JPH06189948A - X-ray tv device - Google Patents

Abstract

PURPOSE:To equip an X-ray TV device with a monitor mechanism having the capability of improving the quality of a monitor image at the time of picking up an image, and allowing an easy use even during a long time of operation. CONSTITUTION:A TV camera 7 allowing the incidence of the optical signal of an image pickup X-ray is fitted with a CCD operable on a frame accumulation mode. An X-ray high voltage device 2 outputs an X-ray radiation signal ST to the camera 7, when the radiation of an X-ray related to image pickup starts. In response thereto, the camera 7 temporarily stops the feed of field shift pulses to the CCD. Also, a part of the optical signals is detected with a photo detector 10, and the detection signal thereof is outputted to the AEC circuit 11a of a control amplifier 11. Then, the circuit 11a integrates an amount of incident light from the start of the X-ray radiation. Also, when the integrated value reaches the predetermined level, the AEC circuit 11a outputs an X-ray interruption signal SP to the camera 7 and the device 2. As a result, the X-ray radiation ends, while the camera 7 resumes the feed of the field shift pulses. Consequently, electrical charge so far accumulated for the odd or even number of fields is called up, because of the resumption of the pulse feed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray TV apparatus, and more particularly to a TV camera having a CCD (Charge Coupled Device).
) And an X-ray TV apparatus using a solid-state image sensor.

[0002]

2. Description of the Related Art Generally, X-ray diagnosis is an indispensable inspection item in the inspection of digestive organs. For example, a digestive organ contrast examination using X-rays is usually performed while repeating fluoroscopy for observing the dynamics of organs and positioning for film photography, and subsequent imaging. The photographed image obtained in this examination is not visible until after film development.
For this reason, if the image is taken in an inappropriate timing, it will be later determined that the image has a low utility value. In particular, in the case of imaging of an esophagus in which the flow of a contrast medium is fast, the imaging timing is often shifted, and a desired imaging image is often not obtained. Therefore, the examination requires an operator to be skilled in imaging.

As a means for eliminating the deviation of the photographing timing as much as possible, there is a device in which the amount of light is controlled so that an appropriate amount of light can be obtained at the moment of photographing so that the photographed image can be directly observed on a TV monitor. However, in this case, since the photographing time is usually several tens of msec to 100 msec, the image that can be observed is only momentary for the operator, and it often fails to judge the quality of the photographing timing.

Therefore, the X-ray TV apparatus for photographing the esophagus has a C
There has been an improvement in which a monitor mechanism using a CD as an image sensor is added so that a monitor image can be continuously displayed.

[0005]

However, in the case of the above-described CCD monitor mechanism, the image display on the monitor screen is related to the pseudo interlaced scanning because the image reading from the CCD is performed by the field signal and the field image is collected. And the vertical resolution is low. Also, in the case of esophageal photography, there is no problem because the imaging time is short, but when imaging other parts that require a relatively long time, such as over 100 msec, the level of the video signal obtained from the CCD is lowered, It was a monitor mechanism that was difficult to use except for esophageal photography.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to obtain a monitor image with an improved image quality by increasing the vertical resolution, and it is easy even when the photographing time is long such as a part other than the esophagus. The purpose is to provide a monitor mechanism that can be used for.

[0007]

In order to achieve the above object, an X-ray TV apparatus according to the present invention is an X-ray tube that irradiates an object with X-rays, and an X-ray transmitted through the object. And a TV camera that generates a video signal according to the optical signal converted by the converter. The TV camera has a built-in solid-state image pickup device which receives the optical signal and operates in a frame accumulation mode based on odd field pulses and even field pulses, while the X-ray exposure at the time of photographing by the X-ray tube is performed. An exposure start determining means for determining the start, a field pulse stopping means for stopping the supply of the odd field pulse and the even field pulse when the exposure start determining means determines the start of the X-ray exposure, Exposure end determination means for determining the end of X-ray exposure at the time of imaging by an X-ray tube, and the odd field pulse and even field pulse when the end of X-ray exposure is determined by this exposure end determination means Field pulse restarting means for restarting the supply of

[0008]

When the X-ray tube starts exposure during imaging, this start is determined by the exposure start determination means. When this determination is made, the odd field pulse and the even field pulse for calling the charges of the odd field and the even field forming one frame from the solid-state image sensor (for example, CCD) are supplied from the field subsequent to the field to which the determination timing belongs. It is stopped by the field pulse stopping means. Therefore, while the field pulse is stopped, the solid-state image sensor accumulates electric charges due to the optical signal corresponding to the imaging X-ray. Then, when the end of the X-ray irradiation is judged by the irradiation end judging means, the supply of the odd field pulse and the even field pulse is restarted by the field pulse restarting means from the field following the field to which the judgment timing belongs.
By this restarted first odd field pulse and even field pulse, all the electric charges accumulated in the solid-state image pickup device (that is, the total amount of light incident on the solid-state image pickup device of the TV camera during the X-ray exposure period) are reduced. It is called in the frame accumulation mode and is generated as a video signal.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

The X-ray TV apparatus shown in FIG. 1 comprises an X-ray tube 1 capable of irradiating X-rays, and an X-ray high voltage device 2 connected to this X-ray tube 1. The X-ray high-voltage device 2 is capable of inputting a start signal for fluoroscopy and exposure based on an operator's command. When this start signal is input, the X-ray high-voltage device 2 outputs a high voltage to the X-ray tube 1 Can be supplied to. As a result, the X-ray tube 1 can irradiate the subject P with X-rays of the command intensity. Further, the X-ray high-voltage device 2 notifies the start of X-ray irradiation when the X-ray exposure signal ST is started.
Is supplied to a TV camera described later.

An X-ray fluorescent multiplier (II) 3 is arranged at a predetermined position in the X-ray irradiation field formed by the X-ray tube 1. The X-ray fluorescence multiplier tube 3 converts the X-rays that have passed through the subject P into optical signals corresponding to their intensities. This X
An X-ray film 4 can be placed at a predetermined position in the X-ray irradiation field between the X-ray fluorescence multiplier 3 and the subject P at the time of photographing. In other words, when the shooting switch SW is turned on,
A spot film mechanism (not shown) allows the X-ray film 4 to quickly move to a predetermined position in the X-ray irradiation field immediately before photographing (see a virtual line in the figure), and photographing is performed. Then, after the photographing is finished, the X-ray film 4 is immediately retracted to the standby (storage) position outside the X-ray irradiation field (see the solid line in the figure).

A TV camera 7 is provided on the output light side of the X-ray fluorescent multiplier 3 via an optical system of a refraction lens group 5 and a light quantity control element 6, and an output end of the TV camera 7 is an image memory 8. It is connected to the image display 9 via the.

The light quantity control element 6 is composed of a liquid crystal and a lens diaphragm. Further, a part of the optical signal passing through the optical system toward the TV camera 7 is input to the photodetector 10 such as a photomultifire. The photodetector 10 converts an input optical signal into a current corresponding to its intensity, and supplies it to a control amplifier 11 and a light quantity controller 12 provided in the subsequent stage. Usually, the lens group 5, the light quantity control element 6 and the photodetector 10 are integrally formed as one optical system.

The light quantity controller 12 controls the light quantity control element 6 on the basis of the detection signal from the photodetector 10 and can adjust the quantity of light passing therethrough. The X-ray diagnosis is performed while repeating fluoroscopy and radiography, and a larger dose of X-rays is emitted during radiography than during fluoroscopy. However, the light amount at the time of shooting is narrowed down by the light amount control element 6, and an appropriate light amount is input to the TV camera 7. It should be noted that the light amount controller 12 is adapted to input imaging information such as the subject thickness and the X-ray condition, and the light amount controller 12 also controls the light amount condition according to such information.

The control amplifier 11 controls the total amount of accumulated X-ray light to be constant even when the subject thickness or X-ray conditions change. This control is performed by an automatic exposure control (AEC) circuit 11a incorporated in the control amplifier 11. The automatic exposure control circuit 11a inputs the detection current corresponding to the transmitted light of the photographing X-ray from the photodetector 10, integrates the detection current, and the integrated value (generally, the voltage value) is predetermined. When the threshold value is reached, the X-ray blocking signal SP for stopping the X-ray exposure is output. This X-ray cutoff signal SP
Are supplied to the X-ray high voltage device 2 and the TV camera 7.
As a result, the X-ray high voltage device 2 stops the X-ray irradiation that has been continued until then. The length of the imaging time (that is, the time from the start of X-ray exposure to the emission of the X-ray blocking signal SP) is determined by the X-ray conditions and the thickness of the subject,
In the case of a fast-moving subject such as esophageal photography, X-ray conditions are selected so that motion blur can be eliminated in a short time of about 30 msec. For a selected X-ray condition, the thicker the subject, the longer the controlled imaging time generally. In other words, the shooting time changes with each shooting.

The TV camera 7 is, as shown in FIG. 2, an interline CCD as a solid-state image sensor (SID).
20 is provided at the incident position of the optical signal. This CC
D20 converts an incident optical signal into a video electric signal, and is configured to be operable in a frame accumulation (integration) mode. A video process circuit 22 is connected to the output side of the CCD 20 via a video amplifier circuit 21, and a video signal processed by the video process circuit 22 is output to the image memory 8.

A pulse generation shaping circuit 25 is connected to the CCD 20 via a horizontal drive circuit 23 and a vertical drive circuit 24. The pulse generation shaping circuit 25 generates various pulse signals necessary for operation control of the CCD 20 and image processing.
The pulse for operation control is a horizontal drive circuit 2 that is shaped.
3 and the vertical drive circuit 24, and the video processing pulse is output to the video amplifier circuit 21 and the video process circuit 22.

The pulse generation shaping circuit 25 has a built-in switching circuit 25a for inputting the X-ray injection signal ST and the X-ray cutoff signal SP described above. Switching circuit 25
a forcibly controls the on / off of the field shift pulse output from the pulse generation shaping circuit 25 to the vertical drive circuit 24 based on those signals ST and SP. That is, the switching circuit 25a is adapted to perform the processing shown in FIG.

Here, the processing of FIG. 3 will be described. The switching circuit 25a constantly monitors the X-ray injection signal SP to determine whether or not the X-ray exposure at the time of imaging is started (step 30 in the figure). By this, it waits while repeating the judgment until the start of exposure is judged, but when the judgment of start of irradiation is made, the output of the field shift pulse is temporarily stopped (step 31 in the figure). . Next, the switching circuit 25a monitors the X-ray cutoff signal SP to determine whether or not the X-ray exposure at the time of image capturing is completed (step 32 in the same figure). Until the end of X-ray exposure is judged in this step, wait while repeating the judgment.
When it is determined that the radiation exposure has been completed, an instruction to restart the output of the field pulse, which has been suspended until then, is issued (step 33 in the figure). Then, the process returns to step 30 again.

Next, the overall operation of this embodiment will be described with reference to FIG.

When the fluoroscopy is completed and the photographing state is entered from the preparation for photographing, the X-ray film 4 is conveyed to a predetermined position in the X-ray irradiation field, and the CCD 20 operates at the timing shown in FIG. That is, as shown in FIGS. 4 (1) to 4 (3),
Field shift pulses P _odd and P _even relating to the odd field accumulation period and the even field accumulation period are alternately supplied to the CCD 20 from the vertical drive circuit 24 for one field, and the CCD 20 operates in the frame accumulation mode. In this state, time t ₀ in the figure (the input field F
In 1), if the high voltage supplied from the X-ray high voltage device 2 to the X-ray tube 1 rises and the X-ray irradiation is started from the X-ray tube 1, the X-ray injection signal ST is output at the time t _0. It stands up (see (4) in the same figure). As a result, the optical signal relating to the imaging X-ray transmitted through the subject P is transferred to the CCD 20 of the TV camera 7.
Then, the CCD 20 starts accumulating the optical signal as an electric charge (see (6) in the figure). At the same time, CCD20
A part of the optical signal incident on is detected as a current by the photodetector 10 and begins to be integrated by the AEC circuit 11a of the control amplifier 11.

On the other hand, in the pulse generation shaping circuit 25 of the TV camera 7, since the switching circuit 25a monitors the X-ray injection signal ST as described above, the X-ray injection signal ST is energized to turn on X. The start of radiation exposure is recognized at time t ₀ . Therefore, the switching circuit 25a causes the vertical drive circuit 24 to temporarily stop the output of the field shift pulse (see step 31 in FIG. 3). As a result, a field shift pulse following the input field F1, that is, a field shift pulse P _even that should have occurred at time t ₁ in the even field and the same pulse thereafter and at time t ₂ in the odd field. The field shift pulse P _odd that has been present and the subsequent shift pulses of the same pulse are cut off, and the CCD 20
Is not output to. Therefore, the field shift pulse P
_{While the odd number} and P _even are cut off, the charge reading of the CCD 20 is not executed, so that the light amount corresponding to the imaging X-ray is continuously accumulated in the CCD 20 as the charge.

During this charge accumulation, the AEC circuit 11 is also used.
In a, the detection light signal is continuously integrated, and it is monitored whether or not the integration value has reached a predetermined threshold value. Now, when the integration value is determined to have reached the threshold at the timing of time t ₃ in FIG. 4, the AEC circuit 11a X-ray blocking signal SP (see FIG. 4 (5)) is X-ray high voltage apparatus 2 and the TV camera 7. Therefore, the high voltage supplied from the X-ray high voltage device 2 to the X-ray tube 1 disappears,
The X-ray exposure ends (see FIG. 4 (6)). Further, the switching circuit 25a of the TV camera 7 also receives the X-ray cutoff signal S
Input P to recognize the end of X-ray exposure and command restart of the field shift pulses P _odd and P _even (see steps 32 and 33 in FIG. 3).

As a result, the field F containing the time t ₃
The field shift pulse following n, that is, the field shift pulse P _odd of the odd field Fn + 1 in the example of FIG. 4 and the subsequent pulses are output to the CCD 20.

With the restart of the pulse supply, the field shift pulse P of the first odd field Fn + 1
_{The odd} charges vertically transfer all the charges A (that is, the total amount of light during the imaging period) accumulated in the light-receiving units in the odd-numbered fields during the X-ray exposure period. Further, by the next field shift pulse P _even of the even field Fn + 2, all the charges B (that is, the total amount of light during the imaging period) accumulated in the light-receiving unit for the even field during the X-ray exposure period are respectively generated. Transferred vertically. These odd fields,
After that, all the charges in the even field are horizontally transferred, converted into a voltage, and then taken out from the CCD 20 as output signals A ′ and B ′ (see FIG. 4 (7)). Since the CCD 20 has almost no afterimage, the CCD output signal becomes almost zero in the field after the even field Fn + 2.

The read image pickup signal A'at the time of photographing,
After that, B ′ is formed into a video signal by the video amplification circuit 21 and the video processing circuit 22, and is stored in the image memory 8. Further, the same one frame image as the film image is continuously displayed on the image display 9 as a monitor image.

As described above, this is different from the conventional method in which the charge accumulation time is limited to within one frame period and the charge is read out in the field. In this embodiment, the total amount of light during the photographing period is accumulated as electric charges, and the accumulated electric charges are completely read out in the frame accumulation mode in the first odd-numbered and even-numbered fields following the field at the end of photographing, and the video signal related to the readout is obtained. It can be stored in the image memory 8 and continuously displayed as a monitor image on the image display 9. As a result, the following various effects can be obtained.

First, the quality of the timing of the photographed image can be judged on the spot, and it can be concluded whether or not re-photographing is necessary.
The efficiency of the entire examination is improved, and the diagnostic ability is also improved as a result.
Further, the X-ray dose is sufficient, the quantum noise is small, and a complete frame image is obtained, and a high vertical resolution equivalent to progressive (non-interlaced) scanning can be obtained. Therefore, the image quality is better than in the past, and it becomes easier to determine the property of the affected area. Furthermore, since the level of the video signal does not drop even during a relatively long shooting time, it is not limited to esophageal shooting and can be used for long-term shooting of other parts.

Here, the above-mentioned light accumulation period (that is, photographing period) will be described. This light accumulation time can be set longer as the field shift pulse is kept blocked (off). However, since the dark current of the solid-state image sensor is also accumulated, the upper limit of the accumulation time is actually determined by the limit of the influence of the dark current on the image quality.
The dark current decreases as the temperature of the solid-state image sensor decreases, so
Forced air cooling and electronic cooling by Peltier element are effective.
In recent years, solid-state image sensors have been designed to reduce dark current.
When the storage time is about 0 msec, the image quality is not adversely affected. If it is desired to accumulate light for a longer period of time, a solid-state image pickup element combined with such a cooling function is suitable.

In the above-mentioned embodiment, the so-called direct photographing using the X-ray film is exemplified, but the X-ray fluorescent multiplier 3
Of an output image of the so-called I. I. The indirect photography can be performed in exactly the same manner, and the same image as the indirect photography can be continuously displayed on the display.

By connecting an imager to the image memory 8, the image memory 8 can be made to function as a backup for photographing, so that the backup system is enhanced and the reliability of the apparatus is improved. In Japan, indirect imaging is often used for mass screening, but in that case, the number of patients is large and screening is the main purpose, so we want to minimize the radiation dose. Therefore, even if the radiography cannot be properly performed, it is possible to avoid an unnecessary increase in the exposure dose due to the re-radiography by utilizing the backup function as described above. From this point of view, the backup function is important.

Further, there is an on-vehicle type mass examination apparatus mounted on a bus, and this on-vehicle apparatus is limited in electric power supplied to the X-ray apparatus (that is, instantaneous electric power cannot be large). There is. In this regard, since the apparatus of this embodiment is suitable for photographing for a relatively long time, it is also suitable for such a vehicle-mounted type.

Although the above embodiment has been described mainly for photographing, if a multi-pixel solid-state image pickup device such as 1000 × 1000 pixels is used for the solid-state image pickup device, direct or indirect photographing may be performed depending on the application. Instead, an X-ray TV apparatus mainly including a solid-state image sensor can be realized. In this case, the X-ray dose can be determined from the viewpoint of the S / N ratio of the image, so that the X-ray dose can be lower than that in direct imaging. Furthermore, if a film is not used for image detection, that is, if it becomes an electronic image, the degree of freedom in shaping the video signal becomes extremely high, so that contrast and resolution can be emphasized and compressed with simple operations. , Which enables image quality control that is incomparable to film-type photography. As a secondary advantage, the diagnostic ability can be further improved and the burden on the patient and the operator can be reduced.

Furthermore, in the above embodiment, the CCD is used as the solid-state image pickup device.
rge Modullation Device).

[0035]

As described above, the X according to the present invention
In the line TV device, the TV camera has a built-in solid-state image sensor that receives an optical signal and operates in a frame accumulation mode based on an odd field pulse and an even field pulse, while starting X-ray exposure at the time of imaging. Therefore, the supply of the odd field pulse and the even field pulse is stopped, and the supply of the odd field pulse and the even field pulse is restarted after judging the end of the X-ray exposure. Can be stored in the solid-state imaging device in the frame storage mode, and after the shooting is completed, the stored charges can be completely read out in a pair of an odd field and an even field. As a result, a complete frame image is obtained as a monitor image, and its image quality is improved by the high vertical resolution equivalent to non-interlaced scanning. Also, for example, the level of the video signal is lowered even in the case of a relatively long shooting time other than the esophagus. Therefore, it is possible to provide a monitor mechanism for an X-ray TV device which is excellent in usability.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an X-ray TV apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing an outline of a TV camera.

FIG. 3 is a flowchart showing control of a field shift pulse for X-ray irradiation.

FIG. 4 is a timing chart illustrating an example of the entire operation.

[Explanation of symbols]

 1 X-ray tube 2 X-ray high-voltage device 3 X-ray fluorescence multiplier tube 5 Refractive lens group 6 Light quantity control element 7 TV camera 10 Photodetector 11 Control amplifier 11a AEC circuit 20 CCD 24 Vertical drive circuit 25 Pulse generation shaping circuit 25a Switching circuit

Claims (1)

[Claims] 1. An X-ray tube for irradiating an X-ray toward a subject, a converter for converting the X-ray transmitted through the subject into an optical signal, and a converter for converting the optical signal converted by the converter. An X-ray TV apparatus including a TV camera for generating a video signal, the solid-state imaging device operating the frame accumulation mode based on an odd field pulse and an even field pulse with the optical signal incident on the TV camera. And an exposure start determination means for determining the start of X-ray exposure at the time of imaging by the X-ray tube, and the odd number when the start of X-ray exposure is determined by this exposure start determination means. The field pulse stopping means for stopping the supply of the field pulse and the even field pulse, the exposure end determining means for determining the end of the X-ray exposure at the time of imaging by the X-ray tube, and the exposure end determining means. Ri when the end of the X-ray irradiation is determined, X-rays TV apparatus being characterized in that a resume field pulse resuming means the supply of the odd field pulse and an even field pulses.