JP5042533B2 - Medical image display device - Google Patents

Description

  The present invention relates to a medical image display apparatus capable of adjusting display characteristics of medical images.

  An X-ray CT (Computed Tomography) apparatus and an MRI (Magnetic Resonance Imaging) apparatus display a medical image using a window function. As a display parameter, a width of a pixel value to be observed (WW: Window Width) and a median value of the pixel value to be observed (WL: Window Level) are set. Pixel values within the range of the pixel value width (WW) are converted into luminance values that change linearly.

  Pixels with a pixel value of “WL + WW / 2” or higher are displayed with the highest luminance value (eg “255”), and pixels with a pixel value of “WL−WW / 2” or lower are the lowest luminance value (eg “0”). Is displayed. In clinical practice, the pixel value width (WW) and the median pixel value (WL) are adjusted according to the target organ and disease.

The impression of the image varies greatly depending on the setting of the pixel value width (WW) and the pixel value median value (WL). For example, when “WW = 200, WL = 100”, pixels in a pixel value range of “0 to 200” are displayed in 256 gradations. When pixels having different pixel values by “10” are compared, the gradation is observed differently by “12.8”.
When the pixel value width (WW) is set wide with “WW = 400, WL = 100”, pixels in a range of pixel values “−100 to 300” are displayed in 256 gradations. When pixels having different pixel values “10” are compared, the gradation is observed differently by “6.4”.
When the pixel value width (WW) is set to be narrow with “WW = 100, WL = 100”, pixels in the pixel value range of “50 to 150” are displayed in 256 gradations. When pixels having different pixel values “10” are compared, the gradation is observed by “25.6” differently.
Thus, by setting the pixel value width (WW) to be narrow, it becomes possible to observe the difference in pixel value as a significant gradation difference.

  Further, a medical image display device has been proposed that can change the value of the pixel value width (WW) and the median pixel value (WL) for a partial region of the displayed image (see “Patent Document 1”). . In addition, an auto window device has been proposed in which an appropriate pixel value width (WW) and pixel value median value (WL) corresponding to collection conditions at the time of imaging of a subject are registered in advance (see “Patent Document 2”). . In addition, an image display device that automatically changes at least one of a pixel value width (WW) and a median pixel value (WL) within a predetermined range has been proposed (see “Patent Document 3”).

Japanese Patent Laid-Open No. 2002-17685 Japanese Patent Laid-Open No. 9-120446 JP-A-8-278873

  However, the medical image display apparatus disclosed in “Patent Document 1” uses a method in which the operator directly inputs the pixel value width (WW) and the pixel value median value (WL). In the automatic window device disclosed in “Patent Document 2”, an operator registers in advance an appropriate pixel value width (WW) and a pixel value median value (WL) corresponding to an imaging region. The image display device according to “Patent Document 3” automatically changes the value of the pixel value width (WW) and the median pixel value (WL) registered by the operator over time. As described above, the techniques of “Patent Document 1” to “Patent Document 3” all change the display parameters when the operator directly inputs the display parameters (WW, WL). Therefore, in order for the operator to display an image with a desired display contrast and display luminance, there is a problem that an operation of inputting display parameters is inevitably required, and the operation becomes complicated.

  In addition, if the pixel value width (WW) is carelessly set for an image including noise (pixel value variation), the number of pixels that fall within the range of the pixel value width (WW) decreases, and the noise is emphasized. There is a problem of becoming. Therefore, in order to observe the difference in pixel value without excessively enhancing the noise, it is necessary to appropriately set the pixel value width (WW) corresponding to the noise.

  Examples of the noise index include an image SD (Standard Deviation: standard deviation of pixel values) and the like. The techniques of “Patent Document 1” to “Patent Document 3” do not have a function of automatically adjusting display parameters in accordance with the image SD, and an operator's experience is necessary to set display parameters for obtaining an appropriate image display. Etc. are big.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a medical image display apparatus that adjusts display parameters of a medical image based on an image feature amount.

In order to achieve the above-described object, the present invention provides an image information acquisition unit that acquires image information in a subject, an arithmetic processing unit that performs arithmetic processing on the acquired image information, and a storage that holds the image information and arithmetic processing results A medical image display device including a display unit and a display unit that displays the image information and the calculation processing result, and irradiates the subject based on an image quality index value that is input or set in advance before subject imaging A dose optimization processing means for adjusting a dose; a display parameter setting means for setting a display parameter for displaying the image information on the display unit based on the image quality index value used in the dose optimization processing means ; The image information acquisition unit acquires image information of the subject with a dose adjusted by the dose optimization processing unit, and the calculation processing unit is configured to display the display parameter. Is a medical image display apparatus, characterized in that the processing to display the image information on the display unit in the display parameters set by chromatography data setting means.

The image information is image data indicating internal information of the subject. The image information is, for example, a tomographic image taken by an X-ray CT apparatus .
Viewing parameter setting means is means for calculating the display parameters (pixel value width (WW) and the pixel Median (WL)). The display parameter may be set by multiplying the image quality index value by a predetermined coefficient.

The medical image display device of the present invention adjusts the dose to be irradiated to the subject based on an image quality index value that is input or set in advance before imaging of the subject, and the image information based on the image quality index value. Display parameters for display on the display unit are set.
As a result, an image is captured at an optimal dose based on a preset image quality index value, and display parameters are set based on the image quality index value .

The medical image display device further includes a display parameter changing unit that receives the change of the display parameter after the image information is displayed on the display unit, and when the display parameter is changed by the display parameter changing unit, The arithmetic processing unit may perform arithmetic processing to redisplay the image information with the changed display parameter .

Further, the image quality index value may be registered in advance for each imaging region or for each operator.

  ADVANTAGE OF THE INVENTION According to this invention, the medical image display apparatus which adjusts automatically the display parameter for displaying a medical image based on an image feature-value can be provided.

  Exemplary embodiments of a medical image display apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. An X-ray CT apparatus will be described as a medical image display apparatus.

(1. Configuration of medical image display apparatus 100)
First, the configuration of the medical image display apparatus 100 will be described with reference to FIG.
FIG. 1 is a configuration diagram of a medical image display apparatus 100.

  The medical image display apparatus 100 includes a scanner unit 103 that scans a subject with X-rays to obtain X-ray CT image data, an operation unit 105 such as an input device that receives input from an operator, and the acquired X-ray CT image data. A calculation unit 107 (CPU: Central Processing Unit) that performs calculation processing using the pixel values to generate display image data, a display unit 109 such as a display that displays the display image data, and the acquired X-ray CT image data And a storage unit 111 that stores calculation processing results, a control program, and the like.

The calculation unit 207 includes a dose optimization unit 201 that performs dose optimization according to the subject size in order to acquire an image having a desired image SD value, and image reconstruction that reconstructs an image from the acquired X-ray CT image data. A configuration processing unit 203 and a display processing unit 205 that sets display parameters for displaying an image created by the image reconstruction processing unit are provided.
Note that an image SD (Standard Deviation) is a standard deviation of pixel values. The image SD is used as an index of noise.

  The scanner unit 103 is an apparatus that detects transmitted X-rays that pass through a living body by irradiating and scanning an X-ray beam in the living body of the subject. The scanner unit 103 converts the measured value of the transmitted X-ray intensity into an electric signal and sends it to the computing unit 107 as X-ray CT image data.

  The operation unit 105 is an input device such as a keyboard, a mouse, a trackball, and a touch panel arranged in the medical image display device 100. The operator performs image quality adjustment, measurement instruction, information input, and the like via the operation unit 105.

  The arithmetic unit 107 loads and executes a control program for the medical image display apparatus 100 stored in the storage unit 111 or the like. The calculation unit 107 performs timing control and calculation processing.

The display unit 109 is a CRT, a liquid crystal display device, or the like that displays image data, measurement values, and an image obtained by graphing the measurement values on a screen.
The storage unit 111 is a device that stores image data, a control program, and the like. The storage unit 111 is, for example, a hard disk, a general-purpose memory, a frame memory, or the like. The storage unit 111 stores irradiation X-ray intensity values, acquired transmission X-ray intensity values, calculated X-ray absorption coefficient values, display parameters, image format files, and the like.

  The dose optimization processing unit 201 has a function of performing dose optimization by adjusting the tube current of the X-ray tube according to the subject size in order to obtain an image having a desired noise level (that is, a desired image SD value). Have. If the image SD value is small, the exposure amount to the subject is large, but a good image quality can be obtained. Conversely, if the image SD value is large, the exposure amount to the subject is small, but the quality of the obtained image quality is inferior. The operator can set an appropriate image SD value before imaging the subject.

  The image reconstruction processing unit 203 has a function of reconstructing an X-ray CT image by calculating an X-ray absorption coefficient of a target tomographic plane from a measured value of the transmitted X-ray intensity of the subject acquired by the scanner unit 103. .

  The display processing unit 205 has a function of setting display parameters (pixel value width (WW) and pixel value median value (WL)) in order to display the image formed by the image reconstruction processing unit 203. By appropriately setting the display parameters, it is possible to display an image with a desired display contrast and display luminance.

(2. Display parameters)
Next, display parameters will be described with reference to FIG.
FIG. 2 is an explanatory diagram of a pixel value width (WW) and a pixel value median value (WL).
The pixel value width 7 is the width of the observed pixel value 3 (WW: Window Width). The pixel value median value 9 is the median value (WL: Window Level) of the pixel value 3 to be observed. Pixel value 3 within the range of pixel value width 7 (WW) is converted to luminance value 5 that changes linearly.
In FIG. 2, the pixel value width is 7 (WW = 200), and the median pixel value is 9 (WL = 100). A luminance value 5 of a pixel having a pixel value 3 in the range of “0” to “200” is linearly converted to “0” to “255”.

(3. Display parameter setting process)
(3-1. Display Parameter Setting Process According to First Embodiment)
Next, display parameter setting processing according to the first embodiment will be described with reference to FIGS. 3 and 4. 1st Embodiment shows the medical image display apparatus which calculates a display parameter from the image SD value of the pixel of the whole acquired X-ray CT image.
FIG. 3 is a flowchart of the display parameter setting process.
FIG. 4 is a diagram showing a comparison of image quality of X-ray CT images based on image SD values.

  The operator inputs a desired image SD value from the operation unit 105 before photographing the subject in consideration of the imaging region shape of the subject, the exposure amount, and the like. As described above, the exposure amount to the subject and the image quality are in a contradictory relationship depending on the set image SD value. The dose optimization processing unit 201 of the calculation unit 107 of the medical image display apparatus 100 adjusts the dose of the scanner unit 103 based on the input image SD value. The scanner unit 103 performs imaging processing to acquire imaging data (measured value of the transmitted X-ray intensity of the subject), and the arithmetic unit 107 reconstructs the acquired imaging data as an X-ray CT image by the image reconstruction processing unit 203. .

  As the image SD value of all pixel values of the obtained X-ray CT image, a value approximating the image SD value set in advance by the operator is obtained. Note that the image SD value set before photographing the subject may be registered in advance for each imaging region or for each operator.

The display parameter pixel value width 7 (WW) and pixel value median value 9 (WL) are:
WW = SD x k ₁ (1)
WL = SD x k ₂ (2)
It is calculated by the following formula. SD is the image SD value. k ₁ and k ₂ are real coefficients.

The display processing means 205 of the calculation unit 107 acquires display parameter coefficients (k ₁ , k ₂ ) that are set uniquely by the operator (step 1001). The operator may input the values of the display parameter coefficients (k ₁ , k ₂ ) from the operation unit 105, or those registered in the storage unit 111 in advance may be used.

The display processing unit 205 displays the display parameter coefficients (k ₁ , k ₂ ) acquired in Expressions (1) and (2) and Step 1001 based on the image SD value (predicted value) set in advance by the operator. Is used to calculate and preset display parameters (WW, WL) (step 1002).
The computing unit 107 displays an X-ray CT image on the display unit 109 with the preset display parameters (WW, WL) (step 1003).

  When the operator observes the displayed X-ray CT image and determines that the display parameter is not appropriate (NO in step 1004), the operator sets an optimal display parameter (step 1005). By freely changing the display parameters for the displayed image, it is possible for the operator himself to set conditions that seem to be most appropriate. As a setting method, for example, the display parameter is changed through an operation such as moving a track bar or inputting a numerical value for an image displayed by the operator.

When changing the display image quality of the X-ray CT image 11 shown in FIG. 4A, the operator resets the value of the pixel value width 7 (WW) of the display parameter, and the X-ray CT shown in FIG. An image 13 is obtained. This process is equivalent to changing the display parameter coefficient (k ₁ ) from “k ₁ = 25” to “k ₁ = 6”. In FIG. 4A, the identification object 14 having a large pixel value width 7 (WW) and low contrast cannot be clearly identified. On the other hand, as shown in FIG. 4B, by setting the pixel value width 7 (WW) to be small, the noise 12 is somewhat emphasized, but the identification object 14 can be displayed more emphasized.

The computing unit 107 redisplays the X-ray CT image on the display unit 109 with the reset display parameters (WW, WL) (step 1006).
When the operator observes the displayed X-ray CT image and determines that the display parameter is appropriate (YES in step 1004), the calculation unit 107 updates the display parameter (WW, WL) and stores it in the storage unit 111. Store (step 1007), and the process ends. Note that the display parameter coefficients (k ₁ , k ₂ ) may be updated as the display parameters are updated.

  Note that the image SD value used for the calculation for calculating the display parameter may be calculated using the pixel value of the X-ray CT image after imaging instead of the image SD value (predicted value) set before imaging. good.

  Regarding the median pixel value 9 (WL), a preset value may be set in advance for each imaging region of the subject, or may be calculated using the pixel value of the actually captured X-ray CT image. Also good.

In addition, regarding the preset values of the display parameter coefficients (k ₁ , k ₂ ), appropriate values may be set for each imaging region of the subject. For example, display parameter coefficients having different values such as “k = 20” for the abdomen and “k = 30” for the head may be set.

When performing a contrast examination, the predicted pixel value of the contrast object may be set as the median pixel value 9 (WL). The value of the display parameter coefficient (k) may be set in advance, or the value of the display parameter coefficient (k) is automatically set for each operator with reference to images with different noise levels taken in the past. May be.
Note that the value of the pixel value width 7 (WW) or the pixel value median value 9 (WL) is not limited to the calculation formulas shown in the formulas (1) and (2).

As described above, the medical image display apparatus according to the first embodiment automatically calculates the display parameters based on the set image SD value and displays the medical image. Visibility and diagnostic ability can be improved. Even if the contrast difference between the identification object and the background is small, it is possible to display with the optimum display parameters.
In addition, the operator can sequentially adjust the display parameters. The operability can be improved by presetting an appropriate display parameter coefficient in advance for each imaging region.

(3-2. Display Parameter Setting Process According to Second Embodiment)
Next, display parameter setting processing according to the second embodiment will be described with reference to FIGS. 5 and 6. The second embodiment shows a medical image display apparatus that calculates display parameters based on image feature amounts of pixels included in a ROI (Region Of Interest) set in an X-ray CT image.
FIG. 5 is a flowchart of the display parameter setting process.
FIG. 6 is a diagram showing the ROI 17 set in the X-ray CT image 15.

  The dose optimization processing unit 201 of the calculation unit 107 adjusts the dose of the scanner unit 103 based on the image SD value input before photographing the subject. The scanner unit 103 of the medical image display apparatus 100 performs an imaging process, acquires imaging data, and sends it to the calculation unit 107. The computing unit 107 reconstructs the acquired imaging data as an X-ray CT image by the image reconstruction processing unit 203. Further, the calculation unit 107 performs display processing by the display processing unit 205, and displays the X-ray CT image 15 (see FIG. 6) on the display unit 109 (step 2001).

The calculation unit 107 acquires image data of the ROI 17 area set by the operator (step 2002). The operator sets the ROI 17 by a mouse operation or the like near the identification target region (region to be observed) of the displayed X-ray CT image 15. The number of ROIs 17 to be set is arbitrary. In FIG. 6, two ROIs 17-1 and ROI 17-2 are set.
The computing unit 107 calculates an average pixel value and an image SD value of the pixel values included in the set ROI 17 (step 2003).

The calculation unit 107 calculates and presets display parameters (WW, WL) based on the calculated average pixel value of the ROI 17 and the image SD value (step 2004). For example, the calculation unit 107 presets the value of the median pixel value 9 (WL) to the average pixel value of the ROI 17. Further, the calculation unit 107 sets the display parameter coefficient (k ₁ ) to an appropriate value using the equation (1) described in the first embodiment, and presets the value of the pixel value width 7 (WW).
The calculation unit 107 displays the X-ray CT image 15 on the display unit 109 with the preset display parameters (WW, WL) (step 2005).

  The processing from step 2006 to step 2009 is the same as the processing from step 1004 to step 1007 of the first embodiment.

  In the second embodiment, the ROI 17 has a circular shape, but an operator's desired shape such as a free curve, a rectangle, or a polygon can be designated. Further, the ROI 17 set on the X-ray CT image 15 can be moved and adjusted in size by the operator operating the mouse. Further, it may have a function of changing the image characteristics based on the image information of the movement destination of the ROI 17.

  If there are a plurality of ROIs 17 set in step 2002, an image is displayed according to the analysis result of each ROI 17. For example, when the operator selects a number assigned to the ROIs 17-1 and 17-2, the calculation unit 107 displays an image with display parameters calculated based on the image feature amount of the ROI 17 to be observed.

  As described above, the medical image display apparatus according to the second embodiment sets a region of interest in an object, calculates a display parameter based on an image feature amount of the region of interest, and displays a medical image. Visibility and diagnostic ability can be improved by improving the discrimination of the object.

(3-3. Display Parameter Setting Process According to Third Embodiment)
Next, display parameter setting processing according to the third embodiment will be described with reference to FIGS. 7 and 8. In the third embodiment, display parameters for CAD image display processing in a CAD (Computer Aided Detection) system for X-ray CT images and the like are calculated.
FIG. 7 is a flowchart of the display parameter setting process.
FIG. 8 is a diagram showing candidate points 21 set on the X-ray CT image 19 by the CAD system and the ROI 22 surrounding the candidate points.

  The medical image display apparatus 100 displays the acquired X-ray CT image 19 (see FIG. 8) on the display unit 109 (step 3001). The medical image display apparatus 100 displays the abnormal candidate point 21 on the X-ray CT image 19 (step 3002). The abnormality candidate point 21 is an area determined to be abnormal based on the pixel value information of the X-ray CT image 19. The abnormality candidate point 21 is automatically extracted by the CAD system. The number of abnormality candidate points 21 is arbitrary. In FIG. 8, two abnormality candidate points 21-1 and 21-2 are set.

The calculation unit 107 sets the ROI 22 in the region including the abnormality candidate point 21, and calculates the average pixel value and the image SD value of the pixels included in the ROI 22 (step 3003).
The computing unit 107 calculates and presets display parameters (WW, WL) based on the calculated average pixel value and image SD value (step 3004). For example, the calculation unit 107 presets the average pixel value of the ROI 22 to the pixel value median value 9 (WL). Further, the calculation unit 107 sets the display parameter coefficient (k ₁ ) to an appropriate value using the equation (1) described in the first embodiment, and presets the value of the pixel value width 7 (WW).
The computing unit 107 displays the X-ray CT image 19 on the display unit 109 with the preset display parameters (WW, WL) (step 3005).

  The processing from step 3006 to step 3009 is the same as the processing from step 1004 to step 1007 of the first embodiment.

  In FIG. 8, when the operator selects the abnormality candidate point 21-1, the display parameter is changed according to the analysis result of the ROI 22-1 surrounding the abnormality candidate point 21-1, and the X-ray CT image 19 is displayed. When the operator selects the abnormality candidate point 21-2, the display parameter is changed according to the analysis result of the ROI 22-2 surrounding the abnormality candidate point 21-2, and the X-ray CT image 19 is displayed.

  In the third embodiment, an image after optimally setting display parameters and an image before being optimized (original image) may be displayed on the display unit 109 at the same time. Further, when there are a plurality of abnormality candidate points 21, an image is displayed according to the analysis result of the ROI 22 at each abnormality candidate point 21. The operator can display the optimum image of the region to be observed by designating the position or number of the abnormality candidate point 21.

  Further, the shape and size of the ROI 22 surrounding the abnormality candidate point 21 can be freely changed by the operator from the shape (for example, a circle) at the time of detecting the lesion of the subject. For example, when the ROI 22 at the time of detecting a lesion extends over an area having very different pixel values, the shape of the ROI 22 is corrected, the appropriate ROI 22 is reset, and the image feature amount is reanalyzed.

  Further, when there are a plurality of ROIs 22, a plurality of images optimized with the image feature amount of each ROI 22 may be displayed together with the original image. Further, in the display parameter setting operation, optimal display parameters (WW, WL) may be set for each part of the subject in advance using a simulation image or a phantom image instead of the displayed medical image.

  As described above, the medical image display apparatus according to the third embodiment sets a region of interest around the abnormal candidate point detected by the CAD system, and displays an image based on the image feature amount of the region of interest. The region of interest can be set efficiently, and the distinguishability of abnormal candidate points can be improved to improve the visibility and diagnostic ability.

  When a plurality of ROIs 22 are set, the display parameters are changed by sequentially specifying the target ROIs 22 by the operator. Therefore, even with the same X-ray CT image 19, images can be observed with different image images, and more accurate diagnosis can be performed.

(3-4. Display Parameter Setting Process According to Fourth Embodiment)
Next, display parameter setting processing according to the fourth embodiment will be described with reference to FIGS. The fourth embodiment shows a medical image display device that calculates display parameters from image feature amounts of pixel values included in a set ROI and image feature amounts of pixel values of a background region of the ROI.
FIG. 9 is a flowchart of the display parameter setting process.
FIG. 10 is a diagram showing the ROI 27 set in the X-ray CT image 23 and the comparison area 25 in the background area.
FIG. 11 is a diagram showing the setting of the luminance correction line 35 based on the pixel value frequency 31 of the pixel value 3 in the ROI 27 and the comparison area 25.

  The scanner unit 103 of the medical image display apparatus 100 performs an imaging process, acquires imaging data, and sends it to the calculation unit 107. The computing unit 107 reconstructs the acquired imaging data as an X-ray CT image by the image reconstruction processing unit 203. Further, the calculation unit 107 performs display processing by the display processing unit 205 to display the X-ray CT image 23 (see FIG. 10) on the display unit 109 (step 4001).

  The calculation unit 107 acquires pixel values related to the comparison region 25 and the ROI 27 set by the operator. In FIG. 10, the operator sets the comparison region 25-1 along the contour of a specific organ, and sets the ROI 27-1 that is the region of interest as a tumor in the organ. Alternatively, the comparison region 25-2 may be set as a rough region, and the ROI 27-2 may be set as a region of interest inside the comparison region 25-2. The number of comparison areas 25 and ROIs 27 to be set is arbitrary. The calculation unit 107 calculates an average pixel value and an image SD value of the pixel values of the comparison area 25 and the ROI 27 (step 4002).

The computing unit 107 creates a histogram 29-1 indicating the pixel value frequency 31 of the pixel value 3 in the comparison area 25-1 (step 4003). In the histogram 29-1 shown in FIG. 11, the minimum pixel value P _MIN 33-1, the maximum pixel value P _MAX 33-2, and the average pixel value P _AVR 33-3 are shown.

The computing unit 107 creates a histogram 29-2 indicating the pixel value frequency 31 of the pixel value 3 of the ROI 27-1 (step 4003). In the histogram 29-2 illustrated in FIG. 11, the average pixel value Q _AVR 33-4 and the image SD value Q _SD 33-5 are obtained.

The computing unit 107 performs luminance value correction based on the calculated histogram 29-1 and histogram 29-2 (step 4004).
By performing the luminance value correction, it is possible to display an image that emphasizes the region of the ROI 27-1 set inside the comparison region 25-1.

  Specifically, in the process of step 4004, the calculation unit 107 creates the brightness correction line 35 shown in FIG. 11 and associates the pixel value 3 and the brightness value 5 with each other. The luminance value correction line 35 is a broken line composed of the luminance correction line 35-1 to the luminance correction line 35-3. Assuming that the value of pixel value 3 is “X” and the value of luminance value 5 is “Y”, the luminance correction lines 35-1 to 35-3 are represented by the following equations (3) to (5), respectively. It is represented by

In the range of “P _MIN ≦ X <Q _AVG -Q _SD / 2”
Y = a (X−x ₁ ) + y ₁ (3)
In the range of “Q _AVG -Q _SD / 2 ≦ X <Q _AVG + Q _SD / 2”,
Y = b (X−x ₂ ) + y ₂ (4)
In the range of “Q _AVG + Q _SD / 2 ≦ X <P _MAX ”,
Y = a (X−x ₃ ) + y ₃ (5)

“A” and “b” indicate the inclination of the straight line. “A” <“b”. x1 to x3 and y1 to y3 are an x intercept and a y intercept, respectively. When “X = P _MIN ”, “Y = 0”, and when “X = P _MAX ”, “Y = 255”.

In the range of the image SD value Q _SD 33-5 of the ROI 27-1 that is the region of interest, the slope (b) of the brightness correction line 35-2 is the slope of the brightness correction line 35-1 and the brightness correction line 35-3 (a ) And larger than that. That is, by setting the pixel value width 7 (WW) of the display parameter to be narrow, the number of gradations of the luminance value 5 assigned to the pixel value 3 of the ROI 27-1 is increased. On the other hand, for the pixel values in the other regions, the number of gradations of the luminance value 5 assigned to the pixel value 3 is reduced by setting the pixel value width 7 (WW) of the display parameter wide. In this way, the display of the ROI 27-1 can be emphasized.

  Returning to FIG. 9, the calculation unit 107 displays the X-ray CT image 23 on the display unit 109 with the set display parameters (WW, WL) (step 4005).

  The processing from step 4006 to step 4009 is the same as the processing from step 1004 to step 1007 of the first embodiment. In step 4007, the calculation unit 107 creates the brightness correction curve 35 according to the operator and updates the display parameters.

The medical image display apparatus 100 displays the histogram 29 and the luminance correction line 35 shown in FIG. 11 on the display unit 109, and the operator freely changes the shape of the luminance correction line 35 by a mouse operation or the like. , WL) may be changed. Further, the luminance correction line 35 is not limited to a straight line, and may be set freely such as a curved shape.
The luminance correction line 35 may be preset for each organ site.

  As described above, the medical image display apparatus according to the fourth embodiment compares the image feature amount of the region of interest with the image feature amount of the comparison region, calculates the display parameter, and displays the medical image. The brightness values of the surrounding organs are also reflected in the analysis results, and optimal display parameters can be set without significantly losing the surrounding information. Therefore, the visibility of the region of interest can be improved and the visibility and diagnostic ability can be improved. . For example, by setting an organ as the comparison region and setting a tumor as the region of interest, the display parameters can be set to highlight the tumor.

(4. Other)
In the present invention, the image SD value is used as the image feature amount, but a CNR (Contrast to Noise Ratio), a Wiener spectrum, or the like can also be used. The Wiener spectrum is a method for frequency analysis of noise fluctuations in an image.

Further, the present invention can be applied not only to optimization of display parameters in a two-dimensional image but also to a three-dimensional image. That is, the display parameter calculation based on the image feature amount according to the present embodiment is applied to a plurality of two-dimensional images for forming a three-dimensional image. When reconstructing a three-dimensional image using the plurality of two-dimensional images, the identification target part can be displayed more clearly.
The present invention can also be applied to medical images other than X-ray CT images. In the above-described embodiment, the X-ray CT apparatus is taken up as the medical image display apparatus, but the present invention can also be applied to other apparatuses such as an MR apparatus.

  The technical scope of the present invention is not limited to the embodiment described above. It will be apparent to those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea disclosed in the present application, and these are naturally within the technical scope of the present invention. Understood.

Configuration diagram of medical image display apparatus 100 Explanatory drawing of pixel value width (WW) and pixel value median value (WL) Flowchart showing the first embodiment The figure which shows the X-ray CT image by the difference in display parameter Flowchart showing the second embodiment Diagram showing ROIs 17-1 and 17-2 Flowchart showing the third embodiment The figure which shows candidate points 21-1 and 21-2 Flowchart showing the fourth embodiment The figure which shows the comparison area | region 25-1 and ROI27-1. The figure which shows the setting of the brightness | luminance correction line 35

Explanation of symbols

3 ... Pixel value 5 ... Luminance value 7 ... Pixel value width (WW)
9 ..... Median pixel value (WL)
11, 13, 15, 19, 23 ......... X-ray CT image 12 ......... noise 14 ......... identification object 17-1, 17-2, 22-1, 22-2, 27-1, 27- 2 ... ROI
21-1, 21-2 .... Abnormal candidate points 25-1, 25-2 .... Comparison areas 29-1, 29-2 .... Histogram 31 .... Pixel value frequency 33-1 .... P _MIN (minimum value of histogram 29-1)
33-2... P _MAX (maximum value of histogram 29-1)
33-3... P _AVG (average value of histogram 29-1)
33-4 ... Q _AVG (average value of histogram 29-2)
33-5 .... Q _SD (standard deviation of histogram 29-2)
35-1 to 35-3... Luminance correction line 100... Medical image display device 103... Scanner unit 105 ... Operation unit 107 ... Calculation unit (CPU)
109 ......... Display unit 111 ......... Storage unit 201 ......... Dose optimization processing means 203 ......... Image reconstruction processing means 205 ......... Display processing means

Claims (3)

An image information acquisition unit that acquires image information in the subject, an arithmetic processing unit that performs arithmetic processing on the acquired image information, a holding unit that holds the image information and arithmetic processing results, and displays the image information and the arithmetic processing results A medical image display device comprising:
Dose optimization processing means for adjusting a dose to be irradiated to the subject based on an image quality index value input or set in advance before subject imaging; and
Display parameter setting means for setting a display parameter for displaying the image information on the display unit based on the image quality index value used in the dose optimization processing means ,
The image information acquisition unit acquires image information of the subject at a dose adjusted by the dose optimization processing unit,
The medical image display device, wherein the arithmetic processing unit performs arithmetic processing to display the image information on the display unit with the display parameter set by the display parameter setting unit. After displaying the image information on the display unit, further comprising a display parameter changing means for accepting the change of the display parameter,
The medical processing according to claim 1, wherein when the display parameter is changed by the display parameter changing unit, the arithmetic processing unit performs arithmetic processing so that the image information is re-displayed with the changed display parameter. Image display device.   The medical image display apparatus according to claim 1, wherein the image quality index value is registered in advance for each imaging region or for each operator.

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