JPS61172541A - Double window display apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a double window display device used in a medical image diagnostic apparatus such as an X-ray CT apparatus.

Although medical imaging diagnostic equipment such as prior art X-ray CT equipment provides significant data for each pixel, determining how to display this data is a problem. For example, when displaying in 256 gray levels from white to black, the problem is which range of data should be displayed within the limited range from white to black. Take the example of an X-ray CT device.

The data obtained for each pixel is called a CT value, and this CT value can take a wide range of values from -1000 to +1000. However, when looking only at areas such as the lungs and heart, the range of possible CT values is narrow. Therefore, if a region has a region of interest, the most appropriate display method for diagnosing that region is to make the maximum and minimum CT values that can be obtained in that region span the entire width of the gray scale. I can do it.

Settings for this display method are 1. Normally, the type of data (X
Based on experience, the display median value (Mean value) and display width (data obtained with a CT scanner or other medical image diagnostic equipment) and location W
This is done by determining the indow value). Although the description has been made using gray level display, the same applies to color display.

By the way, a technique called double window display is often used in X&ICT devices and the like. This is because, for example, when an image of the entire chest is obtained by photographing the chest, images of two areas with different CT values, such as the lungs and the heart, are obtained in one image. In such a case, the display median value and display width are set separately for each part, and the images of these two parts are displayed in one image.

Problems to be Solved by the Invention Conventionally, this double window display was performed by the operator inputting the display median value and display width corresponding to the two parts, so it was necessary to input these values one by one. Not only is it inconvenient to have to do this, but the setting also requires skill and can only be done by a skilled operator. .

The present invention automatically detects an appropriate display median value and display width for each of a plurality of separated data parts when displaying a double window, and automatically sets the values to those values for display. It is an object of the present invention to provide a double window display device which eliminates the above inconvenience and allows even an unskilled operator to easily make appropriate settings.

Means for Solving the Problems A double window display device according to the present invention includes means for creating a histogram of all data for one image;
means for determining the display median value and display width for each region from the intersection of the histogram and the threshold level; means for selecting data based on the display median value and display width for each region; and data conversion means for converting the selected data according to the display median value and display width for each.

Effect First, when a histogram of all data for one image is created, peaks appear corresponding to, for example, the lungs and the heart. Therefore, we decided to display only the data that exceeded the threshold level, and
The intersection point with the field level is found, and from this the display median value and display width for each region are found. Then, if you select only the data within the range determined by the display median value and display width,
0 This means that only the data for the lung and heart parts are selected.
Next, this selected data is converted according to the display median value and display width. Then, the data for the ranges selected for the lung and heart regions are displayed at the desired scale, respectively.
For example, each can be displayed in full grayscale on one screen.

Embodiment In FIG. 1, a memory 1 stores one screen worth of data sent from, for example, an X@CT device. First, this data is read out and sent to the arithmetic unit 2, where a histogram is created.

That is, the number of pixels is checked for each CT value, and a histogram as shown in FIG. 2A is created with the CT value on the horizontal axis and the number of pixels on the vertical axis. Then, the intersection between this histogram and the threshold level T is determined. The threshold level T is the number of pixels determined empirically, and is set automatically or manually. The pixels in the portion exceeding the threshold level T are those of the heart region and the lung region, for example. Therefore, it is sufficient to select only the pixels in the portion exceeding the threshold level T, convert them to a desired gray scale, and mask the other portions.

Therefore, find the intersection of the histogram and the threshold level T, and from this find the display widths W1, W2, the median value of the display width Wl (display median value) M■, and the median value of the display width W2 (display median value) M2. . And this Wl, Ml
The value of W2 is sent to the comparator 3 and the conversion table 5, and
．． The value of M2 is sent to the comparator 4 and the conversion table 6.

The CT value of each pixel read from memory 1 is:

Sent to comparator 3.4. The comparators 3.4 each constitute a so-called window comparator, and select only data whose median values are M1 and M2 and whose widths are within W1 and W2, respectively. These selected data are converted into conversion table 5.
6 for data conversion. For example, W42 diagram B
As shown by the solid line, the data in the wt, W2 range is expressed in full gray scale, that is, from black (0) to white (255).
If you want to display all of the 256 steps up to
Convert each to a numerical value up to J.

Each converted data is converted into an analog signal by the D/A converter 7 and sent to the display device 8. In this way, for example, images of the heart and lungs can be displayed on one screen of the display device 8, even though their original CT values are different from each other.

Displayed in the same full grayscale. In images other than the heart and lungs, the CT value of that pixel is both Wl and W.
Since it does not fall within 2, all CT values are "O"
, that is, it is masked.

Note that instead of displaying both parts in full grayscale as described above, the grayscale is divided in half, and the black half is assigned to the area consisting of data in the range of Wl, and the white half is assigned to the area consisting of data in the range of W2. Apply to the part consisting of the data,
The conversion characteristics can be changed in various ways, such as by performing the conversion shown by the dashed-dotted line in FIG. 2B.

Effects of the Invention By using the double window display device according to the present invention, it is possible to set a plurality of display median values and display widths in a double window display, which is troublesome, time-consuming, and requires skill.
Since this can be done automatically, even an unskilled operator can make appropriate settings without much effort.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2A,
B is for explaining the operation in Fig. 1, and Fig. 2 A is for CT.
A graph showing a histogram of values, Figure 2B is a graph showing conversion characteristics for converting CT values into gray levels =

Claims (1)

[Claims] (1) A means for creating a histogram of all data for one image, a means for determining a display median value and a display width for each region from the intersection of this histogram and a threshold level, and a display median value for each region. A double window display device comprising means for selecting data based on the display width and display width, and data conversion means for converting the selected data according to the display median value and display width for each region.