Patent Publication Number: US-2007110291-A1

Title: Image processing system and method for editing contours of a target object using multiple sectional images

Description:
FIELD OF THE INVENTION  
      The present invention generally relates to image processing systems, and more particularly to an image processing system and method for editing the contours of a target object by using multiple sectional images.  
     BACKGROUND OF THE INVENTION  
      An image processing system, which is used for processing an image of a target object and displaying the processed image, has been widely used. As an example of such an image processing system, an image processing system for conducting ultrasound diagnosis (hereinafter referred to as an “ultrasound diagnostic system”) will be described.  
      Generally, an ultrasound diagnostic system has become an important and popular diagnostic tool due to its wide range of applications. Specifically, due to its non-invasive and non-destructive nature, the ultrasound diagnostic system has been extensively used in the medical profession. Modern high-performance ultrasound diagnostic systems and techniques are commonly used to produce two or three-dimensional (2D or 3D) diagnostic images of a target object. The ultrasound diagnostic system generally uses a probe including an array transducer having a plurality of transducer elements to transmit and receive ultrasound signals. The ultrasound diagnostic system forms ultrasound images of the internal structures of the target object by electrically exciting the transducer elements to generate ultrasound pulses that travel into the target object. The ultrasound pulses produce ultrasound echoes since they are reflected from a discontinuous surface of acoustic impedance of the internal structure, which appears as discontinuities to the propagating ultrasound pulses. Various ultrasound echoes return to the array transducer and are converted into electrical signals, which are amplified and processed to produce ultrasound data for forming an image of the internal structure of the target object.  
      Especially, in a conventional ultrasound diagnostic system, sectional images are extracted from 3D ultrasound image data of the target object at every specified angle by rotating the 3D image data by specified angles. Then, the contours of the target object are automatically detected on the extracted sectional images and a 3D volume image of the target object is formed by using the sectional images including the contours to thereby measure a volume of the target object.  
      In order to more precisely measure the volume of the target object, the conventional ultrasound diagnostic system provides a function for editing the contours detected on the sectional images by the user through an input unit. That is, in the conventional ultrasound diagnostic system, a single sectional image extracted at a specified angle is displayed and the contour detected on the sectional image is edited by the user. After editing the contour, the next sectional image is displayed to edit the contour thereon.  
      However, since only one sectional image is displayed to edit the contour in the conventional ultrasound diagnostic system, the user cannot refer to the contours detected on other sectional images in contour editing. Further, it takes a long time to edit the contours detected on the sectional images.  
     SUMMARY OF THE INVENTION  
      The present invention provides an image processing system and method for editing the contours of a target object in multiple sectional images formed by slicing a 3D ultrasound image containing a target object image in a predetermined interval.  
      In accordance with one aspect of the present invention, there is provided an image processing system, which includes: a 3D image data forming unit for forming three-dimensional (3D) image data based on input image signals; a sectional image extracting unit for extracting sectional images from the 3D image data; a contour detecting unit for detecting contours of a target object on the extracted sectional images; a sectional image forming unit for setting a reference plane in the 3D image data and forming multiple sectional images based on the reference plane; a contour editing unit for editing contours of the target object on the multiple sectional images based on contour editing information provided by a user; and an image forming unit for forming a 3D volume image based on the edited contours.  
      In accordance with another aspect of the present invention, there is provided an image processing method, which includes the following steps: forming 3D image data based on input image signals; extracting sectional images from the 3D image data; detecting contours of a target object on the extracted sectional images; setting a reference plane in the 3D image data and forming multiple sectional images based on the reference plane; editing contours of the target object on the multiple sectional images based on contour editing information; and forming a 3D volume image based on the edited contours. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other objects and features of the present invention will become apparent from the following description of an embodiment given in conjunction with the accompanying drawings, in which:  
       FIG. 1  is a block diagram showing an ultrasound diagnostic system constructed in accordance with one embodiment of the present invention;  
       FIG. 2  is a block diagram showing an image processor constructed in accordance with one embodiment of the present invention;  
       FIG. 3  is a flowchart showing a volume measuring process using a contour editing function for editing contours of a target object in multiple sectional images in accordance with one embodiment of the present invention;  
       FIG. 4  shows an exemplary rotation axis set in 3D ultrasound image data in accordance with one embodiment of the present invention;  
       FIG. 5  shows an example of the multiple sectional images in accordance with one embodiment of the present invention;  
       FIG. 6  is a flowchart showing a contour editing process using the multiple sectional images in accordance with one embodiment of the present invention; and  
       FIGS. 7A  to  7 C show an example of contour editing using the multiple sectional images in accordance with one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PRESENT INVENTION  
      Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings. The ultrasound diagnostic system will be described as an example of an image processing system, which is constructed in accordance with the present invention.  
       FIG. 1  is a block diagram showing an ultrasound diagnostic system constructed in accordance with one embodiment of the present invention. As shown in  FIG. 1 , the ultrasound diagnostic system  100  includes a probe  110 , a beamformer  120 , an image signal processor  130 , a scan converter  140 , an image processor  150  and a display unit  160 . The image signal processor  130  and the image processor  150  may be provided as one processor.  
      The probe  110  includes a 1-dimensional or a 2-dimensional array transducer  112  including a plurality of transducer elements. The transmit signals, which are appropriately delayed in the beamformer  120  to form an ultrasound beam, are transmitted to the array transducer  112 . Then, the focused ultrasound beam, which is produced in response to the transmit signals, is transmitted along a scan line set in a target object (not shown). The probe  110  receives ultrasound echo signals reflected from the target object and converts the ultrasound echo signals into electrical signals (hereinafter referred to as “receive signals”). The receive signals are transmitted to the beamformer  120 .  
      The beamformer  120  provides delays of transmit signals to be transmitted to the array transducer  112  included in the probe  110  such that the ultrasound signals outputted from the array transducer  112  are focused on a focal point. Further, the beamformer  120  focuses the receive signals, which are received from the array transducer  112  included in the probe  110 , in consideration of the delays with which the echo signals are arrived at each transducer element. It then outputs a focused receive beam representing the energy level of the ultrasound echo signals reflected from the focal point.  
      The image signal processor  130  (e.g., a digital signal processor (DSP)) performs an envelope detection for detecting the intensities of the focused receive signals to form ultrasound image data. That is, the image signal processor  130  forms ultrasound image data based on the receive focused signals acquired from each focal point and position information of a plurality of focal points on each scan line. Te ultrasound image data include coordinates information of each focal point, angle information of each scan line and intensity information of the echo signals received at each focal point. The ultrasound image data may be 2D ultrasound data or 3D ultrasound data.  
      The scan converter  140  scan-converts the 3D ultrasound image data to a data format capable of being displayed on a screen of the display unit  160 . As shown in  FIG. 2 , the image processor  150  includes a sectional image extracting unit  151 , a contour detecting unit  152 , a 3D volume image forming unit  153 , a sectional image forming unit  154 , a contour editing unit  155 , a volume measuring unit  156  and a control unit  157 .  
      The sectional image extracting unit  151  sets a rotation axis passing through a center of 3D ultrasound image data provided from the scan converter  140 . Then, the sectional image extracting unit  151  extracts sectional images at every specified angle (θ) from the 3D ultrasound image data by rotating it around the rotation axis.  
      The contour detecting unit  152  automatically detects the contours of the target object on the respective sectional images extracted from the 3D ultrasound image data by the sectional image extracting unit  151 . The 3D volume image forming unit  153  forms a 3D volume image of the target object based on the contour of the target object provided from the contour detecting unit  152  and/or multiple sectional images provided from the contour editing unit  155 .  
      The sectional image forming unit  154  sets a reference plane in the 3D ultrasound image and forms the multiple sectional images parallel to the reference plane by slicing the 3D ultrasound image in a predetermined interval. The contour editing unit  155  receives contour editing information upon the contours of the target object on the multiple sectional images through an input unit (not shown) from the user. For example, when a mouse is used as the input unit, the user can input contour editing information by drawing or dragging. It then edits the contours of the target object on the multiple sectional images based on the received editing information.  
      The volume measuring unit  156  measures the volume of the target object in the 3D volume image formed based on the contours of the target object, which are detected on the sectional images or edited on the multiple sectional images. The control unit  157  controls the overall operations of the image processor  150 . For example, the control unit  157  checks whether the user selects contour editing and then operates each unit of the image processor  150  according to whether or not contour editing has been selected.  
      Hereinafter, the operations of the image processor will be described with reference to FIGS.  3  to  7 C.  
       FIG. 3  is a flowchart showing a process for measuring the volume of the target object using a contour editing function for editing the contours of a target object in the multiple sectional images in accordance with one embodiment of the present invention.  
      As shown in  FIG. 3 , at step S 110 , the 3D ultrasound image data are formed by the image signal processor  130  and the scan converter  140 . At step S 120 , the sectional image extracting unit  151  of the image processor  150  sets a rotation axis passing through a center of the 3D ultrasound image data provided from the scan converter  140 . Then, at step S 130 , the sectional image extracting unit  151  extracts sectional images at every specified angle θ from the 3D ultrasound image data  210  by rotating it around the rotation axis  220 , as shown in  FIG. 4 .  
      At step S 140 , the contour detecting unit  152  detects the contours of the target object on the extracted sectional images. Next, at step S 150 , the 3D volume image forming unit  153  forms a 3D volume image of the target object by using the detected contours of the target object.  
      Next, at step S 160 , the control unit  157  checks whether the user sets a reference plane in the 3D ultrasound image to form multiple sectional images. If it is determined that the user has set the reference plane at step S 160 , then the process proceeds to step S 170 , wherein the sectional image forming unit  154  forms the multiple sectional images parallel to the reference plane by slicing the 3D ultrasound image in a predetermined interval. Then, at step S 180 , the multiple sectional images are displayed on the screen of the display unit  160 , as shown in  FIG. 5   
      At step S 190 , the control unit  157  checks whether contour editing is selected by the user. If it is determined that contour editing has been selected at step SI 90 , then the process proceeds to step S 200 , wherein a contour editing process using the multiple sectional images is conducted. The contour editing process at step S 200  will be described later with reference to FIGS.  6  to  7 C.  
      If it is determined that contour editing has not been selected at step S 190  or after the contour editing process at step S 200 , then the volume measuring unit  156  measures the volume of the target object in the 3D volume image provided from the 3D volume image forming unit  153  at step S 210 . After the volume of the target object is measured, the image processor  150  completes the process.  
       FIG. 6  is a flowchart showing a contour editing process using the multiple sectional images in accordance with one embodiment of the present invention. As shown in  FIG. 6 , if it is determined that the user has selected contour editing at step S 190  shown in  FIG. 3 , then the contour editing unit  155  receives contour editing information on the multiple sectional images provided by the user through the input unit at step S 202 . It then edits the contours on the multiple sectional images based on the received contour editing information step S 204 . Steps S 202  and S 204  are explained as follows with reference to  FIGS. 7A  to  7 C.  
      (1)  FIG. 7A  shows the multiple sectional images of the 3D ultrasound image formed by the sectional image forming unit  154 , which are displayed on the screen of the display unit  160 . In  FIG. 7A , solid lines represent the contours automatically detected by the contour detecting unit  152 .  
      (2) The user edits the detected contours on the multiple sectional images through the input unit, as shown in  FIG. 7B . For example, the user selects parts to be edited on the multiple sectional images through the input unit. As shown in  FIG. 7B , dashed dotted lines represent the contours edited by the user.  
      (3) The contour editing unit  155  edits the contours on the multiple sectional images based on the contour editing information provided by the user through the input unit, as shown in  FIG. 7C .  
      Then, the control unit  157  checks whether the user requests the completion of the contour editing process on the multiple sectional images at step S 206 . If it is determined that the user has not requested the completion of the contour editing process, then the process returns to step S 202 . However, if it is determined that the user has requested the completion of the contour editing process, then the 3D volume image forming unit  153  forms a 3D volume image by using the multiple sectional images at step S 208  and then the process proceeds to step S 210 .  
      In this embodiment, a 3D volume image of a target object is formed by using sectional images extracted at every specified angle by rotating the 3D ultrasound image data by specified angles. Then, the multiple sectional images are formed based on a reference plane in the 3D ultrasound image. However, in another embodiment, the multiple sectional images can be formed directly from the 3D ultrasound image data based on the reference plane.  
      In accordance with the present invention, the contour of the target object is edited on the multiple sectional images formed by slicing the 3D ultrasound image. Accordingly, the user can easily observe how the contours are changed as the user edits them and the user can easily edit the contours.  
      While the present invention has been described and illustrated with respect to an embodiment of the invention, it will be apparent to those skilled in the art that variations and modifications are possible without deviating from the broad principles and teachings of the present invention, which should be limited solely by the scope of the claims appended hereto.