JP5345715B2 - Bone density measuring device - Google Patents

Description

  The present invention relates to a bone density measuring apparatus, and more particularly to a bone density measuring apparatus that displays a one-dimensional bone density distribution together with a two-dimensional bone density image.

  The bone density measuring device is a device that measures bone density at a measurement site based on transmission data obtained by irradiating a predetermined measurement site within a subject with X-rays (Patent Document 1). The bone density measuring device may be referred to as a bone mineral content measuring device.

  In bone density measurement, usually, high-energy X-rays and low-energy X-rays are irradiated onto a two-dimensional region of a subject, and a two-dimensional distribution of bone density is obtained based on two types of X-ray transmission data obtained by them. Calculated. It is displayed as a two-dimensional bone density image. A conventional bone density measuring device has a function of displaying a profile (one-dimensional bone density distribution) corresponding to a horizontal line designated by a user on a bone density image. Typically, the profile is displayed as a relatively small image in an empty space around the bone density image on the display screen. The horizontal axis of the profile is an axis representing distance, and the scale of the horizontal axis (horizontal line) in the bone density image does not necessarily match.

JP 2011-167388 A

  In the conventional display method, it is difficult to recognize the correspondence between the bone density image and the profile. For example, it is not possible to quickly recognize where a specific peak in the profile corresponds to a bone density image, and it is not possible to quickly recognize which part on a profile a specific site on the bone density image corresponds to. Problems have been pointed out.

  An object of the present invention is to support image diagnosis when a two-dimensional bone density image and a one-dimensional bone density distribution are displayed. Alternatively, an object of the present invention is to make it possible to quickly and easily grasp the correspondence between a two-dimensional bone density image and a one-dimensional bone density distribution. Alternatively, an object of the present invention is to provide information that supports the designation and correction of an analysis target region on a two-dimensional bone density image.

The bone density measuring apparatus according to the present invention includes a bone density image forming unit that forms a two-dimensional bone density image based on detection data obtained by irradiating a subject with X-rays, and the two-dimensional bone Reference line setting means for setting a reference line on a density image, extraction means for extracting a one-dimensional bone density distribution corresponding to the reference line from the two-dimensional bone density image, and analyzing the one-dimensional bone density distribution Analyzing means for specifying the feature point, and means for displaying the two-dimensional bone density image and the one-dimensional bone density distribution, wherein the two- dimensional position of the feature point is indicated on the two-dimensional bone density image. Display means for displaying a one-dimensional position marker for displaying a one-dimensional position of the feature point on the one-dimensional bone density distribution.

  According to the above configuration, when the reference line is set on the two-dimensional bone density image, the corresponding one-dimensional bone density distribution is extracted from the two-dimensional bone density image, and the analysis is performed on the extracted result. A feature point on the original bone density distribution is identified. The feature point indicates, for example, a maximum value, a minimum value, a maximum value, a minimum value, a boundary point, or a barycentric point. In this case, one or a plurality of feature points are specified. A two-dimensional position marker indicating the two-dimensional position of the feature point is displayed on the two-dimensional bone density image, while a one-dimensional position marker indicating the one-dimensional position of the feature point is displayed on the one-dimensional bone density image. By displaying them in association with each other, the position of the feature point on the one-dimensional bone density distribution corresponds to the position on the two-dimensional bone density image, and conversely, the feature on the two-dimensional bone density image. It is possible to quickly recognize without error which position on the one-dimensional bone density distribution the point corresponds to. This makes it possible to easily determine whether or not a feature point corresponds to a target site for bone density analysis. For example, it is possible to accurately set an analysis target range or a region of interest for a two-dimensional bone density image.

Preferably, the analysis means specifies a plurality of feature points in the one-dimensional bone density distribution, and the display means displays a plurality of two-dimensional positions indicating the two-dimensional positions of the plurality of feature points on the two-dimensional bone density image. A three-dimensional position marker is displayed, and a plurality of one-dimensional position markers indicating one-dimensional positions of the plurality of feature points are displayed on the one-dimensional bone density distribution. For each individual feature point, it is desirable to assign a specific hue or the like to the pair of the two-dimensional position marker and the one-dimensional position marker so that each pair can be distinguished from the other pairs. That is, it is desirable to configure so that the marker correspondence can be instantly recognized for each feature point. Shapes other than hue, line type, brightness, etc. may be made different, or identification may be made by adding characters or symbols.

  Preferably, when the reference line is moved on the two-dimensional bone density image, a position of the two-dimensional position marker on the reference line is updated in real time, and the primary in the one-dimensional bone density distribution is updated. The position of the original position marker is updated in real time. Preferably, when the reference line is moved on the two-dimensional bone density image, a movement locus of the two-dimensional position marker is displayed. It is also possible to recognize a bone axis, a boundary side, and the like from the shape of the movement locus.

The bone density measuring apparatus according to the present invention includes a bone density image forming unit that forms a two-dimensional bone density image based on detection data obtained by irradiating a subject with X-rays, and the two-dimensional bone Reference line setting means for setting a reference line on a density image, extraction means for extracting a one-dimensional bone density distribution corresponding to the reference line from the two-dimensional bone density image, and analyzing the one-dimensional bone density distribution Analyzing means for specifying a characteristic portion, and means for displaying the two-dimensional bone density image and the one-dimensional bone density distribution, the first area marker indicating the characteristic portion on the two-dimensional bone density image And a display means for displaying a second area marker indicating the feature portion on the one-dimensional bone density distribution. According to this configuration, the characteristic portion can be quickly specified on the two-dimensional bone density image, can be quickly specified even in the one-dimensional bone density distribution, and the correspondence between both can be easily recognized. The first area marker may be a line segment indicating a section, and the second area marker may be a solid portion. The characteristic portion is, for example, a metal portion, a calcified portion, a compression fracture portion, or the like. For example, the characteristic portion is extracted by thresholding the bone density distribution.

  Preferably, when the reference line is moved on the two-dimensional bone density image, a position of the first area marker on the reference line is updated in real time, and the one-dimensional bone density distribution in the one-dimensional bone density distribution is updated. The position of the second area marker is updated in real time. Preferably, when the reference line is moved on the two-dimensional bone density image, a two-dimensional image corresponding to the movement locus of the first area marker is displayed. According to this configuration, for example, it is possible to express only a high-luminance metal portion.

  According to the present invention, image diagnosis can be supported when a two-dimensional bone density image and a one-dimensional bone density distribution are displayed. Alternatively, the correspondence between the two-dimensional bone density image and the one-dimensional bone density distribution can be grasped quickly and easily. Alternatively, it is possible to support the designation and correction of the analysis target region on the two-dimensional bone density image.

It is a block diagram which shows suitable embodiment of the bone density measuring apparatus which concerns on this invention. It is a figure which shows the 1st display example. It is a figure which shows the 2nd example of a display. It is a figure which shows the 3rd example of a display. It is a figure which shows the display of a colored image. It is a figure for demonstrating a movement locus | trajectory. It is a figure for demonstrating the setting of arbitrary reference lines. It is a flowchart which shows the operation example of the apparatus shown in FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the drawings.

  FIG. 1 shows a preferred embodiment of a bone density measuring apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration thereof. This bone density measuring device is a device that is installed in a medical institution and measures the bone density, ie, bone mineral content, of a subject.

  In FIG. 1, the bone density measuring apparatus is roughly divided into a measuring unit 10 and a calculating unit 12. First, the measurement unit 10 will be described. The measurement unit 10 includes an X-ray generation unit 18. The X-ray generation unit 18 has an X-ray tube 20 that generates X-rays. For this, electric power is supplied from the high voltage source 21. In the present embodiment, the X-ray generation unit 18 forms a fan beam-shaped X-ray beam 23.

  The bed 14 is used to place a subject, that is, a subject 16. The X-ray beam 23 passes through the subject 16 and reaches the X-ray detection unit 22. The X-ray detection unit 22 includes a plurality of X-ray sensors arranged one-dimensionally in the present embodiment. In the present embodiment, the X-ray generation unit 18 and the X-ray detection unit 22 are transported in the body axis direction, that is, the direction perpendicular to the paper surface by the transport mechanism. As a result, a two-dimensional irradiation region is formed. In order to calculate the bone density, that is, to discriminate the bone part from the soft tissue part, in this embodiment, high energy X-rays and low energy X-rays are alternately irradiated. That is, two detection data are obtained for each measurement position.

  The bone density image forming unit 24 is a module that forms a two-dimensional bone density image based on such two detection data. In the present embodiment, a bone density image is formed as an image representing a bone part, but soft tissue may be reflected there. The image data of the formed bone density image is sent to the display unit 28 via the display processing unit 26, and the bone density image is displayed on the display screen of the display unit 28.

  In the present embodiment, a reference line can be set on a bone density image by an examiner using the input unit 30, and a profile as a one-dimensional bone density distribution corresponding to the reference line is displayed on the screen. Is displayed. This will be described below.

  The profile creation unit 32 extracts a one-dimensional bone density distribution corresponding to the reference line set there from the two-dimensional bone density image. This creates a profile. Data indicating the profile is sent to the display unit 28 via the display processing unit 26. The profile is sent to the profile analysis unit 34. The profile analysis unit 34 performs analysis of one or a plurality of feature points, that is, calculation for specifying the feature points, according to the conditions specified by the examiner.

  Here, examples of the feature point include a maximum value, a minimum value, a maximum value, a minimum value, a boundary point corresponding to a boundary value, a center of gravity point, and the like. By performing waveform analysis on the one-dimensional bone density distribution, for example, by specifying a peak point, the maximum value can be specified, and each feature point can be automatically calculated using a similar method. For example, the boundary point can be automatically recognized by specifying the rising point and falling point of the waveform. With regard to the maximum value and the minimum value, it is possible to perform waveform differentiation and identify them from changes in the differential value. The barycentric point is obtained by the barycentric calculation for the portion above the threshold.

  The analysis result of the profile analysis unit 34 is output to the first graphic image forming unit 36 and the second graphic image forming unit 38. The first graphic image forming unit 36 is a module that forms a first graphic image that is superimposed and displayed on the two-dimensional bone density image. The first graphic image includes a graphic representing a reference line, a graphic representing one or more markers on the reference line, and other graphics. The second graphic image is a module that generates a second graphic image that is superimposed or displayed on a one-dimensional bone density distribution, that is, a profile. The second graphic image includes one or more lines as markers.

  The display processing unit 26 has an image synthesis function and the like, synthesizes the two-dimensional bone density image and the first graphic image, and outputs image data of the first synthesized image thereby to the display unit 28. The display processing unit 26 combines the profile and the second graphic image, and outputs the image data of the second combined image to the display unit 28. Incidentally, the functions shown in each block can be realized by software functions.

  FIG. 2 shows a first display example. In FIG. 2, a first display area 42 and a second display area 48 are set on the display screen 40. A bone density image 44 is displayed in the first display area 42, and a first graphic image 46 as a reference image or an auxiliary image is displayed superimposed on the image. The bone density image 44 is an image representing the bone density value at each position as luminance. In this case, only the bone portion is displayed, but of course, the portion corresponding to the soft tissue may be imaged. The first graphic image 46 has a profile creation line 47 and also has a plurality of markers 54, 56, 58 and 60. Here, the marker 54 indicates the position of the highest value on the line 47, the marker 56 indicates the position of the lowest value on the line 47, and the markers 58 and 60 indicate both ends of the bone portion on the line 47. That is, it is a marker indicating a boundary point. Incidentally, reference numeral 62 denotes a region of interest (ROI) for determining a region for calculating an average bone density value. In the bone density image 44, the horizontal axis is the X direction, and the vertical axis is the Y direction.

  In the second display area 48, the profile 50 is displayed as a waveform. In addition, the second graphic image 52 is displayed superimposed on it. The horizontal axis of the profile 50 corresponds to the X direction, and the vertical axis of the profile 50 corresponds to the bone density value D. Both ends of the horizontal axis in the profile 50 are associated with both ends of the line 47, and the profile 50 represents a one-dimensional bone density distribution on the line 47. This can also be called a profile curve.

  As described above, when the position of the line 47 is designated on the bone density image 44 by the examiner, a bone density value data string corresponding to the line 47 is extracted from the bone density image 44, and the profile 50 has a waveform based on the data string. Formed as. Then, by executing waveform analysis on the profile 50, it is possible to specify the positions of one or more feature points. In the example shown in FIG. 2, the marker 54A in which the maximum value, the minimum value, and the two bone boundary points are specified indicates the position of the maximum value, and the marker 56A indicates the position of the minimum value. Yes, the markers 58A and 60A indicate two boundary points.

  Incidentally, in the example shown in FIG. 2, each marker constituting the element of the first graphic image 46 has a dot or circle shape, while the markers 54A, 56A, 58A, constituting the element of the second graphic image 52 are formed. 60A is configured as a vertical line. A different hue is assigned to each feature point. For example, the marker 54 and the marker 54A are displayed with the same hue. Similarly, the marker 56 and the marker 56A are displayed with the same hue, and the marker 58 and the marker 58A and the marker 60 and the marker 60A are also expressed with the same hue for each pair. As a result, the user can instantly recognize the marker pair relationship between the two graphic images 46 and 52, that is, can quickly specify the position of each feature point on the image. It becomes.

  When the position of the line 47 in the vertical or Y direction is changed by the inspector, the content of the second graphic image 52 is updated in real time, that is, the generation and analysis of the profile are executed in real time, and at the same time, the first graphic The contents of the image 46 are also updated in real time. Since such a process is continuously performed, it becomes possible for the user to grasp the details of each part of the bone density image 44, so that the region of interest 62 can be accurately set. In addition, it is easy to take various measures such as excluding the metal portion from the analysis target, excluding the compression fracture portion from the analysis target, or excluding the calcification portion from the analysis target. In addition, it becomes easy to apply measures such as addition to a bone portion for a portion that is not automatically recognized as a bone portion due to a low bone mass.

  In the above-described embodiment, each feature point is identified using the hue. However, each feature point may be identified using other display modes such as changing the line type.

  FIG. 3 shows a second display example. In addition, the same code | symbol is attached | subjected to the structure similar to the structure shown in FIG. 1, and the description is abbreviate | omitted. The same applies to other display examples.

  In the first display area 42, a bone density image 44A and a first graphic image 46A are displayed. On the other hand, in the second display area 48, a profile 50A and a second graphic image 52A are displayed. The profile 50A represents a one-dimensional bone density distribution on the line 47, and a plurality of maximum positions and a plurality of minimum positions are specified by the analysis, and the respective positions are shown as markers 64A to 76A. . Here, the markers 70A, 72A, 74A, and 76A are markers that indicate maximum positions, and the markers 64A, 66A, and 68A are markers that indicate minimum positions, respectively.

  Correspondingly, the first graphic image 64 </ b> A has a plurality of markers 64 to 76 displayed on the line 47. Here, the markers 70, 72, 74, and 76 are markers that indicate maximum positions, and the markers 64, 66, and 68 are markers that indicate minimum positions, respectively. It is possible to intuitively recognize the state or state of the bone density distribution on the line 47 from the arrangement, interval, density, and periodicity of a plurality of markers. Similar to the first display example described above, also in the second display example, when the position of the line 47 is changed by the examiner, the contents of the second graphic image 52A and the first graphic image 46A are updated in real time accordingly. The

  FIG. 4 shows a third display example. A bone density image 44B is displayed in the first display area 42, and a first graphic image 46B is displayed. A profile 50B is displayed in the second display area 48, and a second graphic image 52B is displayed. In the second display example, only a portion exceeding a predetermined threshold is automatically extracted in the profile 50B, and the portion 82 is expressed in color as a colored portion. For example, such a part corresponds to a metal part.

  Correspondingly, in the first graphic image 46B, the section 80 corresponding to the above-described portion 82 is displayed on the line 47 as a colored section. The display color of the portion 82 and the display color of the section 80 are the same, and the correspondence between them is expressed with the same hue. Incidentally, reference numeral 78 denotes a metal tool embedded in the bone. If such a metal tool 78 is included, a particularly high bone density value will be observed only in that portion, and such a portion is identified as a portion 82 as a solid-coated portion in the profile 50B, and It is specified as a section 80 in the bone density image 44B.

  Therefore, by observing such a display, the user can quickly take measures such as excluding the portion from the target of the average bone density calculation.

  FIG. 5 shows a fourth display example. In this display example, the line 47 is scanned on the bone density image 44C as indicated by reference numeral 84, and in this case, the colored section remains as an afterimage, and as a result, a colored image spreading two-dimensionally. 86 has occurred. That is, the portion corresponding to the metal tool is expressed in color as a solid image. Thus, the colored image 86 can be easily generated by leaving the movement trajectory of the section as a colored portion.

  FIG. 6 shows a fifth display example. In this fifth display example, a specific feature point on the line 47, that is, a marker 88 indicating the position of the highest value in this example is displayed on the screen, and at the same time, the movement locus 90 of the marker 88 is displayed as a curve. ing. That is, when the line 47 is moved from the bottom to the top as indicated by the reference numeral 84, the highest position on the line 47 is observed in real time, and as a result, the movement locus 90 can be displayed as connecting the positions of the highest points. Is possible. It is possible to recognize the bone axis from such a movement locus 90, or to intuitively understand how a portion having a high bone density value changes along the bone axis. Of course, it is also possible to display the movement trajectory of the marker indicating the lowest value, and it is possible to display the outline of the bone part clearly by displaying two movement trajectories indicating both ends of the bone part. It is also possible to display the center of gravity line.

  FIG. 7 shows a sixth display example. In this display example, a line 92 is set with an arbitrary direction and an arbitrary length by the examiner on the bone density image 44E. One point of the line 92 is indicated by A and the other point is indicated by B. Correspondingly, a profile 50E is generated, with one end on the horizontal axis corresponding to A and the other end corresponding to B. As a result, it is possible to designate an arbitrary path on the two-dimensional bone density image and display the one-dimensional bone density value distribution on the path. In the example shown in FIG. 7, the line is configured by a straight line, but it may be configured by a curve.

  FIG. 8 is a flowchart showing an operation example of the apparatus shown in FIG.

  In S10, the subject is placed on the bed, and measurement for the subject is executed. In S12, a bone density image is displayed on the screen. In S <b> 14, a region of interest to be calculated such as average bone density is set on the bone density image by the examiner. For example, a region of interest may be set individually for each of a plurality of lumbar vertebrae. It is also possible to automate the setting of the region of interest. In S <b> 16, addition / subtraction of a portion that is a calculation target of the average bone density value in the region of interest is executed. For example, various measures such as exclusion of a metal part, exclusion of a compression fracture part, exclusion of a calcified part, or addition of a low bone mass part are applied. S14 and S16 may be executed in the reverse order.

  In the setting of the region of interest and the addition / removal of the analysis target as described above, it is difficult to make various determinations from only the bone density image, and when it is determined that the investigation is necessary in S18, that is, the display and analysis of the profile. Is determined to be necessary, each step after S20 is executed.

  In S20, a line is designated by the examiner on the bone density image. In S22, a bone density data string corresponding to the line is extracted from the bone density image, and a profile as a waveform is created based thereon. The profile is displayed on the image. In S24, the profile is analyzed. That is, one or more feature points are specified according to the conditions selected by the user. In S26, a first graphic image and a second graphic image showing one or a plurality of feature points are generated and displayed on the screen together with the bone density image and the profile. In S28, it is determined whether or not to continue the above operation. When returning to the main routine, each process from S14 is executed. That is, if it is necessary to correct the region of interest that has been set so far by referring to the profile analysis results as described above, such correction work is executed in S14, and similarly, the addition and removal of the analysis target is necessary. For example, such an addition / removal operation is executed in S16. It is also possible to incorporate the steps S14 and S16 into the steps S20 to S28. The operation example shown in FIG. 8 is merely an example.

  When it is determined in S18 that the survey is completed, S30 is executed by a predetermined input by the user, and in S30, analysis of the bone density image is executed. Specifically, the bone density value in the region is referred to the region recognized as the bone portion in the region of interest, and the average bone density is calculated based on the bone density value. In S32, the analysis result is displayed on the screen as a numerical value or the like.

  According to the above operation example, the profile analysis result can be specified on the two-dimensional image and the one-dimensional image when setting the region of interest and adding / subtracting the analysis target, so that there is an advantage that the operation can be performed quickly and accurately. It is done. In that case, for example, if the method shown in FIG. 4 or the like is applied, the metal portion can be recognized as a solid color portion, and therefore the portion can be easily excluded. It is also possible to easily separate individual vertebrae. According to the above-described embodiment, the present invention is not limited to the advantages described above, and the positional relationship between the bone density image and the profile can be intuitively and easily recognized.

  10 measuring unit, 12 calculating unit, 24 bone density image forming unit, 32 profile creating unit, 34 profile analyzing unit, 36 first graphic image forming unit, 38 second graphic image forming unit.

Claims (6)

Bone density image forming means for forming a two-dimensional bone density image based on detection data obtained by irradiating the subject with X-rays;
A reference line setting means for setting a reference line on the two-dimensional bone density image;
Extracting means for extracting a one-dimensional bone density distribution corresponding to the reference line from the two-dimensional bone density image;
Analyzing means for analyzing the one-dimensional bone density distribution to identify feature points;
Means for displaying the two-dimensional bone density image and the one-dimensional bone density distribution, displaying a two-dimensional position marker indicating a two-dimensional position of the feature point on the two-dimensional bone density image; Display means for displaying a one-dimensional position marker indicating the one-dimensional position of the feature points on the density distribution;
Only including,
When the reference line is moved on the two-dimensional bone density image, the position of the two-dimensional position marker on the reference line is updated in real time, and the one-dimensional position marker in the one-dimensional bone density distribution is updated. The location of is updated in real time,
A bone density measuring device characterized by the above. The apparatus of claim 1.
The analysis means identifies a plurality of feature points in the one-dimensional bone density distribution,
The display means displays a plurality of two-dimensional position markers indicating the two-dimensional positions of the plurality of feature points on the two-dimensional bone density image, and the one-dimensional one of the plurality of feature points on the one-dimensional bone density distribution. A bone density measuring apparatus characterized by displaying a plurality of one-dimensional position markers indicating positions. The apparatus of claim 1.
The bone density measuring apparatus according to claim 1, wherein the feature point indicates a maximum value, a minimum value, a maximum value, a minimum value, a boundary point, or a center of gravity point. The apparatus of claim 1 .
The bone density measuring apparatus, wherein a movement locus of the two-dimensional position marker is displayed when the reference line is moved on the two-dimensional bone density image. Bone density image forming means for forming a two-dimensional bone density image based on detection data obtained by irradiating the subject with X-rays;
A reference line setting means for setting a reference line on the two-dimensional bone density image;
Extracting means for extracting a one-dimensional bone density distribution corresponding to the reference line from the two-dimensional bone density image;
Analyzing means for analyzing the one-dimensional bone density distribution and identifying a characteristic part;
Means for displaying the two-dimensional bone density image and the one-dimensional bone density distribution, wherein a first area marker indicating the feature portion is displayed on the reference line of the two-dimensional bone density image; Display means for displaying a second area marker indicating the characteristic portion on the bone density distribution;
Only including,
When the reference line is moved on the two-dimensional bone density image, the position of the first area marker on the reference line is updated in real time, and the second area in the one-dimensional bone density distribution is updated. The area marker position is updated in real time.
A bone density measuring device characterized by the above. The apparatus of claim 5 .
The bone density measuring apparatus, wherein a two-dimensional image corresponding to a movement locus of the first area marker is displayed when the reference line is moved on the two-dimensional bone density image.

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