JP4920260B2 - Image diagnostic apparatus, image display apparatus, and image data generation method - Google Patents

Description

  The present invention relates to an image diagnosis apparatus, an image display apparatus, and an image data generation method, and more particularly to an image diagnosis apparatus, an image display apparatus, and an image data generation method that enable display of fly-through image data.

  Medical image diagnostic technology has made rapid progress with X-ray CT apparatuses and MRI apparatuses that have been put into practical use with the development of computer technology in the 1970s, and is indispensable in today's medical care. In particular, recent X-ray CT apparatuses and MRI apparatuses are capable of real-time display of image data as the biological information detection apparatus and arithmetic processing apparatus increase in speed and performance, and further, generation and display of three-dimensional image data. Became easy to do.

  For example, in an X-ray CT apparatus, an X-ray tube and an X-ray detector arranged opposite to the periphery of a subject are rotated at a high speed, and the subject is continuously moved in the body axis direction to obtain a plurality of slices. Three-dimensional data (volume data) is generated by collecting X-ray projection data in a cross section and reconstructing these X-ray projection data. In recent years, the time required for collecting X-ray projection data is further reduced by the multi-slice method using an X-ray detector in which detection elements are two-dimensionally arranged, and real-time display of three-dimensional image data becomes possible. It was.

  On the other hand, an observer's viewpoint is virtually set in the volume data obtained by the above method, for example, in a hollow organ, and three-dimensional image data (hereinafter referred to as fly-through image data) of the organ surface observed from this viewpoint. A virtual endoscope mode (hereinafter referred to as a fly-through mode) that generates and displays the image has already been put into practical use (see, for example, Patent Document 1).

With the development of the fly-through mode, endoscopic images can be generated based on volume data collected from outside the body, and the degree of invasiveness to the subject has been greatly reduced. In addition, according to this fly-through mode, it becomes easy to set the line of sight for a part that was impossible in the conventional endoscopic examination, so that a high-precision examination can be performed safely and efficiently. .
JP 2000-51207 A

  The fly-through image data described above is generated based on the viewpoint and line-of-sight direction set for the volume data. Conventionally, the viewpoint and line-of-sight direction are set by three-dimensional information processing of volume data. It was. For this reason, it takes a long time for these settings, and it is difficult to set a suitable line of sight and line of sight for each of the volume data collected in real time. In particular, when the viewpoint set in advance in the luminal organ in the volume data relatively moves outside the luminal organ due to the movement of the luminal organ accompanying the respiratory movement or pulsatile movement of the subject, It was impossible to correct the position in a short time. For this reason, stable fly-through image data could not be obtained in real time.

  In addition, a method in which the operator who has observed the fly-through image data displayed on the display unit manually resets the viewpoint moved relative to the outside of the luminal organ to a suitable position is conceivable. It has been difficult to obtain good quality fly-through image data for a luminal organ, and it has a problem of imposing a great load on the operator.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an image diagnostic apparatus and an image that enable stable display of fly-through image data based on volume data obtained for a subject. A display device and an image data generation method are provided.

In order to solve the above-described problem, the diagnostic imaging apparatus according to the first aspect of the present invention sets a viewpoint and a line-of-sight direction with respect to volume data obtained in a time series from a subject, and provides a time-series fly-through image. In the diagnostic imaging apparatus for generating data, the first viewpoint used for generating fly-through image data of the previous time phase in two time phases adjacent in the time direction is the contour of the luminal organ in the volume data of the later time phase determining means for determining whether or not present in the external data, if the first view point is present outside the outline data, the second viewpoint newly set inside the contour data, wherein the 1 viewpoint and the first line of sight set from the first viewpoint
Based on viewpoint / line-of-sight direction setting means for setting a second line-of-sight direction on a line connecting the attention point determined by the direction and the second viewpoint, and information on the second viewpoint and the second line-of-sight direction A fly-through image data generation unit that performs image processing on the volume data of the later time phase and generates fly-through image data of the later time phase, and a display unit that displays the fly-through image data of the later time phase. It is said.

According to a sixth aspect of the present invention, there is provided an image display apparatus according to the present invention, wherein a viewpoint and a line-of-sight direction are set for time-series volume data of a subject generated by an image diagnostic apparatus, and time-series fly-through image data is displayed. In the image display device that performs generation and display, the first viewpoint used to generate fly-through image data of the previous time phase in two time phases adjacent in the time direction is the lumen organ in the volume data of the later time phase. determining means for determining whether or not exist outside of the contour data, when said first viewpoint is present on the outside of the contour data, the second viewpoint newly set inside the contour data, wherein The first viewpoint and the first viewpoint set from the first viewpoint
Viewpoint / line-of-sight direction setting means for setting a second line-of-sight direction on a line connecting the point of interest determined by one line- of-sight direction and the second viewpoint, and information on the second viewpoint and the second line-of-sight direction A fly-through image data generating means for processing the volume data of the later time phase based on the image data to generate fly-through image data of the later time phase, and a display means for displaying the fly-through image data of the later time phase. It is characterized by that.

On the other hand, the image data generation method of the present invention according to claim 8 is an image for generating time-series fly-through image data by setting a viewpoint and a line-of-sight direction for volume data obtained from a subject in time series. In the data generation method, the first viewpoint used by the determination unit to generate fly-through image data of the previous time phase in two time phases adjacent in the time direction is a luminal organ in the volume data of the later time phase Determining whether it exists outside the contour data of
The viewpoint / line-of-sight direction setting means newly sets a second viewpoint in the contour data based on the determination result of the determination means, and is set with the first viewpoint and the first viewpoint as the starting point.
A step of setting a second line-of-sight direction on a line connecting the point of interest determined by the first line-of-sight direction and the second viewpoint, and a fly-through image data generating means for the second viewpoint and the line-of-sight direction The method includes a step of performing image processing on the volume data of the later time phase based on the information to generate fly-through image data of the later time phase.

  According to the present invention, stable fly-through image data can be displayed in a fly-through mode performed using volume data obtained for a subject.

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

  In the first embodiment of the present invention described below, first, volume data of the first time phase (first time phase) in the volume data obtained in time series with respect to the diagnosis target region of the subject is used. Volume rendering image data is generated, and the first time point viewpoint and line-of-sight direction are set for the luminal organ of the volume rendering image data. Then, the first time phase fly-through image data is generated and displayed based on the volume data, the viewpoint, and the line-of-sight direction.

  Next, a pipe in the plane data including the first time phase viewpoint and perpendicular to the viewing direction of the first time phase (hereinafter referred to as the viewpoint plane) and volume data of the second time phase following the first time phase. Second-phase two-dimensional contour data (hereinafter referred to as contour data) is generated based on the intersection line with the cavity organ contour, and the first time-phase viewpoint is the interior of the second time-phase contour data. It is determined whether or not it exists.

  When the viewpoint of the first time phase is outside the contour data of the second time phase, the center position (lumen center) of the luminal organ is detected, and the newly set second position with respect to this center position is detected. The second time phase fly-through image data is generated based on the second time phase viewpoint and line-of-sight direction and the second time phase volume data. On the other hand, when the viewpoint of the first time phase is inside the contour data of the second time phase, the viewpoint and the line-of-sight direction of the first time phase are set to the viewpoint and the line-of-sight direction of the second time phase as they are. Fly-through image data in the second time phase is generated based on the viewpoint and line-of-sight direction in the two time phases and the volume data in the second time phase. Further, by repeating the same procedure, fly-through image data after the third time phase is generated.

  The image diagnostic apparatus of the present embodiment described below will be described by taking an X-ray CT apparatus as an example, but may be another image diagnostic apparatus such as an MRI apparatus or an ultrasonic diagnostic apparatus. In this embodiment, the case where the viewpoint and the line-of-sight direction are set for time-series volume data will be described. However, the present invention is not limited to time-series volume data, but is stationary volume data of a predetermined time phase. May be.

(Configuration of diagnostic imaging equipment)
Hereinafter, the configuration of the diagnostic imaging apparatus according to an embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a block diagram showing the overall configuration of an image diagnostic apparatus according to the present embodiment. The image diagnostic apparatus 100 obtains volume data based on projection data obtained almost simultaneously on a plurality of slice surfaces of a subject by a multi-slice method. A data generation unit 1 that generates data, a data storage unit 2 that stores the obtained volume data, and a fly-through processing unit that reads out the volume data and performs data processing for generating volume rendering image data and fly-through image data 3, a display unit 4 that displays volume rendering image data and fly-through image data, an input unit 5 that specifies a viewpoint position and a line-of-sight direction for fly-through image data for the displayed volume rendering image data, System control unit 6 for overall control of each unit It is provided.

  FIG. 2 is a block diagram showing the configuration of the data generation unit 1 in the present embodiment. The data generation unit 1 having a volume data generation function by the X-ray CT method is a gantry that rotates around the subject 150. A rotating unit 11, a bed 12 on which the subject 150 is placed and moves in the body axis direction at the opening of the gantry rotating unit 11, and a bed / gantry moving mechanism unit that rotates the gantry rotating unit 11 and moves the bed 12. 13, and further, a mechanism control unit 14 that controls the bed / table movement mechanism unit 13, an X-ray generation unit 15 that irradiates the subject 150 with X-rays, and an X-ray that has passed through the subject 150 are projected. A projection data collection unit 16 that collects data as data and a volume data generation unit 17 that reconstructs the projection data to generate volume data are provided.

  The bed 12 has a top plate (not shown) that can be slid in the longitudinal direction by driving the bed / base movement mechanism unit 13, and the subject 150 has a body axis direction that substantially coincides with the longitudinal direction of the top plate. Placed on. The mechanism control unit 14 controls the movement of the top plate in the longitudinal direction and the rotation of the gantry rotating unit 11 according to a control signal from the system control unit 6.

  On the other hand, the X-ray generation unit 15 includes an X-ray tube 152 that irradiates the subject 150 with X-rays, and a high voltage generator 151 that generates a high voltage applied between the anode and the cathode of the X-ray tube 152. An X-ray restrictor 153 that collimates the X-rays emitted from the X-ray tube 152, and a slip ring 154 that supplies a high voltage of the high-voltage generator 151 to the X-ray tube 152 installed on the gantry rotating unit 11. I have.

  The X-ray tube 152 is a vacuum tube that generates X-rays, and accelerates electrons by a high voltage supplied from the high voltage generator 151 to collide with a tungsten target to generate X-rays. The X-ray diaphragm 153 is located between the X-ray tube 152 and the subject 150 and has a function of narrowing the X-ray beam emitted from the X-ray tube 152 to a predetermined imaging size. For example, an X-ray beam emitted from the X-ray tube 152 is formed into a cone beam (quadrangular pyramid) -like X-ray beam or a fan beam-like X-ray beam corresponding to the effective field of view.

  On the other hand, the projection data collecting unit 16 attached to the gantry rotating unit 11 detects an X-ray that has passed through the subject 150, and the detection signal in the X-ray detector 161 is set to a predetermined number of channels. A switch group 162 to be bundled, a DAS (Data Acquisition System) 163 for A / D converting the output signal from the switch group 162, and an output of the DAS 163 are supplied to the volume data generation unit 17 provided in the gantry fixing unit 10 without contact. The data transmission circuit 164 is provided.

  That is, the X-ray tube 152, the X-ray restrictor 153, the slip ring 154, and the projection data collection unit 16 are provided in the gantry rotating unit 11 that can rotate with respect to the gantry fixing unit 10, and drive control signals of the mechanism control unit 14 Thus, high-speed rotation of 1 rotation / second to 2 rotations / second is performed around the rotation center axis (Z axis) substantially parallel to the body axis of the subject 150.

  In the X-ray detector 161 of the projection data collection unit 16, X-ray detection elements having scintillators and photodiodes are two-dimensionally arranged, for example, a slice direction (Z direction) set in the body axis direction of the subject 150. ), And about 900 X-ray detection elements are arranged in the channel direction orthogonal to the slice direction. However, the X-ray detection elements arranged in the channel direction are mounted on the gantry rotating unit 11 along an arc centered on the focal point of the X-ray tube 152.

  Next, when the switch group 162 supplies the detection signal output from the X-ray detector 161 to the DAS 163, the detection signal from the X-ray detection element in the slice direction is “data bundled” to a predetermined number of channels and supplied to the DAS 163. . That is, the slice interval in the slice direction is determined by this “data bundling”. The DAS 163 has a multi-channel receiving unit (not shown). The receiving unit converts the current signal output from the X-ray detector 161 through the switch group 162 into a voltage signal. Is A / D converted to generate projection data.

  The data transmission circuit 164 supplies the projection data output from the DAS 163 to the volume data generation unit 17 by optical communication means, for example. Note that this data transmission method can be replaced with another method as long as signal transmission between the rotating body and the stationary body is possible. For example, the slip ring described above may be used. However, in the X-ray detector 161, two-dimensional projection data is detected during one rotation (about 1 second). In order to realize transmission of such a huge amount of projection data, the DAS 163 and the data transmission are performed. The circuit 164 is required to have a high-speed processing function.

  Next, the volume data generation unit 17 includes a projection data storage unit 171 and a reconstruction calculation unit 172. The projection data storage unit 171 is a storage circuit that stores projection data detected by the X-ray detector 161 and supplied via the data transmission circuit 164 and the like, and collected for a plurality of slice planes of the subject 150. Projection data is saved. On the other hand, the reconstruction calculation unit 172 reads projection data once stored in the projection data storage unit 171, performs data interpolation processing in the slice direction, and then performs reconstruction processing to generate volume data. Then, the generated volume data is stored in the data storage unit 2 of FIG.

  Returning to FIG. 1, the fly-through processing unit 3 includes a volume rendering image data generation unit 31, a viewpoint / gaze direction setting unit 32, a fly-through image data generation unit 33, a viewpoint plane setting unit 34, and a viewpoint position determination. And a lumen center detecting unit 36.

  The volume rendering image data generation unit 31 includes an opacity / color tone setting unit and a rendering processing unit (not shown). Then, the opacity / color tone setting unit reads the first time phase volume data stored in the data storage unit 2 and, for example, sets the opacity and color tone based on each pixel value (voxel value) of the volume data. Set in pixel units. On the other hand, the rendering processing unit renders the volume data of the first time phase based on the opacity and tone information set by the opacity / color tone setting unit to generate volume rendering image data.

  On the other hand, the viewpoint / line-of-sight direction setting unit 32 performs the first time based on the position information of the viewpoint and line-of-sight direction specified by the input unit 5 for the luminal organ in the volume rendering image data described above displayed on the display unit 4. The viewpoint and line-of-sight direction in the generation of phase fly-through image data are initialized. Further, when the viewpoint / line-of-sight direction setting unit 32 moves relative to the outside of the luminal organ along with the respiratory movement or pulsatile movement of the subject during generation of time-series fly-through image data. First, the viewpoint and the line-of-sight direction are updated based on the center position information of the luminal organ.

  FIG. 3 schematically shows the viewpoint and line-of-sight direction set by the viewpoint / line-of-sight direction setting unit 32. The viewpoint Vp and the line-of-sight direction VL are set at desired positions in the luminal organ of the volume rendering image data. Is done. In this case, a projection plane PP of fly-through image data perpendicular to the line-of-sight direction VL is set at a position away from the viewpoint Vp by a predetermined distance Zx, and a point of interest P0 is set at the intersection of the line-of-sight direction VL and the projection plane PP. The

  Next, the fly-through image data generation unit 33 in FIG. 1 generates volume data of each phase generated by the data generation unit 1 and the viewpoint and line-of-sight direction set by the viewpoint / line-of-sight direction setting unit 32 for this volume data. Predetermined image processing is performed using the information to generate fly-through image data. For example, the first time phase fly-through image data is generated based on the first time phase viewpoint and line-of-sight direction set using the volume rendering image data described above, and further, the respiratory movement and pulsation of the subject are generated. The fly-through image data after the second time phase is generated based on the viewpoint and line-of-sight direction information newly set (updated) along with the sex movement.

  On the other hand, the viewpoint plane setting unit 34 has two time phases adjacent in the time direction (hereinafter, the preceding time phase is referred to as the previous time phase, and the time phase subsequent to the preceding time phase is referred to as the back time phase). Based on the viewpoint and line-of-sight direction information used to generate the fly-through image data of the previous time phase in FIG. 5, the viewpoint plane that includes the viewpoint and is perpendicular to the line-of-sight direction is read from the data storage unit 2 to the volume data of the later time phase Set.

  The viewpoint position determination unit 35 generates contour data based on the intersection line between the contour of the luminal organ in the volume data of the later time phase and the viewpoint plane set in the volume data by the viewpoint plane setting unit 34. Then, it is determined whether or not the viewpoint of the previous time phase exists in the contour data, and the determination result is supplied to the lumen center detection unit 36 or the viewpoint / gaze direction setting unit 32.

  FIG. 4 is a diagram for explaining the contour data of the luminal organ formed on the viewpoint plane set by the viewpoint plane setting unit 34, and the viewpoint Vp and the line-of-sight direction VL of the previous time phase are the positions and directions shown in the figure. In this case, the viewpoint plane setting unit 34 sets a viewpoint plane PL that includes the viewpoint Vp and is perpendicular to the line-of-sight direction VL. At this time, the contour data Ct of the luminal organ Da in the volume data of the later time phase is formed on the viewpoint plane PL.

  On the other hand, FIG. 5 shows a viewpoint position determination method by the viewpoint position determination unit 35. FIG. 5A shows a case where the viewpoint Vp of the previous time phase is inside the contour data Ct, FIG. 5B shows a case where the viewpoint Vp is outside the contour data Ct. In order to determine the presence position of the viewpoint Vp with respect to the contour data Ct, the viewpoint position determination unit 35 sets a half line (hereinafter referred to as a determination line) in an arbitrary direction starting from the viewpoint Vp. The number of intersections between the determination line and the contour data Ct is counted. If the number of intersections is odd, the viewpoint is present inside the contour data. If the number of intersections is an even number, it is determined that the viewpoint exists outside the contour data.

  That is, when the viewpoint Vp exists inside the contour data Ct as shown in FIG. 5A, the determination line L1 set as a half line starting from the viewpoint Vp is the intersection Pc1, and the determination line L2 is the intersection. Crosses the contour data Ct at Pc2. On the other hand, when the viewpoint Vp exists outside the contour data Ct as shown in FIG. 5B, the determination line L3 set with the viewpoint Vp as the starting point intersects with the contour data Ct at two points of the intersection Pc31 and the intersection Pc32. The determination line L4 set in the same manner also intersects the contour data Ct at two points of the intersection point Pc41 and the intersection point Pc42.

  Next, the lumen center calculation unit 36 in FIG. 1 detects the position coordinates of the viewpoint that is newly set (updated) based on the determination result of the viewpoint position determination unit 35. That is, when the viewpoint position determination unit 35 finds that the viewpoint of the previous time phase exists outside the contour data generated on the viewpoint plane, the lumen center detection unit 36, for example, The center position of the formed contour data is detected, and information on the center position is supplied to the viewpoint / line-of-sight direction setting unit 32.

  FIG. 6 shows a method of detecting the center position of the contour data Ct by the lumen center detection unit 36 when the viewpoint Vp of the previous time phase exists outside the contour data Ct. First, as shown in FIG. 6A, the radius ra of the circle Ca inscribed in the contour data Ct and the radius rb of the circle Cb circumscribed in the contour data Ct around the viewpoint Vp are calculated, and then the viewpoint Vp is determined. A circle Cm having a radius r3 (r3 = (r1 + r2) / 2) as a center is set.

  Next, as shown in FIG. 6B, the lumen center detection unit 36 sets evaluation points P1 to PN at a predetermined interval on the circumference of the circle Cm, and each of these evaluation points P1 to PN is set as contour data Ct. Is determined by a method similar to the method shown in FIG. When it is found that the evaluation points P1 to PM (PM <PN) exist inside the contour data Ct, the evaluation points Pm (for example, m = M / 2) at the center of the evaluation points P1 to PM are determined. The position coordinates are detected as the center coordinates of the contour data Ct (that is, the center position coordinates of the hollow organ).

  Returning to FIG. 1, the display unit 4 includes a display data generation circuit, a conversion circuit, and a monitor (not shown). The display data generation circuit superimposes additional information related to the image data on the volume rendering image data generated by the volume rendering image data generation unit 31 or the fly-through image data generated by the fly-through image data generation unit 33. To generate display data. Then, the conversion circuit performs D / A conversion and television format conversion on the display data and displays the data on the monitor. By using the display unit 4 and the input unit 5, the operator can interact with the diagnostic imaging apparatus 100.

  Next, the input unit 5 is an interactive interface including input devices such as a display panel, a keyboard, various switches, a selection button, a mouse, and the operator uses the above-described input device provided in the input unit 5. Then, the projection data collection conditions and reconstruction conditions are set in the volume data generation. Furthermore, the input device of the input unit 5 is used to specify the viewpoint and line-of-sight direction of the first time phase using the volume rendering image data displayed on the display unit 4 and to input various command signals.

  The system control unit 6 includes a CPU and a storage circuit (not shown), and information such as the viewpoint / projection plane distance Zx in FIG. 3, the judgment line direction in FIG. 5, and the evaluation point interval in FIG. Furthermore, various information such as the above-described projection data collection conditions and reconstruction conditions set by the input unit 5 are also stored in the storage circuit. The CPU performs overall control of the units of the data generation unit 1, the fly-through processing unit 3 and the display unit 4 based on these pieces of information to generate and display fly-through image data.

(Fly-through image data generation procedure)
Next, a procedure for generating fly-through image data in the first embodiment of the present invention will be described with reference to the flowchart of FIG.

  Prior to the generation of fly-through image data, the operator of the diagnostic imaging apparatus sets projection data collection conditions, reconstruction conditions, and the like in volume data generation using the input unit 5, and the system control unit 6 sets these settings. Is stored in its own memory circuit (step S1 in FIG. 7).

  Here, a volume data generation method according to the present embodiment will be described with reference to FIG. In this embodiment, the X-ray detector 161 in which 80 X-ray detection elements are arranged in the slice direction (the body axis direction of the subject) is used to collect projection data on the 80 slice plane while the bed 12 is fixed. Describe the case. For example, by detecting X-rays irradiated by the X-ray tube 152 while rotating an X-ray detector 161 having an X-ray detection element having an array interval of 1 mm in the slice direction around the subject, the slice interval ΔZ is determined. Projection data is collected at slice positions Z1 to Z80 of 1 mm.

  When the initial setting of the apparatus in step S1 is completed, the operator places the subject on the top plate of the bed 12, and the slice position Z = Z1 to Z1 of the gantry rotating unit 11 on the examination site of the subject. The subject is moved to a suitable position in the slice direction so that Z80 corresponds.

  Next, the operator inputs a command signal for generating volume data at the input unit 5. The system control unit 6 that has received this command signal from the input unit 5 supplies the control signal to the bed / stand mechanism unit 13 via the mechanism control unit 14 so that the X-ray tube 152 and the X-ray detector 161 face each other. In the first time phase (first time phase), X-ray irradiation and detection are repeated while the gantry rotating unit 11 is rotated around the subject at a speed of 1 to 2 rotations / second. Start collecting projection data.

  When the subject is irradiated with X-rays, the high-voltage generator 151 uses the power (tube voltage and tube current) necessary for X-ray irradiation according to the tube voltage and tube current setting conditions stored in the storage circuit of the system control unit 6. Is supplied to the X-ray tube 152, and the X-ray tube 152 receiving the supply of power irradiates the subject with fan beam X-rays.

  X-rays irradiated from the X-ray tube 152 and transmitted through the subject are detected by the X-ray detector 161 of the projection data collection unit 16. That is, X-rays that have passed through the subject are converted into charges (current) proportional to the transmitted dose in the X-ray detector 161 having 80 elements in the slice direction and 900 elements in the channel direction. Further, this current is supplied to the DAS 163 via the switch group 162, converted into a voltage, and then A / D converted, and projection data for 80 slices is collected.

  The collected projection data is sent to the transmission unit of the data transmission circuit 164 mounted on the gantry rotating unit 11 and converted into an optical signal, and received by the data transmission circuit 164 attached to the gantry fixing unit 10 via the air. Received by the department. The received projection data is temporarily stored in the projection data storage unit 171 of the volume data generation unit 17.

  X-ray irradiation and X-ray transmission data detection on the subject are continuously performed while the X-ray tube 152 and the X-ray detector 161 are rotated around the subject, for example, at a frequency of 1000 times / rotation. When the subject is irradiated with X-rays, projection data of 80,000 / second to 160000 / second is collected for 80 slices. The projection data in the first time phase collected at each slice position (Z = Z1 to Z80) is stored in the projection data storage unit 171.

  Next, the reconstruction calculation unit 172 of the volume data generation unit 17 reads out the first time phase projection data stored in the projection data storage unit 171 within a range of, for example, 180 degrees + fan beam angle. Then, if necessary, the interpolation processing in the slice direction is performed, and then reconstruction processing is performed to generate volume data in the first time phase, which is stored in the data storage unit 2 (step S2 in FIG. 7).

  On the other hand, the volume rendering image data generation unit 31 of the fly-through processing unit 3 reads the volume data stored in the data storage unit 2 and performs a predetermined rendering process, and the first time phase in which the contour of the luminal organ is emphasized. Volume rendering image data is generated. Then, the generated volume rendering image data is supplied to the display unit 4 and displayed on the monitor provided in the display unit 4 (step S3 in FIG. 7).

  Next, the operator who has observed the volume rendering image data of the first time phase displayed on the display unit 4 generates fly-through image data for the substantially central portion of the luminal organ in the volume rendering image data. Specify the position and direction of the viewpoint and line-of-sight direction. The viewpoint / gaze direction setting unit 32 that receives the position information of the viewpoint and the direction information of the line of sight in the first time phase output from the input unit 5 via the system control unit 6 is based on these information. The viewpoint and line-of-sight direction in the first time phase are set, and information on the viewpoint and line-of-sight direction is supplied to the fly-through image data generation unit 33 and the viewpoint plane setting unit 34 (step S4 in FIG. 7).

  The fly-through image data generation unit 33 that has received the information on the viewpoint and the line-of-sight direction from the viewpoint / line-of-sight direction setting unit 32 reads out the first time phase volume data stored in the data storage unit 2 again, and The volume data is processed based on the information on the line-of-sight direction to generate first time phase fly-through image data. Then, the generated fly-through image data is displayed on the monitor of the display unit 4 (step S5 in FIG. 7).

  On the other hand, the data generation unit 1 generates volume data in the second time phase following the generation of volume data in the first time phase by the same procedure as in step S2, and stores the obtained volume data in the data storage unit 2. Save (step S6 in FIG. 7).

  Further, the viewpoint plane setting unit 34 reads the second time phase volume data stored in the data storage unit 2, and information on the first time phase viewpoint and line-of-sight direction supplied from the viewpoint / line-of-sight direction setting unit 32. The viewpoint plane that includes the viewpoint and is perpendicular to the line-of-sight direction is set as the volume data of the second time phase. The position information of the viewpoint plane is supplied to the viewpoint position determination unit 35 (step S7 in FIG. 7).

  Next, the viewpoint position determination unit 35 generates contour data based on the intersection line between the contour of the luminal organ in the volume data of the second time phase and the viewpoint plane set by the viewpoint plane setting unit 34. Then, it is determined whether or not the viewpoint of the first time phase exists inside the contour data (step S8 in FIG. 7).

  Then, when it is determined that the viewpoint of the first time phase exists outside the contour data by the method illustrated in FIG. 5, the determination result is supplied to the lumen center detection unit 36. The lumen center detection unit 36 to which the determination result is supplied detects the center position of the contour data formed on the viewpoint plane, for example, by the method shown in FIG. 6, and this center position information is detected in the viewpoint / line-of-sight direction. It supplies to the setting part 32 (step S9 of FIG. 7).

  Next, the viewpoint / line-of-sight direction setting unit 32 updates the viewpoint and line-of-sight direction of the first time phase based on the center position information, and sets the viewpoint and line-of-sight direction of the second time phase (step S10 in FIG. 7). Then, the fly-through image data generation unit 33 processes the second time phase volume data read from the data storage unit 2 based on the viewpoint and line-of-sight direction of the second time phase, and the fly-through image data in the second time phase. Is generated and displayed on the monitor of the display unit 4 (step S11 in FIG. 7).

  On the other hand, when it is determined in step S8 described above that the viewpoint of the first time phase exists within the contour data, the viewpoint position determination unit 35 supplies the determination result to the viewpoint / gaze direction setting unit 32. . Next, the viewpoint / line-of-sight direction setting unit 32 sets the viewpoint and line-of-sight direction of the first time phase as they are to the viewpoint and line-of-sight direction of the second time phase, and the fly-through image data generation unit 33 sets the second time phase viewpoint and line-of-sight direction. Based on the viewpoint and the line-of-sight direction, fly-through image data of the second time phase is generated and displayed on the monitor of the display unit 4 (step S11 in FIG. 7).

  Hereinafter, the steps S6 to S11 are repeated to generate and display fly-through image data after the third time phase, so that the fly-through image data in a state where the viewpoint is always set inside the luminal organ. Is displayed in approximately real time.

  In step S10 described above, the viewpoint / line-of-sight direction setting unit 32 updates the viewpoint position based on the central position information of the luminal organ and sets the viewpoint of the next time phase as described above. A specific method for updating the line-of-sight direction associated with the update will be described with reference to FIG.

  FIGS. 9A and 9B show the viewpoint Vp1 and the line-of-sight direction VL1 in the previous time phase before the update, and the viewpoint Vp2 and the line-of-sight direction VL2 in the later time phase after the update. The updated line-of-sight direction VL2 in a) starts from the updated viewpoint Vp2, and is on the line connecting the viewpoint Vp2 (see FIG. 3) uniquely determined by the viewpoint Vp1 before the update and the line-of-sight direction VL1 and the viewpoint Vp2. Set to

  On the other hand, the updated line-of-sight direction VL2 in FIG. 9B is set on a line substantially parallel to the line-of-sight direction VL1 before the update, starting from the updated viewpoint Vp2.

  According to the first embodiment of the present invention described above, when generating and displaying fly-through image data based on volume data obtained in time series for the subject, a stable and high-quality fly Through image data can be displayed in substantially real time.

  In particular, since the viewpoint and line-of-sight direction in generating fly-through image data can always be set in the luminal organ of the volume data regardless of the respiratory movement or pulsatile movement of the subject, stable fly-through image Data can be displayed.

  In addition, the update of the viewpoint and the line-of-sight direction is based on the contour data of the luminal organ formed on the viewpoint plane that includes the viewpoint and is perpendicular to the line-of-sight direction, and more specifically, the viewpoint is centered. Since this is performed using a circle inscribed and circumscribed to the luminal organ, the cross-sectional shape is not a simple shape such as a blood vessel, but the luminal organ has a complicated shape as shown in FIGS. Even in such a case, it is possible to accurately update the viewpoint for each of the time-series volume data, and it is possible to display stable and high-quality fly-through image data in substantially real time. Other configurations that can be applied only to a simple shape such as a blood vessel having a substantially circular cross section will be described later.

  For the above reasons, according to the present embodiment, diagnostic accuracy and diagnostic efficiency can be improved, and the burden on the operator can be reduced.

  In the above description of the diagnostic imaging apparatus 100 in the present embodiment, the case where the data storage unit 2 that temporarily stores the volume data generated by the data generation unit 1 is described. When the processing speed in each unit is sufficiently high, the data storage unit 2 is not necessarily required, and the volume data generated by the data generation unit 1 may be directly supplied to the fly-through processing unit 3.

  As described above, the image diagnostic apparatus of the present embodiment has been described by taking the X-ray CT apparatus as an example. However, the present invention is not limited to this. For example, other images such as an MRI apparatus and an ultrasonic diagnostic apparatus may be used. It may be a diagnostic device.

  Next, a second embodiment of the present invention will be described. The difference of this embodiment from the first embodiment is that an image display device that generates and displays fly-through image data is provided independently of an image diagnostic device that generates volume data.

(Configuration of image display device)
The configuration of the image display apparatus in this embodiment will be described with reference to FIG. In the block diagram showing the overall configuration of the image display device shown in FIG. 10, units having the same functions as those of the units of the first embodiment shown in FIG. Omitted.

  In other words, the image display device 150 shown in FIG. 10 reads the volume data and stores volume data of the subject in advance and generates volume rendering image data and fly-through image data. The fly-through processing unit 3 that performs the image processing, the display unit 4 that displays the volume rendering image data and the fly-through image data, and the viewpoint and line of sight for generating the fly-through image data based on the displayed volume rendering image data An input unit 50 that designates the position and direction of a direction and a system control unit 60 that comprehensively controls each unit described above are provided.

  The data storage unit 20 includes a large-capacity storage circuit capable of storing a large amount of image data. The data storage unit 20 is generated by a separately installed diagnostic imaging apparatus and is not shown via a network (not shown) or a storage medium such as an MO (magneto-optical disk). The time-series volume data of the supplied subject is stored.

  On the other hand, the input unit 50 is an interactive interface including input devices such as a display panel, a keyboard, various switches, selection buttons, and a mouse, and the operator uses the input device described above to display the volume displayed on the display unit 4. The position and direction in the first time phase viewpoint and line-of-sight direction are designated for the rendering image data.

  The system control unit 60 includes a CPU and a storage circuit (not shown), and information such as the viewpoint / projection plane distance Zx, the determination line direction, and the evaluation point interval is stored in advance in the storage circuit. The CPU performs overall control of each unit of the fly-through processing unit 3 and the display unit 4 based on these pieces of information to generate and display fly-through image data.

  Note that the generation procedure of fly-through image data by this image display device is the same as that in the first embodiment except for the generation of volume data, and thus the description thereof is omitted.

  According to the second embodiment described above, when generating and displaying fly-through image data using the time-series volume data of the subject supplied from a separately installed diagnostic imaging apparatus, it is stable. High-quality fly-through image data can be displayed as a moving image, and the above-described fly-through image data can be displayed in substantially real time by directly connecting to the image diagnostic apparatus.

  In particular, the viewpoint and line-of-sight direction in generating fly-through image data are always set in the luminal organ of the volume data regardless of the respiratory movement or pulsatile movement of the subject. Display is possible.

  Further, since the viewpoint and the line-of-sight direction are updated based on the contour data of the luminal organ formed on the viewpoint plane that includes the viewpoint and is perpendicular to the line-of-sight direction, and the position information of the viewpoint, The viewpoint for each of the volume data can be updated in a short time, and the moving image display and real-time display of the fly-through image data can be easily performed.

  Furthermore, since the image display apparatus according to the present embodiment can cope with volume data obtained from a plurality of different types of image diagnostic apparatuses, fly-through using volume data obtained by a desired image diagnostic apparatus. Image data can be generated and displayed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and may be modified. For example, the image diagnostic apparatus 100 or the image display apparatus 200 according to the above-described embodiment has described the case where the viewpoint and the line-of-sight direction of the first time phase are set using the volume rendering image data. An MPR image data generation unit that generates arbitrary two-dimensional image data (MPR image data: Multi-Planar-Reconstruction) using volume data is provided, and the first time phase is generated using the MPR image data displayed on the display unit 4. The viewpoint and line-of-sight direction may be set. According to this method, in particular, setting of the viewpoint / line-of-sight direction for a thin luminal organ can be performed with high accuracy.

  In addition, volume rendering image data and MPR image data after the second time phase are generated in time series by the volume rendering image data generation unit 31 and the above-described MPR image data generation unit, and fly images in the same time phase as these image data are generated. The through image data may be displayed in parallel or synthesized on the display unit 4. More effective information can be obtained by this method.

  Furthermore, in the above-described embodiment, the case where fly-through image data is generated using volume data obtained in time series has been described. However, the present invention is not limited to this. For stationary volume data of a predetermined time phase, The fly-through image data may be generated by updating the viewpoint and the line-of-sight direction.

  On the other hand, in the determination of the viewpoint position in the above-described embodiment, the determination accuracy of the viewpoint position can be improved by using a plurality of determination lines and statistically processing the number of intersection points obtained in a plurality of directions. When data is obtained, the viewpoint position may be determined by one determination line.

  In the above-described embodiment, the viewpoint can be accurately set or updated even for a hollow organ having a complicated shape by the center position detection method of the contour data shown in FIG. For a hollow organ having a simple shape as described above, for example, the viewpoint may be set by a method as shown in FIG. That is, as shown in FIG. 11, when the viewpoint Vp exists outside the contour data Ct of the luminal organ having a substantially circular cross section, the lumen center detection unit 36 starts from the viewpoint Vp and is perpendicular to the contour data Ct. A determination line L5 is set, and the coordinates of intersections Q1 and Q2 between the determination line L5 and the contour data Ct are calculated. Then, the coordinates of the internal position Px in the luminal organ are calculated based on the position information of the intersection point Q1 and the intersection point Q2, and the internal position Px is set as a new viewpoint. In this case, it is preferable to set the midpoint of the line segment connecting the points Q1 and Q2 to the internal position Px, but the present invention is not limited to this. By applying the above-described method to a hollow organ having a simple shape, it becomes possible to update the line-of-sight position stably in a short time.

1 is a block diagram showing the overall configuration of an image diagnostic apparatus according to a first embodiment of the present invention. The block diagram which shows the structure of the data generation part in the Example. The figure which shows typically the viewpoint and gaze direction which are set by the viewpoint and gaze direction setting part of the Example. The figure which shows the contour data of the luminal organ in the viewpoint plane set by the viewpoint plane setting part of the Example. The figure which shows the determination method of the viewpoint position by the viewpoint position determination part of the Example. The figure which shows the center position detection method of the contour data by the lumen center detection part of the Example. The flowchart which shows the production | generation procedure of the fly through image data in the Example. The figure which shows the production | generation method of the volume data in the Example. The figure which shows the update method of the gaze direction in the Example. The block diagram which shows the whole structure of the image display apparatus which concerns on 2nd Example of this invention. The figure which shows the modification of the viewpoint position setting method in the 1st Example of this invention, and a 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Data generation part 2, 20 ... Data storage part 3 ... Fly-through process part 4 ... Display part 5, 50 ... Input part 6, 60 ... System control part 31 ... Volume rendering image data generation part 32 ... Viewpoint and gaze direction setting Unit 33 ... fly-through image data generation unit 34 ... viewpoint plane setting unit 35 ... viewpoint position determination unit 36 ... lumen center detection unit 11 ... gantry rotation unit 12 ... couch 13 ... couch / gantry moving mechanism unit 14 ... mechanism control unit 15 ... X-ray generator 16 ... Projection data collector 17 ... Volume data generator 151 ... High voltage generator 152 ... X-ray tube 153 ... X-ray restrictor 154 ... Slip ring 161 ... X-ray detector 162 ... Switch group 163 ... DAS
164 ... Data transmission circuit 171 ... Projection data storage unit 172 ... Reconstruction calculation unit 100 ... Image diagnostic apparatus 200 ... Image display apparatus

Claims (8)

In an image diagnostic apparatus for generating time-series fly-through image data by setting a viewpoint and a line-of-sight direction for volume data obtained in time series from a subject,
Whether or not the first viewpoint used for generating fly-through image data of the previous time phase in two time phases adjacent in the time direction is outside the contour data of the luminal organ in the volume data of the later time phase Determining means for determining
When the first viewpoint exists outside the contour data, a second viewpoint is newly set inside the contour data, and the first viewpoint and the first viewpoint are set as the starting points. 1's
Viewpoint / line-of-sight direction setting means for setting the second line-of-sight direction on a line connecting the point of interest determined by the line-of-sight direction and the second viewpoint ;
Fly-through image data generating means for performing image processing on the volume data of the later time phase based on the information on the second viewpoint and the second line-of-sight direction, and generating fly-through image data of the later time phase;
An image diagnostic apparatus comprising display means for displaying the fly-through image data of the later time phase. A lumen center detecting unit configured to detect a center position of the contour data; and the viewpoint / line-of-sight direction setting unit sets the second viewpoint at the center position of the contour data detected by the lumen center detecting unit. The diagnostic imaging apparatus according to claim 1. The determination means determines an existence position of the first viewpoint with respect to the contour data based on the number of intersections between the determination line set with the first viewpoint as a starting point and the contour data. The diagnostic imaging apparatus according to claim 1. Input means for designating a viewpoint and a line-of-sight direction; and at least one of volume rendering image data generation means and MPR image data generation means, wherein the input means includes volume rendering image data generated by the volume rendering image data generation means or 2. The diagnostic imaging apparatus according to claim 1, wherein the viewpoint and line-of-sight direction of the initial time phase are designated for the MPR image data generated by the MPR image data generation means. 5. The diagnostic imaging apparatus according to claim 4 , wherein the display means displays at least one of the volume rendering image data and MPR image data and the fly-through image data in parallel or in a composite manner in correspondence with time phases. . In an image display device for generating and displaying time-series fly-through image data by setting a viewpoint and a line-of-sight direction for time-series volume data of a subject generated by an image diagnostic apparatus,
Whether or not the first viewpoint used for generating fly-through image data of the previous time phase in two time phases adjacent in the time direction is outside the contour data of the luminal organ in the volume data of the later time phase Determining means for determining
When the first viewpoint exists outside the contour data, a second viewpoint is newly set inside the contour data, and the first viewpoint and the first viewpoint are set as the starting points. 1's
Viewpoint / line-of-sight direction setting means for setting the second line-of-sight direction on a line connecting the point of interest determined by the line-of-sight direction and the second viewpoint ;
Fly-through image data generating means for performing image processing on the volume data of the later time phase based on the information on the second viewpoint and the second line-of-sight direction, and generating fly-through image data of the later time phase;
An image display device comprising display means for displaying the fly-through image data of the later time phase. The image display apparatus according to claim 6 , wherein the volume data is generated by any one of an X-ray CT apparatus, an MRI apparatus, an X-ray apparatus, and an ultrasonic diagnostic apparatus. An image data generation method for generating time-series fly-through image data by setting a viewpoint and a line-of-sight direction for volume data obtained in a time series from a subject,
The first viewpoint used by the determination means to generate fly-through image data of the previous time phase in two time phases adjacent in the time direction exists outside the contour data of the luminal organ in the volume data of the later time phase Determining whether or not to do;
The viewpoint / line-of-sight direction setting means newly sets a second viewpoint in the contour data based on the determination result of the determination means, and is set with the first viewpoint and the first viewpoint as the starting point.
Setting a second line-of-sight direction on a line connecting the point of interest determined by the first line-of-sight direction and the second viewpoint ;
The fly-through image data generation means has a step of generating image data of the later time phase by processing the volume data of the later time phase based on the information on the second viewpoint and the line-of-sight direction. Is an image data generation method.

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