JPH0381999A - X-ray continuous radiographing device - Google Patents

Abstract

PURPOSE:To have alignment of the radiographing times even with different thicknesses of motives to be radiographed and perform radiographing with proper density by varying the voltage of a radiographing tube during exposure so that the actual measurement of penetrative X-ray dosing becomes equal to the integrated value of the dosing factor which is calculated from the set radiographing time and the set density. CONSTITUTION:The X-rays having penetrated a motive to be radiographed 6 are received by a photoelectron booster tube 20 from an image intensifier 7 and integrated by a photo-current integrator 40. When this integral value becomes the density reference voltage 12 set by a density setting device 42, a density comparator 41 sends an X-ray shutoff signal 43 to an X-ray controller 44, and the X-ray is cut. This X-ray exposure time t varies according to the penetrative X-ray dosage. To have coincidence of the t with radiographing time, the dosing factor signal 13 calculated from the set radiographing time and the set density reference voltage 12 is integrated by another density integrator 14, and the difference from the integral value of the integrating device 40 is made as a difference signal by a differential amplifier 15. In case the operation time of the comparator 41 becomes longer than the radiographing time, the photographing voltage is raised to increase the penetrative X-ray dosage, and control is made so that the operation time of the comparator 41 becomes radiographing time.

Description

[Detailed description of the invention] [Industrial application field] The invention is utilized in the field of xmm shadows.

The present invention relates to a continuous X-ray imaging apparatus, and in particular, X-ray imaging of the vascular system of the head and abdomen is performed by automatic exposure control. The present invention relates to a continuous X-ray imaging device.

[Prior Art] Automatic exposure control is hardly performed in continuous X-ray imaging devices for the vascular system of the head and abdomen. It is known that automatic exposure control is performed in X-ray photography using multiple exposures, and that appropriate photographic density is obtained depending on the intensity of the subject.

[Mission Mi to be Solved by the Invention] Therefore, in continuous X-ray imaging, proper exposure may not be obtained due to differences in subject thickness, and re-imaging may be performed.

Automatic exposure control can be applied even if the shooting time changes significantly in general shooting, which is used to take single shots such as the chest, but with continuous shooting devices equipped with a film changer, the shooting time is determined by the shooting speed of each shot. It was considered difficult to apply automatic exposure vI control.

SUMMARY OF THE INVENTION An object of the present invention is to provide a continuous X-ray imaging device that is capable of automatic exposure control and is equipped with a film changer.

[Means for Solving Problem J] The purpose described in 11 A is to provide a continuous photographing device control section that controls each setting means for the photographing speed and the number of shots; a film changer that operates according to the set values; The density setting device of the photographic film and the initial tube voltage ([11 setting device) are used to compare the measured integral value of the transmitted
The automatic exposure control unit sends the data to the Hc controller, the concentration integrator calculates the dose rate based on the set imaging speed and the set density value, and the exposure rate is calculated based on the difference between its output value and the actually measured integral value of transmitted X-ray b':. By being equipped with an arithmetic unit that adjusts and changes the voltage and sends the signal to the X-ray controller, and a microcomputer that calculates the tube current based on the 8 constant or adjusted tube voltage value and sends the signal to the X-ray controller. , are distant relatives.

[Function] Behind the film changer, an automatic exposure control unit is arranged which includes an image intensifier, a photomultiplier tube, a photocurrent integrator, a density setting device, a comparator, and the like. On the other hand, the integrated value of the dose rate calculated from the set imaging time and the set concentration and the actual transmitted X-ray dose IT! The camera tube voltage is changed during exposure so that the I integral value becomes equal, and even if the thickness of the subject is different, the photography time is the same, and a photographic film with an appropriate density can be obtained.

[Example] A preferred embodiment of the invention will be explained based on the drawings.

FIG. 1 is a 4iIIIi and system block diagram showing one embodiment thereof, and FIG. 2 is a diagram illustrating the output relationship between a photocurrent integrator and a concentration integrator according to the present invention.

When the continuous imaging device controller 11 sets the imaging speed by selecting the number of images to be taken per second according to the rating of the film changer 10 and also determining the number of images, the microcomputer calculates the possible X-ray exposure time as the imaging time. , is set in the timer of the X-ray controller 44.

From the set number of images to be imaged, the number of images to be imaged from the X-ray tube high-speed continuous imaging rating diagram 2, that is, the number of images to be imaged, the load for one time to be imaged can be determined.

On the other hand, the initial value of the imaging tube voltage is set by the tube voltage initial value setting device 32.

The imaging tube current is calculated from the imaging load, imaging time, and imaging tube voltage using the following formula. Imaging tube current (mA) Imaging load (HU) / (1,41X imaging time (msec)
X-ray tube voltage (KV)) and X-ray tube short time 11fj rating From FIG. 3, the photography tube current is calculated from the photography time and the photography tube voltage, and the lower value is set as the photography tube current.

The above photographing conditions are calculated by a microcomputer,
line controller 44 and is further sent to the high voltage generator 4 through the X-RAY switch 19. X-ray radiation from the X-ray tube 5 is started.

X-rays transmitted through the object 6 are received by a photomultiplier tube 20 from an image intensifier 7 and integrated by a photocurrent integrator 40. When the integrated value reaches the concentration reference voltage 12 set by the concentration setting device 42, the concentration comparator 41 outputs an X-ray cutoff signal 4.
3 to the X-ray controller 44 to turn off the X-rays.

At the time of this XS exposure] the amount of light changes depending on the amount of transmitted X-rays. Therefore, in order to match t with the imaging time, the dose rate signal 13 calculated from the set imaging time and the set concentration reference voltage t2 is integrated by another concentration integrator 14, and the photocurrent integrator 40
The difference between the integrated value and the integral value is transmitted as a difference signal by the differential amplifier 15.

That is, when it is determined that the operating time of the density comparator 41 is longer than the imaging time, control is performed such that the operating time of the density comparator 41 is equal to the imaging time by increasing the imaging tube voltage and increasing the amount of transmitted X-rays.

That is, as illustrated in FIG. 2, the output voltage of the photocurrent integrator 40 is compared with that of the concentration integrator 14 by the differential amplifier 15, and vice versa. The tube voltage is adjusted and changed by the adder 6 so that the former becomes larger if it is smaller, and the signal is sent to the X-ray controller 44 on the one hand, and the tube current 4iα calculated via the microcomputer 1 on the other hand. is sent to the X-ray controller 44.

The second imaging starts with the imaging tube voltage at the end of the first imaging, the imaging load for one imaging, or the imaging tube current calculated from the X-ray tube short duration rating Figure 3, and the same imaging time as the first imaging. be done. - Similar to the second shooting, the signal is received from the photomultiplier tube 20, and the density comparator 41 receives the signal by changing the photomultiplier tube voltage.
control so that the operating time corresponds to the shooting time.

Repeat this until the series of shots is completed.

f (In case of imaging areas where it is difficult for the contrast agent to change the overall density, for example the background of blood vessels, etc., press the LOCK button 17 to fix the imaging conditions for the third time, and the imaging will end. Photography can be performed under the same photographic conditions without using a phototimer.

These fixed photographing conditions are the optimum photographing tube voltage and photographing time according to the thickness of the subject, and the maximum photographing tube current calculated therefrom.

In addition, for thin subjects such as children where the tube voltage is too low to be photographed, when the THIN button 18 is pressed, the adder 16 performs only addition, and the tube voltage is raised to a constant value and fixed. can.

[Effects] During shooting, the photocurrent from the photomultiplier tube is integrated, and when the density reaches the set value, the X-rays are cut off, so the density of the photographed film becomes the appropriate value, and there is no need to take another shot.Automatic exposure control allows continuous shooting as is. But it's being kept alive.

Further, during the photographing, the photographing tube voltage is changed in conjunction with the photocurrent from the photomultiplier tube, and photographing is performed under photographing conditions according to the thickness of the subject, so that the photographing time can be kept constant.

Roughly prioritize i-imaging time and emphasize contrast as much as possible. For example, in areas where the overall density changes when contrast agent enters, imaging conditions are fixed to the values immediately before the contrast agent enters.
Automatic exposure control for shooting with low tube voltage can also be applied.

[Brief explanation of drawings]

FIG. 1 is a configuration and system block diagram showing an embodiment of the present invention, and FIG. 2 is a diagram illustrating the output relationship between a concentration integrator and a photocurrent integrator according to the present invention. 1 is a microcomputer; 10 is a film changer; 11 is a continuous photographing device controller; 14 is a density integrator;
is a differential amplifier, 16 is an adder, 40 is a photocurrent integrator, 4
1 is a concentration comparator, 42 is a concentration setting device, and 44 is an X-ray controller.

Claims (1)

[Claims] 1. A continuous photographing device control unit having means for setting the photographing speed and number of photographic images, a film changer that operates based on the set values, a photographic film density setting device, a tube voltage initial value setting device, and a transmission X an automatic exposure control unit that compares the measured integrated value of the dose with the set concentration value and sends an X-ray cutoff signal to the X-ray controller; and a concentration integrator for the dose rate calculated from the set imaging speed and the set density value; A calculator that adjusts and changes the tube voltage based on the difference between the output value and the actually measured integral value of the transmitted X-ray amount and sends the signal to the X-ray controller, and a calculator that calculates the tube current based on the set or adjusted tube voltage value. A continuous X-ray imaging device characterized by comprising a microcomputer that sends signals to an X-ray controller.