JPH0232894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image display window control device used in a computer-based tomographic imaging device (hereinafter simply referred to as a CT device), etc. This invention relates to an improvement of an image display window control device that has been made possible.

Images reconstructed by a CT device are generally
As shown in Figure 1, the X-ray absorption coefficient (CT value) of water
is "0", the X-ray absorption coefficient of air is "-1000",
The X-ray absorption coefficient of bone is displayed as "+1000".

Here, if X-ray absorption coefficients from -1000 to +1000 are actually displayed on a cathode ray tube (CRT), fine differences in X-ray absorption coefficients cannot be discerned. Therefore, a window mechanism is used to enlarge and display a portion of the X-ray absorption coefficients, for example, 0 to 100, so that fine differences in X-ray absorption coefficients can be observed in black and white. At this time, if it is desired to change the displayed portion of the X-ray absorption coefficient to be enlarged, it is necessary to be able to independently vary the setting of the window center level and window width for enlarged display.

FIGS. 2A and 2B are diagrams showing a conventional example of an image display window control device in which the settings of the window center level and window width are variable.

In the conventional example shown in FIG. 2A, two levers, a lever LEVEL for setting the window center level and a lever WIDTH for setting the window width, are provided on the operation panel. When the lever LEVEL is manually moved and held upward, the window center level gradually rises, and when it is moved and held downward, the window center level gradually falls. Further, when the lever WIDTH is moved and held upward, the window width gradually increases, and when the lever WIDTH is moved and held downward, the window width is gradually reduced.

Here, the number of control pulses increases and decreases according to the movement and holding time of the levers LEVEL and WIDTH, respectively, and the window center level and window width are controlled by the number of control pulses. It's getting old.

The conventional example shown in Fig. 2B uses a dial system instead of the lever system, and the direction of vertical movement of the window center level and the expansion or contraction of the window width are determined by the direction of rotation of the dial. . The amount of change in the window center level and window width is controlled by the number of control pulses depending on the rotation angle of the dial.

In such conventional image display devices, large adjustments when the amount of change in the window center level and window width are large, and fine adjustments when the amount of change is small conflict with each other in terms of operational interests. The drawbacks were that it took too much time to set the window center level and window width, and the operability was poor.

An object of the present invention is to eliminate the drawbacks of the prior art, to rotate a slit rotary plate having one or a plurality of slits arranged at equal intervals in the radial direction, and to rotate the slit rotary plate according to the rotational speed of the slit rotary plate. To provide an image display window control device, which is equipped with a means for setting the amount of change, and rotates a rotary plate quickly when a large amount of change is desired, and rotates slowly when a small amount of change is desired. be.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 3 is a sectional view showing the control pulse signal generation mechanism of this embodiment, and FIG. 4 is a plan view of the slit rotating plate of FIG. 3.

In the figure, 1 is the control panel, 2 is the window control dial, and 3 is the window control dial 2.
The rotating shaft 4 is a slit rotary plate, and as shown in FIG.
A is provided. This slit rotary plate 4 is attached to the rotary shaft 3 of the window control dial 2, and the rotary shaft 3 is rotatably supported by a support member 5. 6 is a slit detector that uses light and converts the slit into a pulse signal.

FIG. 5 is a configuration diagram of the window control circuit of this embodiment, where 7 is a counter that counts the pulse signal from the slit detector 6 of FIG. 3, 8 is a latch circuit that latches the output of the counter 7, and 9 is a nonlinear circuit for increasing the number of set window levels, and uses, for example, a squaring circuit consisting of a multiplier.
10 is a computer read gate circuit, and 11 is a control circuit for controlling each of the circuits.

FIG. 6 is a diagram for explaining the operation of this embodiment, in which a is a counter reset signal, b is a latch signal, c is a nonlinear circuit calculation output signal, and d is a computer read gate signal.

Next, the operation of this embodiment will be explained.

When the window control dial 2 is rotated to the right, the slit rotating plate 4 is rotated. The amount of rotation of the slit rotating plate 4 is output as a pulse signal by detecting the number of slits in the slit 4A with the slit detector 6. The pulse signal from the slit detector 6 is input to the counter 7, but at this time, the counter 7 resets the count to zero by the counter reset signal a from the control circuit 11, and then inputs the pulse signal. It's getting old. The pulse signal is input to a counter 7 and counted for a certain period of time T, for example 0.2 seconds.
This counted value is transferred to the latch circuit 9 at the next stage by the next latch signal b, and the counter 7 is reset by the counter reset signal a to start the next count. The output of the latch circuit 8 is input to a non-linear circuit 9 and calculated. After this calculation, the calculated value is read by the computer CPU using the computer read gate signal d, and the window center level and window width of the window display are changed.

Here, when the window control dial 2 is rotated quickly, a large number of slits 4A provided on the slit rotary plate 4 are detected during a certain period of time, and when the window control dial 2 is rotated slowly, the number of slits 4A detected is large. Taking advantage of the fact that the number of 4A is small, the window control dial 2 is rotated quickly for adjustment with a large amount of change, and rotated slowly for fine adjustment with a small amount of change. Furthermore, the reason why the number of slits detected is increased by the non-linear circuit 9 is to expand the number of set window levels and to speed up the operation when the amount of change is large.
FIG. 7 shows the relationship between the window control dial rotation speed and the number of computer read pulses.

It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without changing the gist thereof. For example, although a square circuit is used as the non-linear circuit, it is also possible to use a circuit multiplied by n, such as a 1.5 power or a cube circuit, and obtain the value through experiment. Further, all functions of the control circuit shown in FIG. 5 may be performed by a computer.

As explained above, according to the present invention, the slit rotating plate having one or more slits in the radial direction is rotated, and the amount of change can be set according to the rotational speed of the slit rotating plate. The amount of change can be controlled by changing the rotational speed of the window control dial, and it can be changed continuously in response to the rotational speed as well as low and high speeds. As a result, the window center level and window width can be freely set, and the setting time can also be shortened. Moreover, operability can also be improved.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining the window function, FIGS. 2A and B are diagrams showing a conventional example of an image display window control device with variable settings for the window center level and window width, and FIG. 3 4 is a plan view of the slit rotating plate of FIG. 3, and FIG. 5 is a window control circuit of an embodiment of the present invention. FIG. 6 is a diagram for explaining the operation of the embodiment shown in FIGS. 3 to 5, and FIG. 7 is a diagram showing the relationship between the number of rotations of the window control dial and the number of computer read pulses. It is. In the figure, 1... Operation panel panel, 2... Window control dial, 3... Window control dial rotation axis, 4... Slit rotary plate, 5... Support member, 6... Slit detector, 7...Counter, 8...Latch circuit, 9...Non-linear circuit, 10
. . . Computer read gate circuit, 11 . . . Control circuit.

Claims (1)

[Claims] 1. In an image display window control device having means for controlling the window center level and window width, a slit rotary plate provided with one or a plurality of equally spaced slits in the radial direction for setting the window center level and window width. a slit detector that uses light to detect the slits in the slit rotary plate and convert them into electrical signals; and a sample-and-hold circuit that samples the output of the slit detector at a fixed time and holds it. An image display window control device comprising: a non-linear circuit that converts the output of the sample-and-hold circuit into a non-linear output.