SU893204A1 - X-ray irradiation linear coordinate indicator - Google Patents

Description

(5) THE INDICATOR OF THE LINEAR COORDINATES OF THE X-RAY RADIATOR

one

The invention relates to X-ray technology and can be used in the composition of tripod-mechanical devices of X-ray diagnostic devices to establish the exact location of the X-ray emitter relative to the object under study.

A linear indicator of the emitter linear coordinate in an X-ray computed tomography is known. The emitter moves along the ruler in both directions of the MS.

A disadvantage of the known device is the discrepancy between the period of the electrical output signal and the scale step of the ruler in the extreme

positions of the radiator relative to the ruler (at the beginning of the ruler with odd, at the end with even passages of the radiator). This is caused by the presence of a transient at the output of the separation capacitor, which makes it impossible to use the device for indicating the position of the radiator in stand-by-mechanical devices of X-ray diagnostic apparatus.

ten

The closest to the present invention is a photoelectric device for measuring linear dimensions, which contains a light source, a stationary transparent ruler with a scale, a terminal that is rigidly connected to the light source, an amplifier, a voltage comparator, and an amplifier output connected to the source. and a pulse counter connected to the output of the comparator associated with the operation of the additional relay C2. The disadvantages of this device are considerable measurement errors caused by changes in the sensitivity of the photocell depending on the ambient temperature, and in the instability of the light flux of the light source and the gain of the amplifier, which requires adjustment of the device during operation. The purpose of the invention is to improve the accuracy and stability of the indicator of the linear coordinate of the X-ray emitter. The goal is achieved by the fact that the linear indicator of the X-ray emitter, containing a source of light rigidly connected to the emitter, a fixed transparent ruler with an opaque scale applied to it, a photoelectric converter behind the line, an amplifier connected rigidly to the light source, connected to the output of the converter, voltage comparator, to one input of which the output of the amplifier is connected, and a pulse counter connected to the voltage comparator output, additionally The series-connected peak detector and voltage divider are connected between the amplifier's output and the second input of the voltage comparator. Figure 1 shows the indicator of the linear coordinates of the x-ray emitter; Fig. 2 shows voltage diagrams at the inputs and outputs of a voltage comparator at various photodetector sensitivities. The X-ray emitter 1 is rigidly connected to a light source 2 and a photoelectric converter, for example, a semiconductor photodetector 3. A transparent line k with an opaque scale is located between the semiconductor photodetector 3 and the light source 2. An amplifier 5 is connected to the output of photodetector 3, the output of which is connected through a peak detector 6 and a voltage divider 7 with one input of a voltage comparator 8, to another input of which amplifier output 5 is connected. A counter 9 of pulses is connected to the output of comparator 8. The device works as follows. t4 The X-ray emitter 1, which is rigidly connected to the source 2 of the light and the semiconductor photodetector 3, moves along a transparent ruler with a scale fixedly fixed relative to the object to be removed, for example, on a deck of a turntable tripod or table of pictures. The light flux from the light source 2, for example, an infrared LED, passage through a transparent ruler, excites the EMF in the photodetector 3. The voltage amplified with the help of amplifier 5 supplies directly to one of the inputs of the voltage comparator 8 (U- |) and simultaneously through the peak detector 6 and the voltage divider 7 to the other input of the voltage comparator 8 (Urj). When the radiator 1 moves along the ruler ij, the light flux is attenuated by the opaque scale of the ruler scale. In this case, the voltage decreases, and the voltage Un is remembered by the peak detector 6 and remains constant. This is because the charge time of the storage capacitor of the peak detector is 6 T-), i 1c, and the discharge time of IMWH is constant, which is comparable with the thermal drift of the photodetector 3. At the moment of equal voltage U / i and UQ, the comparator works 8 the voltage and at its output a pulse U / iB appears; the end of the opaque risks of the ruler scale, when the voltage U / i becomes higher than the voltage Un, the voltage comparator 8 returns to its original state. With the passage of subsequent opaque scratches applied on the ruler scale with an interval of, for example, 1 mm, the process is repeated, and the number of times the voltage comparator 8 operates corresponds to the number of scratches. The pulses from the comparator 8 voltage. arrive at the counter 9 pulses, which controls the executive body of the X-ray diagnostic apparatus, which is triggered in a predetermined position of the X-ray emitter 1. As can be seen from the voltage diagrams, the voltage Uii or varied in accordance with the change in the sensitivity of the voltage U. is constant AND proportional to the electrical signal of the photodetector 3 corresponding to the transparent part of the ruler. The voltage Uxi (UJf) is equal to the signal corresponding to the instantaneous position of the photodetector 3. As a result, the electrical signal at the output of the voltage comparator 8 does not depend on the change in sensitivity of the photodetector 3 caused by thermal or temporal drift, but is determined only by the value specified by the divider 7 is the ratio of the attenuation of the light flux to the transparent and opaque portions of the ruler.

The proposed indicator can be used in tripod-mechanical devices of X-ray diagnostic devices and X-ray computed tomographs.

Claims (2)

1. Technical Description of EMI Scanner CT101 O, EMI (UK). 2.Turichin A.M. Electrical measurements of non-electrical quantities. M., Gosenergoizdat, .1959, p.13 (prototype). J t Csj t