JP2014000291A - Ultrasound diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide improvement technologies for display of images obtained through reconstruction processing.SOLUTION: A reconstruction processing unit 20 extracts a plurality of tomographic images, which periodically correspond to each other, from a plurality of tomographic image data with a plurality of periods stored in a preceding memory 14 and forms each reconstruction image data from the plurality of tomographic images, which periodically correspond to each other, to store the data in a subsequent memory 26. A mask processing unit 30 determines an attention region by mask-processing regions other than the attention region including objects in each reconstruction image data. A display processing unit 40 forms display images with images in the attention region successively acquired from a plurality of reconstruction image data at a plurality of time phases arranged at certain positions, displaying these display images on a display unit 42.

Description

  The present invention relates to an ultrasonic diagnostic apparatus that displays an image of an object that moves periodically.

  Reconstruction processing is known in the art of forming a three-dimensional image of an object that moves periodically, such as the heart. For example, Patent Document 1 discloses that a plurality of scan planes are formed in a three-dimensional space while moving the scan planes over a plurality of periods of motion related to an object, and a plurality of images corresponding to the plurality of scan planes are included. Describes a technique for extracting a plurality of images periodically corresponding to each other and forming a display image of an object based on the extracted images. Thereby, for example, it is possible to obtain a display image that three-dimensionally shows how the object moves over a plurality of time phases within a cycle.

  However, depending on the specific processing contents, the display position of the target object may move as a whole in a display image of a plurality of time phases formed by the reconstruction process. On the other hand, when trying to fix the display position of the object, the outer frame of the display image may move.

JP 2010-246630 A

  In view of the background art described above, the inventor of the present application has conducted research and development on reconstruction processing in ultrasonic waves. In particular, attention was paid to a technique related to display of an image obtained by reconstruction processing.

  The present invention has been made in the course of research and development, and an object thereof is to provide an improved technique relating to display of an image obtained by reconstruction processing.

  A suitable ultrasonic diagnostic apparatus that meets the above-mentioned purpose forms a plurality of scanning planes while moving the scanning plane over a plurality of cycles of the movement in a three-dimensional space including an object that periodically moves. An ultrasonic transmission / reception unit for transmitting / receiving ultrasonic waves and a plurality of images corresponding to a plurality of scanning planes formed over a plurality of periods are extracted from each other periodically to reconstruct each of the images. By forming an image, a reconstruction processing unit that obtains a plurality of reconstructed images corresponding to a plurality of different time phases within a period, and a region of interest based on the object in each reconstructed image are determined An area determination unit, and a display processing unit that displays images of a region of interest obtained one after another from a plurality of reconstructed images over a plurality of time phases at a certain position.

  According to the preferable ultrasonic diagnostic apparatus, an attention area is determined based on an object in each reconstructed image, and images of the attention area obtained one after another from a plurality of reconstructed images over a plurality of time phases. There is provided an improved technique for displaying the image at a certain position. For example, it is possible to obtain a display image in which the overall movement of the object is suppressed by determining the attention area so that the entire movement of the object is suppressed with reference to the object. For example, if the size of the attention area is kept constant, it is possible to suppress the movement of the outer frame of the display image corresponding to the attention area.

  In a preferred specific example, the region determination unit determines a region of interest by performing mask processing on a region other than the region of interest including the object in each reconstructed image.

  In a preferred specific example, the region determination unit extracts an image of a region of interest from each of the reconstructed images with a constant size of the region of interest for a plurality of reconstructed images.

  In a preferred embodiment, the reconstruction processing unit arranges a plurality of images periodically corresponding to each other in a reconstruction space in association with positions according to their arrangement order, and reconstructs each of the plurality of images. Forming an image so that the object moves as a whole in a plurality of reconstructed images over a plurality of time phases, and the region determining unit includes the plurality of reconstructed images. The region of interest is moved so as to follow the movement of the object, and an image of the region of interest is extracted from each reconstructed image.

  In a preferred embodiment, the reconstruction processing unit arranges each of a plurality of images periodically corresponding to each other in the reconstruction space in association with the position of the corresponding scanning plane, and from each of the plurality of images A reconstructed image is formed, whereby the object is formed so as not to move as a whole in a plurality of reconstructed images over a plurality of time phases, and the region determination unit is formed over a plurality of reconstructed images. Then, the image of the region of interest is extracted from each reconstructed image with the position of the region of interest kept constant so as to include the object.

  Further, a suitable program for the above purpose is to form a plurality of scanning planes while moving the scanning plane over a plurality of cycles of the movement in a three-dimensional space including an object that periodically moves. A program for processing an image obtained by transmitting and receiving ultrasonic waves, based on a plurality of images periodically corresponding to each other among images obtained from a plurality of scanning surfaces formed over a plurality of cycles Reconstruction processing function for obtaining a plurality of reconstructed images corresponding to a plurality of different time phases in a cycle by forming each reconstructed image, and a region of interest in each reconstructed image with reference to the object And a display processing function for displaying an image of a region of interest obtained one after another from a plurality of reconstructed images over a plurality of time phases at a certain position. And features.

  The program is stored in a computer-readable storage medium such as a disk or a memory, and is provided to the computer via the storage medium. Of course, the program may be provided to the computer via a telecommunication line such as the Internet.

  According to the present invention, an improved technique for displaying an image obtained by reconstruction processing is provided. For example, according to a preferred aspect of the present invention, it is possible to obtain a display image in which the overall movement of the object is suppressed, and it is possible to suppress the movement of the outer frame of the display image.

1 is an overall configuration diagram of an ultrasonic diagnostic apparatus suitable for implementing the present invention. It is a figure for demonstrating the three-dimensional scanning by the ultrasonic diagnosing device of FIG. It is a figure for demonstrating the process in the reconstruction process part 20 of FIG. It is a figure which shows the specific example 1 from a reconstruction process to obtaining a display image. It is a figure which shows the specific example 2 from a reconstruction process to obtaining a display image.

  FIG. 1 is an overall configuration diagram of an ultrasonic diagnostic apparatus (present ultrasonic diagnostic apparatus) suitable for implementing the present invention. The probe 10 transmits and receives ultrasonic waves in a three-dimensional space including a diagnostic object. The probe 10 includes a plurality of vibration elements that transmit and receive ultrasonic waves, and transmission of the plurality of vibration elements is controlled by the transmission / reception unit 12 to form a transmission beam. Further, the plurality of vibration elements receive the ultrasonic waves reflected from the object, and signals obtained thereby are output to the transmission / reception unit 12, and the transmission / reception unit 12 forms a reception beam.

  The probe 10 is a 3D probe that three-dimensionally collects echo data by scanning an ultrasonic beam (a transmission beam and a reception beam) in a three-dimensional space. For example, the ultrasonic beam is scanned three-dimensionally by mechanically moving a scanning surface formed electronically by a plurality of vibration elements (1D array transducers) arranged one-dimensionally. Alternatively, the ultrasonic beam may be scanned three-dimensionally by electronically controlling a plurality of vibration elements (2D array transducers) arranged two-dimensionally.

  The transmission / reception unit 12 forms an ultrasonic transmission beam by supplying a transmission signal corresponding to each of the plurality of vibration elements included in the probe 10. In addition, the transmission / reception unit 12 forms an ultrasonic reception beam by performing phasing addition processing or the like on the reception signal obtained from each of the plurality of vibration elements included in the probe 10, and is obtained along the reception beam. Output echo data.

  FIG. 2 is a diagram for explaining three-dimensional scanning by the ultrasonic diagnostic apparatus. In this ultrasonic diagnostic apparatus, the object to be diagnosed is a periodically moving tissue such as the heart. Then, for example, about several hundred to several thousand scans are performed while moving the scanning surface S over a plurality of cycles of the movement of the object in a three-dimensional space including the object such as the heart that moves periodically. Ultrasonic waves are transmitted and received so as to form the surface S.

  That is, as shown in FIG. 2, an ultrasonic beam formed along the depth r direction is scanned in the beam angle θ direction to form a scanning surface S, and the scanning surface S is further moved in the scanning φ direction. A plurality of scanning planes S are formed while being. For example, the scanning surface S is formed by electronic scanning, and the scanning surface S is mechanically moved in the scan φ direction by scanning. Of course, the scanning surface S may be moved in the scan θ direction by electronic scanning. If the object is a fetal heart, for example, the scan plane S is formed by slowly moving in the scan φ direction over a period including about 20 heartbeats in about 8 seconds.

  Returning to FIG. 1, when a plurality of scanning planes are formed, tomographic image data relating to the scanning planes are collected for each scanning plane, and a plurality of tomographic image data corresponding to the plurality of scanning planes are successively stored in the previous memory 14. Remembered. Each tomographic image data may be stored in the front memory 14 in the rθ coordinate system (FIG. 2), or may be stored in the front memory 14 after being converted into the xy orthogonal coordinate system.

  The reconstruction processing unit 20 extracts a plurality of tomographic image data periodically corresponding to each other from a plurality of tomographic image data stored in the previous memory 14 over a plurality of cycles, and the plurality of tomographic image data periodically corresponding to each other. Each reconstructed image data is formed from the tomographic image data and stored in the rear memory 26.

  FIG. 3 is a diagram for explaining processing in the reconstruction processing unit 20. FIG. 3 shows the correspondence between the data stored in the front memory 14 (FIG. 1) and the data stored in the rear memory 26 (FIG. 1). In FIG. 3, “tomographic image φn (n = 1, 2, 3,..., 60)” means tomographic image data corresponding to the coordinate φn in the scan φ direction (FIG. 2).

  The previous memory 14 stores a plurality of tomographic image data corresponding to a plurality of scanning planes formed one after another along the φ direction. That is, the previous memory 14 stores a plurality of tomographic image data in the order of tomographic image φ1, tomographic image φ2,..., Tomographic image φ60,.

  In the reconstruction process, the images are rearranged on the basis of a representative temporal phase tomographic image. When the target tissue is the heart, for example, the end diastole is used as a reference. That is, a tomographic image corresponding to the end diastole is extracted as a reference image among the plurality of tomographic images stored in the previous memory 14. In FIG. 3, a tomographic image φ1, a tomographic image φ15,..., A tomographic image φ51 are a plurality of reference images. The reconstruction processing unit 20 first extracts a tomographic image φ1, a tomographic image φ15,..., A tomographic image φ51, which are reference images, as a plurality of tomographic image data periodically corresponding to each other. The extracted tomographic image φ1, tomographic image φ15,..., And tomographic image φ51 are stored in the rear memory 26 as one data block.

  Next, the reconstruction processing unit 20 extracts a plurality of tomographic images adjacent to the positive side in the φ direction with respect to each of the plurality of reference images as a plurality of tomographic image data periodically corresponding to each other. That is, the tomographic image φ2, the tomographic image φ16,..., And the tomographic image φ52 are extracted and stored as one data block in the rear memory 26.

  Further, the reconstruction processing unit 20 extracts a plurality of tomographic images adjacent on the positive side in the φ direction with respect to each of the tomographic image φ2, the tomographic image φ16,. In this way, reconstructed image data composed of data blocks of a plurality of tomographic images periodically corresponding to each other from each of the plurality of reference images is sequentially extracted and stored in the rear memory 26.

  Returning to FIG. 1, the mask processing unit 30 determines a region of interest based on the object in each reconstructed image data. The mask processing unit 30 determines a region of interest by performing mask processing on a region other than the region of interest including the object in each reconstructed image data. In addition, the display processing unit 40 forms a display image in which images of a region of interest obtained one after another from a plurality of reconstructed image data over a plurality of time phases are arranged at a certain position, and the display image is displayed on the display unit 42. Is displayed. Each unit in the ultrasonic diagnostic apparatus is controlled by the control unit 50.

  Therefore, the processing from the reconstruction processing to the display image being obtained in the ultrasonic diagnostic apparatus will be described in detail. There are two specific examples of the process described below.

  FIG. 4 is a diagram showing a specific example 1 from the reconstruction process to obtaining a display image. In the reconstruction process of the first specific example, a plurality of tomographic image data periodically corresponding to each other are arranged in the reconstruction space in association with positions according to their arrangement order, and each of the plurality of tomographic image data is Time-phase reconstructed image data is formed.

  FIG. 4 (1) shows reconstructed image data of time phase 0, time phase N / 2, and time phase N (N is a natural number). Each reconstructed image data shown in FIG. 4A corresponds to an image on the rφ plane in the rθφ coordinate system (FIG. 2).

  For example, the tomographic image φ1, the tomographic image φ15,..., The tomographic image φ51 stored in the rear memory 26 in FIG. 3 are arranged along the φ direction in order from the end (head position) of the space in the reconstruction space. Thus, the reconstructed image data of time phase 0 in FIG. 4A is formed. Further, for example, the tomographic image φ10, the tomographic image φ24,..., And the tomographic image φ60 stored in the rear memory 26 of FIG. 3 are arranged along the φ direction in order from the end (head position) of the space in the reconstruction space. The reconstructed image data of time phase N in FIG. 4A is formed.

  In this example, the tomographic image data arranged at the end (leading position) in the reconstructed image data of time phase 0 is the tomographic image φ1 (FIG. 3), and the end ( The tomographic image data arranged at the head position) is a tomographic image φ10 (FIG. 3). That is, the tomographic image φ1 and the tomographic image φ10 at different positions in the scan φ direction are arranged at the same position in the reconstructed image data.

  Thus, since the reconstructed image data of time phase 0 and time phase N are formed by tomographic images obtained from different positions (shifted positions), the reconstructed image data in time phase 0 and time phase N In, for example, the heart, which is an object, is arranged at a different position. This relationship is not limited to between the time phase 0 and the time phase N, and if the time phases are different, the heart is disposed at a position shifted as a whole. As a result, as in the example shown in FIG. 4A, the heart as the object is formed to move as a whole in a plurality of reconstructed image data over a plurality of time phases.

  Therefore, in the mask processing shown in FIG. 4 (2), each reconstructed image data is moved by moving the mask region over a plurality of reconstructed image data so as to follow the movement of the object. The image of the attention area is extracted from the inside.

  In each of the reconstructed image data of time phase 0, time phase N / 2, and time phase N shown in FIG. 4 (2), the hatched area is a mask area and an image including the heart other than the mask area. The area is the attention area. The size (area) of the region of interest is constant over a plurality of time phases. Therefore, the size of the mask region is also constant over a plurality of time phases.

  In the reconstructed image data of FIG. 4A, there is a shift of one tomographic image along the scan direction φ of FIG. That is, there is a shift of the angle Δφ between the tomographic images adjacent to each other in FIG. Therefore, in the mask process shown in FIG. 4B, the mask region is moved by Δφ in the negative direction (to the left in the figure) along the scan direction φ for each time phase.

  In other words, the mask region that occupies the negative side (left side) of the scan direction φ in time phase 0 moves in the negative direction by Δφ in each subsequent time phase, and is positive in the scan direction φ by the amount of protrusion. A mask area appears on the side (right side). Then, in the time phase N / 2 which is an intermediate time phase, the areas of the mask regions on the positive side and the negative side (right side and left side) are equal. Further, when the time phase advances and reaches the time phase N which is the final time phase, all the mask regions move to the positive side (right side) of the scanning direction φ.

  In order to realize the mask processing shown in FIG. 4 (2) by moving the mask region by Δφ for each time phase from time phase 0 to time phase N, the size (area) of the mask region is set. N × Δφ may be used. Further, the area of the attention area can be obtained by subtracting the area of the mask area from the size of the reconstructed image data, for example, the area of each reconstructed image data shown in FIG. If the area N × Δφ of the mask region is constant over a plurality of time phases, the area of the attention region is also constant.

  In this way, as shown in FIG. 4 (2), by moving the mask region over a plurality of time phases, the region of interest is moved so as to follow the overall movement of the heart as the object, and each time An image of the region of interest is extracted from the reconstructed image data for each phase. Note that, for each time phase, the same mask region is applied to all rφ planes arranged along the θ direction (see FIG. 2).

  When the attention area is determined for each time phase, the reconstructed image data is arranged so that the image of the attention area is arranged in the center of the display area for each time phase in the display process shown in FIG. Move the rotation. Only the image of the attention area arranged at the center of the display area is displayed as the display image shown in FIG.

  Since the region of interest is determined so as to follow the overall movement of the target heart, the display image shown in FIG. 4 (4) assumes that the overall position of the heart is constant over a plurality of time phases. Is done. Further, since the size of the attention area is also constant, in the display image shown in FIG. 4 (4), a display image in which the frame of the displayed image (that is, the extension of the attention area) is fixed is obtained.

  The display image may be formed, for example, in an XYZ orthogonal coordinate system. For example, each tomographic image data of the rθ coordinate system shown in FIG. 2 is stored in the previous memory 14 of FIG. 1 after being converted into the xy orthogonal coordinate system, and further, in parallel with the mask processing shown in FIG. Thus, conversion from the yφ coordinate system (y corresponds to the r direction) to the YZ orthogonal coordinate system is performed. As a result, if the x direction of each tomographic image data previously converted to the orthogonal coordinate system is directly used as the X direction, a display image can be obtained in the XYZ orthogonal coordinate system.

  FIG. 5 is a diagram illustrating a second specific example from the reconstruction process to the display image acquisition. In the reconstruction process of Example 2, each of a plurality of tomographic image data periodically corresponding to each other is arranged in the reconstruction space in association with the position of the scanning plane from which the tomographic image data was obtained, Reconstructed image data of each time phase is formed from a plurality of tomographic image data.

  FIG. 5A shows reconstructed image data of time phase 0, time phase N / 2, and time phase N (N is a natural number). Each reconstructed image data shown in FIG. 5A corresponds to an image on the rφ plane in the rθφ coordinate system (FIG. 2).

  For example, the tomographic image φ1, tomographic image φ15,..., And tomographic image φ51 stored in the rear memory 26 in FIG. 3 are arranged at coordinates φ1, φ15,. The reconstructed image data of time phase 0 in FIG. 5 (1) is formed. Further, for example, the tomographic image φ10, the tomographic image φ24,..., And the tomographic image φ60 stored in the rear memory 26 of FIG. 3 are arranged at coordinates φ10, φ24,. Thus, the reconstructed image data of time phase N in FIG. 5A is formed.

  In the example of FIG. 5, since the tomographic image data is arranged according to the position of the scanning plane in the reconstructed image data, the heart image is also arranged at the initial position before the reconstruction process. Therefore, if the heart does not move as a whole before the reconstruction process, the heart does not move as a whole in a plurality of reconstructed image data over a plurality of time phases.

  However, in the example of FIG. 5, the tomographic image data arranged at the end of the reconstructed image data at time phase 0 becomes a tomographic image φ1 (FIG. 3), and is arranged at the end of the reconstructed image data at time phase N. The tomographic image data is a tomographic image φ10 (FIG. 3). Since the tomographic image φ1 and the tomographic image φ10 are at different positions in the scan φ direction, they are arranged at different positions in the reconstructed image data. That is, the position of the end of the reconstructed image data at time phase 0 and the position of the end of the reconstructed image data at time phase N are different from each other.

  As described above, the reconstructed image data of time phase 0 and time phase N are shifted from each other in the position of the edge of the image. This relationship is not limited to between the time phase 0 and the time phase N. If the time phases are different, the position of the end of the reconstructed image data is shifted. As a result, as in the example shown in FIG. 5A, the position of the edge of the reconstructed image data, that is, the outer frame of the reconstructed image data, is shifted in a plurality of reconstructed image data over a plurality of time phases. .

  Therefore, in the mask processing shown in FIG. 5 (2), a mask area is set in a portion where the outer frame is shifted over a plurality of reconstructed image data, and the position of the attention area including the object is fixed at the center. Thus, the image of the attention area is extracted from each reconstructed image data.

  In each of the reconstructed image data of time phase 0, time phase N / 2, and time phase N shown in FIG. 5 (2), the hatched area is a mask area, and the image includes the heart other than the mask area. The area is the attention area. The size (area) of the region of interest is constant over a plurality of time phases. Therefore, the size of the mask region is also constant over a plurality of time phases. The position of the attention area is also constant over a plurality of time phases. Note that, for each time phase, the same mask region is applied to all rφ planes arranged along the θ direction (see FIG. 2).

  When the attention area is determined for each time phase, in the display process, the image of the attention area is maintained as it is arranged in the center of the display area, and the attention area arranged in the center of the display area is maintained. Only the image is displayed as the display image shown in FIG.

  Since the position of the scanning plane is taken into consideration in the reconstruction process, in the display image shown in FIG. 5 (3), the position of the heart that is the object is also the initial position before the reconstruction process. In addition, since only the image of the attention area arranged in the center of the display area is displayed, the display image shown in FIG. 5 (3) is a display in which the frame of the displayed image (that is, the extension of the attention area) is also fixed. An image is obtained.

  The display image may be formed, for example, in an XYZ orthogonal coordinate system. For example, each tomographic image data in the rθ coordinate system shown in FIG. 2 is stored in the previous memory 14 in FIG. 1 after being converted into the xy orthogonal coordinate system, and further, in parallel with the mask processing shown in FIG. 5 (2). Thus, conversion from the yφ coordinate system (y corresponds to the r direction) to the YZ orthogonal coordinate system is performed. As a result, if the x direction of each tomographic image data previously converted to the orthogonal coordinate system is directly used as the X direction, a display image can be obtained in the XYZ orthogonal coordinate system.

  The ultrasonic diagnostic apparatus according to the preferred embodiment of the present invention has been described above. For example, a part or all of the processes from the reconstruction process described with reference to FIGS. 4 and 5 to obtaining a display image are performed. A corresponding program realizes part or all of the functions of the reconstruction processing unit 20, the mask processing unit 30, and the display processing unit 40 shown in FIG. 1 by a computer, and causes the computer to function as an ultrasonic image processing apparatus. Also good.

  The above-described embodiments are merely examples in all respects, and do not limit the scope of the present invention. The present invention includes various modifications without departing from the essence thereof.

  10 probe, 12 transmission / reception unit, 20 reconstruction processing unit, 30 mask processing unit, 40 display processing unit.

Claims (6)

An ultrasonic transmission / reception unit that transmits and receives ultrasonic waves so as to form a plurality of scanning planes while moving the scanning plane over a plurality of cycles of the movement in a three-dimensional space including an object that performs periodic movement;
By extracting a plurality of images periodically corresponding to each other from a plurality of images corresponding to a plurality of scanning planes formed over a plurality of cycles and forming each reconstructed image, the images are different from each other in the cycle. A reconstruction processing unit for obtaining a plurality of reconstructed images corresponding to a plurality of time phases;
An area determination unit for determining an attention area based on the object in each reconstructed image;
A display processing unit that displays images of a region of interest obtained one after another from a plurality of reconstructed images over a plurality of time phases at a certain position;
Having
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1,
The region determination unit determines a region of interest by masking a region other than the region of interest including the object in each reconstructed image;
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to claim 1 or 2,
The region determination unit extracts a region of interest image from each reconstructed image while keeping the size of the region of interest constant for a plurality of reconstructed images.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The reconstruction processing unit arranges a plurality of images periodically corresponding to each other in a reconstruction space in association with positions according to their arrangement order, and forms each reconstructed image from the plurality of images, Thereby, it is formed so that the object moves as a whole in a plurality of reconstructed images over a plurality of time phases,
The region determining unit extracts an image of the attention area from each reconstructed image by moving the attention area so as to follow the movement of the object over a plurality of reconstruction images.
An ultrasonic diagnostic apparatus. The ultrasonic diagnostic apparatus according to any one of claims 1 to 3,
The reconstruction processing unit arranges each of a plurality of images periodically corresponding to each other in a reconstruction space in association with the position of the corresponding scanning plane, and forms each reconstructed image from the plurality of images Thus, the object is formed so as not to move as a whole in a plurality of reconstructed images over a plurality of time phases,
The region determination unit extracts a region of interest image from each reconstructed image while keeping the position of the region of interest constant so as to include the object over a plurality of reconstructed images.
An ultrasonic diagnostic apparatus. Processes images obtained by transmitting and receiving ultrasonic waves so as to form a plurality of scanning planes while moving the scanning plane over a plurality of cycles of the movement in a three-dimensional space including an object that periodically moves A program to
By forming each reconstructed image based on a plurality of images periodically corresponding to each other among images obtained from each of a plurality of scanning planes formed over a plurality of cycles, a plurality of different images in the cycle can be obtained. A reconstruction processing function for obtaining a plurality of reconstructed images corresponding to time phases;
A region determination function for determining a region of interest based on the object in each reconstructed image;
A display processing function for displaying images of a region of interest obtained one after another from a plurality of reconstructed images over a plurality of time phases at a certain position;
The computer
A program characterized by that.

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