JPH0628658B2 - X-ray diagnostic device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an X-ray diagnostic apparatus that visualizes an X-ray image of a subject based on the X-rays that have passed through the subject for diagnosis.

[Technical background of the invention and its problems]

In recent years, various digital image acquisition and processing methods have been developed as diagnostic X-ray image technology to improve diagnostic ability.

By the way, in the visualization of the X-ray image of the subject, when the imaged part moves quickly like a heart, a small field of view and high-speed imaging is desirable, and the imaged part does not move much like the head but requires high resolution. Wide field of view and magnified photography are desirable for the part to be exposed. Further, it is desirable that the fluoroscopic mode for positioning the radiographing has a high speed (30 FL / sec or more), a wide field of view, and high sensitivity, and a wide dynamic range ( 80 dB or more), wide field of view and high resolution are desirable.

However, the conventional apparatus does not satisfy all the conditions of wide dynamic range, wide field of view, high resolution, and high sensitivity, and it is possible to appropriately visualize an X-ray image according to an imaged region, a fluoroscopic mode, and an imaging mode. The current situation is that it cannot be done.

[Object of the Invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray diagnostic apparatus capable of appropriately visualizing an X-ray image according to an imaging region, a fluoroscopic mode, and an imaging mode. To provide.

[Outline of Invention]

An outline of the present invention for achieving the above object is to provide an X-ray generation unit that irradiates an object with X-rays, and an X image formed on an imaging surface.
An image pickup unit that picks up a line image in pixel units and outputs information of each pixel, a unit that displays an image by a plurality of display pixels, and information of pixels that are close to each other on the image pickup surface are added. An X-ray diagnostic apparatus comprising: a unit for obtaining one display pixel information based on the display pixel information.

Example of Invention

 Hereinafter, the present invention will be specifically described with reference to examples.

FIG. 1 is a block diagram of an X-ray diagnostic apparatus which is an embodiment of the present invention. In the figure, XT is an X-ray tube that irradiates the subject P with X-rays, and 1 is a detector that detects X-rays that have passed through the subject P. The detector 1 is capable of converting the transmitted X-ray information of the subject P into electric signals in pixel units and accumulating them, and reading out the accumulated electric signals in pixel units.
A scintillator that converts X-rays that have passed through to light (for example, Cs
I) 2, a photoelectric body (for example, Cs ₃ Sb) 3 that emits electrons in response to light from the scintillator 2, and a fluorescent body (for example, (( Z
nCd) S) 5 and a two-dimensional solid-state detector 6 that converts light from the fluorescent body 5 into an electric signal and stores the electric signal.
A control unit 7 controls the read address of the detector 1 according to the fluoroscopic mode, the photographing mode, and the photographing region. Reference numeral 8 denotes an integrator group including a plurality of integrators for integrating the information (electrical signal) read by the control of the control unit 7, and 9 indicates a plurality of A / Ds for converting the output of the integrator 9 into a digital signal. An A / D converter group consisting of (analog / digital) converters, 10 is an arithmetic unit for performing arithmetic processing based on the output of this A / D converter group 9, 11 is a memory for storing the output of this arithmetic unit 10, 12 is this memory 11
It is a monitor that displays an image based on the stored contents of the.

Here, the two-dimensional solid-state detector 6 has, for example, 2048 parallel circuits (corresponding to one pixel) of a diode 13a and a capacitor 13b as shown in the equivalent circuit of FIG.
2048 switches are arranged two-dimensionally in order, and switches 13c using thin film transistors are connected in series for each image parallel circuit. Read signals S _{1 to} S ₂₀₄₈
By turning on the switch 13c, the information I _{1 to} I ₂₀₄₈ for each pixel can be read. For example, this 2
The dimensional solid state detector 6 is formed on a large area glass substrate by making full use of thin film deposition technology and IC process technology.

Next, the connection relationship between the two-dimensional solid state detector, the control unit, the integrator and the A / D converter will be described with reference to FIG.

Figure 3 shows a two-dimensional solid-state detector, controller, integrator, and A / D.
It is a block diagram which shows the connection relation of a converter.

The control unit 7 has, for example, RAMs (random access memories) 7a and 7b. RAM7a read signals _{S 1} in response to input of the address clock _{B X}
To S ₂₀₄₈ and is adapted to output the two-dimensional solid-state detector 6, also, RAM 7b is integral switch the switch driving signal _SY 1 to SY ₂₀₄₈ in response to the input of the address clock _{B Y 14-1~14-2048} It is designed to output to. These integration switches 14-1 to 14-2048 are the same as the above 2
The three-dimensional solid-state detector 6 is connected in series to the output terminal, and a transistor or the like is applied. Integration switch 14
Information I _{1 to} I output via -1 to 14-2048
₂₀₄₈ is input to the integrators 8-1 to 8-2048, and then to the A / D converters 9-1 to 9-2048, respectively.

Next, the configuration of the calculation unit will be described with reference to FIG.

FIG. 4 is a block diagram showing the configuration of the arithmetic unit in this embodiment. The calculation unit 10 includes A / D converters 9-1 to 9-9.
A latch circuit arranged corresponding to −2048, an adder unit 10a for adding the outputs of the four latch circuits, and a selector 10b for selecting and outputting the output of each latch circuit or the output of the adder unit 10a. To have. In FIG. 4, 10 out of the latch circuits 10-1 to 10-2048 are shown.
Only -1 to 10-4 are shown.

Next, the operation of the embodiment apparatus configured as described above will be described with reference to FIGS. 5 and 6.

5 and 6 are operation timing charts of the apparatus of this embodiment.

X that has been exposed from the X-ray tube XT and that has passed through the subject P
When a line is incident on the scintillator 2 of the detector 1, the scintillator 2 emits light in response to the incident X-ray, and electrons are emitted from the photoelectric body 3 in response to this emission. The emitted electrons are accelerated in the space portion 4 and reach the fluorescent body 5. Then, the fluorescent body 5 emits light, and the information by this emission is accumulated in the two-dimensional solid state detector 6.

The reading of information from the two-dimensional solid state detector 6 is performed as follows.

<Fluoroscopic mode> In the fluoroscopic mode, because of the positioning of shooting,
High speed, wide field of view, and high sensitivity are desirable.

Therefore, in this perspective mode, by adding 16 pixels of a 2048 × 2048 matrix image, 512 × 51
A high-speed addition mode (SUM-HS) is applied in which two matrix images are used and collected at 32 frames / sec.
(See FIG. 5).

The RAM 7a has read signals S _{1 to} S ₄ , S ₅ to.
As in S ₈ , S _{9 to} S ₁₂ , ..., High level data is written simultaneously for every four signals, and RAM 7b
It is assumed that the switch drive signals SY _{1 to} SY ₂₀₄₈ are simultaneously set to high level. This writing is performed when switching modes.

In response to the input of the address clock B _X, the read signal S
_{1 ~S 4, S 5 ~S 8} , S 9 ~S 12, ... it becomes sequentially a high level for each. Then, information reading is performed for every four columns on the matrix of the two-dimensional solid-state detector 6. At this time, RAM7
Since the switch drive signals SY _{1 to} SY _{2048 which} are the outputs of b are simultaneously at the high level, the information of the pixels corresponding to S _{1 to} S ₄ in each row is added for each row and output. Then, after being integrated by the integrator group 8 and converted into a digital signal by the A / D converter 9, it is input to the arithmetic unit 10.

In the arithmetic unit 10, the input data is first input to the latch circuit 1
The latching is performed by 0-1 to 10-2048, and the addition processing is performed for every four latch circuits by the adding means 10a arranged for every four latch circuits. Then, the addition processing result is the selector 10b.
Is written in the memory 11 via. The latch of the latch circuit is performed at a speed of around 100 ms. The memory address signal is reset every time 512 pieces of data are written, and 512 × 512 images are collected one after another.

According to this mode, it is possible to reduce the number of pixels by performing addition processing for every several neighboring pixels on an image composed of a large number of pixels on a large screen.
By keeping the pixel collection speed unchanged, the collection time can be shortened by the number of pixels reduced. Further, by performing the pixel addition processing, sufficient sensitivity can be obtained even under a low dose, and good image quality can be obtained.

<Radiographing Mode> In the radiographing mode, a wide dynamic range, a wide field of view, and a high resolution are desirable because the target region of the subject is imaged.

Therefore, the high-resolution low-speed mode (HR-LS) that collects a 2048 × 2048 matrix image at 2 frames / sec is applied to this mode (see FIG. 6).

Data such as read signals S ₁ , S ₂ , S ₃ , ... Which sequentially become high level are written in the RAM 7a, and
It is assumed that data in which the switch drive signals SY _{1 to} SY ₂₀₄₈ simultaneously become high level are written in the RAM 7b. This writing is performed when switching modes.

In response to the input of the address clock B _X, the read signal S
₁ to S ₂₀₄₈ is sequentially a high level, the two-dimensional solid-state detector 6
The information for each pixel is read out. The read information is integrated by the integrator group 8, converted into a digital signal by the A / D converter group 9, and then input to the arithmetic unit 10.

In the arithmetic unit 10, the input data is latched by the latch circuit 10-
Latch 1 to 10-2048. Then, the data latched by each latch circuit is read at a speed of about 100 msec and written in the memory 11. This allows
2048 × 2048 matrix images are collected at 2 sheets / sec.

According to this mode, a high-resolution image with a small number of pixels can be obtained, and a wide dynamic range according to the dose can be secured.

In the shooting mode, if a small field of view and high-speed shooting are required, such as when the desired part of the shooting is the heart,
Do the following:

By reading out only a desired region in the 2048 × 2048 matrix image, a 512 × 512 matrix image is collected at 30 frames / sec. RA for example
Data in which the read signals S _{769 to} S ₁₂₈₀ sequentially become high levels are written in advance in the M7a, and the RAM 7
to b, in assumed that data switch driving signal SY ₇₆₉ to SY ₁₂₈₀ goes high at the same time is written in advance.
The writing of this data is performed at the time of mode switching as in the above.

In response to the input of the address clock B _X, the read signal S
_{From 769 to} S _{1280, the} level becomes higher, and 2
The information in the corresponding area is sequentially read from the three-dimensional solid state detector 6. Then, since the switch driving signals SY _{769 to} SY ₁₂₈₀ simultaneously become high level in response to the input of the address clock _BY , they are stored in the memory 11 via the integrator group 8, the A / D converter group 9, and the arithmetic unit 10. What is written is a 512 × 512 matrix image. Moreover, 5
Since a 12 × 512 matrix image can be collected at 30 frames / sec, a small field of view and high-speed imaging can be performed.

In this imaging mode, data other than the desired region for imaging becomes unnecessary, so it is preferable to regulate the X-ray beam so that the subject region in this unnecessary region is not irradiated with X-rays. The regulation of the X-ray beam is, for example, as shown in FIG.
This is performed by interlocking the X-ray slit 15 arranged on the X-ray exposure side of the X-ray tube XT as indicated by A or B.

The interlocking control can be performed as follows.

The FDD distance between the X-ray tube XT and the detector 1 is measured by a distance meter that counts following the mechanical movement of both. X
If the line slit 15 is at a distance D ₁ from the X-ray tube focal position and the area of the region 512 × 512 in the detector 1 is L ² , the slit opening width W is obtained by the following equation. The X-ray slit 15 is controlled according to W.

The FDD can be measured by a distance measuring method using laser light, ultrasonic waves, or the like.

Further, the slit opening width W may be determined before setting the field of view to 512 × 512. For example, while irradiating a weak X-ray, only the read signal S ₁₀₂₄ is repeated at high and low levels to narrow the slit in the Y direction. At this time, the switch drive signals SY769 and SY ₁₂₈₀ is previously set to a high level. Then, if the output of the A / D converter is compared with a value in the vicinity of "0" by the comparator, the output of the A / D converter becomes "0" at the moment when the slit crosses these two channels. The motor for moving the aperture of the line slit 15 may be stopped. The X direction may be set to be the same as the Y direction.

By thus controlling the X-ray slit 15 to regulate the X-ray beam, it is possible to prevent X-ray irradiation to an unnecessary area.

As described above, in the apparatus of the present embodiment, it is possible to perform appropriate visualization of the X-ray image according to the imaging region, the fluoroscopic mode, and the imaging mode.

Although the embodiment apparatus of the present invention has been described above, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made within the scope of the gist of the present invention.

For example, in the above-described embodiment, the control unit 7 is configured with the RAM, but it may be configured with a ROM (read only memory) that stores different data for each mode.
It is also possible to have a shift register or the like.

Further, in the perspective mode, if data is written so that every four contents of the RAM are output at a high level, a 512 × 512 matrix image without addition can be obtained. In this case, it is preferable to interpolate the defective pixel with the same data or an intermediate value between two neighboring points. Also, A
An analog adder may be arranged in the preceding stage of the / D converter group 9 and the outputs thereof may be added to every four integrators. This makes it possible to perform A / D conversion by sequentially switching by one A / D converter, which is advantageous in terms of hardware.

〔The invention's effect〕

As described in detail above, according to the present invention, it is possible to provide an X-ray diagnostic apparatus capable of appropriately visualizing an X-ray image in accordance with an imaging region, a fluoroscopic mode, and an imaging mode.

[Brief description of drawings]

FIG. 1 is a block diagram of an X-ray diagnostic apparatus as an embodiment of the present invention, FIG. 2 is an equivalent circuit diagram of a two-dimensional solid state detector in the apparatus of this embodiment, and FIG. 3 is a two-dimensional solid state in the apparatus of this embodiment. FIG. 4 is a block diagram showing the connection relationship between the detector, the integrator, and the A / D converter, FIG. 4 is a block diagram showing the configuration of the arithmetic unit in the device of this embodiment, and FIGS. An operation timing chart, FIG. 7 is an explanatory diagram for explaining control of the X-ray slit in the apparatus of this embodiment. 1 ... Detector, 7 ... Control part, 10a ... Addition means, P
…… Subject.

Claims (1)

[Claims] 1. X-ray generating means for irradiating a subject with X-rays,
An X-ray image formed on the image pickup surface is picked up on a pixel-by-pixel basis, and an image pickup unit that outputs information of each pixel, a unit that displays an image by a plurality of display pixels, and a pixel that is close to the image pickup surface. An X-ray diagnostic apparatus comprising: means for adding information and obtaining one display pixel information based on the addition result.