATE) type in which an X-ray tube and an X-ray detector are rotated as one body, and a large number of detections in a ring shape. There are various types such as a stationary / rotating type in which elements are arrayed and only an X-ray tube rotates around the subject, and any type is applicable. Here, the rotation / rotation type that currently occupies the mainstream will be described.

  In addition, the mechanism for converting incident X-rays into electric charges is based on an indirect conversion type in which X-rays are converted into light by a phosphor such as a scintillator, and the light is further converted into electric charges by a photoelectric conversion element such as a photodiode. The generation of electron-hole pairs in semiconductors and their transfer to the electrode, that is, the direct conversion type utilizing a photoconductive phenomenon, is the mainstream.

  In addition, in recent years, a so-called multi-tube type X-ray CT apparatus in which a plurality of pairs of an X-ray tube and an X-ray detector are mounted on a rotating ring has been commercialized, and development of peripheral technologies has been advanced. . The X-ray CT apparatus of the present embodiment can be applied to both a conventional single-tube type X-ray CT apparatus and a multi-tube type X-ray CT apparatus. Here, a single tube X-ray CT apparatus will be described.

  FIG. 1 is a hardware configuration diagram illustrating an X-ray CT apparatus according to the present embodiment.

  In FIG. 1, the structure of the X-ray CT apparatus 1 which concerns on this embodiment is shown. The X-ray CT apparatus 1 is mainly composed of a scanner device 11 and an image processing device 12. The scanner device 11 of the X-ray CT apparatus 1 is usually installed in an examination room and configured to generate X-ray transmission data regarding a patient (subject) O. On the other hand, the image processing apparatus 12 is usually installed in a control room adjacent to the examination room, and is configured to generate projection data based on transmission data and generate / display a reconstructed image.

  The scanner device 11 of the X-ray CT apparatus 1 includes an X-ray tube (X-ray source) 21, a diaphragm 22, an X-ray detector 23, a DAS (Data Acquisition System) 24, a rotating unit 25, a high voltage power supply 26, and a diaphragm driving device. 27, a rotation drive device 28, a contrast medium injection device (injector) 29, an electrocardiograph unit 30, a top plate 31, a top plate drive device 32, and a controller 33 are provided.

  The X-ray tube 21 generates X-rays by causing an electron beam to collide with a metal target according to the tube voltage supplied from the high-voltage power supply 26 and irradiates the X-ray detector 23 toward the X-ray detector 23. Fan beam X-rays and cone beam X-rays are formed by X-rays emitted from the X-ray tube 21. The X-ray tube 21 is supplied with electric power necessary for X-ray irradiation under the control of the controller 33 via the high voltage power supply 26.

  The diaphragm 22 adjusts the irradiation range in the slice direction of the X-rays irradiated from the X-ray tube 21 by the diaphragm driving device 27. That is, by adjusting the aperture of the diaphragm 22 by the diaphragm driving device 27, the X-ray irradiation range in the slice direction can be changed.

  The X-ray detector 23 is a one-dimensional array type detector having a plurality of detection elements in the channel direction and a single detection element in the column (slice) direction. Alternatively, the X-ray detector 23 is a two-dimensional array detector (also referred to as a multi-slice detector) having a matrix, that is, a plurality of detection elements in the channel direction and a plurality of detection elements in the column direction. The X-ray detector 23 detects X-rays irradiated from the X-ray tube 21 and transmitted through the patient O.

  The DAS 24 amplifies the transmission data signal detected by each X-ray detection element of the X-ray detector 23 and converts it into a digital signal. Output data of the DAS 24 is supplied to the image processing apparatus 12 via the controller 33 of the scanner apparatus 11.

  The rotating unit 25 integrally holds the X-ray tube 21, the diaphragm 22, the X-ray detector 23, and the DAS 24. The rotating unit 25 can rotate around the patient O together with the X-ray tube 21, the diaphragm 22, the X-ray detector 23, and the DAS 24 with the X-ray tube 21 and the X-ray detector 23 facing each other. It is configured. A direction parallel to the rotation center axis of the rotating unit 25 is defined as a z-axis direction, and a plane orthogonal to the z-axis direction is defined as an x-axis direction and a y-axis direction.

  The high voltage power supply 26 supplies electric power necessary for X-ray irradiation to the X-ray tube 21 under the control of the controller 33.

  The aperture driving device 27 has a mechanism for adjusting the irradiation range of the aperture 22 in the X-ray slice direction under the control of the controller 33.

  The rotation drive device 28 has a mechanism for rotating the rotating unit 25 so that the rotating unit 25 rotates around the hollow portion while maintaining the positional relationship under the control of the controller 33.

  The contrast medium injection device 29 continuously injects the contrast medium into the patient O under the control of the controller 33. The contrast medium injection device 29 can control the amount and concentration of the contrast medium injected into the patient O based on the behavior of the contrast medium in the patient O.

  Inside the patient O, a coronary artery branches from the aorta, and a capillary vessel further branches from the branched coronary artery. The capillaries are guided into the myocardium, and the myocardium is composed of capillaries and cardiomyocytes. Cardiomyocytes have a region called stroma, which has a structure in which blood can enter and exit between the stroma and capillaries. For this reason, when a contrast medium is injected into the patient O, the contrast medium is guided along with blood from the aorta to the coronary artery and from the coronary artery to the capillaries.

  Further, when the contrast medium flows together with blood in the capillaries and reaches the cardiomyocytes, a part of the contrast medium flows from the capillaries into the stroma in the cardiomyocytes. Further, part of the blood that has flowed into the stroma in the cardiomyocytes flows out of the cardiomyocytes again and moves into the capillaries.

  The electrocardiograph unit 30 includes an electrocardiograph electrode, an amplifier, and an A / D (Analog To Digital) conversion circuit (not shown). The electrocardiograph unit 30 amplifies electrocardiographic waveform data as an electric signal sensed by the electrocardiograph electrodes by an amplifier, removes noise from the amplified signal, and converts it into a digital signal. The electrocardiograph unit 30 is attached to the patient O.

  The top plate 31 can place the patient O thereon.

  The top plate driving device 32 has a mechanism for moving the top plate 31 up and down along the y-axis direction and moving in and out along the z-axis direction under the control of the controller 33. The central portion of the rotating unit 25 has an opening, and the patient O placed on the top plate 31 of the opening is inserted.

  The controller 33 includes a CPU (Central Processing Unit) and a memory. The controller 33 controls the X-ray detector 23, the DAS 24, the high voltage power supply 26, the diaphragm drive device 27, the rotation drive device 28, the contrast medium injection device 29, the electrocardiograph unit 30, the top plate drive device 32, and the like. To scan.

  The image processing apparatus 12 of the X-ray CT apparatus 1 is configured based on a computer and can communicate with a network N such as a hospital-based LAN (Local Area Network). The image processing apparatus 12 is mainly composed of basic hardware such as a CPU 41, a memory 42, an HDD (Hard Disc Drive) 43, an input device 44, and a display device 45.

  The CPU 41 is interconnected to each hardware component constituting the image processing device 12 via a bus as a common signal transmission path. Note that the image processing apparatus 12 may include a storage medium drive 46. The CPU 41 executes a program stored in the memory 42 when a command is input by operating the input device 44 by an operator such as a doctor. Alternatively, the CPU 41 reads a program stored in the HDD 43, a program transferred from the network N and installed in the HDD 43, or a program read from the recording medium installed in the storage medium drive 46 and installed in the HDD 43. It is loaded into the memory 42 and executed.

  The memory 42 is a storage device having a configuration having elements such as a ROM (Read Only Memory) and a RAM (Random Access Memory). The internal storage device stores IPL (Initial Program Loading), BIOS (Basic Input / Output System) and data, and is used for temporary storage of the work memory and data of the CPU 41.

  The HDD 43 is a storage device having a configuration in which a metal disk coated or vapor-deposited with a magnetic material is incorporated in a non-detachable manner. The HDD 43 is a storage device that stores programs installed in the image processing apparatus 12 (including application programs as well as OS (Operating System)), projection data, and image data. In addition, the OS can be provided with a GUI (Graphical User Interface) that can use a lot of graphics for displaying information to the operator and perform basic operations by the input device 44.

  The input device 44 is a pointing device that can be operated by an operator, and an input signal according to the operation is sent to the CPU 41.

  The display device 45 includes an image composition circuit (not shown), a video random access memory (VRAM), a display, and the like. The image synthesizing circuit generates synthesized data obtained by synthesizing character data of various parameters with image data. The VRAM develops the composite data as display image data to be displayed on the display. The display is configured by a liquid crystal display, a CRT (Cathode Ray Tube), or the like, and sequentially displays display image data as a display image.

  The storage medium drive 46 can be attached to and detached from a recording medium, reads out data (including a program) recorded on the recording medium, outputs the data on the bus, and records data supplied via the bus. Write to media. Such a recording medium can be provided as so-called package software.

  The image processing device 12 generates projection data by performing logarithmic conversion processing or correction processing (pre-processing) such as sensitivity correction on the raw data input from the DAS 24 of the scanner device 11, and generates projection data in a storage device such as the HDD 43. Remember.

  Further, the image processing device 12 performs scattered radiation removal processing on the preprocessed projection data. The image processing device 12 removes scattered radiation based on the value of the projection data within the X-ray exposure range, and based on the projection data to be subjected to scattered radiation correction or the value of the adjacent projection data. The estimated scattered radiation is subtracted from the target projection data to perform scattered radiation correction.

  FIG. 2 is a block diagram showing functions of the X-ray CT apparatus 1 of the present embodiment.

  When the CPU 41 shown in FIG. 1 executes the program, the X-ray CT apparatus 1 has a scan control unit 51, a projection data generation unit 52, a volume generation unit 53, a region extraction unit 54, a region center, as shown in FIG. It functions as a setting unit 55, a viewpoint setting unit 56, a rendering processing unit 57, and an image display control unit 58.

  In addition, although each component 51 thru | or 58 which comprises the X-ray CT apparatus 1 shall function when CPU41 runs a program, it is not limited to that case. There may be a case where all or a part of the constituent elements 51 to 58 constituting the X-ray CT apparatus 1 are provided in the X-ray CT apparatus 1 as hardware.

  The scan control unit 51 controls the controller 33 of the scanner device 11 and collects raw data for each view by performing an electrocardiographic scan of the heart of the patient O while continuously injecting a contrast medium into the patient O. Have That is, the scan control unit 51 controls the controller 33 to acquire electrocardiographic waveform data via the electrocardiograph unit 30 attached to the patient O, and sends a control signal based on the electrocardiographic waveform data to the high voltage power supply 26. To give. Therefore, a tube current or tube voltage is supplied from the high voltage power supply 26 to the X-ray tube 21 in synchronization with the electrocardiographic waveform data, and the patient O is irradiated with X-rays.

  The projection data generation unit 52 performs projection processing such as logarithmic conversion processing and sensitivity correction on the raw data input from the DAS 24 of the scanner device 11 to generate projection data, and stores the projection data in the HDD 43. Further, the projection data generation unit 52 may perform a scattered radiation removal process on the projection data. The scattered radiation removal process is to remove scattered radiation based on the value of projection data within the X-ray exposure range, and the projection data to be subjected to scattered radiation correction or the value of the adjacent projection data is large. Then, the scattered radiation correction is performed by subtracting the estimated scattered radiation from the target projection data.

  The volume generation unit 53 generates cross section data of a plurality of cross sections orthogonal to the z-axis direction based on the projection data input from the projection data generation unit 52 (or HDD 43), and volume data based on the cross section data of the plurality of cross sections. It has the function to generate. Since the contrast agent is injected into the patient O, the volume data becomes contrast data. Further, since the electrocardiographic synchronization imaging is used, volume data of myocardial contrast in the same period of each part of the myocardium can be obtained in the contraction or diastole of the myocardium.

  The region extraction unit 54 has a function of extracting a predetermined three-dimensional region from the volume data of the patient O. For example, the region extraction unit 54 can extract all or part of the heart or brain as a predetermined region. Specifically, the region extraction unit 54 can extract the heart as a volume data portion from the volume data generated by the volume generation unit 53. The left ventricular region can be extracted.

  In this embodiment, as an example, the case of extracting the left ventricular region of the heart as the volume data portion will be described, but the present invention is not limited to the left ventricular region. For example, the right ventricular region of the heart as the volume data portion may be extracted.

  The region center setting unit 55 has a function of setting a center point in a predetermined three-dimensional region extracted by the region extraction unit 54. For example, the region center setting unit 55 generates cross section data of a plurality of cross sections based on the left ventricular region of the heart, and based on the cross section data of the plurality of cross sections, the center point is determined from the spatial position information of the left ventricular region. Set. In this case, the region center setting unit 55 performs cross-sectional data of a plurality of cross sections by calculation based on any one of a plurality of axial cross-section image data, coronal cross-section image data, or sagittal cross-section image data of the patient O. And the spatial position information of the left ventricular region can be calculated.

  The region center setting unit 55 generates a plurality of cross-sectional data based on the left ventricular region of the heart extracted by the region extracting unit 54, and includes a plurality of data from at least the base to the apex of the entire left ventricular region. Cross section data of the short axis cross section (long vertical axis cross section) is generated, and the myocardial region and ventricular region as a part of the generated cross section data of the plurality of short axis cross sections are extracted for each short axis cross section. Also good. In this case, the region center setting unit 55 can calculate from the heart base to the apex as the center axis of the left ventricular region, and set the center point in the middle (midpoint) of the center axis. The region center setting unit 55 may be set as a central point anywhere within the left ventricular region (within a predetermined region), and is not limited to a structural center.

  The viewpoint setting unit 56 has a function of setting a plurality of viewpoints on a plurality of lines extending radially in the three-dimensional direction from the center point set by the region center setting unit 55. For example, the viewpoint setting unit 56 sets a plurality of viewpoints on a plurality of lines extending radially in the three-dimensional direction from the center point of the left ventricle region, and also draws the center point of the left ventricle region for ray casting (hereinafter, referred to as “line casting”). This is also called a drawing point.) Note that the viewpoint setting unit 56 sets a plurality of viewpoints in directions in which the angle at the center point (drawing point) or the angle from the cross section including the drawing point is different. Here, the angle at the drawing point can be set by applying spherical coordinates. The angle from the cross section including the drawing point will be described with reference to a flowchart described later.

  The rendering processing unit 57 has a function of performing volume rendering by performing ray casting from a plurality of viewpoints set by the viewpoint setting unit 56 toward the center point. In volume rendering, the density of voxel values from each of a plurality of viewpoints to the center point is summed. In this embodiment, along each line of sight (Ray) from each of the plurality of viewpoints to the center point, respectively. Sum the density of voxels.

  The image display control unit 58 has a function of displaying an image with the density of each voxel summed up by the rendering processing unit 57 corresponding to each of the three-dimensional directions of a plurality of viewpoints. In this case, the total value of the density of each voxel is displayed on the display device 45 as a rendered image. In addition, the image display control unit 58 displays an image so that the reference viewpoint becomes the center of the image among the plurality of viewpoints, and the other viewpoints are more than 90 degrees away from the direction of the reference viewpoint. The total value of voxel density is displayed as an image including the viewpoint.

  Next, the operation of the X-ray CT apparatus 1 according to the present embodiment will be described using the flowchart shown in FIG.

  FIG. 3 is a flowchart showing the operation of the X-ray CT apparatus 1 according to this embodiment.

  The X-ray CT apparatus 1 controls the controller 33 of the scanner apparatus 11 to collect raw data for each view by performing an electrocardiographic scan of the heart of the patient O while continuously injecting a contrast medium into the patient O. (Step ST1).

  The X-ray CT apparatus 1 performs projection processing such as logarithmic conversion processing and sensitivity correction on the raw data input from the DAS 24 of the scanner device 11 to generate projection data (step ST2).

  The X-ray CT apparatus 1 generates cross-sectional data of a plurality of cross sections orthogonal to the z-axis direction based on the projection data generated in step ST2, and generates three-dimensional volume data based on the cross-sectional data of the plurality of cross sections ( Step ST3).

  The X-ray CT apparatus 1 extracts the left ventricular region of the three-dimensional heart as the volume data portion from the three-dimensional volume data generated by the volume generation unit 53 (step ST4).

  The X-ray CT apparatus 1 sets a center point in the left ventricular region of the three-dimensional heart extracted in step ST4 (step ST5). For example, the region center setting unit 55 generates cross section data of a plurality of cross sections based on the extracted left ventricular region of the heart, and based on the spatial position information of the left ventricular region based on the cross section data of the plurality of cross sections. Set the center point. In this case, the center point setting condition may be designated in advance and automatically set by software.

  In addition, when generating the cross-sectional data of a plurality of cross sections based on the left ventricular region, the region center setting unit 55 generates a plurality of short-axis cross-sectional data from at least the base to the apex of the entire left ventricular region. Then, the myocardial region and the ventricular region as a part of the generated cross-sectional data of the plurality of short-axis cross sections may be extracted for each short-axis cross-section. In this case, the region center setting unit 55 can calculate the center axis of the left ventricular region from the heart base to the apex and set the center point in the middle of the center axis.

  FIG. 4 is an explanatory diagram showing a concept when the region center setting unit 55 calculates the center axis in the left ventricular region and sets the center point CT.

  As shown in FIG. 4, the region center setting unit 55 generates cross-sectional data P1 to P3 as a part of cross-sectional data of a plurality of cross-sections, and in the middle of the central axis of the left ventricular region by the base and apex, A center point CT can be set.

  Returning to the flowchart of FIG. 3, the X-ray CT apparatus 1 sets a plurality of viewpoints on a plurality of lines extending radially in the three-dimensional direction from the center point CT of the left ventricle region set in step ST5, Is set as a drawing point (step ST6).

  FIG. 5 is an explanatory diagram illustrating a concept when the viewpoint setting unit 56 sets a plurality of viewpoints in a three-dimensional direction from the center point CT of the left ventricular region RN and sets the center point CT as a drawing point.

  In FIG. 5, as an example, a plurality of viewpoints from the viewpoint A to the viewpoint N are set in the three-dimensional direction of the left ventricular region RN, and the center point CT is set as a drawing point. FIG. 5 shows a concept when the left ventricle region RN is viewed from a direction perpendicular to the coronal section. In addition, since a part from the set viewpoints A to N overlaps in the drawing, a part of the overlapping display is appropriately omitted.

  Here, with reference to the drawing when viewed from the direction perpendicular to the coronal section in FIG. 5, the drawing when viewed from the direction perpendicular to the sagittal section and the drawing when viewed from the direction perpendicular to the axial section are referred to. The viewpoint A to viewpoint N will be described.

  FIG. 6 is an explanatory diagram showing a concept of setting a plurality of viewpoints in a three-dimensional direction when the left ventricle region RN is viewed from a direction perpendicular to the sagittal section.

  FIG. 7 is an explanatory diagram showing a concept of setting a plurality of viewpoints in a three-dimensional direction when the left ventricle region RN is viewed from a direction perpendicular to the axial cross section.

  For example, the viewpoint NT is set from the center point CT (drawing point) of the left ventricular region RN shown in FIG. A line connecting the viewpoint NT and the center point CT is taken as a reference line. Here, consider a case where a plurality of viewpoints are set in increments of 45 degrees to the opposite side of the left ventricular region RN 180 degrees along the sagittal section with the center point CT as the center and the reference line as a reference. The reference line connecting the viewpoint NT and the center point CT is an example, and the present invention is not limited to this.

  Referring to FIG. 6, first, the viewpoint setting unit 56 sets a line connecting the center point CT indicating the drawing point and the viewpoint NT as a reference line. The viewpoint setting unit 56 sets the viewpoint A at a position deviated from the viewpoint NT by 45 degrees along the sagittal section with the center point CT as the center and the reference line as a reference, and is also deviated by 90 degrees from the viewpoint NT. The viewpoint B is set at the selected position. The viewpoints A and B in FIG. 6 correspond to the same positions as the viewpoints A and B indicating the three-dimensional direction in FIG.

  Similarly, the viewpoint setting unit 56 sets the viewpoint C at a position shifted by 135 degrees from the viewpoint NT along the sagittal section with respect to the center point CT and with reference to the reference line, and from the viewpoint NT. The viewpoint D is set at a position shifted by 180 degrees. As described above, the viewpoint setting unit 56 can set the viewpoint D from the viewpoint NT to the 180 ° opposite side of the viewpoint NT along the sagittal section with the center point CT of the left ventricular region RN as the center.

  In addition, the viewpoint setting unit 56 sets the viewpoint E at a position shifted by minus 45 degrees from the viewpoint NT along the sagittal section with respect to the center point CT and with reference to the reference line, and from the viewpoint NT. The viewpoint F is set at a position shifted by minus 90 degrees. The viewpoints E and F in FIG. 6 correspond to the same positions as the viewpoints E and F indicating the three-dimensional direction in FIG.

  Similarly, the viewpoint setting unit 56 sets the viewpoint G at a position deviated by minus 135 degrees from the viewpoint NT along the sagittal section with respect to the center point CT and with reference to the reference line. The position shifted by minus 180 degrees from the position corresponds to the viewpoint D. As described above, the viewpoint setting unit 56 can set the viewpoint G from the viewpoint A along the sagittal section around the center point CT of the left ventricle region RN.

  Next, a plurality of viewpoints in 45 degree increments from the center point CT of the left ventricular region RN shown in FIG. 5 to the 180 degree opposite side of the left ventricular region RN along the axial section with reference to the reference line. Consider the case of setting.

  Referring to FIG. 7, the viewpoint setting unit 56 sets the viewpoint H at a position shifted from the viewpoint NT by 45 degrees along the axial section with the center point CT as the center and the reference line as a reference. The viewpoint I is set at a position shifted by 90 degrees from the viewpoint NT. The viewpoints H and I in FIG. 7 correspond to the same positions as the viewpoints H and I indicating the three-dimensional direction in FIG.

  Similarly, the viewpoint setting unit 56 sets the viewpoint J at a position shifted by 135 degrees from the viewpoint NT along the axial section with the center point CT as the center and the reference line as a reference, and from the viewpoint NT. A viewpoint K (same as viewpoint D) is set at a position shifted by 180 degrees. In this way, the viewpoint setting unit 56 can set the viewpoint K (viewpoint D) up to 180 degrees opposite to the viewpoint NT with the center point CT of the left ventricular region RN as the center.

  In addition, the viewpoint setting unit 56 sets the viewpoint L at a position shifted by minus 45 degrees from the viewpoint NT along the axial section with the center point CT as the center and the reference line as a reference, and from the viewpoint NT. The viewpoint M is set at a position shifted by minus 90 degrees. The viewpoint L and viewpoint M in FIG. 7 correspond to the same positions as the viewpoint L and viewpoint M indicating the three-dimensional direction in FIG.

  Similarly, the viewpoint setting unit 56 sets the viewpoint N at a position deviated by minus 135 degrees from the viewpoint NT along the axial section with respect to the center point CT and with reference to the reference line. The position shifted by minus 180 degrees from the position corresponds to the viewpoint K (viewpoint D). As described above, the viewpoint setting unit 56 can set the viewpoint N from the viewpoint H along the axial cross section around the center point CT of the left ventricular region RN (step ST6).

  In the present embodiment, the direction setting unit 56 is not limited to these directions, and the viewpoint setting unit 56 can set a plurality of viewpoints in an arbitrary direction from the viewpoint NT, for example, in a direction of 45 degrees obliquely. .

  Returning to the flowchart of FIG. 3, the X-ray CT apparatus 1 performs volume rendering by performing ray casting from a plurality of viewpoints set in step ST6 toward the center point CT (drawing point). In this case, the rendering processing unit 57 sums up the density of each voxel along each line of sight from the plurality of viewpoints to the center point CT (step ST7).

  Then, the X-ray CT apparatus 1 displays an image on the display device 45 as a rendering image in association with the total value of the density of each voxel in each of the three-dimensional directions of a plurality of viewpoints (step ST8).

  FIG. 8 is an explanatory diagram in a case where the total value of the density of each voxel is displayed as a rendered image.

  As shown in FIG. 8, the rendering image displayed on the display device 45 indicates that the total value of the density of voxels is mapped in the three-dimensional direction around the center point CT.

  In this embodiment, since the viewpoint setting unit 56 sets the viewpoint A to the viewpoint N along the sagittal section and the axial section around the center point CT in step ST6, the image display control section 58 starts from the viewpoint A. The total value of the voxel values from each viewpoint N to the center point CT is displayed on the display device 45 as a rendering image.

  In addition, the image display control unit 58 displays an image so that a reference viewpoint (for example, the viewpoint NT) of the plurality of viewpoints is the center of the image, and the other viewpoints are 90 from the direction of the reference viewpoint. The total value of the density of voxels is displayed on an image, including viewpoints that are far apart than the degree.

  Thereby, in the X-ray CT apparatus 1 of this embodiment, the whole left ventricular region RN of the heart can be observed at a time.

  Here, a rendering image to which a total value of voxel densities is mapped using a specific image will be described.

  FIG. 9 is an image diagram showing an example of a conventional 3D rendering image.

  As shown in FIG. 9, in the conventional 3D rendering image FT, for example, a 3D rendering image shaped like a fruit is displayed on the display device. In the conventional technique, the back side of such a 3D rendering image FT cannot be viewed at a time.

  FIG. 10 is an image view of a conventional 3D rendering image FT viewed from directly above.

  As shown in FIG. 10, the conventional 3D rendering image FT has a fruit-like shape, so that the lower side of the 3D rendering image FT is hidden as in the case of FIG. As a result, in the conventional 3D rendering image FT, the lower side of the 3D rendering image FT cannot be seen at a time.

  Therefore, in the present embodiment, ray casting from a plurality of viewpoints is set in a three-dimensional direction, and as an example, a reference line BL (a line corresponding to the line connecting the viewpoint NT and the center point CT described above) is set. Volume rendering is executed from the viewpoint.

  Note that the reference line BL can be set at any viewpoint, and can be set at a viewpoint that the operator wants to see as a reference. For example, when it is desired to see the coronary artery or the aorta, it is desirable to see the whole from directly above the heart, so it is desirable to set the reference line BL directly above the 3D rendering image FT as shown in FIG. Similarly, when conducting a brain examination, it is desirable to set a reference line at the top of the head.

  FIG. 11 is an image diagram of a rendering image when ray casting is set from a plurality of viewpoints from the three-dimensional direction and volume rendering is executed from a plurality of viewpoints with respect to the 3D rendering image FT of FIG. 10 in the present embodiment. is there.

  The rendered image shown in FIG. 11 is subjected to volume rendering from a plurality of viewpoints in the three-dimensional direction with respect to the center of the 3D rendered image FT, and the total value of each voxel value is made to correspond to the angular position in FIG. It is an image display.

  Thereby, in this embodiment, the back side of the 3D rendering image FT can be displayed entirely at a time with respect to the 3D rendering image FT shaped like a fruit in the X-ray CT apparatus 1.

  As described above, in the present embodiment, the total value of the respective voxel values is displayed as an image on the display device 45 as a rendering image, and the process ends.

  As described above, according to the X-ray CT apparatus 1 of the present embodiment, a predetermined three-dimensional region such as the heart and brain is extracted from the captured image data, and the entire predetermined three-dimensional region is displayed. Therefore, the operator can observe the entire predetermined area at a time.

  In the present embodiment, in step ST5, the region center setting unit 55 sets the center point in the left ventricular region (predetermined three-dimensional region) extracted by the region extracting unit 54. The set position is not limited.

  For example, in the spatial position information of the left ventricular region, the operator may specify an arbitrary position using the input device 44, and the center point is set from the center of gravity and surface area of the left ventricular region. Also good.

  Although several embodiments of the present invention have been described, these embodiments are 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 changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 X-ray CT apparatus 11 Scanner apparatus 12 Image processing apparatus 21 X-ray tube 23 X-ray detector 24 DAS
33 Controller 41 CPU
43 HDD
44 input device 45 display device 51 scan control unit 52 projection data generation unit 53 volume generation unit 54 region extraction unit 55 region center setting unit 56 viewpoint setting unit 57 rendering processing unit 58 image display control unit

Claims (8)

An area extracting unit for extracting a predetermined three-dimensional area from the volume data of the subject;
A region center setting unit for setting a center point in the extracted predetermined three-dimensional region;
A viewpoint setting unit for setting a plurality of viewpoints on a plurality of lines extending radially in a three-dimensional direction from the center point;
A rendering processor that performs volume rendering by performing ray casting from the plurality of viewpoints toward the central point;
A medical image processing apparatus comprising: The rendering processing unit sums up the density of voxel values from each of the plurality of viewpoints to the center point,
An image display control unit configured to display an image corresponding to the total value of the voxel density in each of the three-dimensional directions of the plurality of viewpoints;
The medical image processing apparatus according to claim 1, further comprising: The image display control unit
Among the plurality of viewpoints, an image is displayed so that a reference viewpoint is the center of the image, and the other viewpoints include viewpoints that are more than 90 degrees away from the direction of the reference viewpoint, The medical image processing apparatus according to claim 2, wherein the total density value is displayed as an image. The region center setting unit includes:
Generate cross-section data of a plurality of cross sections based on the extracted predetermined three-dimensional area, and set the center point from the spatial position information of the predetermined three-dimensional area based on the cross-section data of the plurality of cross sections The medical image processing apparatus according to any one of claims 1 to 3. The region center setting unit includes:
The medical image processing apparatus according to any one of claims 1 to 3, wherein a central axis of the predetermined three-dimensional area is calculated, and the central point is set in the middle of the central axis. The region extraction unit
The medical image processing apparatus according to any one of claims 1 to 5, wherein all or part of a heart or a brain is extracted as the predetermined region from the volume data of the subject. An image data display method in a medical image processing apparatus,
A region extracting step of extracting a predetermined three-dimensional region from the volume data of the subject;
An area center setting step for setting a center point in the extracted predetermined three-dimensional area;
A viewpoint setting step for setting a plurality of viewpoints on a plurality of lines extending radially in a three-dimensional direction from the center point;
A rendering process step for performing volume rendering by performing ray casting from the plurality of viewpoints toward the center point;
An image data display method in a medical image processing apparatus including: An imaging unit for imaging a subject;
A data collection unit for collecting image data of the subject;
A volume data generation unit that generates volume data from the collected image data;
An area extracting unit for extracting a predetermined three-dimensional area from the generated volume data;
A region center setting unit for setting a center point in the extracted predetermined three-dimensional region;
A viewpoint setting unit for setting a plurality of viewpoints on a plurality of lines extending radially in a three-dimensional direction from the center point;
A rendering processor that performs volume rendering by performing ray casting from the plurality of viewpoints toward the central point;
An X-ray CT apparatus comprising:

Images