SU1248083A2 - X-ray photographic exposure meter - Google Patents

Abstract

In the X-ray photoexponometer, the PMT 6 is quickly calibrated using an electrically controlled radioluminescent source 4, to which high-voltage pulses of adjustable amplitude are fed from block -7 during calibration. The current of the PMT 6 is recorded by the gauge 14. The introduction of the means of rapid calibration ensures a decrease in the accuracy during the operation of the photoexposure meter and reduces the time for its adjustment. 1 il.

Description

The invention relates to X-ray technology, in particular to X-ray photoelectron spectrometers used in X-ray diagnostic apparatuses, and is an improvement of the invention according to the author. No. 959299.

The purpose of the invention is to increase the accuracy and performance of the setting. The drawing shows a peijTreHOBCKoro photoexonometer.

The X-ray photoexpononometer contains a power source 1, a LED 2 ,. Scheme 3 specifies the law of change in the intensity of radiation of the LED 2, an electrically controlled radio-luminescent light source (RLI) 4, an X-ray converter 5, a photomultiplier tube (PMT) 6, a unit 7 for obtaining controlled high-voltage pulses an integrated capacitor 8, an adjustable resistor 9 , resistor 10, source voltage follower .11 voltage, current source 12, threshold device 13, and PM meter 14 of the PMT 6.

The PMT 6, the source follower 11 with the current source 12 is powered from the source 1, the LED 2 through the circuit 3 sets the law-variation of the radiation intensity. A current source 12 is connected to the integrating capacitor .8 through an adjustable resistor 9 and a contact group 15. The photomultiplier anode 6 through a capacitor 10 is connected to a source follower 11, a threshold device 13 and a current meter 14. FPI 4 is connected to block 7 receive controlled high voltage pulses. The X-ray converter 5, the LED 2 and the RADI 4 are optically coupled to the PMT 6 photocathode.

A row 4 is made in the form of two electrodes isolated from each other, between which a sealed mixture of a radioactive substance with a crystal phosphorus is contained in a low concentration, one electrode (from the photomultiplier) is transparent and made in the form of an optically transparent surface deposited on the glass substrate. conductive layer.

The device works as follows.

When the power source 1 is turned on, the voltage is applied to the PMT 6c by a resistive voltage divider and

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a voltage source 11 voltage source with a current source 12. At the same time through an adjustable resistor 9 and the contact group 15; the integrating capacitor 8 is almost instantly charged to a voltage, the value of which corresponds to the chosen blackening density of the exposed photographic material. At the same time, the LED 2 is turned on through the circuit 3 for setting the law of change in the intensity of the radiation, and its intensity is proportional to the voltage on the integrating capacitor 8 in the selected sensitivity range of the device. Under the action of light radiation, an anode current is formed at the output of the photomultiplier, whose magnitude is proportional to the intensity of the radiation, which is specified using scheme 3.

Before turning on the X-ray unit, the LED 2 is turned on by the contact group 16 and, at the same time, the integrating capacitor 8 is disconnected from the adjustable resistor 9 by the contact group 15, the photoexposure meter is ready to work with the X-ray unit.

X-rays in a converter 5, for example, a Csl scintillator, are converted into light, which excites a photocurrent in the photomultiplier tube 6, amplified by a system of diodes. The anodic current generated at the output of the PMT 6 discharges the integrating capacitor 8-. The discharge time of the integrating capacitor 8 to a voltage value determined by the value of a predetermined triggering threshold corresponds to that selected on the integrating capacitor 8, and the output of the threshold device 13 is an x-ray shutdown signal.

After the end of the exposure, the switching device,. including an LED 2 and connecting an integrating capacitor 8 to an adjustable resistor 9, through which the capacitor is charged again. Using an adjustable resistor 9, the exposure time and the density of the blackening of the exposed photographic material are also corrected within the selected sensitivity range of the instrument.

The use of a source follower voltage 11 with a current source 12 and a resistor 10 eliminates the dependence of the anode current on the voltage across the integrating capacitor 8 and improves the accuracy of the integration.

By irradiating the PMT 6 during the preparation of the photoexposure meter to the operating mode using the LED 2, the radiation intensity of which is set according to a certain law, the anode current of the PMT 6 is preliminarily increased, which significantly reduces the time to change the sensitivity of the PMT to a constant (steady). values in the selected sensitivity range of the photoexposure meter.

When the unit 7 for receiving controlled high-voltage pulses is turned on, high voltage pulses and, for example, with a frequency of 50 Hz, are applied to RLI 4 electrodes, the emission spectrum of which coincides with the emission spectrum of the X-ray converter 5. In this case, there is an intense detonation of RLI 4 at the time of the rise and fall of the pulses, and the intensity of the light pulses is proportional to the amplitude of the high-voltage imruls and at least an order of magnitude higher than the intensity of the RLI's own glow in the same part of the spectrum.

Under the action of light emission RFI 4, an anode current is generated at the output of the PMT 6, the value of which is proportional to the intensity of the radiation of MRI 4. The magnitude of the output current of the PMT 6 is recorded by a current meter 14, for example, a microammeter on the scale of which the arrow is set in the sector 6

By setting discretely different values of the amplitude of high-voltage pulses, it is possible to check the linearity of the characteristics of the PMT 6 according to the editor M. Bandura

 Compiled-K. Kononov Tehred I. Gaidot Proofreader S. Shekmar

4142/59

Circulation 765 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5

Production and printing company, Uzhgorod, st. Project, 4

mark the scale of the microammeter and estimate the sensitivity of the photomultiplier 6 of the working spectrum of the glow of the converter 5. If the pointer of the microammeter is not set to the desired spectrum, only in this case it is necessary to turn on the LED 2 and prepare the photomultiplier 6 for the operating mode.

Measuring the current of the PMT 6 can determine its sensitivity and if it corresponds to a given value, then the preparation of the PMT 6 for the operating mode can be omitted, since each

it takes 1-5 minutes, which, with a large number of images, significantly increases the C-millimeter time of the X-ray equipment.

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Claims (1)

Invention Formula X-ray photoexponometer on aut.St. No. 959299, from L with the fact that, in order to improve the accuracy and performance of the tuning, an electrically controlled radio-luminescent light source was additionally introduced, the unit for producing controlled high-voltage pulses and a photoelectric multiplier current meter, the radio-luminescent light source containing the radiating composition located in an airtight casing with the transparent window on the side of the photomultiplier between the electrodes isolated from each other, one of which is deposited on the inner surface of the transparent window, the unit for receiving controlled high-voltage pulses is connected to the electro- luminescent light source electrodes, and the photomultiplier current meter is connected to the output of the source follower .