JP4864532B2 - Ultrasonic diagnostic apparatus, image data display apparatus, and three-dimensional image data generation method - Google Patents

Description

  The present invention relates to an ultrasonic diagnostic apparatus, an image data display apparatus, and a three-dimensional image data generation method, and more particularly, an ultrasonic wave that generates three-dimensional image data by rendering a three-dimensional ultrasonic data collected from a subject. The present invention relates to a diagnostic device, an image data display device, and a three-dimensional image data generation method.

  The ultrasonic diagnostic apparatus performs ultrasonic transmission / reception in a plurality of directions of a subject using an ultrasonic probe in which a plurality of vibration elements are arranged, and displays image data generated based on the obtained reflected wave on a monitor. Is displayed. This device is widely used for morphological diagnosis and functional diagnosis of various organs because it can observe a two-dimensional image and a three-dimensional image in the body in real time with a simple operation by simply bringing an ultrasonic probe into contact with the body surface. Yes.

  Conventionally, in order to obtain three-dimensional image data of a subject using ultrasonic waves, an ultrasonic probe in which vibration elements are arranged one-dimensionally is moved or rotated in a direction perpendicular to the arrangement direction of the subject. Ultrasound has been transmitted to and received from a three-dimensional area, and three-dimensional image data has been generated by rendering the ultrasonic data (volume data) collected at this time.

  In recent years, an ultrasonic probe (two-dimensional array ultrasonic probe) in which vibration elements are two-dimensionally arranged has been put into practical use. By using this ultrasonic probe, the setting of the ultrasonic transmission / reception direction with respect to the three-dimensional region can be performed by electronic control. Therefore, the time required for collecting volume data is greatly reduced, and the real-time of the three-dimensional image data is reduced. Display is also becoming possible.

By the way, when rendering volume data collected from a subject to generate three-dimensional image data, first, spatial interpolation processing is performed on amplitude information of a received signal obtained by ultrasonic transmission / reception with respect to a three-dimensional region. To generate volume data composed of a set of small cubes. Next, a normal unit vector of the voxel (hereinafter referred to as a normal vector) based on a gradient value calculated from signal intensities (hereinafter referred to as voxel values) in a predetermined voxel and surrounding voxels in the volume data. Further, a line-of-sight unit vector (hereinafter referred to as a line-of-sight vector) is set on a line connecting the viewpoint of the image observer and the center position of the voxel. Then, it is set based on the shading value set based on the inner product value of the normal vector and the line-of-sight vector (shadow value for representing the organ etc. in three dimensions) and the distance from the viewpoint of the image observer to the voxel. Three-dimensional display of the organ surface or the like is performed by processing the volume data using the determined opacity (see, for example, Patent Document 1).
JP 2003-61956 A

  In ultrasonic diagnosis, when the transmission / reception direction of ultrasonic waves is perpendicular to the boundary surface of an organ or the like, an ultrasonic reflected wave (hereinafter referred to as high echo) whose signal amplitude has a specifically large value. It is generally known to be received. Then, a normal vector is calculated for each voxel of the volume data including the influence of this high echo, and when the rendering process is performed based on the inner product value of the normal vector and the line-of-sight vector, the voxel value A large error occurs between the direction of the normal vector obtained based on the gradient and the normal direction to the actual organ boundary surface, making it difficult to perform accurate shading on volume data Will occur.

  As a method for solving such a problem, a so-called spatial compound method is conceivable in which ultrasonic transmission / reception is performed from a plurality of different directions with respect to a predetermined part of the organ boundary surface, and the received signals obtained at this time are added and synthesized. . However, in this method, since it is necessary to perform ultrasonic transmission / reception a plurality of times with respect to a predetermined part, when collecting volume data at a normal scanning density, it takes a lot of time to collect the three-dimensional image data. Has a drawback that the frame frequency (the number of image data to be displayed per unit time) is reduced.

  In addition, when ultrasonic transmission / reception is performed at a low scanning density in order to maintain a normal frame frequency, the image quality of the three-dimensional image data deteriorates. That is, in the spatial compound method using ultrasonic wave transmission / reception in multiple directions, the above-mentioned problems relating to high echoes while maintaining both temporal resolution (frame frequency) and spatial resolution (scanning density) of 3D image data in a good state. The point cannot be improved.

  On the other hand, in the method of performing the spatial compound method only during reception by applying a technique such as parallel simultaneous reception, the temporal resolution and spatial resolution are not degraded, but the influence of high echo depending on the transmission direction is effectively eliminated. In the method of smoothing the influence of high echo by applying uniform filtering to all areas of the collected volume data, the time resolution is the same as the spatial compound method only at the time of reception. However, there is a problem that spatial resolution and contrast resolution are deteriorated.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to generate an ultrasonic beam on an organ boundary surface or the like when generating three-dimensional image data based on volume data collected from a subject. Ultrasonic diagnostic apparatus, image data display apparatus, and three-dimensional image data capable of obtaining good three-dimensional image data by reducing influence of high echo depending on incident angle without degrading time resolution or spatial resolution It is to provide a generation method.

  In order to solve the above problems, an ultrasonic diagnostic apparatus according to a first aspect of the present invention includes an ultrasonic probe having a vibration element for transmitting and receiving ultrasonic waves to and from a three-dimensional region of a subject, and the vibration Based on transmission means for transmitting an ultrasonic wave by driving an element, reception means for receiving a reflected signal from the subject obtained by transmission / reception of the ultrasonic wave, and three-dimensional data obtained by the reception means Volume data generating means for generating volume data, calculating a normal vector and a scanning vector in a voxel of the volume data, and correcting the normal vector based on angle information between the normal vector and the scanning vector. Based on the vector calculation means and the corrected normal vector, the volume data generated by the volume data generation means is rendered. It is characterized in that a rendering computation means for generating a 3-dimensional image data and management.

  According to a second aspect of the present invention, there is provided an ultrasonic diagnostic apparatus according to the present invention, comprising: an ultrasonic probe having a vibration element for transmitting and receiving ultrasonic waves to and from a three-dimensional region of a subject; Volume data is generated based on transmission means for transmitting sound waves, reception means for receiving reflected signals from the subject obtained by transmitting and receiving the ultrasonic waves, and three-dimensional data obtained by the reception means The volume data generation means calculates a normal vector and a scan vector for the voxel of the volume data, and influences the high echo depending on the ultrasonic incident angle based on angle information between the normal vector and the scan vector. Vector calculation means for specifying the received voxel, volume data correction means for correcting the volume data based on the specification result, and the voxel Based on the normal vector newly calculated by the vector calculation means for the volume data voxel corrected by the volume data correction means, the volume data generated by the volume data generation means is rendered to generate three-dimensional image data. And a rendering operation means.

  Furthermore, the image data display device of the present invention according to claim 9 includes volume data generation means for generating volume data based on three-dimensional data obtained from a subject, normal vectors and scans in voxels of the volume data. Vector calculation means for calculating a vector and specifying a voxel affected by a high echo depending on an ultrasonic incident angle based on angle information between the normal vector and the scanning vector, and based on the specification result, Volume data correction means for correcting the volume data, and the volume data generation means generated based on the normal vector newly calculated by the vector calculation means for the voxels of the volume data corrected by the volume data correction means 3D image data by rendering volume data And rendering arithmetic means to be generated, is characterized by comprising a display means for displaying the 3-dimensional image data.

  On the other hand, in the three-dimensional image data generation method of the present invention according to claim 11, the volume data generation means generates volume data based on the three-dimensional data obtained by transmitting / receiving ultrasonic waves to / from the subject, The calculation means calculates a normal vector and a scanning vector in the voxel of the volume data, and is affected by a high echo depending on an ultrasonic incident angle based on angle information between the normal vector and the scanning vector. Identifying the volume data in a predetermined area based on the identification result of the vector computing means, and the vector computing means for the voxel of the corrected volume data. New normal vector calculation and rendering operations Stage, is characterized by a step of generating a rendering three-dimensional image data based on the normal vector which is newly calculated volume data in which the volume data generating means has generated.

  According to the present invention, when generating three-dimensional image data based on volume data collected from a subject, the influence of high echoes depending on the incident angle of an ultrasonic beam with respect to an organ boundary surface or the like can be determined with respect to temporal resolution or spatial. It is possible to reduce the resolution without degrading, and therefore, good three-dimensional image data can be obtained.

  Embodiments of the present invention will be described below with reference to the drawings.

  In the ultrasonic diagnostic apparatus according to the first embodiment of the present invention described below, when the volume data obtained by ultrasonic transmission / reception with respect to the three-dimensional region of the subject is rendered to generate three-dimensional image data, the organ boundary A normal vector indicating the normal direction of the surface is calculated based on the gradient of the voxel value of the volume data, and further, a scan vector indicating the ultrasonic wave transmission / reception direction for each voxel of the volume data is calculated.

  Next, based on the inner product value of the normal vector and the scanning vector calculated for each voxel, the voxel affected by the high echo depending on the ultrasonic incident angle is specified, and a predetermined region centered on this voxel is determined. The voxel value is corrected by filtering processing or gradation processing. Then, the volume data before correction is rendered on the basis of the normal vector newly calculated based on the gradient of the voxel value in the volume data after correction and the line-of-sight vector indicating the line-of-sight direction of the image data observer, and three-dimensional image data is rendered. Is generated.

  In this embodiment, a case where volume data collected using a so-called two-dimensional array ultrasonic probe in which vibration elements are two-dimensionally arranged is rendered to generate three-dimensional image data will be described. However, the present invention is not limited to this. For example, three-dimensional image data may be generated based on volume data obtained by mechanically moving or rotating an ultrasonic probe in which a plurality of vibration elements are arranged one-dimensionally.

  Further, although the case where the volume data is generated based on the B mode data will be described, other ultrasonic data such as color Doppler data may be used.

(Device configuration)
The configuration of the ultrasonic diagnostic apparatus according to this embodiment will be described with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of the ultrasonic diagnostic apparatus, and FIG. 2 is a block diagram of a transmission / reception unit and a received signal processing unit provided in the ultrasonic diagnostic apparatus. FIG. 6 is a block diagram showing a specific configuration of a vector calculation unit provided in the three-dimensional image data generation unit of the ultrasonic diagnostic apparatus.

  The ultrasonic diagnostic apparatus 100 of the present embodiment shown in FIG. 1 transmits an ultrasonic pulse (transmitted ultrasonic wave) to a three-dimensional region of a subject, and an ultrasonic reflected wave (received ultrasonic wave) obtained by this transmission. ) Is converted into an electric signal (received signal), and an ultrasonic probe 3 in which a plurality of vibration elements are two-dimensionally arranged, and a drive signal for transmitting an ultrasonic pulse in a predetermined direction of the subject are vibrated. A transmission / reception unit 2 that supplies a plurality of channels received from the vibration element to perform phasing addition; a reception signal processing unit 4 that processes the reception signal after phasing addition and generates B-mode data; A three-dimensional image data generation unit 5 that generates three-dimensional image data using B-mode data obtained in units of ultrasonic transmission and reception directions is provided.

  Further, the ultrasonic diagnostic apparatus 100 has a display unit 7 for displaying the 3D image data generated by the 3D image data generation unit 5 described above, and an input for inputting subject information and setting image data generation conditions. And a system control unit 9 that controls the above-described units in an integrated manner.

  The ultrasound probe 3 has N (N = N1 × N2) vibration elements (not shown) arranged two-dimensionally at its tip, and the tip is brought into contact with the body surface of the subject to transmit / receive ultrasound. To do. Each of the vibration elements of the ultrasonic probe 3 is connected to the transmission / reception unit 2 via an N-channel multi-core cable (not shown). The vibration element is an electroacoustic transducer, which converts an electric pulse (drive signal) into an ultrasonic pulse (transmitted ultrasonic wave) at the time of transmission, and converts an ultrasonic reflected wave (received ultrasonic wave) into an electric reception signal at the time of reception. It has the function to convert to.

  The ultrasonic probe 3 has a sector scan support, a linear scan support, a convex scan support, and the like, and the operator can arbitrarily select according to the diagnosis part. In the present embodiment, the case of using the ultrasonic probe 3 for sector scanning in which N vibration elements are two-dimensionally arranged will be described. However, an ultrasonic probe compatible with linear scanning or convex scanning may be used.

  Next, the transmission / reception unit 2 shown in FIG. 2 performs a phasing addition on the transmission unit 21 that supplies a drive signal to the vibration element of the ultrasonic probe 3 and the N-channel reception signal obtained from the vibration element. A receiving unit 22 is provided.

  The transmission unit 21 includes a rate pulse generator 211, a transmission delay circuit 212, and a drive circuit 213. The rate pulse generator 211 generates a rate pulse that determines the repetition period of the transmission ultrasonic wave and transmits the transmission delay. Supply to circuit 212. The transmission delay circuit 212 is composed of the same number of N-channel independent delay circuits as the number of vibration elements used for transmission, and includes a focusing delay time for focusing the transmission ultrasonic wave to a predetermined depth, and a transmission ultrasonic wave. A deflection delay time for transmitting in a predetermined direction is given to the rate pulse, and this rate pulse is supplied to the drive circuit 213. The drive circuit 213 has the same number of N-channel drive circuits as the transmission delay circuit 212, drives N vibration elements built in the ultrasonic probe 3, and transmits ultrasonic waves into the body of the subject. Radiate.

  On the other hand, the receiving unit 22 includes an A / D converter 221 and a reception delay circuit 222 configured by N channels, and an adder 223. An N channel received signal supplied from the vibration element is an A / D signal. The signal is converted into a digital signal by the converter 221 and sent to the reception delay circuit 222.

  The reception delay circuit 222 determines a focusing delay time for focusing a received ultrasonic wave from a predetermined depth and a deflection delay time for setting a reception directivity with respect to a predetermined direction. The adder 223 adds the reception signals from the reception delay circuit 222 to each of the N channel reception signals output from. That is, the reception delay circuit 222 and the adder 223 perform phasing addition on the reception signal obtained from a predetermined direction.

  FIG. 3 shows the ultrasonic transmission / reception direction (θp, φq) in orthogonal coordinates (XYZ) with the central axis of the ultrasonic probe 3 as the Z axis. In this case, the vibration element is X Arranged in the axial direction and the Y-axis direction, θp and φq indicate transmission / reception directions projected on the XZ plane and the YZ plane.

  The reception delay circuit 222 and the adder 223 can perform so-called parallel simultaneous reception in which reception ultrasonic beams in a plurality of directions are simultaneously formed by controlling the delay time. By applying this parallel simultaneous reception method, the time required for collecting volume data is greatly reduced.

  Next, the received signal processing unit 4 in FIG. 2 includes an envelope detector 411 and a logarithmic converter 412, and the envelope detector 411 receives the phased and added signals supplied from the adder 223 of the receiving unit 22. The signal is subjected to envelope detection, and the amplitude of the envelope detection signal is logarithmically converted by a logarithmic converter 412 to generate B-mode data. Note that the envelope detector 411 and the logarithmic converter 412 may be configured in the reverse order.

  Returning to FIG. 1, the three-dimensional image data generation unit 5 includes a data storage unit 51 that sequentially stores the B-mode data generated in the reception signal processing unit 4 in association with the three-dimensional ultrasonic transmission / reception direction, A volume data generation unit 52 that generates volume data composed of isotropic voxels by interpolating B-mode data, and an inner product value of a normal vector and a scan vector calculated by a vector calculation unit 54 described later. A volume data correction unit 53 that corrects the volume data based on the above, and the three-dimensional image data generation unit 5 calculates a normal vector, a scan vector, and a line-of-sight vector, and further includes a normal vector and a scan vector, A vector calculation unit 54 that performs an inner product calculation of the volume, and a volume data rendering process based on the normal vector and the line-of-sight vector And a rendering computer 55 that generates dimensional image data.

  FIG. 4 schematically shows B-mode data stored in the data storage unit 51. In the data storage unit 51, the signal intensity a11 of the B-mode data collected in the transmission / reception direction S1, A, a31,..., B-mode data signal strengths a12, a22, a32... collected in the transmission / reception direction S2, B-mode data signal strengths a13, a23, collected in the transmission / reception direction S3. a33... are stored, and information of transmission / reception angles (θ, φ) supplied from the system control unit 9 is added to the data in each transmission / reception direction as supplementary information.

  Returning to FIG. 1, the volume data generation unit 52 includes an arithmetic circuit and a storage circuit (not shown), and the center position of the ultrasonic probe 3 (the center position of the two-dimensionally arranged vibration element group) and the storage circuit The center position of each voxel formed with a predetermined size is uniquely determined.

  When generating the volume data, the arithmetic circuit of the volume data generation unit 52 reads out the B mode data stored in the data storage unit 51, and each voxel set in the storage circuit by the interpolation process of the B mode data. Volume data is generated by calculating the voxel value at. Then, the obtained volume data is stored in the storage circuit.

  FIG. 5 schematically shows an interpolation process performed by the arithmetic circuit. In order to make the explanation easy to understand, B mode data (● in FIG. 5) stored in the data storage unit 51 is associated. Is displayed. However, FIG. 5 shows a case where the voxel value of each voxel is calculated by performing interpolation processing in one-dimensional direction (X direction) on the B-mode data, but actually, a plurality of Bs surrounding the voxel. A three-dimensional interpolation process using mode data is desirable.

  For example, in the voxel B12 in which the center position of the voxel coincides with the ultrasonic transmission / reception direction S1, the signal intensity a11 in the B mode data is set as the voxel value c12. Similarly, the voxel in which the center position of the voxel coincides with the transmission / reception direction S4. In B14, the signal intensity a14 of the B mode data is set as the voxel value c14. On the other hand, in the voxel B13 in which the center position of the voxel does not coincide with the transmission / reception direction, the voxel value c13 is calculated by interpolation processing based on the signal intensity a12 of the B mode data, the position information thereof, the signal intensity a13, and the position information thereof.

  Further, for the voxels B22, B23, B24, B32, B33, B34,... Where the center position of the voxel does not coincide with the transmission / reception direction, the signal strength of the adjacent B-mode data is determined in the same manner as in the case of the voxel B13. Voxel values c22, c23, c24, c32, c33, c34,... Are calculated by interpolation processing based on the position information. The obtained voxel values are stored in the storage circuit to generate volume data.

  Next, a specific configuration of the vector calculation unit 54 will be described with reference to the block diagram of FIG. As shown in FIG. 6, the vector calculation unit 54 includes a normal vector calculation unit 541, a scanning vector calculation unit 542, a line-of-sight vector calculation unit 543, and an inner product calculation unit 544.

  The normal vector calculation unit 541 of the vector calculation unit 54 includes volume data generated by the volume data generation unit 52 or volume data after correction in which the influence of high echo is reduced by the volume data correction unit 53 described later. Calculate the normal vector of the voxel.

For example, when the normal vector N (x, y, z) in the voxel B (x, y, z) is calculated, the normal vector calculation unit 541 first of the volume data generation unit 52 or the volume data correction unit 53 Voxel B (x + 1, y, z), B (x-1, y, z), B (x, y + 1) adjacent to voxel B (x, y, z) from the volume data stored in the storage circuit. , Z), B (x, y-1, z), B (x, y, z + 1), B (x, y, z-1), voxel values c (x + 1, y, z), c ( x-1, y, z), c (x, y + 1, z), c (x, y-1, z), c (x, y, z + 1), c (x, y, z-1) are read. The normal vector N (x, y, z) is calculated by substituting these voxel values into the following equation (1).

  Further, the normal vector calculation unit 541 supplies the normal vector information calculated for the volume data by the volume data generation unit 52 to the inner product calculation unit 544, and for the volume data corrected by the volume data correction unit 53. The normal vector information calculated in this way is supplied to a rendering operation unit 55 described later.

  On the other hand, the scanning vector calculation unit 542 of the vector calculation unit 54 transmits and receives ultrasonic waves based on the center position of the voxel and the center position of the ultrasonic probe 3 in the volume data stored in the storage circuit of the volume data generation unit 52. Is calculated. The line-of-sight vector calculation unit 543 calculates a line-of-sight vector indicating the line-of-sight direction based on the center position of the voxel and the viewpoint position of the image observer in the volume data described above.

  FIG. 7 shows the above-described three unit vectors calculated by the vector calculation unit 54. A method for the organ boundary surface with the center P (x, y, z) of the voxel B constituting the volume data as a reference. A normal vector N (x, y, z) indicating the line direction, a scanning vector M (x, y, z) indicating the ultrasonic transmission / reception direction, and a line-of-sight vector L (x, y) indicating the line of sight of the image observer , Z) are calculated respectively.

  Next, the inner product calculation unit 544 of the vector calculation unit 54 calculates the inner product value β between the scanning vector for the voxel calculated by the scanning vector calculation unit 542 and the normal vector calculated by the normal vector calculation unit 541 for this voxel. The voxel is calculated for each voxel, and the inner product value β is compared with a threshold value α stored in advance in its own storage circuit. If there is a voxel whose inner product value β is larger than the threshold value α, the comparison result is supplied to the volume data correction unit 53. If there is no voxel whose inner product value β is larger than the threshold value α, the comparison result Is supplied to the normal vector calculation unit 541.

  On the other hand, the volume data correction unit 53 in FIG. 1 reads out one or all of the volume data stored in the storage circuit of the volume data generation unit 52 based on the above comparison result, and the above inner product value β is the threshold value α. Filtering or gradation processing is performed on the voxel values of a larger voxel and surrounding voxels.

  That is, when there is a voxel whose inner product value β is larger than the threshold value α, the volume data correction unit 53 transmits / receives an ultrasonic wave substantially perpendicular to the organ boundary surface corresponding to the voxel, and therefore the voxel value is high. Determined to be affected by echo. In order to eliminate the influence of this high echo, the volume data is corrected by performing filtering processing or gradation processing on the voxel values in a predetermined range of voxels centered on the voxel. The range information of the filtering process for the volume data is normally stored in advance in a storage circuit (not shown) provided in the volume data correction unit 53, but may be set by the operator using the input unit 8.

  Next, the rendering calculation unit 55 calculates the normal vector information calculated by the normal vector calculation unit 541 of the vector calculation unit 54 with respect to the volume data corrected by the volume data correction unit 53 and the line-of-sight vector calculation unit 543. Information on the line-of-sight vector thus received is received from the vector calculation unit 54 in units of voxels. Then, the shading value based on the inner product value of the normal vector and the line-of-sight vector and the opacity based on the distance from the viewpoint of the image observer to the center of the voxel are calculated for each voxel.

  Next, the rendering calculation unit 55 reads the uncorrected volume data stored in the storage circuit of the volume data generation unit 52, and renders the voxel value of the volume data using the above-described shading value and opacity information. Then, three-dimensional image data is generated.

  On the other hand, the display unit 7 includes a display data generation circuit, a conversion circuit, and a monitor (not shown). The display data generation circuit covers the 3D image data generated by the rendering operation unit 55 of the 3D image data generation unit 5. Display data is generated by adding incidental information such as sample information. On the other hand, the conversion circuit performs D / A conversion and television format conversion on the display data generated by the display data generation circuit and displays the display data on the monitor.

  The input unit 8 includes an input device such as a liquid crystal display panel, a keyboard, a trackball, and a mouse on the operation panel. The input unit 8 inputs subject information, selects an image data collection mode, sets image data generation conditions and display conditions, The viewpoint position is set, and various command signals are input.

  The system control unit 9 includes a CPU and a storage circuit (not shown), and performs overall control of the units and control of the entire apparatus based on various command signals and control signals supplied from the input unit 8. In particular, the delay times in the transmission delay circuit 122 of the transmission unit 21 and the reception delay circuit 132 of the reception unit 22 shown in FIG. 2 are controlled, and ultrasonic transmission / reception is performed with respect to the three-dimensional region of the subject.

(Procedure for generating 3D image data)
Next, the procedure for generating the three-dimensional image data in this embodiment will be described with reference to the flowchart of FIG.

  Prior to the collection of the three-dimensional data for the subject, the operator of the ultrasonic diagnostic apparatus 100 inputs the subject information at the input unit 8, and further selects the image data collection mode, the conditions for generating the image data, and the display conditions. Make settings. In this embodiment, the “three-dimensional B mode” is selected as the image data collection mode, but the present invention is not limited to this. Then, the above-described input information, selection information, and setting information input at the input unit 8 are stored in the storage circuit of the system control unit 9 (step S1 in FIG. 8).

  When the above initial setting is completed, the operator inputs a three-dimensional data collection start command from the input unit 8 while the ultrasonic probe 3 is in contact with the body surface of the subject. By being supplied to the control unit 9, the collection of three-dimensional data for the subject is started.

  When collecting the three-dimensional data, the rate pulse generator 211 of the transmission unit 21 shown in FIG. 2 generates a rate pulse in accordance with the control signal input from the system control unit 9 and supplies it to the transmission delay circuit 212. The transmission delay circuit 212 has a delay time for focusing ultrasonic waves to a predetermined depth in order to obtain a narrow beam width in transmission, and a delay time for transmitting ultrasonic waves in the first transmission / reception direction (θ1, φ1). Is supplied to the rate pulse, and this rate pulse is supplied to the N-channel drive circuit 213. Next, the drive circuit 213 generates a drive signal having a predetermined delay time based on the rate pulse supplied from the transmission delay circuit 212, and supplies this drive signal to the N vibration elements in the ultrasonic probe 3. The transmitted ultrasonic wave is emitted into the body of the subject.

  A part of the radiated transmission ultrasonic wave is reflected by an organ boundary surface or tissue having different acoustic impedance, received by the vibration element, and converted into an N-channel electrical reception signal. Next, this received signal is converted into a digital signal by the A / D converter 221 of the receiving unit 22, and then the delay time for converging the received ultrasonic wave from a predetermined depth in the N-channel receiving delay circuit 222. And a delay time for setting a strong reception directivity with respect to the reception ultrasonic wave from the transmission / reception direction (θ1, φ1) is given, and the adder 223 performs phasing addition.

  Then, the envelope detector 411 and the logarithmic converter 412 of the reception signal processing unit 4 to which the reception signal after the phasing addition is supplied perform envelope detection and logarithmic conversion on the reception signal to obtain B-mode data. The data is generated and stored in the data storage unit 51 of the three-dimensional image data generation unit 5.

  When the generation and storage of B-mode data for the transmission / reception direction (θ1, φ1) is completed, φq = φ1 + (q−1) Δφ (q = 2 to Q) in which the ultrasonic transmission / reception direction is updated by Δφ in the φ direction. ), Ultrasonic waves are transmitted and received in the same procedure with respect to the transmission / reception directions (θ1, φ2 to φQ) set. At this time, the system control unit 9 updates the delay times of the transmission delay circuit 212 and the reception delay circuit 222 in accordance with the transmission / reception direction of the ultrasonic wave according to the control signal.

  When the ultrasonic transmission / reception in the transmission / reception direction (θ1, φ1 to φQ) is completed by the above-described procedure, θp = θ1 + (p−1) Δθ (p = 2 to P) in which the transmission / reception direction is updated by Δθ in the θ direction. And the ultrasonic transmission / reception of φ1 to φQ described above is repeated for each of the transmission / reception directions θ2 to θP, thereby performing three-dimensional scanning on the subject. The B-mode data obtained by ultrasonic transmission / reception in each transmission / reception direction is sequentially stored in the data storage unit 51 together with information on the transmission / reception direction to generate three-dimensional data. (Step S2 in FIG. 8).

  Next, the volume data generation unit 52 of the three-dimensional image data generation unit 5 reads out the B mode data stored in the data storage unit 51 and its accompanying information (that is, information on the ultrasonic transmission / reception direction), The three-dimensional voxel value calculated by the interpolation processing used is stored in its own storage circuit to generate volume data (step S3 in FIG. 8).

  Then, the normal vector calculation unit 541 of the vector calculation unit 54 calculates the normal vector in each voxel of the volume data generated by the volume data generation unit 52 based on the above equation (1) (step of FIG. 8). S4).

  On the other hand, the scan vector calculation unit 542 of the vector calculation unit 54 calculates a scan vector based on the center position of each voxel and the center position of the ultrasonic probe 3 in the volume data generated by the volume data generation unit 52, and calculates the line-of-sight vector. The unit 543 calculates a line-of-sight vector based on the center position of the voxel and the viewpoint position of the image observer (step S5 in FIG. 8).

  However, in the flowchart shown in FIG. 8, the case where the scan vector and the line-of-sight vector are calculated subsequent to the calculation of the normal vector (step S4) is not limited to this. That is, the calculation of the scanning vector and the line-of-sight vector can be performed independently for the generation of the three-dimensional data and the volume data, and therefore, any of the procedures in the above-described steps S1 to S4 is followed or in parallel with any of them. It is also possible to do this.

  Next, the inner product calculation unit 544 of the vector calculation unit 54 calculates the inner product value β between the scanning vector calculated by the scanning vector calculation unit 542 and the normal vector calculated by the normal vector calculation unit 541 for each voxel. (Step S6 in FIG. 8). Then, the calculated inner product value β in each voxel is compared with the threshold value α stored in advance in its own storage circuit (step S7 in FIG. 8), and when there is a voxel in which the inner product value β is larger than the threshold value α. The comparison result is supplied to the volume data correction unit 53.

  Receiving the comparison result, the volume data correction unit 53 reads the volume data stored in the storage circuit of the volume data generation unit 52, and the voxel values of the voxel in which the inner product value β is larger than the threshold value α and the surrounding voxels are obtained. Then, the volume data is corrected by performing filtering processing or gradation processing (step S8 in FIG. 8).

  Next, the normal vector calculation unit 541 calculates the normal vector by performing the same operation as in step S4 described above for each voxel of the volume data corrected by the volume data correction unit 53 (step S9 in FIG. 8). Then, the calculated normal vector information is supplied to the rendering calculation unit 55.

  On the other hand, if there is no voxel whose inner product value β is larger than the threshold value α in step S7 described above, the inner product calculation unit 544 supplies the comparison result to the normal vector calculation unit 541, and the normal vector calculation unit 541 The normal vector information calculated in step S4 is supplied to the rendering operation unit 55.

  Next, the rendering calculation unit 55 calculates the shading value of each voxel based on the normal vector calculated by the normal vector calculation unit 541 in step S4 or step S9 and the line-of-sight vector calculated by the line-of-sight vector calculation unit 543. Further, the opacity of each voxel is calculated based on the distance from the observer's viewpoint to the center position of the voxel. In step S3, the volume data generated by the volume data generation unit 52 is read from the storage circuit, and the volume data is subjected to rendering processing using the above-described shading value and opacity to generate three-dimensional image data ( FIG. 8 step S10).

  The display data generation circuit of the display unit 7 generates display data by adding incidental information such as subject information to the 3D image data generated by the rendering operation unit 55 of the 3D image data generation unit 5. The conversion circuit of the display unit 7 performs D / A conversion and television format conversion on the display data generated by the display data generation circuit and displays the display data on the monitor (step S11 in FIG. 8).

  Next, the effect of the present embodiment will be schematically described with reference to FIGS. 9 and 10. FIG. 9A shows the volume data generated by the volume data generation unit 52 based on the three-dimensional data obtained from the subject. FIG. 9B shows the volume data based on the voxel value of the volume data. The normal vector of each voxel calculated by the normal vector calculation unit 541 of the vector calculation unit 54 is indicated by an arrow.

  On the other hand, FIG. 10A shows the volume data corrected by the volume data correction unit 53, and FIG. 10B shows the normal vector calculation unit 541 based on the voxel value of the corrected volume data. The calculated normal vector of each voxel is shown. However, for ease of explanation, FIG. 9A and FIG. 10A show voxel values in a predetermined section (XZ section) of the volume data, and FIG. 9B and FIG. b) shows the normal vector of each voxel calculated based on the gradient of the voxel values in the X direction and the Z direction of the cross section.

  Also, the numerical values shown in the respective voxels in FIG. 9A show specific examples of the voxel values. Here, with respect to the boundary surface C between the organ A having the voxel value “0” and the organ B having the voxel value “1”. The case of calculating the normal vector will be described. However, the voxel B25 in which the boundary surface C intersects substantially perpendicularly to the transmission / reception direction of the ultrasonic waves is affected by a high echo depending on the ultrasonic incident angle, and is specifically higher than the voxel values of other voxels. It has a voxel value of “5”.

  When calculating a normal vector for volume data having such a voxel value, for example, the voxel B24 and the voxel B26 are affected by a specific voxel value “5” in the voxel B25, and the true value for the boundary surface C is calculated. Normal vectors N24 and N26 in a direction different from the normal direction are calculated.

  As described above, the inner product calculation unit 544 uses the normal vector of each voxel calculated by the normal vector calculation unit 541 for the volume data generated by the volume data generation unit 52 and the voxel of each voxel calculated by the scan vector calculation unit 542. An inner product value β with the scanning vector is measured, and the inner product value β is compared with a threshold value α. Then, the volume data correction unit 53 corrects the above-described volume data based on the comparison result. At this time, the volume data correction unit 53 detects the voxel B25 in which the inner product value β is larger than the threshold value α in the volume data, and performs filtering processing or gradation processing on the voxel B25 to reduce the influence of the high echo described above. To do.

  FIG. 10A shows the voxel value of the volume data corrected by the volume data correction unit 53, and the voxel value of the voxel B25 is substantially equal to the voxel value of the surrounding voxels by filtering processing or gradation processing. It is corrected. Then, a normal vector N24 and a normal vector N26 that substantially coincide with the true normal direction are calculated by normal vector calculation using the corrected volume data (see FIG. 10B).

  According to the first embodiment of the present invention described above, the voxel that is affected by the high echo depending on the ultrasonic incident angle is determined based on the inner product value of the normal vector and the scanning vector in each voxel of the volume data. By specifying and performing a filtering process or a gradation process on a predetermined region centered on this voxel, the influence of the high echo can be effectively reduced without distorting other ultrasonic information.

  Then, by using the volume data in which the influence of the high echo is reduced by filtering processing or the like, it is possible to calculate an accurate normal vector on the organ boundary surface or the like, and a good three-dimensional image can be obtained by rendering processing based on this normal vector. Data can be generated.

  In the above-described embodiment, since the volume data before correction is rendered using information on the normal vector and the line-of-sight vector calculated in each voxel of the volume data after correction, the spatial resolution and contrast resolution are deteriorated. It is possible to perform an effective shading process without causing it to occur.

  Furthermore, since it is not necessary to apply the spatial compound method when reducing the high echo, the time resolution is not deteriorated.

  For the above-described reason, it is possible to reduce the influence of high echo depending on the incident angle of the ultrasonic beam without degrading time resolution, spatial resolution, and contrast resolution, and obtain good three-dimensional image data. be able to.

  Next, a second embodiment of the present invention will be described. In the first embodiment described above, three-dimensional data of a subject is collected using its own transmission / reception unit 2, ultrasonic probe 3, and reception signal processing unit 4, and three-dimensional image data is obtained based on this three-dimensional data. Although the ultrasonic diagnostic apparatus 100 to be generated has been described, in the following second embodiment, an image for generating and displaying three-dimensional image data based on three-dimensional data supplied from a separately installed ultrasonic diagnostic apparatus. A data display device will be described.

  That is, in the image data display apparatus according to the present embodiment, when the volume data generated using the 3D data supplied from the ultrasonic diagnostic apparatus via a network or the like is rendered to generate 3D image data, The normal vector and the scan vector are calculated for each voxel of the volume data. Next, based on the inner product value of the obtained normal vector and scanning vector, the voxel affected by the high echo depending on the ultrasonic incident angle is specified, and the voxel value in a predetermined region centered on this voxel is filtered. Correction is performed by processing or gradation processing. Then, the volume data before correction is rendered on the basis of the normal vector newly calculated based on the gradient of the voxel value in the volume data after correction and the line-of-sight vector indicating the line-of-sight direction of the image data observer, and three-dimensional image data is rendered. Is generated.

  The overall configuration of the image data display apparatus according to the second embodiment of the present invention will be described with reference to the block diagram of FIG. However, units having substantially the same functions as the units of the ultrasonic diagnostic apparatus shown in FIG.

  The image data display device 200 includes a 3D image data generation unit 5x that generates 3D image data using the 3D data collected by the ultrasonic diagnostic apparatus, and a display unit 7 that displays the 3D image data. , An input unit 8 for inputting subject information, various command signals, and the like, and a system control unit 9 for comprehensively controlling the above-described units.

  The three-dimensional image data generation unit 5x includes a data storage unit 51x that stores the three-dimensional data of the subject collected by the separately installed ultrasonic diagnostic apparatus via the network 10 or a storage medium (not shown). Based on an inner product value of a normal vector and a scanning vector calculated by a volume data generation unit 52 that generates volume data composed of isotropic voxels by interpolating the dimensional data, and a vector calculation unit 54 described later A volume data correction unit 53 that corrects the volume data, and further calculates a normal vector, a scanning vector, and a line-of-sight vector, and performs an inner product calculation of the normal vector and the scanning vector, Volume data is rendered based on normal vector and line-of-sight vector, and 3D image data And a rendering computer 55 that generates.

  When generating three-dimensional image data based on the three-dimensional data supplied from the ultrasonic diagnostic apparatus, the volume data generating unit 52 of the three-dimensional image data generating unit 5x receives data supplied from the ultrasonic diagnostic apparatus via the network 10 or the like. Volume data is generated by interpolating the three-dimensional data once stored in the storage unit 51x, and the vector calculation unit 54 calculates a normal vector and a scanning vector in each voxel of the volume data. Further, the vector calculation unit 54 calculates the inner product value of the obtained normal vector and the scanning vector, and compares this inner product value with a preset threshold value.

  On the other hand, the volume data correction unit 53 identifies a voxel affected by high echo depending on the ultrasonic incident angle based on the comparison result between the inner product value and the threshold value by the vector calculation unit 54 in the volume data, and this voxel A voxel value in a predetermined area centering on is corrected by filtering processing or gradation processing. The vector calculation unit 54 newly calculates a normal vector based on the gradient of the voxel value in the corrected volume data, and the rendering calculation unit 55 indicates the normal vector and the line-of-sight direction of the image data observer. Three-dimensional image data is generated by rendering the volume data before correction based on the line-of-sight vector.

  According to the second embodiment of the present invention described above, the voxel that is affected by the high echo depending on the ultrasonic incident angle is determined in each voxel of the volume data in the same manner as the first embodiment. By specifying the inner product value of the normal vector and the scanning vector, and performing a filtering process or a gradation process on a predetermined area centered on this voxel, the high echo can be obtained without distorting other ultrasonic information. The influence can be effectively reduced. Then, by using the volume data in which the influence of the high echo is reduced by filtering processing or the like, it is possible to calculate an accurate normal vector on the organ boundary surface or the like, and a good three-dimensional image can be obtained by rendering processing based on this normal vector. Data can be generated.

  In the above-described embodiment, since the volume data before correction is rendered using information on the normal vector and the line-of-sight vector calculated in each voxel of the volume data after correction, the spatial resolution and contrast resolution are deteriorated. It is possible to perform an effective shading process without causing it to occur.

  For the above-described reason, it is possible to reduce the influence of high echo depending on the incident angle of the ultrasonic beam without degrading time resolution, spatial resolution, and contrast resolution, and obtain good three-dimensional image data. be able to.

  Furthermore, since the image data display device in the above-described embodiment can generate 3D image data based on 3D data supplied from a separately installed ultrasonic diagnostic apparatus via a network or the like, the operator Can generate or observe three-dimensional image data of the subject without much restrictions on time and place.

  As mentioned above, although the Example of this invention has been described, this invention is not limited to the above-mentioned Example, It can change and implement. For example, in the first and second embodiments described above, the case where the volume data is generated based on the B-mode data has been described. However, the volume data is generated based on other ultrasonic data such as color Doppler data. It may be generated.

  Further, the three-dimensional scanning by the two-dimensionally arranged vibration elements has been described. However, the present invention is not limited to this. For example, the one-dimensionally arranged vibration elements are moved or rotated in a direction perpendicular to the arrangement direction. By doing so, a three-dimensional scan may be performed. Furthermore, the volume data may be generated by a scanning method other than sector scanning, such as convex scanning, linear scanning, or radial scanning.

  On the other hand, the range information of the filtering process in the correction of the volume data and the information of the threshold value α are described as being stored in advance in the storage circuit of the volume data correction unit 53 and the vector calculation unit 54. May be set or updated. According to this method, optimum conditions can be set under observation of three-dimensional image data.

  Also, the case where the voxel affected by the high echo is specified based on the inner product value of the normal vector and the scan vector has been described, but this is another method that can calculate the intersection angle between the normal vector and the scan vector. It doesn't matter.

  Furthermore, in the above-described embodiment, the case where the vector calculation unit 54 has a function of identifying the voxel affected by the above-described high echo based on the inner product value of the normal vector and the scanning vector has been described. The volume data correction unit 53 may have this function.

1 is a block diagram showing the overall configuration of an ultrasonic diagnostic apparatus according to a first embodiment of the present invention. The block diagram which shows the structure of the transmission / reception part and reception signal processing part with which the ultrasound diagnosing device of the Example is provided. The figure which shows the relationship between the coordinate of the ultrasonic probe and ultrasonic transmission / reception direction in the Example. The figure which shows typically the B mode data preserve | saved at the data storage part of the Example. The figure which shows typically the interpolation process which the volume data generation part of the Example performs. The block diagram which shows the specific structure of the vector calculating part in the Example. The figure which shows the normal vector, scanning vector, and line-of-sight vector which the vector calculating part of the Example calculates. The flowchart which shows the production | generation procedure of the three-dimensional image data in the Example. The figure which shows the volume vector before correction | amendment in the same Example, and the normal vector calculated in this volume data. The figure which shows the volume vector after correction | amendment in the same Example, and the normal vector calculated in this volume data. The block diagram which shows the whole structure of the image data display apparatus in the 2nd Example of this invention.

Explanation of symbols

2. Transmission / reception unit 21 ... Transmission unit 211 ... Rate pulse generator 212 ... Transmission delay circuit 213 ... Drive circuit 22 ... Reception unit 221 ... A / D converter 222 ... Reception delay circuit 223 ... Adder 3 ... Ultrasonic probe 4 ... Received signal processing unit 411 ... envelope detector 412 ... logarithmic converter 5, 5x ... 3D image data generation unit 51, 51x ... data storage unit 52 ... volume data generation unit 53 ... volume data correction unit 54 ... vector calculation unit 541 ... normal vector calculation unit 542 ... scanning vector calculation unit 543 ... line-of-sight vector calculation unit 544 ... inner product calculation unit 55 ... rendering calculation unit 7 ... display unit 8 ... input unit 9 ... system control unit 10 ... network 100 ... ultrasonic diagnostic apparatus 200: Image data display device

Claims (11)

An ultrasonic probe having a vibration element for transmitting and receiving ultrasonic waves to and from a three-dimensional region of a subject;
Transmitting means for transmitting the ultrasonic wave by driving the vibration element;
Receiving means for receiving a reflected signal from the subject obtained by transmitting and receiving the ultrasonic wave;
Volume data generating means for generating volume data based on the three-dimensional data obtained by the receiving means;
A vector calculation means for calculating a normal vector and a scanning vector of the volume data and correcting the normal vector based on angle information between the normal vector and the scanning vector;
An ultrasonic diagnostic apparatus, comprising: a rendering calculation unit that generates a three-dimensional image data by rendering the volume data generated by the volume data generation unit based on the corrected normal vector. An ultrasonic probe having a vibration element for transmitting and receiving ultrasonic waves to and from a three-dimensional region of a subject;
Transmitting means for transmitting the ultrasonic wave by driving the vibration element;
Receiving means for receiving a reflected signal from the subject obtained by transmitting and receiving the ultrasonic wave;
Volume data generating means for generating volume data based on the three-dimensional data obtained by the receiving means;
A normal vector and a scan vector are calculated for the voxels of the volume data, and a voxel affected by a high echo depending on an ultrasonic incident angle is specified based on angle information between the normal vector and the scan vector. Vector computing means;
Volume data correction means for correcting the volume data based on the identification result;
Based on the normal vector newly calculated by the vector calculation unit for the voxel of the volume data corrected by the volume data correction unit, the volume data generated by the volume data generation unit is subjected to rendering processing to obtain three-dimensional image data. An ultrasonic diagnostic apparatus comprising: a rendering calculation means for generating.   The ultrasonic diagnosis according to claim 1, wherein the volume data generation unit generates the volume data by interpolating three-dimensional data collected from a three-dimensional region of the subject. apparatus.   The vector calculation means calculates the normal vector based on the voxel value gradient in the volume data generated by the volume data generation means or the volume data corrected by the volume data correction means. The ultrasonic diagnostic apparatus according to claim 1 or 2.   The vector calculation means calculates the scanning vector indicating the ultrasonic transmission / reception direction with respect to the voxel based on the center position information of the voxel and the center position information of the ultrasonic probe in the volume data generated by the volume data generation means. The ultrasonic diagnostic apparatus according to claim 1 or 2, characterized in that   The vector calculation means calculates an inner product value of the normal vector and the scanning vector, and identifies a voxel affected by the high echo by comparing the inner product value with a preset threshold value. The ultrasonic diagnostic apparatus according to claim 2.   The volume data correction unit performs at least one of filtering processing and gradation processing on the voxel specified by the vector calculation unit in the volume data generated by the volume data generation unit or a predetermined region centered on the voxel. The ultrasonic diagnostic apparatus according to claim 2, which is performed.   The rendering calculation means generates the three-dimensional image data by shading the volume data generated by the volume data generation means based on the normal vector newly calculated by the vector calculation means and the line-of-sight vector of the image observer. The ultrasonic diagnostic apparatus according to claim 2, wherein: Volume data generation means for generating volume data based on three-dimensional data obtained from a subject;
A vector for calculating a normal vector and a scan vector in the voxel of the volume data, and specifying a voxel affected by a high echo depending on an ultrasonic incident angle based on angle information between the normal vector and the scan vector Computing means;
Volume data correction means for correcting the volume data based on the identification result;
Based on the normal vector newly calculated by the vector calculation means for the voxel of the volume data corrected by the volume data correction means, the volume data generated by the volume data generation means is subjected to rendering processing to obtain three-dimensional image data. Rendering operation means for generating
An image data display device comprising display means for displaying the three-dimensional image data.   The vector calculation means calculates the normal vector based on the voxel value gradient in the volume data generated by the volume data generation means or the volume data corrected by the volume data correction means. The image data display device according to claim 9. Volume data generation means generates volume data based on three-dimensional data obtained by transmitting and receiving ultrasonic waves to the subject;
A vector calculation means calculates a normal vector and a scan vector in the voxel of the volume data, and is affected by a high echo depending on an ultrasonic incident angle based on angle information between the normal vector and the scan vector. Identifying a voxel;
Volume data correction means corrects the volume data of a predetermined area based on the identification result of the vector calculation means;
The vector calculation means newly calculating a normal vector for the corrected voxel of the volume data;
A rendering calculation unit comprising: a step of rendering the volume data generated by the volume data generation unit based on the newly calculated normal vector to generate three-dimensional image data. Data generation method.

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