JP2625954B2 - X-ray movie camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an X-ray cinematography apparatus, and more particularly, to an X-ray cinematography apparatus with improved film quality.

[Prior art]

In the conventional X-ray cinematography apparatus, in order to keep the film density constant, the X-ray pulse width and the X-ray tube voltage are changed according to the dose after passing through the subject to keep the dose constant, and the tube voltage and the tube current are kept constant. Method to change to a constant load (IS
OWATT method).

[Problems to be solved by the invention]

However, in such a conventional X-ray cinematography apparatus, since the film density is simply kept constant, there is a problem that it is not possible to set the photographic tube voltage to improve the film contrast. Furthermore, since the value of the photographing tube current cannot be changed according to the thickness of the subject, it is necessary to correct the film density with the tube voltage, and this also sacrifices the film contrast. According to the present invention, it is possible to set a photographing tube voltage at which an appropriate contrast is obtained according to a photographing region and direction before starting photographing, and furthermore, it is possible to automatically set a photographing tube current according to a subject thickness before photographing starts, Accordingly, it is an object of the present invention to provide an X-ray cinematography apparatus capable of obtaining a cinema film having good contrast while keeping the film density constant.

[Means for Solving the Problems]

In order to achieve the above object, in an X-ray cinematography apparatus according to the present invention, an X-ray tube, an image intensifier to which X-rays emitted from the X-ray tube and transmitted through a subject are incident, and the image intensifier A TV camera to which an output image of the TV camera is input, a TV monitor device to which a video signal from the TV camera is sent, and a high-voltage generator to which a signal from the TV monitor device is fed back to control a tube voltage during fluoroscopy. A cine camera to which an output image of the image intensifier is guided, a photo timer circuit for sending an X-ray cutoff signal to the high-voltage generator according to output light of the image intensifier, a subject thickness, a movie shooting portion,
An input device for inputting a cinema tube voltage, a cinema tube current, and a cinema pulse width, and the relationship between the fluoroscopy condition and the subject thickness and the relationship between the subject thickness and the cinema tube current for each imaging site are written in advance. In the storage device, a fluoroscopic condition is input at the time of fluoroscopy, a subject thickness is obtained from the relationship between the fluoroscopic condition and the subject thickness, and movie shooting is performed from the relationship between the subject thickness and the movie tube current in accordance with the subject thickness. And a control device for controlling the high-voltage generator so as to obtain a tube current and perform movie shooting with the tube current and a preset movie shooting tube voltage.

[Action]

When a fluoroscopic image with the optimal brightness is obtained on a TV monitor device when a fluoroscopy is performed on an actual subject, the relationship between the fluoroscopy condition stored in the storage device and the subject thickness is calculated based on the fluoroscopic condition. Automatically obtains the subject thickness. When the subject thickness is obtained in this manner, the movie tube current is obtained from the relationship between the subject thickness and the movie tube current previously stored in the storage device and corresponding to the movie shooting site. On the other hand, the optimum movie shooting tube voltage corresponding to the movie shooting site can be input by the input device. Therefore, movie shooting can be performed with the tube voltage set so as to obtain the optimum contrast according to the imaging region and the tube current automatically determined as appropriate for the subject thickness. As a result, a movie film having good contrast while maintaining a constant film density can be obtained.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a high voltage and a filament heating current are supplied to an X-ray tube 1 by a high voltage generator 6.
The X-rays emitted from the X-ray tube 1 and transmitted through the subject 2 are incident on an image intensifier (II) 3 and converted into light. This light output is guided to the TV camera 4, converted into a video signal, and sent to the TV monitor device 5, where an X-ray fluoroscopic image of the subject 2 is displayed on the screen. In this perspective, TV
The tube voltage control signal is fed back to the high-voltage generator 6 to control the tube voltage so that the brightness of the fluoroscopic image on the screen of the monitor device 5 becomes constant. The X-ray conditions during the fluoroscopy, ie, the fluoroscopy tube voltage and the fluoroscopy tube current, are taken into the CPU 23 via the A / D converters 21 and 22, and the CPU 23 has an image intensifier 3 during the fluoroscopy. A visual field signal indicating the size of the visual field is transmitted via the interface circuit 24. The CPU 23 includes a subject thickness setting switch 41, a movie shooting part / direction selection switch 42, and a movie shooting tube current setting switch.
43, a movie shooting tube voltage setting switch 44, a movie shooting pulse width setting switch 45, and a data writing switch 46 are connected via an interface circuit 26, and a memory 31 is connected. A tube voltage control signal and a heating control signal can be sent to the generator 6. The memory 31 stores the relationship between the fluoroscopy conditions and the subject thickness and the relationship between the subject thickness and the imaging tube current. At the time of movie shooting, the output light of the image intensifier 3 is guided by the spectroscope 8 and enters the cine camera 7. At the time of this movie shooting, another spectroscope 9 guides the output light of the image intensifier 3 to a photomultiplier (PMT) 10, and the phototimer circuit 11 generates a high voltage by the photocurrent output from the photomultiplier 10. And outputs an X-ray cutoff signal to the
The irradiation time (X-ray pulse width) is controlled. The memory 31 stores in advance the relationship between the fluoroscopic conditions and the subject thickness and the relationship between the subject thickness and the imaging tube current. First, an acrylic plate having a thickness equivalent to a human body is placed as a subject to perform a fluoroscopy, and a tube voltage is controlled so that a fluoroscopic image displayed on the monitor device 5 has an appropriate brightness. The thickness at this time is set by manually operating the thickness setting switch 41. When the data write switch 46 is manually operated,
The set thickness data is loaded into the CPU 23, and the data of the fluoroscopic tube voltage and the fluoroscopic tube current are loaded into the CPU 23, and these are written into the memory 31. By repeating this operation while changing the thickness of the acrylic plate, the relationship between the see-through conditions (the see-through tube voltage and the see-through tube current) and the subject thickness as shown in FIG. Next, the imaging part / direction selection switch 42 is manually operated to select one imaging part / direction, and the imaging tube voltage at which an appropriate contrast is obtained in that part / direction is manually operated by the imaging tube voltage setting switch 44. Set by. Also, place an acrylic plate as the subject, and manually set the thickness with the thickness setting switch 41,
A pulse width suitable for photographing is manually set by a photographing palace width setting switch 45, and a tube current expected to be necessary is set by manually operating a photographing tube current setting switch 43. Then, operate the data write switch 46 to store these data in the memory.
Store it in 31. At this time, the CPU 23 sends a tube current control signal and a heating control signal to the high voltage generator 6 via the interface circuit 25 based on these data written in the memory 31. X-ray irradiation is performed with the conditions set as described above, and the imaging tube current setting switch is set so that the X-ray pulse width cut off by the photo timer circuit 11 becomes the value set by the imaging pulse width setting switch 45. Operate 43 to change the actual shooting tube current. The tube current when the pulse width becomes the set value is a tube current necessary when the acrylic plate thickness and the pulse width are assumed, and the tube current is stored in the memory 31 by operating the data write switch 46. The expected tube current at the written destination is rewritten. By repeating this operation while changing the thickness of the acrylic plate, the relationship between the subject thickness and the imaging tube current as shown in FIG. 3A for one imaging region and direction is stored in the memory 31. Become. The same operation is performed for other imaging parts and directions. For example, the relationship between the subject thickness and the imaging tube current as shown in FIG. This is performed for all imaging regions and directions. After such storage in the memory 31, the actual subject 2 is subjected to fluoroscopy and movie shooting. At the time of fluoroscopy, TV
The see-through condition under which the brightness of the see-through image on the monitor device 5 becomes appropriate is sent to the CPU 23. At this time, assuming that the fluoroscopic tube voltage is FKV1 and the fluoroscopic tube current is FmA2, the CPU 23 determines that the thickness of the subject 2 at this time is T1 from the relationship shown in FIG. Therefore, before the start of movie shooting, if the shooting site / direction is input by the switch 42 and the tube voltage (for example, KV1) suitable for the site / direction is input by the switch 44, the subject in the memory 31 relating to this site / direction is input. From the relationship between the thickness and the photographing tube current, for example, the photographing tube current mA1 (or mA2 from the relationship in FIG. 3B) is obtained by the CPU 23 from the relationship in FIG. 3A. This tube voltage KV
A tube voltage control signal and a heating control signal for realizing 1 and the tube current mA1 are sent from the CPU 23 to the high voltage generator 6 via the interface circuit 25. As a result, with the tube voltage set before movie shooting to obtain appropriate contrast according to the imaging region and direction, and with the tube current suitable for the subject thickness automatically determined during fluoroscopy, Photographing is performed.
The control of the film density corresponding to the presence or absence of the contrast agent is performed by pulse width control. For example, as shown in FIG. 4, the above tube voltage KV1 and tube current m
A1 does not change, and the pulse width changes, and imaging is performed. Before and after the contrast agent flows into the field of view, the pulse width is as short as t because the amount of light incident on the photomultiplier 10 per time is large. However, the flow of the contrast agent causes When the amount of incident light per unit time decreases, the pulse width t '
The amount of light incident on the image intensifier 3 is kept constant by extending the X-ray irradiation time, and the film density is kept constant. As described above, the pulse voltage is set as a tube voltage set before movie shooting so that an appropriate contrast can be obtained according to the imaging region and direction, and as a tube current suitable for the subject thickness automatically obtained during fluoroscopy. Since the film is shot by compensating the incident dose to the image intensifier 3 only by the width control, it is possible to obtain an X-ray film having a good film contrast and a constant film density.

【The invention's effect】

According to the X-ray cinematography apparatus of the present invention, an appropriate contrast is obtained according to the photographic region / direction, with the photographic tube voltage set before the cinematography, and automatically set during fluoroscopy before the start of the cinematography. Since movie shooting can be performed with a shooting tube current corresponding to the thickness of the subject, a movie film with good contrast can be obtained while maintaining a constant film density.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a graph showing a relationship between a fluoroscopic tube voltage and a fluoroscopic tube current and a subject thickness, and FIGS. FIG. 4 is a time chart showing a tube voltage waveform and a tube current waveform during movie shooting. 1 X-ray tube, 2 subject, 3 image intensifier, 4 TV camera, 5 TV monitor device,
6 High voltage generator, 7 Cine camera, 8, 9 Spectroscope, 10 Photomultiplier, 11 Photo timer circuit, 21, 22 A / D converter, 23 CPU, 24 ~ 26…
... Interface circuit, 31 ... Memory, 41 ... Subject thickness setting switch, 42 ... Movie shooting part / direction selection switch, 43 ... Movie shooting tube current setting switch, 44 ... Movie shooting tube voltage setting switch, 45 … Movie shooting pulse width setting switch, 46 …… Data write switch.

Claims (1)

(57) [Claims] 1. An X-ray tube, an image intensifier into which X-rays emitted from the X-ray tube and transmitted through a subject are incident, a TV camera to which an output image of the image intensifier is input, and the TV. Video signal from camera is sent
A TV monitor device, a high-voltage generator in which a signal from the TV monitor device is fed back to control a tube voltage during fluoroscopy, a cine camera to which an output image of the image intensifier is guided, and a A photo timer circuit for sending an X-ray cutoff signal to the high voltage generator according to the output light, an input device for inputting a subject thickness, a movie shooting part, a movie shooting tube voltage, a movie shooting tube current, and a movie shooting pulse width; A storage device in which the relationship between the fluoroscopy condition and the subject thickness and the relationship between the subject thickness and the cinema tube current for each imaging region are pre-written, The thickness of the subject is determined from the relationship between the subject thickness and the current of the movie tube according to the thickness of the subject. And a control device for controlling the high-voltage generator so as to perform movie shooting with a movie tube voltage set in advance.