JPH01243398A - X-ray photographing device - Google Patents

Abstract

PURPOSE:To enable easy setting of optimal brightness by, at time of test X-ray exposure, fixing a lamp voltage and making an exposure time variable to obtain conditions for optimal brightness and also by, at time of cine-photographing, fixing the exposure time for optimal conditions and making variable a lamp voltage and a lamp current. CONSTITUTION:A CPU14 compares an integrated value of a brightness signal sent from a sample-and-hold circuit with a brightness setting value sent from an input terminal 17. If the brightness signal is higher than the brightness setting value, the CPU decreases X-ray conditions and vice versa, to enable the observation of picture elements with a constant brightness always. In this case, the X-ray conditions are controlled by the CPU14 and the values of kV and mA are both converted by a D/A converter 18 and then sent to a generator unit 2. An exposure time is sent for a time lapse set to a programmable timer 19. With this, the system compares the signal as against the shortest X-ray exposure time and, when the formal output signal waveform has neared an optimal output value, sets an X-ray exposure time based on a ratio between that signal output and the optimal output in order to obtain the optimal X-ray conditions.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an X-ray imaging device that can automatically adjust brightness, and in particular, to reduce the dependence on tube voltage to achieve proper brightness. The present invention relates to an X-ray imaging device capable of performing imaging.

(Prior Art) Conventionally, the automatic brightness adjustment provided in X-ray imaging apparatuses is a method that fixes the exposure time (ms) and adjusts the tube voltage (kV) and tube current (mA) as appropriate to achieve the optimum brightness. It becomes.

(Problem to be Solved by the Invention) Conventional X-ray imaging apparatuses equipped with such automatic brightness adjustment have a problem with I! during cine imaging. L-brightness adjustment is achieved by varying the kV under the planned exposure time and mA, but the kV changes greatly depending on the thickness of the subject; if the body is thin, the kV is low, and the body k if thick
There was a problem that V was too high.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an X-ray imaging apparatus that can reduce the dependence on kV and set the luminance to I and appropriate brightness during cine imaging.

[Structure of the invention] (Means for solving the problem of espionage) The present invention has a structure that takes the following means in order to solve the above problems and achieve the object.

That is, the present invention provides an X-ray imaging apparatus capable of automatic brightness adjustment, in which the tube voltage is fixed and the exposure time is variable in advance of cine imaging and during test The present invention is characterized in that it is equipped with a control means that determines line conditions, fixes the exposure time that provides the optimum brightness condition in cine photography, and adjusts the brightness automatically by varying the tube voltage and tube current.

(Function) According to such a configuration, the maximum fl.
Since cine photography can be started under the X-ray conditions of ff degrees, optimal brightness can be achieved by simply adjusting the tube voltage to the pre-fixed tube voltage value or a value close to it during cine photography. .

(Embodiment) An embodiment of the X-ray imaging apparatus according to the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 denotes an X-ray tube that emits X-rays, and is connected to a high voltage generator 2. The X-ray tube 1 is operated under X-ray conditions (
(kV, mA, ms), the X-rays pass through the subject 3 and enter the image intensity fire 4, where they are photoelectrically converted and generate a transmitted image of the subject. This image is optically distributed to a cine camera 6 and a television camera 7 by an optical distributor (optical system) 5.
Then, the image is displayed on a cine film, and in the television camera 7 via the television camera control unit 8, it is displayed as an image on the TV monitor 9.

Here, an automatic brightness adjustment mechanism is provided so that these images can always be observed at a constant brightness, and its operating principle is as follows. The optical system 5 includes a built-in photomultiplier that detects the brightness of an image, and converts the amount of light, that is, the brightness of the image, into an electrical signal. This signal is amplified by amplifier 10. Amplifier 11 is amplifier 1
This is an operational amplifier for integrating a signal amplified by 0 using a capacitor 11. The switch 13 opens when X-ray exposure starts and closes when X-ray exposure ends. A circuit constituted by this amplifier 11, capacitor 12, and switch 13 is a sample-and-hold circuit, and the brightness of an image can be detected by this sample-and-hold circuit. The detected brightness is passed through the multiplexer 15 controlled by the CPU 14 to the A/
Analog/digital conversion is performed by the D converter 16 and the CP
The data is taken into U14 as data.

On the other hand, a setting value for optimizing the brightness is inputted from the input terminal 17 and taken into the CPU 14 via the multiplexer 15 in the same way as the image brightness signal. Here, C.P.
In U14, both the integrated value of the luminance signal from the sample and hold circuit and the luminance setting value from the input terminal 17 are compared,
If the integrated value of the brightness signal is higher than the brightness setting value,
It operates to lower the MA condition, and if it is lower, to raise the X4 condition. Thereby, pixels can always be observed with constant brightness regardless of changes in object thickness, that is, regardless of the magnitude of X-ray absorption.

In this case, the X-ray conditions are controlled by the CPU 14 and k
V and mA are each converted into digital/analog by D/'A converters 18 and 18, and sent as signals to the high voltage generator 2.

In addition, the XIl exposure time is controlled by the CPU 14, and the XIl exposure time is controlled by the CPU 14.
High voltage generation bag for radiation exposure signal! Send to 2. The high voltage generator 2 generates X-rays from the X-ray tube 1 in response to these kV flaw signals, mA flaw signals, and X-ray emission signals.

In the X-ray control system as described above, in order to determine the maximum 3+1 X-ray conditions before starting cine imaging, a test XIS is performed at a preset tube voltage, and the integrated value of the luminance signal is compared with the set value. However, as shown in Figure 2 (a) and (b), the signals are first compared using the shortest X-ray exposure time, and if the signal output is small compared to the set value, the next second test is performed. X-ray exposure is performed for the maximum allowable X-ray exposure time.

If the signal output in the second X-ray exposure is larger than the set value in the signal comparison, the third X-ray The test X-ray exposure is stopped when the integrated value of the photomultiplier output signal reaches the optimal output value, which is the brightness setting value. The xiai shooting time at this time is set in one programmable timer, and the xiai shooting time is set in one programmable timer. l [l shot time.

When the shooting started, this X1! The exposure time is fixed, and automatic brightness adjustment is performed while controlling kV and mA as before.

If the signal output from the second test X-ray exposure is still small compared to the set value, the third test X-ray exposure increases the tube voltage by a predetermined value (several kV). The signal comparison is performed using the shortest X-ray exposure time. This case is shown in FIGS. 3(a) and 3(b). Thereafter, the method up to finding the a*X-ray condition is the same as that described above.

If the optimum signal output cannot be obtained even with the longest XR exposure time when the kV is increased, it is assumed that imaging is not possible, and the test exposure is stopped and the imaging sequence is also stopped.

If the signal output from the first test X-ray exposure is large compared to the set value, the second test X-ray exposure is
The tube voltage is lowered by a predetermined value (several kV), and signal comparison is performed at a short X-ray emission time. This case is shown in FIGS. 4(a) and 4(b). After that, f&suite
The method up to finding the line conditions is the same as in the case described above. If the signal output is still large compared to the set value in the signal comparison at the second f&short X-ray exposure time, it is determined that the test X-ray exposure is not possible and the imaging sequence is also stopped.

When comparing signals based on the shortest X-ray exposure time, the formal output signal waveform is! & When the output value is close to the optimum output,
Instead of setting the next X-ray exposure to the maximum xi exposure time, set the X-ray exposure time based on the ratio of that signal output to the optimal output and f! It goes without saying that the kaX-ray conditions must be determined.

As described above, in this embodiment, the preset kV
When performing test X-ray exposure while changing the exposure time, test X-ray exposure is performed at the maximum and minimum exposure time that can be set, and within the range of the two fk
If weekly X-ray exposure conditions are required, the third test
For radiation exposure, once the optimum conditions are reached, press X! By stopping I@ radiation, memorizing the exposure time, and starting imaging with that aax4tq radiation time, imaging can be started at any kV depending on the area to be imaged, and automatic brightness control after starting. Adjustments can also be made to take pictures near the starting kV.

Therefore, since automatic brightness adjustment is performed in kV and mA,
It can follow large changes in subject thickness, and can always obtain photographs with stable density depending on the purpose of photography.

The present invention is not limited to the above embodiments, but can be implemented with various modifications without departing from the gist of the present invention.

[Effects of the Invention] As described above, in the present invention, in the test X-ray exposure prior to cine imaging, the tube voltage is fixed and the exposure time is varied to find the X-ray conditions that give the highest Wi brightness. When it comes to photography, the above-mentioned 3i! ! ! By fixing the exposure time as the one-time condition and automatically adjusting the brightness by varying the tube voltage and tube flow, cine imaging can be performed under the X-ray conditions that achieve the maximum i!i brightness at the pre-fixed tube voltage. Therefore, when shooting a cine, it is possible to obtain the fiWi brightness by simply adjusting the tube voltage to a pre-fixed tube voltage value or a value close to it. It is possible to provide an X-ray imaging bag that allows imaging to be set at the optimum brightness with less dependence on kV!

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the x4tm shadow device according to the present invention, and FIGS. 2 to 4 are operation waveform diagrams of simultaneous embodiments, respectively. DESCRIPTION OF SYMBOLS 1... X-ray source, 2... High voltage generator, 3... Subject, 4... Image intensifier, 5...
Optical distributor, 6... Cine camera, 7... Television camera, 8... Television camera control unit, 9... TV
Monitor, 10° 11...Amplifier, 12...Capacitor, 13...Switch, 14...CPU, 15...
- Multiplexer, 16 A/D converter, 17... Input terminal, 18... A/D converter, 19... Programmable timer. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] In an X-ray imaging device that can automatically adjust brightness, during test X-ray exposure prior to cine imaging, the tube voltage is fixed and the exposure time is varied to find the X-ray conditions that provide the optimal brightness. An X-ray imaging apparatus characterized by comprising a control means for fixing the exposure time that provides the optimum brightness condition and for automatically adjusting the brightness by varying the tube voltage and tube current.