JPS596804Y2 - Automatic distance measurement device from focal point in X-ray photography equipment - Google Patents

Description

[Detailed explanation of the invention] Distance between focal films during X-ray photography (F.F.D.)
is the determination of the servo aperture, and the distance between the focal objects (F.S.
．． D) It is necessary for dose rate or volumetric dose measurement, etc., and conventionally there are actual measurements and potentio-based methods, but the former has accuracy problems because it is set by visual measurement using the scale plate of the device, and the latter has been used frequently. Failures are common due to friction and unnecessary pressure, and mechanical methods have drawbacks such as the complexity of the device and the need for modification in order to incorporate it into an already designed device.

The present invention does not have the above drawbacks and can measure the above distance,
It can also be used as data for automatic control of a servo diaphragm, or for measuring dose rate, volumetric dose, etc. An example of implementation will be described with reference to the attached drawings. Reference numeral 1 indicates an X-ray tube and A indicates its focal point.

2 is a top plate, 3 is a subject, 4 is a film for X-ray photography,
5 is an X-ray servo aperture device, 6 is a directional sound wave, such as an ultrasonic transmitter, and 7 is a receiver, and the ultrasonic wave emitted from the transmitter is reflected by the subject 3 or by the top plate 2 when there is no subject. and received by the receiver 7.

The transmitter 6 is connected to an ultrasonic wave transmitting circuit 8 via a gate circuit 9 which is opened by a signal from a measurement start signal generator 10, and emits an ultrasonic wave using its oscillation wave.

In addition, the ultrasonic wave from the ultrasonic transmitting circuit 8 is used as a starting signal for the high-frequency oscillator 12 that generates a certain number of high-frequency waves.
The detection output of the sound wave receiver 7 is amplified by the amplifier 11 and input to the high frequency oscillator 12 as a stop signal for the high frequency oscillator 12, and the oscillation wave of the high frequency oscillator 12 is supplied to the counter circuit 14.

The counter circuit includes a distance D between the focal point A and the acoustic wave transmitter/receiver.
1. Distance D2 between top plate 2 and film 4 or subject 3
A correction device 13 is attached to correct the wave number obtained by converting the distance D3 between the film 4 and the like by the wavelength of the oscillation wave from the high frequency oscillator 12, and supplies the output of the counter circuit 14 to a calculator 15 that calculates and displays the distance.

The present invention has the above-mentioned structure, in which the gate circuit 9 is opened by the signal from the measurement start signal generator 10, and the output of the ultrasonic wave transmitting circuit 8 is transmitted to the transmitter 6 to transmit ultrasonic waves and to generate a high frequency oscillator. 12 is started, and the wave number of the oscillation wave is counted by the counter circuit 14.

On the other hand, the ultrasonic waves emitted from the transmitter 6 are reflected by the subject 3 or the top plate 2, and the reflected waves are detected by the receiver 7, amplified by the amplifier 11, and supplied to the high frequency oscillator 12 as a stop signal, which is then sent to the counter circuit 14. The frequency from the start to the stop of the high frequency oscillation circuit 12 is counted.

Since the count value of the counter circuit 14 is proportional to the time required for the sound wave to travel back and forth between the transmitter and the reflector, and the oscillation frequency of the high frequency oscillator 12 as well as the speed of sound are known, the distance is calculated from the count wave number. be able to.

However, since the wave number counted by the counter circuit is proportional to the round trip distance between the transmitter and the reflector, the distance between the focal point A and the film 4 (F.F.D.) is equal to the counting frequency. A high frequency oscillator 12 corresponding to the distance D1 between the acoustic wave transmitter and receiver and the focal point and the distance D2 or D3 between the reflector and the film.
The wave number of the oscillation wave is subjected to addition correction by the correction device 13, and the output thereof is calculated into a distance by the calculator 15.

The distance between the focusing films (F.F.
．． D. ), the servo print device 5 controls its aperture to keep the X-ray irradiation field of the film 4 constant.

As shown in FIG. 2, in this servo diaphragm device 5, when the stepping motor is rotated, a gear 17 fixed to its rotating shaft rotates, and a feed plate 18 fixed to the gear 17 approaches or separates.

Therefore, since the lead plate blades 19 fixed to the feed plate 18 approach or separate, the angle of the stepping motor is controlled based on the distance between the focusing films (F.F.D.) determined by the calculator 15. Since the position of the lead plate blade is proportional to the angle, a constant X-ray irradiation field can be obtained at all times.

Further, the distance between the focal objects (F.S.D.) is determined in the same manner as the distance between the focal films (F.F.D.),
Respective distances (F.F.D.) and (F.S.D.)
When displayed on a display (not shown), it can be used as area dose and other measurement data.

The electric circuit in the above embodiment is just an example; for example, a sound wave reception signal that operates as a stop signal for the high frequency oscillator 12 may be used as a counter stop signal for the counter circuit 14, or the output of the correction device 13 may be used as a stop signal for the counter circuit 14, or the output of the correction device 13 may be The same result is obtained even if the data is supplied to the calculator 15, and such changes can be made freely.

The present invention is as described above, and since it is possible to accurately measure the distance between focal films (F.F.D.), if the aperture of the servo aperture device is controlled based on this measurement value, it will always be constant. This provides an X-ray irradiation field, which has the effect of making it possible to obtain X-ray photographs suitable for diagnosis.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the present invention, and FIG. 2 is a schematic diagram showing an example of a servo aperture device. 1... X-ray tube, 2... Top plate, 3...
...Subject, 4...Film, 6...
・Sound wave transmitter, 7...Sound wave receiver, 12...
... High frequency oscillator, 13 ... Correction device, 14
... Counter circuit, 12 ... Calculator,
A...Focus.

Claims (1)

[Scope of utility model registration request] A sonic wave transmitter that emits a directional sound wave in response to a measurement start signal, a receiver that receives the emitted sound wave from the sonic wave transmitter, a high frequency oscillator that generates a high frequency wave of a constant frequency, and a X consisting of a force counter circuit that counts the wave number of the oscillation wave of the high frequency oscillator, a correction circuit that adds a correction wave number to the counted value by this counter circuit, and a calculator that calculates the distance from the counted and corrected wave number.
An automatic distance measuring device from a focal point in a line photography device.