JP3219105B2 - X-ray image processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray image processing apparatus, and more particularly to an X-ray image processing apparatus suitable for performing an image cropping process in an X-ray imaging apparatus such as an X-ray digital angiography apparatus.

[0002]

2. Description of the Related Art An X-ray digital angiography apparatus enhances an X-ray image of a blood vessel by using a contrast agent. In an image obtained by these X-ray imaging apparatuses, X-rays do not pass through a human body. The area directly incident on the screen (that is, through the space around the human body) has a very high brightness, making it difficult to observe even on a monitor device. Too bad for diagnosis.

Therefore, conventionally, at the time of film exposure, a process (cropping process) of covering this area with data representing black is manually performed while observing an image with a monitor device.

[0004]

However, if the cropping process is performed manually as in the prior art, the operation is complicated, and in some cases, it is very difficult to perform each operation. That is, in angiography of the lower limb, an X-ray image is often obtained while moving the subject relatively to the X-ray optical system and tracking the flow of the contrast agent. In this case, the X-ray is directly incident. Since the area changes from moment to moment, when these images are formed into a film, the cropping process must be manually adjusted one by one, which is a very difficult operation.

SUMMARY OF THE INVENTION In view of the above, the present invention makes it possible to automatically perform a cropping process, increase the efficiency of film exposure work, and improve the inspection throughput.
It is an object to provide an X-ray image processing device.

[0006]

In order to achieve the above object, an X-ray image processing apparatus according to the present invention creates a density profile on a plurality of parallel lines crossing a subject image shown on an X-ray image. Means for extracting the boundary between the object portion and the direct X-ray incident part from the density profile, means for comparing these boundary positions for each density profile, and selecting the outermost boundary, Means for generating a signal that represents a portion outside the boundary with a low-luminance color. That is, a density profile on a plurality of parallel lines crossing the subject image shown on the X-ray image is created, and a boundary between the subject portion and the direct X-ray incident portion is extracted from the density profile, and these boundary positions are determined. It is characterized by comparing each density profile, selecting the outermost boundary, and generating a signal that expresses a portion outside the selected boundary with a low luminance color such as black. Can be automatically performed, so that the film exposure operation can be made more efficient, and the inspection throughput of the subject can be improved.

[0007]

An embodiment of the present invention will be described below in detail with reference to the drawings. In FIG. 1, it is assumed that a recording medium 11 such as a magnetic tape or a hard disk device stores a digital X-ray image obtained by an X-ray imaging device (not shown). The X-ray imaging apparatus generally includes an X-ray generator and an X-ray TV image receiving system (an image intensifier for receiving X-rays transmitted through a subject, a TV camera,
V monitor device) and a device for digitizing a video signal obtained therefrom.

The recording medium 11 stores, for example, a digital angiographic image of the lower limb as shown in FIG. In this image, a human body tissue of a lower limb portion such as a bone 21, a soft tissue 22, a blood vessel 23 is shown, and the periphery thereof is a portion 24 where X-rays are directly incident.

[0009] Such an X-ray image is read from the recording medium 11 and sent to the density profile creation circuit 12.
In this embodiment, the density profile creation circuit 12 extracts image data on three horizontal scanning lines A, B, and C (see FIG. 3) and creates a density profile (signal intensity distribution). You. The horizontal scanning line for creating this density profile can be specified at an arbitrary position so as to cross the subject image, or can be set in advance at an appropriate position. The density profiles on these three horizontal scanning lines A, B, and C are, for example, A, B, and
It looks like C.

Next, these density profiles are sent to the boundary extracting circuit 13 to extract the boundary between the object portion, that is, the soft tissue 22 in this case, and the direct X-ray incident portion 24. More specifically, for example, the profile is differentiated and its sudden change position is caught, and among the sudden change positions, those at the extreme end (leftmost and rightmost) in the scanning line direction (X direction). Take out). In this way, the boundary position is obtained as shown by the arrows in FIGS.

The boundary position information (X coordinate position) for each of these profiles is sent to the maximum value detection circuit 14 and the minimum value detection circuit 15. The maximum value detection circuit 14 and the minimum value detection circuit 15 compare the boundary positions on the three horizontal scanning lines A, B, and C, and determine the maximum value, that is, the boundary position located at the rightmost position, and the minimum value, that is, the position located at the leftmost position. And the boundary position to be detected.

The detected boundary position data is sent to a cropping generator 16. The cropping generation circuit 16 is a circuit for generating a low-luminance color signal that appears black on an image. Based on the input boundary position data, the cropping generation circuit 16 includes the entire part from the left boundary position to the left end and the right boundary position. A signal that represents the portion from to the right end in black is generated. When this signal is superimposed on the original X-ray image, FIG.
Most of the direct X-ray incidence part 24 is covered with a black image as shown in FIG. Since the black image is an appropriate one that does not enter the boundary of the subject image (soft tissue 22), there is no problem in diagnosis.

In the above-described embodiment, the density profiles on a plurality of horizontal scanning lines arbitrarily or preset are created. However, the density profiles may be created for all the horizontal scanning lines. Also, instead of a horizontal line, a density profile is created for a line at a predetermined angle, a subject boundary is extracted, the outermost boundary is detected, and a black image having an edge perpendicular to the line is used. It is also possible to configure to generate a signal that covers the outside of the boundary.

[0014]

As described above, according to the X-ray image processing apparatus of the present invention, the boundary between the subject portion and the direct X-ray incident portion is extracted from the density profiles on a plurality of parallel lines crossing the subject image. Since the portion outside the outermost boundary is represented by a low-luminance color, optimal cropping processing can be automatically performed, the efficiency of film exposure work can be improved, and the inspection throughput can be improved. Especially in the case of images obtained by moving the subject so as to track the contrast agent like lower limb angiography, optimal cropping processing can be automatically performed every time the image changes, so conventional manual work Extremely difficult tasks can be easily performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a view showing an X-ray angiographic image used in the embodiment.

FIG. 3 is a diagram showing horizontal scanning lines for creating a density profile in the angio image.

FIG. 4 is a diagram showing an image of the same angio image after cropping processing.

FIG. 5 is a graph showing a density profile in the example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Recording medium 12 Density profile creation circuit 13 Boundary extraction circuit 14 Maximum value detection circuit 15 Minimum value detection circuit 16 Cropping generation circuit 21 Bone 22 Soft tissue 23 Blood vessel 24 Direct X-ray incidence part

Claims (1)

(57) [Claims] 1. A means for creating a density profile on a plurality of parallel lines crossing a subject image shown on an X-ray image, and a means for extracting a boundary between a subject part and a direct X-ray incident part from the density profile. And a means for comparing these boundary positions for each density profile and selecting an outermost boundary, and a means for generating a signal for expressing a portion outside the selected boundary with a low-luminance color. An X-ray image processing apparatus characterized by the following.