JPS61172539A - X-ray diagnostic 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 an X-ray diagnostic apparatus having a thickness measurement function.

Conventional technology X-ray images conventionally used for X-ray diagnosis, including X-ray film, are X-ray transmission images based on changes in the intensity of X-rays that have passed through the object being examined, and the information obtained includes thickness This information is a combination of information on absorption per unit volume and information on absorption per unit volume.

In FIG. 5, consider the X-rays that pass through the object 1 to be inspected. Adjust the intensity of X-rays incident on the object to be inspected 1. .

The X-ray intensity after passing through the object to be inspected is I, , I, and the thickness of the object 1 to be inspected through which the X-rays pass is x 1. x 2 e
Assuming that the average absorption coefficient of the portion through which the line passes is μm and μ2, the following equation holds true.

I, = Ioexp (-μm ・x,) ・
"..."(') I = I exp (-μ ・I )
・・・・・・・・・(Smell 2 o
2 2 Thus, as a component of an image called a normal X-ray transmission image, it has the parameter μ·I, which is the product of the absorption coefficient of the path through which X-rays pass and the length of the path.

An example of a conventional X-ray transmission image including such parameters is shown in FIG. In Fig. 6, a is a schematic diagram of a chest X-ray transmission image, and bK shows the transmitted X-ray intensity distribution on the line connecting A-.
show. In the X-ray transmission image shown in b, if there is a part with weak transmitted X-ray intensity, it can be analyzed that the value of μ・I is large. I can't tell if it's thick or not. Therefore, in order to interpret (diagnose) a normal X-ray image, it is necessary to memorize the shape and morphological pattern of the human body (examined body) through medical training, and then to make a mental image while looking at the X-ray image from experience. Performing pattern recognition.

Problems to be solved by the invention In recent years, it has become possible to perform various types of image processing electrically.
The diagnostic ability of X-ray transmission images has also been improved through image processing, but as mentioned above, the X-ray transmission images themselves contain information on the thickness of the object being examined, which is the most important information in diagnosis. Information regarding only the absorption coefficient, which is a parameter, cannot be obtained, and image processing is also limited.

The present invention solves the above-mentioned drawbacks, and by removing the parameter of the thickness of the object to be inspected from the X-ray transmission image, a new image consisting of only the average absorption coefficient of the object to be inspected is created. It is an object of the present invention to provide an X-ray diagnostic apparatus having a new diagnostic function that facilitates morphological observation.

Means for Solving the Problems The X-ray diagnostic apparatus of the present invention measures the thickness of the photographed portion of the object to be examined, and converts the X-ray transmission image into an electrical signal into an electrical image of the object to be examined. This method removes parameters depending on the thickness of the .

Effect of the present invention By using the above-described means to remove the parameter based on the thickness of the subject, the parameter based on the thickness of the subject included in the X-ray transmission image information obtained by conventional imaging is removed. By separating the X-ray absorption coefficient and the parameter based on the X-ray absorption coefficient of the substance constituting the object to be inspected, it is possible to obtain an image consisting only of the average absorption coefficient of the substance.

Example: Potato The principle of the invention will be explained below with reference to the drawings.

FIG. 2 is a principle diagram showing changes in intensity when X-rays pass through an object to be inspected. In the figure, the horizontal axis I indicates position, and the vertical axis d(x) indicates thickness. Tested object 1 at position I
Manipulate the incident X-ray intensity. (Transmission of the tested pot body 1 etc.
The line intensity is I (x), and X at the position X of the inspected object 1
The thickness of the line passing through is d(z)', and the passing part (
If the average absorption coefficient of the ray part in the figure is μ(I), the following equation holds true.

I(”)=Eng.0(x)exp(-μ0・dO) −
−−(3) Taking the logarithm on both sides, f(z) = μ(x)−d(x) −
...--4 It can be expressed as the product of absorption coefficient μ(I) and thickness d(ri).The signal of a conventional X-ray transmission image is
Transmitted X-ray ■ By taking the logarithm of the image signal, the X-ray transmitted image signal becomes a signal consisting of the product of the average absorption coefficient μ and the thickness d. Here, by measuring the information on the thickness d in advance and subtracting the value of the thickness of the object to be inspected from the X-ray transmission image signal, the It is possible to convert the image into an image consisting only of values of the average absorption coefficient.

Embodiments using the principles of the present invention as described above will be described with reference to the drawings. FIG. 1 is a configuration diagram of an X-ray diagnostic apparatus according to the present invention. To obtain a conventional X-ray transmission image, the inspected object 1 is irradiated with X-rays emitted from the X-ray generator 2 whose output is controlled by the X-ray controller 5, and the intensity of the transmitted X-rays is The line sensor 3 detects the image, and the image is displayed on the display 8 through the main controller 6 and image processor 7.

In order to remove the thickness parameter from the obtained X-ray transmission image, first, the thickness of the photographed region of the subject is measured using the thickness measuring devices 4, 4'. Next, the main controller 6,
By removing the thickness parameter included in the transmitted X-ray intensity through the image processor 7, an image of the average absorption coefficient distribution can be obtained.

The thickness measuring devices 4 and 4' used in this example are measuring devices that measure the thickness from a moire image, and include a checkered stripe projector, a camera that takes a moire image generated on the object to be inspected, and a moire image (i.e., a contour line). It consists of a processing section that measures the two-dimensional thickness distribution of the inspected object from the image). An example of the thickness distribution obtained by this measuring device is shown in FIG. In the figure, a is the obtained moiré image, and the thickness distribution of the object to be inspected can be determined from the contour lines. The thickness distribution on the line connecting A-A' in a is obtained by connecting the contour lines by quadratic curve approximation, as shown in b.

FIG. 4 shows an example of obtaining an image of the average absorption coefficient distribution by the above method. A is a normal X-ray transmission image, and A in the figure
If we take the transmitted X-ray intensity on the line connecting -A/, its value is the product of the average absorption coefficient μ(x) and the thickness d
The thickness distribution on the line connecting l/CA-A' is shown. By dividing the logarithm value of the transmitted X-ray intensity distribution by this value d, a distribution d consisting of the average absorption coefficient can be obtained.

As the X-ray sensor that can be used in the present invention, a sensor that can convert transmitted X-ray intensity into an electrical signal can be used.

For example, if a combination of an X-ray image intensifier and an image pickup tube (so-called X-ray television) is used, the transmitted X-ray intensity can be extracted as a video signal. Also, S i
, Go, GaAs.

The transmitted X-ray intensity is measured by scanning an X-ray sensor array using a semiconductor detector such as CdTe or HgI, an Xs ionization sensor array, a sensor array using a phosphor and an optical sensor, etc., and converted into an electrical signal. can be converted.

In addition to the above-mentioned moiré image measuring device, the thickness measuring device used in the present invention can be used to measure the thickness by scanning the object to be inspected with a laser beam and detecting the distance to the object from the reflected light. It is also possible to use a measuring device etc.

Effects of the Invention The present invention includes an X-ray diagnostic apparatus equipped with a thickness measuring device for an object to be inspected,
By removing the parameter of the thickness of the object contained in the X-ray transmission image information obtained by conventional radiography, it is possible to convert it into image information consisting only of the absorption coefficient of the object. Diagnosis efficiency can be greatly increased because only information from absorption can be directly viewed.

Furthermore, if this device is used not only for medical purposes but also for destructive inspection, by removing the shape of the object to be inspected from the image, it is possible to identify not only the shape inside the object but also the substance.
In addition, for example, when there is a cavity in both parts, the depth of the cavity was previously unknown, but by removing the parameter of the thickness of the object, it is now possible to measure the depth of the cavity, which is extremely useful. Useful.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the outline of the configuration of the X-ray diagnostic device of the present invention, Fig. 2 is a principle diagram showing the change in intensity when X-rays pass through an object, and Fig. 3 is a diagram showing how the Figure 4 is a diagram showing an example of the obtained thickness distribution. Figure 4 is a diagram showing a method for obtaining an image of the average absorption coefficient distribution. Figure 6 is a diagram showing changes in X-rays passing through the object to be inspected. is a schematic diagram showing a chest X-ray transmission image. , 1...Object to be inspected, 2...X-ray generator, 3...X-ray sensor, 4, 41...
・Thickness measuring device, 6. Old... Main controller. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure I (χ2 Figure 3 ((S・N Q Figure 4 Figure 5 ■.■. -I, I2

Claims (4)

[Claims] (1) An X-ray generator that generates X-rays, an X-ray detector that detects the X-rays that have passed through the object to be inspected and converts them into electrical signals, and a thickness measuring device that measures the thickness of the object to be inspected. An X-ray diagnostic apparatus comprising: a function of correcting an X-ray transmission image signal obtained by the X-ray detector using an output signal of the thickness measuring device as a coefficient. (2) The X-ray diagnostic apparatus according to claim 1, wherein the X-ray detector comprises a semiconductor X-ray detector, a semiconductor X-ray detector array, or a semiconductor X-ray surface detector. (3) The X-ray diagnostic apparatus according to claim 1, wherein the X-ray detector comprises a gas ionization chamber detector or a gas ionization chamber detector array. (4) Claim 1, wherein the X-ray detector comprises an image intensifier and an image pickup tube.
The X-ray diagnostic device described in Section 1.