JPS58159729A - Radioactive ray fluoroscopic 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 [Technical Field of the Invention] The present invention relates to a radiographic fluoroscope, and more particularly to perspective image distortion correction.

[Technical background of the invention]

Radiation, especially X-rays, is used as a means of fluoroscopy in various fields by utilizing their ability to penetrate materials, and in the field of non-destructive testing, the role of X-ray fluoroscopy equipment is to obtain a fluoroscopic image of a subject. big.

By the way, this equipment can be roughly divided into an X-ray source that irradiates the subject with X-rays, an X-ray sensor that receives radiation and outputs a signal according to the radiation intensity, and It is composed of an image creation section that creates an image (dry plate image or television image) according to the intensity. Among these, the X-ray sensor includes an area sensor that irradiates the subject with a conical radiation beam with a solid angle so as to cover the area of the subject and detects it, and a fan-shaped radiation beam with a plane angle. There is a line sensor that detects the radiation by irradiating it linearly onto the subject.

Conventional equipment uses exclusively X-ray area sensors. The reason for this is that the entire fluoroscopic image of the subject can be obtained at once using a fluorescent plate or the like, and the image visually represents the shape of the subject better than when using a line sensor.

[Problems with background technology]

By the way, normally in an X-ray fluoroscope, the X-ray source is point-shaped, and the X-rays are radiated from this point source to the subject, so the fluoroscopic image is slightly enlarged compared to the actual subject. It becomes an image.

With conventional X-ray fluoroscopy equipment that uses an X-ray area sensor,
The enlargement of the fluoroscopic image as described above occurs in all directions from the center and is visually easy to see since it is similar to the subject. However, since the X-ray area sensor captures the subject in a planar area, detection points in units of pixels forming a planar image are arranged over the entire surface of the X-ray receiving surface.

Therefore, at adjacent detection points, radiation of pixel signals at a plurality of locations is detected due to scattered rays from various parts of the subject, which deteriorates the S/N of the fluoroscopic image.

On the other hand, when an X-ray line sensor is used, there are very few scattered rays (and a fluoroscopic image with good S/N can be obtained. However, when an X4I line sensor is used, a fluoroscopic image is
Deformation (mainly expansion) of the fan-shaped irradiation beam in the width direction of the fan surface is unavoidable, resulting in an image that is distorted in only one direction and visually differs from the subject. For this reason, area sensors are exclusively used in conventional devices despite the drawbacks of area sensors.

[Purpose of the invention]

The present invention corrects the distortion of fluoroscopic images when using an X-ray sensor by using a fan-shaped radiation beam as a radiation beam, and provides fluoroscopic images that are faithful to the subject and have better S and /'N than when using an X-ray area sensor. An object of the present invention is to provide a radiographic apparatus that can obtain images.

[Summary of the invention]

The present invention achieves the above-mentioned objective by storing each fluoroscopic line image of a subject linearly seen through a fan beam of radiation in a memory as a fluoroscopic plane image of the subject. Then, the readout is performed by inverting the perspective plane image by 90° and displaying it on a television monitor. At this time, the radiographic fluoroscopy apparatus controlled the vertical scanning signal of the television monitor to correct nine distortions occurring in the width direction of the fan-shaped beam in the fluoroscopic plane image of the subject.

[Embodiments of the invention]

First, to give an overview of the X-ray line sensor used in this embodiment, in FIG. 1 (, ), l is a curved ionization chamber housing containing gas inside. This ionization chamber housing 1
The inside of the curve is an opening 2, which is closed off by a plurality of high-voltage electrodes 3. A signal electrode 4 is arranged in each room, and each signal electrode 4 detects a signal in pixel units. The radius of curvature of the ionization chamber housing 1 is made equal to the radius R of a circle centered on the point X-ray source A, as shown in FIG. This is the direction in which the X-ray source A is focused. As a result, the detection room for each pixel is in a state directly facing the X-ray source6, and it is possible to prevent the incidence of scattered radiation in the width direction of the irradiation beam irradiated from the X-ray source in the fan-shaped ABC plane. .

Further, the curved shape is because it is easier to manufacture a structure in which all the rooms separated by the high-voltage electrodes 3 are directed toward the X-ray source A than a straight shape.

Furthermore, in terms of performance, since each X-ray detection room is at a small distance from the X-ray source person, dose errors due to the distance from the X-ray source A in each detection room can be eliminated.

For the above reasons, a dog-shaped X-ray line sensor as shown in FIG. 1 is often used.

Therefore, an embodiment of a radiographic fluoroscope using the above-mentioned X-ray line sensor is shown in the configuration diagram of FIG. 2 and will be described.

10 is an X-ray tube that emits X-rays in a fan shape;
0, an X-ray line sensor 11 as described above is installed on the fan-shaped X-ray beam surface of the Xg tube 10. The subject 12 moves between the X-ray line sensor 11 and the Xff5 tube 10 in the direction of the arrow perpendicular to the fan-shaped beam plane and is irradiated with X4I. The X-rays that have passed through the subject 12 are transmitted to the X-ray line sensor 11 at different intensities.
The gas is ionized and a current is passed through each signal electrode. The X-ray input sensor 11 sends the signals of each signal electrode to the integrator 13. This integrator 13 integrates the signals of each of the signal electrodes, and the next-stage analog switch 14 takes out each integrated signal. These integrator 13 and analog switch 1
Each operation timing, such as the take-out period of 4, is controlled by a timing controller 15, and this timing controller is controlled by an object detection signal output from the object detector 16 when the object 12 passes through the fan beam of the X-rays. Operate.

On the other hand, each integral signal taken out by the analog switch 14 is converted into a digital signal for storage by an A-D converter 17, and this is stored as a fluoroscopic image of the subject 12 in the memory I8. Write and read commands for this memory 18 are issued by a memory controller 19. This memory control 19 outputs a write clock oscillator 19-1 for write control and a write control signal, and a read clock oscillator 19-3 for read control and outputs a read control signal. and a read controller 19-4 for controlling the readout controller 19-4. A DA converter 20 for converting the digital signal of the fluoroscopic image read from the memory 18 into an analog signal is provided, and a television monitor 21 is provided for displaying the fluoroscopic image in accordance with this analog signal.

Furthermore, a scan controller 22 is provided that starts controlling the vertical scan signal of the television monitor 21 at the timing when the read control signal of the memory controller 19 is output.

Next, to explain the operation of the device configured as above,
Radiation is emitted from the radiation tube 1o to the subject in a fan-shaped beam.

The line enters each channel separated by high voltage electrodes of the line sensor 11. Therefore, an electrical signal for each channel is output from the X-ray line sensor 11, this signal is integrated by the integrator 13, and the integrated signal of each channel is extracted by the analog switch 14 and sent to the A-D converter 17. input. The A/D converter 17 converts each integral signal into a digital signal for storage, and the digital signal is sequentially stored in the memory 18.

In this way, as the subject 12 moves, line-shaped fluoroscopic images of the subject 12 are sequentially stored in the memo 9111, and become fluoroscopic image data of the subject 12.

By the way, this perspective plane image data is obtained by transmitting a fan-shaped X-ray irradiation beam through the subject 12 located horizontally and detecting it with an X-ray line sensor 11 having a curvature concentric with the fan center of the fan-shaped irradiation beam. , is image data with distortion in which the enlargement ratio decreases as one goes from the center of the subject 12 to the periphery.

In other words, the central image has fine data, and the peripheral images have coarse data. This will be explained using the X-ray irradiation configuration diagram shown in FIG. That is, the X-rays that irradiate the central part of the subject 12 at an angle α from the center A of the fan-shaped beam are projected onto the projection plane S formed on the horizontal plane S and the projection chord 11 formed on the detection surface of the X-ray line sensor 11. are parallel. On the other hand, subject 1
The X-rays irradiated around 20 at an angle ρ are obliquely directed at the subject 12, where the projection plane s2 of the horizontal plane S and the projection chord 11 of the detection plane of the X-ray line sensor 11 have a certain angle. This is because it is irradiated. Therefore, the projection surface s1
To obtain the same size as , the X-ray irradiation angle β in the peripheral area is β
In other words, it must be α〉β→. Therefore, l! >i! Therefore, the above-mentioned distortion occurs in the perspective image. The perspective image data with such distortion is stored in the memory 18 as, for example, jl! The image signals are stored in a predetermined writing order at the addresses (pixel units) arranged as shown in Figure 4 (The storage arrangement of the image signals stored here is equivalent to the image signal arrangement detected by the area sensor. ). In other words, the vertical axis is divided into 1 to N, the horizontal axis is divided into A-H, and each address is divided into (IA→IB→...IH)→(2A
→2B→...2H)→...→(N A'-+ N
Writing can be performed in the order of B→...→NH). The reading order is IH→2H→...→NH)→(IG→2
G→...→NG)-10...→(IA→2A→...
→NA). By performing such readout, a perspective image in the moving direction of the subject 12 can be displayed in the left-right direction (horizontal direction) on the television monitor 21. Therefore, the direction of distortion of the fluoroscopic image produced by the X-ray line sensor 11 (the direction perpendicular to the moving direction of the subject 12) can be reversed by 90 degrees. Note that the write and read operations use write and read clock signals as shown in FIG. 5. In other words, the write clock signals as shown in FIG.
The number of clock signal groups corresponds to N rows, and the number of clock signals in each group corresponds to the number of horizontal columns. Further, the read clock signal as shown in FIG.
The number of clock signal groups corresponds to the horizontal A/A-H columns of the address shown in the figure (eight in the figure), and the number of clock signals in each group is the number of vertical lines 1 to N rows. corresponds to Then, the write is used for writing and reading data for one line at address. However, each of the addresses shown in FIG. 4 corresponds to each pixel of the perspective image. Therefore, the number of vertical and horizontal addresses can be changed depending on the display density of the perspective image.

As described above, the fluoroscopic image data read out from the memory 18 is converted into an analog signal for the television monitor 21 by the DA converter 2o, and is input to the television monitor 21. At the same time, the scan controller 22 is operated by the read control signal output from the memory controller 19.
A vertical scanning control signal is output to the television monitor 21.

The vertical scanning signal of the television monitor 21 is controlled by this vertical scanning control signal.

This will be explained using FIG. 6, which is an explanatory diagram of vertical scanning signal control. That is, in the cathode ray tube display of an ordinary television monitor, a sawtooth wave-like vertical deflection scanning signal shown in FIG. 1 (1) is used.

However, 0 represents the output at the top edge of the screen, P the output at the center of the screen, and Q the output at the bottom edge of the screen. As a result, equally spaced vertical scanning lines v1 to v1 are created on the screen of the television monitor as shown in FIG.

Therefore, the scan controller 2
2, a vertical scanning control signal as shown in FIG. 2(c) is added. However, this output curve can be changed as appropriate depending on the image on the television monitor 21. Due to this control signal, the vertical deflection scanning signal becomes a changed signal between OP and between P and Q as shown in FIG. 3(d). Due to this change in signal level, the vertical scanning speed of the television monitor 21 gradually slows down from the top to the center of the screen and gradually increases from the center to the bottom of the screen. In other words, with this scanning signal,
The scanning lines y, /~vn' on the screen are dense in the center and sparse in the upper and lower parts, as shown in the figure (.).

In this state, when the image signal with the distortion of the center enlargement of the D-A converter 20 is input to the television monitor 21, the center enlargement part is corrected and the size of the center, upper and lower parts of the image is adjusted. The ratio becomes 1=1. Therefore, the object 12 without distortion
A fluoroscopic image can be obtained.

In this way, after displaying the fluoroscopic image of the subject 12 for an arbitrary period of time, when the next subject detection signal is output from the subject detector 16, the timing controller 15 again performs the same process as described above. Fluoroscopic image data can be imported.

As described above, by reading data from the memory 18 in units of line data at 90 degrees with respect to the write address line, as in the above embodiment, not only distortion correction but also correction of new images on the screen of the television monitor is performed. The flow can be seen on the conventional screen.
The downward direction can be changed to the left and right direction. Therefore, it is easy to observe from the position of the human eye.

Note that the present invention is not limited to the above-mentioned embodiments; for example, the subject may be fixed and the radiation source and sensor may be moved. Writing and reading may be performed in the opposite manner to the above embodiment, and the present invention can be modified in various ways without departing from the gist thereof.

〔Effect of the invention〕

According to the present invention, the irradiation beam of radiation is fan-shaped, and 2
Distortion in a fluoroscopic image of a subject detected by an in-sensor can be easily corrected using line-by-line image data stored in a memory. Therefore, compared to an area sensor, the influence of scattered radiation can be extremely reduced, and a high-quality fluoroscopic image with improved SA can be obtained.

In addition, even when digital signal processing is performed on image data using external equipment (such as a defect detector for an object to be examined), radiographic fluoroscopy has the advantage of requiring less processing because data can be corrected for each line of memory. equipment can be provided.

[Brief explanation of drawings]

Fig. 1 is an outline diagram of the X-ray fin sensor, Fig. 2 is a configuration diagram of an embodiment of the radiographic apparatus according to the present invention, Fig. 3 is a diagram of the X-ray irradiation configuration, and Fig. 4 is the configuration of Fig. 2. 5 shows the write and read clock signals of the device having the configuration shown in FIG. 2, and FIG. 6 shows the vertical 10...X-ray tube 11 of the device having the configuration shown in FIG. ...X-ray line sensor, 12
...Subject, No.8...Memory, 19...Memory controller 5', 21...TV monitor, 22...
scan controller. Applicant's representative Patent attorney Takehiko Suzue: Figure 1 (a) (b) Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] A radiation source that outputs a radiation beam that sequentially passes through a subject in linear units; a radiation detector that detects the linear radiation after passing through the subject and sequentially outputs line image signals of the subject; and this radiation detector. a storage means that sequentially converts each line image signal into a writing surface image signal as a pixel array line image signal in a predetermined direction; A radiation radiation source comprising: a display means for displaying arranged plane images; and an interval control means for controlling the predetermined line image interval of the display means, and the distortion of the fluoroscopic image of the subject is corrected by the interval control means. Fluoroscopy device.