Abstract:
A method is disclosed for processing a digital medical image using a computer with a display for viewing an input digital medical image The method includes steps of: accessing the input digital medical image; displaying the input digital medical image at a first size in an image display area of the display, the first size being smaller than the image display area; allowing a user to define a region of interest for the digital medical image displaying at least a portion of the defined region of interest in the image display area by mapping the digital medical image and at least a portion of the defined region of interest to a second, larger size within the image display area; and masking any portion of the digital image not disposed within the region of interest.

Description:
FIELD OF THE INVENTION 
     The invention relates generally to the field of digital image processing, and in particular to the image processing of digital medical images. 
     BACKGROUND OF THE INVENTION 
     It is well known in the medical field to capture an x-ray image for diagnostic purposes. Once captured, the image can be distributed and/or analyzed. Some health professionals prefer to distribute and/or analyze the x-ray image in digital form. Known modalities/methods can be employed to obtain a digital medical image. For example, a medical image can be captured using x-ray film and then digitized into a digital medical image using a digitizer. In computed radiography, an image is captured on a stimulable storage phosphor medium and then converted to a digital image using CR reader. With a digital radiography system, a digital medical image can be captured directly, for example, MRIs and CTs. 
     Once a digital image is obtained, the image can be reviewed and/or processed for diagnostic purposes. As part of the review/diagnosis, it may be desired to focus in on a region of interest within the digital image. The ability to quickly and accurately select an area of interest is therefore important to a radiologist. 
     US Patent Application No. 2001/0024200 (Gupta) is directed to a method of providing a display for a graphical user interface in which a user may define a selected region of a subject image. 
     US Patent Application No. 2002/0136466, is directed to a radiation image displaying apparatus for displaying a target region to be diagnosed or trace-read. 
     U.S. Pat. No. 5,644,649 (Schoeters) is directed to a processing method in radiographic image recording systems. 
     An integrated radiological information system having display enhancement tools, including a Frame and Fill function, is disclosed in two papers: (1) “The use of IRIS image enhancement facilities on digital images by radiologists during a clinical trial at the Ottawa Civic Hospital”, by M. Coristine et al., SPIE Proceedings, Vol. 1233, Medical Imaging IV: Image Processing, Feb. 6-8, 1990, Pages 426-438; and (2) “Comparative evaluation of reporting analog films versus digital images using IRIS”, by Millward et al., SPIE Proceedings, Vol. 1232, Medical Imaging IV: Image Capture and Display, Feb. 4-5, 1990, Pages 2-12. 
     While such systems may have achieved certain degrees of success in their particular applications, there is a need to for a method for selecting a region of interest quickly and accurately, and displaying the selected region of interest for viewing. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a method for processing a digital medical image for diagnostic purposes. 
     Another object of the present invention is to provide such a method which enables a user (i.e., doctor, radiologist, health professional) to select a region of interest. 
     Still another object of the present invention is to provide such a method which displays the selected region of interest for viewing by the user. 
     These objects are given only by way of illustrative example, and such objects may be exemplary of one or more embodiments of the invention. Other desirable objectives and advantages inherently achieved by the disclosed invention may occur or become apparent to those skilled in the art. The invention is defined by the appended claims. 
     According to one aspect of the invention, there is provided a method of processing an input digital medical image using a computer with a display for viewing an input digital medical image. The method includes steps of: accessing the input digital medical image; displaying the input digital medical image at a first size in an image display area of the display, the first size being smaller than the image display area; allowing a user to define a region of interest for the digital medical image displaying at least a portion of the defined region of interest in the image display area by mapping the digital medical image and at least a portion of the defined region of interest to a second, larger size within the image display area; and masking any portion of the digital medical image not disposed within the region of interest. The second larger size may fill the image display area. Portions of the region of interest not within the digital medical image may be masked. 
     According to a second aspect of the invention, there is provided a method of processing a digital medical image using a computer with a display for viewing an input digital medical image. The method includes steps of: accessing the digital medical image; displaying the digital medical image at a first size on the display; defining an image display area on the display, the image display area being of a second size larger than the first size and the digital medical image being displayed within the image display area allowing a user to define a region of interest for the digital medical image displaying at least a portion of the defined region of interest in the image display area by mapping the digital medical image and at least a portion of the defined region of interest to a size larger than the first size within the image display area; and masking any portion of the digital image not disposed within the region of interest. Again, the second larger size may fill the image display area. Portions of the region of interest not within the digital medical image may be masked. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other objects, features, and advantages of the invention will be apparent from the following more particular description of the embodiments of the invention, as illustrated in the accompanying drawings. The elements of the drawings are not necessarily to scale relative to each other. 
         FIG. 1  shows a system which can be employed to review and process a digital medical image in accordance with the methods of the present invention. 
         FIG. 2  shows an exemplary display displaying a digital image. 
         FIG. 3  shows the digital image of  FIG. 2  displayed on the display in a reduced size. 
         FIG. 4  shows one method of defining a region of interest in accordance with the present invention. 
         FIG. 5  shows a second method of defining a region of interest in accordance with the present invention. 
         FIG. 6  shows the defined region of interest of  FIG. 4  displayed on the display, but with portions of the digital medical image masked to uniform density value outside the region of interest. 
         FIG. 7  shows an outline of the defined region of interest of  FIG. 6 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following is a detailed description of the preferred embodiments of the invention, reference being made to the drawings in which the same reference numerals identify the same elements of structure in each of the several figures. 
     A digital image can be obtained from a plurality of modalities using methods known to those skilled in the art. Once obtained, an exemplary system  10  (diagrammatically shown in  FIG. 1 ) can be employed to review and process the digital image for diagnostic purposes in accordance with the method of the present invention. As illustrated, system  10  includes a monitor/display  12 , an input device  14 , and a computer or other control member  15 . Input device  14  can be a keypad, mouse, joystick, or the like, as is known to those skilled in the art. Alternatively, display  12  can include a touchscreen to enable input. 
     System  10  accesses a digital image  16  for display on display  12 . The digital image can be obtained from various sources, for example, but not limited to, a digitizer, a server, database, or one or more modalities. Once digital image  16  has been displayed/processed using system  10 , the digital image (either the input digital image or a processed digital image) can be deleted, stored on a system  20 , transmitted across a communication network  22 , printed on a printer  24 , transmitted to a modality  26 , transmitted to another output device  28 , or the like. 
     Once the digital image is accessed, it is displayed on display  12 , as shown in  FIG. 2 . As shown, display  12  includes an image display area  30  for displaying the digital image and a control area  32  comprising viewing information as well as control members for controlling the operation of system  10  and processing of the digital image. For example, but not limited to, the viewing information might include patient information as well as zoom information. The control members might include members for manipulating the digital image displayed in image display area  30 . Input device(s)  14  can also be employed to control the operation of system  10  and processing of the digital image. 
     When digital image  16  is accessed by system  10  and displayed in image display area  30 , an individual/user (e.g., health professional, doctor, radiologist, and the like) may desire to more particularly view a particular region of interest of the digital image for diagnostic purposes. Accordingly, control area  32  or device input  14  allows for the selection of a region of interest of the digital image displayed in image display area  30  by the individual. 
     Once a determination has been made to select a region of interest from the displayed digital image, digital image  16  is displayed on display  12  in a reduced size. That is, as shown in  FIG. 3 , image display area  30  has not changed in size relative to display  12 , but digital image  16  (displayed within image display  30 ) has been reduced in size. As shown in  FIG. 3 , digital image  16  has been reduced by about 25 percent. Other size reductions can be employed, though the contents of digital image  16  need to be discernable/viewable to the individual since the individual is operating under visual control to select the region of interest. 
     The individual can now select/define a region of interest anywhere within image display area  30 . Such a selection can be within image  16 . In addition, such a selection can be made outside of image  16  but within display area  30 . This area within display area  30  but outside image  16  is herein referred to as a non-image area or a border area  31 . 
     The region of interest can be selected/defined/identified by several methods. 
     In one embodiment, the region of interest is selected/defined by marking corner points of the region of interest within display area  30 . That is, the region of interested is defined as comprising all the image points comprised within a polygon formed by the marking of the corner points. The corner points can be marked by methods known to those skilled in the art, including but not limited to, moving a cross-hairs or a light mark within image display area  30 . Acceptance/selection of a particular corner point can be noted, for example, by pressing one of the control members within control area  32  or pressing a key on keypad  14  (i.e., an input device). As shown in  FIG. 4 , four points (P 1 , P 2 , P 3 , P 4 ) within border area  31  are marked, defining a polygon shaped region of interest  40 . 
     In another embodiment, the region of interest can be selected/defined by marking an upper right corner and a lower left corner. The rectangle formed by these two corner points can be defined as the region of interest, wherein the image points comprised within the rectangle are the image points of interest. 
     In yet a further embodiment, shown in  FIG. 5 , four linear members (L 1 , L 2 , L 3 , L 4 ), such as collimator blades, can be employed to define a polygon shaped region of interest. Linear members L 2  and L 4  can be moved in the direction shown by arrow A 1  to define two sides of the polygon. Similarly, linear members L 1  and L 3  can be moved in the direction shown by arrow A 2  to define two other sides of the polygon. 
     Other embodiments for identifying/defining a region of interest are known to those skilled in the art. For example, a center point and a radius. 
     As shown in  FIGS. 3-5 , since digital image  16  is smaller in size than image display area  30 , the region of interest may comprise a portion of image display area  30  that is not within digital image  16 . This can be seen in  FIG. 4  wherein all four points (P 1 , P 2 , P 3 , P 4 ) were selected within border area  31  (i.e., within image display area  30 , but not within digital image  16 ). This arrangement allows the individual to more particularly control/select a particular region of interest. 
     Once the region of interest has been selected/defined, the region of interest can be accepted. This acceptance can be accomplished by activation of one of the control members within control area  32  or my employing one of the input devices  14 , such as a left or right mouse click. 
     Once the defined region of interest has been indicated/accepted as in  FIG. 4 , the digital medical image  16  and at least a portion of the region of interest are mapped to image display area  30 . That is, the digital medical image and the portion of the region of interest with the digital medical image are increased in size so as to fill image display area  30 . An example can be seen with reference to FIGS.  4  and  6 .A portion of the region of interest (element  40 ) that was selected/defined in  FIG. 4 , has now been enlarged to fit within image display area  30  as seen in  FIG. 6 . That is, the boundary/intersection of the region of interest  40  with image  16  (shown in  FIG. 7  as element  50 ) is enlarged in size to be mapped to display area  30 . 
     It is noted that the defined region of interest  40  comprises portions of image  16  and portions of border area  31  (i.e., non-imaged area). The portion of image  16  within the defined region of interest is what is mapped to image display area  30 . 
     There are portions of digital image  16  that are not within the defined region of interest that are viewable in image display area  30  when the mapping occurs. These portions of the digital image are applied with a uniform maximum density value or blackened (i.e., a density value of 3 or greater) to mask out the area that is not the region of interest, so as to reduce visual distractions for the individual making the diagnosis. That is, any portion of digital image  16  disposed within image display area  30  which is not comprised within the region of interest, is applied with a uniform maximum density value or blackened. 
     As seen in  FIG. 4 , the defined region of interest is displayed in the image display area by mapping the defined region of interest to the image display area. The portion of the defined region of interest not within the digital the image may be masked or adjusted to a uniform maximum density value, not illustrated. As seen in  FIG. 6 , the portion of the digital image not disposed within the region of interest also may be masked or adjusted to a uniform maximum density value. 
     To return to the original digital image (i.e., as shown in  FIG. 2 ), a control member within control area  32  can be activated. Alternatively, the resulting masked image (i.e., as shown in  FIG. 6 ) can be stored, transmitted, or printed. 
     A computer program product may include one or more storage medium, for example; magnetic storage media such as magnetic disk (such as a floppy disk) or magnetic tape; optical storage media such as optical disk, optical tape, or machine readable bar code; solid-state electronic storage devices such as random access memory (RAM), or read-only memory (ROM); or any other physical device or media employed to store a computer program having instructions for controlling one or more computers to practice the method according to the present invention. 
     The invention has been described in detail with particular reference to a presently preferred embodiment, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, and all changes that come within the meaning and range of equivalents thereof are intended to be embraced therein.