SU603981A1 - Registering device - Google Patents

Description

(54) RECORDING DEVICE

Sensor unit 1 is designed to convert gamma quanta to electrical pulses and consists of a collimator, a scintillation crystal, a photoelectric multiplier, and a preamplifier.

Spectroalnator 2 is designed to isolate electrical signals from the sensor unit in a given range of radiation energy and is designed as an amplifier and amplitude discriminator.

Intensimeter 3 is designed to convert the pulse frequency into a DC voltage and is designed as a frequency-analog converter.

Photometer 4 is a prednaz:, achen for applying visually perceivable marks on a scansgram (film) and is made, for example, in the form of an LED of the type “ALN2A or

The photo marker control unit 5 is designed to drive the photo tag 4 and is designed as a DC amplifier with an adjustable gain factor, the load of which is the photo tag 4.

The scanning mechanism 6 with the control unit 7. is intended for automatic raster synchronous movement along a predetermined path of the block, and sensor 1 and the marker 4.

The device is also equipped with a subtractor 8, a function converter 9, a splitter of the f-range, a multi-input adder 1, a non-linear element 12, an inverter 13.;

Subtractor 8 is designed to subtract from the input signal the average pulse frequency corresponding to the background of the signal from the sources of ionizing radiation distributed outside the object under study.

The function transducer 9 is intended to change the functional dependence of the operation of the divider 10 of the range on the change in the level of the output voltage of the intensity meter. 3. The use of different functional dependencies is dictated by the need to obtain the output signal levels on the scanograph, in one case, with the same value of their statistical probability, or, in another case, the need to obtain uniformly distributed output signal levels over the entire recorded range of pulse counting rates.

The function converter 9 is designed as an operational amplifier, an integrated feedback and a set of potentiometers.

 The range divider 10 is intended to divide the voltage coming from the function converter 9 into a certain number of by-ranges — levels. The number of levels is set before the start of the research, the outcome, of the parameters of the object under study ..

The 10-range divider is designed as a system of comparators, the outputs of which are loaded on the multi-input adder I, and the inputs are connected to the output of the function converter 9. Comparators are triggered by the output voltage of the function converter 9 when it exceeds the set levels (thresholds). The output signal of each comparator is normalized by the value.

Multi-input adder 11 is designed to sum the normalized, output signals of the divider I) dia 1 zone. The total output voltage of the adder II is equal to the sum of the output voltages of each of the triggering comparators of the 10-range divider.

Nonlinear element 12 with adjustable dead zones and limits is designed to select a certain interval in the voltage coming from adder II, which ultimately leads to the selection of the area in the studied range of pulse counting rates, which must be registered.

Nonlinear element 12 is made in the form of an operational amplifier, a feedback diode circuit and a set of potentiometers.

Inverter 13 is intended to change the direct dependence of the blackening of the photographic material on the counting rate (see Fig. 2) to the opposite

o (see Fig. 3), thus allowing to obtain, in one case, a positive image of the object under study, and in the other - negative Dark details are recognized on a light background more easily than light ones on a dark background. % lower than for light. Therefore, "cold foci will be more easily recognized in a negative image, and" hot ones in a positive one, which leads to an increase in measurement accuracy.

Before the start of the study,

0 pre-setting the device on the level of subtraction. The sensor unit 1 is installed outside the object under study to measure the amount of background radiation, and by adjusting the subtractor 8, the intensity meter 3 is set to zero. Then, a block 1 of sensor 1 is installed above the area corresponding to the maximum accumulation of the radioactive drug in the object under study, and according to the indications of the intensity meter 3, the range of reproducible pulse count rates is estimated. By adjusting the dead zones and limits in the nonlinear element 12, the range of count rate rates is selected, for example, from Ni to Nz, then in the range divider 10 the required number of subdividing levels is determined (the maximum number of levels is determined by the number of comparators used in the divider 10). Adjusting the gain in the photometer control unit 5

the gain is set so that the maximum detectable signal level corresponds to the limit value of the current of the marker 4 (LED). After presetting, the sensor unit I is output to the top of the scan floor and the device is turned on in automatic mode provided by

3 by the scanning engine 6 and the control circuit 7.

The device works as follows. At the beginning of the study, while the sensor unit 1 is outside the object under study, the signal

9 at the output of the intensity meter 3 and converter