SU833203A1 - Method of controlling x-ray unit - Google Patents

Description

(54) METHOD OF MANAGEMENT OF X-RAY WORK

APPARATUS

one

The invention relates to X-ray technology and can be applied when setting up reytgenodiagnostic devices and when adjusting them to the input of operation.

It is known that the magnitude of the half-absorption layer depends on the efficiency of the x-ray wavelength and, through it, is related to the magnitude of the anode voltage on the x-ray tube 1.

The closest technical solution is a method of controlling the operation of an X-ray emitter, which consists in transmitting radiation through a standard of a given thickness, register the intensity of radiation transmitted through the standard, which is a measure of the effective anode voltage, compare the intensity with an anodic voltage. emitter to match the values 2.

This method is implemented by ionizing registration of the radiation passing through, the reference radiation, which allows operational control over the parameters of the emitter.

In fact, a known method is reduced to measuring the multiplicity of attenuation of radiation by a layer of known material of known thickness and comparing this value to the attenuation of radiation by this layer with a given effective wavelength, i.e. corresponding to some effective value of the anode voltage. Since the tabular magnitude of attenuation for various materials is a half attenuation layer, in a known method it is preferable to work with standards corresponding in thickness to the half attenuation layers, although this is not an essential characteristic of the known method.

A disadvantage of the known technical solution is that in order to realize it, it is necessary to introduce a special control loop into the X-ray machine, which is absent in the large number of X-ray machines used. However, the task of setting up and adjusting such devices is very relevant from the point of view of obtaining optimal conditions for images, since the effective value of the anode voltage tends to temporarily drift, which is caused, for example, by changing the filtering properties of the medium between the x-ray tube and the object under study (oil, window emitter), as well as changing the parameters of the power supply device.

The purpose of the invention is to simplify the means of implementing the method by using a photographic method of detecting radiation.

The goal is achieved by the fact that in the method of controlling the operation of an X-ray apparatus, based on measuring the thickness of the HALF-Damping layer, determining from the measured value the effective anode voltage, comparing this anode voltage with a given magnitude and adjusting the anode voltage on the radiator until it coincides compared values, the thickness of the half-weakening layer is preliminarily measured at all the anode voltage settings on the radiator, and the measured values are determined by the measured values The effective values of the anode voltage for each setpoint and their deviations from the nominal values of the setpoint determine the magnitude of the regulating effect on the anode voltage for each setpoint, and in each subsequent cycle of the radiator's operation, the effective value of the anodic voltage is determined in this way from the nominal for one selected setpoint, and the value of the regulating action for any other setpoint is defined as Cd Uy, ged1 / g measured before each cycle of the deviation e is the effective anode voltage from the nominal for the th setpoint, tUi then the deviation is for the same setpoint when preliminarily determining the values of the regulating influence, and is the deviation of the effective anode voltage from the nominal for the jth setpoint when preliminary determining the values of the regulating action.

In this case, the determination of the half-retinal attenuation layer is performed by double exposure of the x-ray film, part of which is covered by the measuring wedge, and during one exposure the rest of the film is shielded from radiation, and during the other exposure, and the exposure parameters are chosen identical.

The method is implemented as follows.

For each of the main anode voltage settings, a half absorption layer of some material is determined. Preferably aluminum. At each setting, for this, an X-ray film is partially exposed, partially covered with a measuring wedge, the rest of the film being shielded from radiation during one exposure, for example, with a lead plate, and during the other open. The exposure time is equal. After processing the film, that part of it that is under the wedge and has equal blackening with the part of the film exposed during one of the exposures indicates the thickness of the wedge that corresponds to the thickness of the half absorption layer for the given anode voltage setting on the X-ray tube.

For each setpoint, the effective value of the anode voltage is determined from the measured thicknesses of the half absorption slab, which will determine the quality of the radiation with which the patient images are obtained. As a rule, the effective value of the anode voltage differs from the nominal voltage specified by the setpoint, since the quality of the radiation emitted from the emitter is generally different from the quality of the radiation emitted directly from the x-ray anode. In this case, the deviations for each device will be individual, since they are determined by the design features and conditions of the previous operation of the device. Thus, for each device, a table of deviations is composed as follows:

The obtained deviation values Uvn themselves determine the magnitudes of the regulatory actions that must be made at each setpoint of the apparatus, since the range of voltages that are optimal for obtaining images of good quality overlaps the error of this method. For intermediate setpoints, the magnitude of the control action is obtained by interpolation.

During the subsequent operation of the x-ray apparatus, it is sufficient to measure the deviation from the nominal value of the setpoint for only one selected i-th setpoint of the anode voltage. The point is that OR; another change in the apparatus, leading to the determination of the deviation from the setpoint, acts for all setpoints in a roughly proportional manner, with the result that the deviation for the jth setpoint can be defined as (A C / year). where Aui is the measured deviation value for the i-th statute; ki, and lSHc are the measured deviation values for the i-th and j-th set points with preliminary determination of the values of the regulating action.

After a long period of operation apparatus:

5 or after repair and changeover, the whole measurement cycle can be repeated.

As a result of the use of the proposed method, the possibility appears for.

for any device, select the characteristic anode voltage regulation values for each setpoint, which will lead to an increase in the quality of the images.

For the wide use of the method it is necessary to compile the tables. determining the effective anode voltage by the thickness of the half absorption layer.

The advantage of the proposed method is its simplicity and accessibility when working with personnel of medium qualification.

 The proposed method may be carried out in part during the acquisition of test shots.

Claims (2)

1. A method of controlling the operation of an x-ray apparatus, based on measuring the thickness of a half-attenuation layer, determining from the measured value the effective anodic voltage value, comparing this effective anodic voltage with a predetermined value and regulating the anodic voltage on the emitter to match the compared values differing from that, in order to simplify the means of implementing the method by using a photographic method of detecting radiation, the thickness Half attenuation for all installations of the anode voltage on the emitter from the measured values determined effective values of the anode voltage for each setpoint and their deviations from nominal values settings that determine the magnitude of the regulating effect on the anode voltage for each setpoint; for each subsequent cycle of the radiator, in this way, the deviation of the effective anodic voltage from the nominal value for one selected setpoint, and the magnitude of the regulating effect for any other setpoint determined as (AUi / AUta) dU rAeUi measured before each work cycle deviation of the effective anode voltage nominal for the i-th unit, the same deviation for the same set point upon preliminary determination of the values of the regulating effect and –l-UjH - the deviation of the effective anode voltage from the nominal for the J-th setting in the preliminary determination of the values of the regulating action. 2. A method according to claim 1, characterized in that the determination of the half-attenuation layer is carried out by double exposure of an x-ray film, part of which is covered with a measuring wedge, and during one exposure the rest part of the film is shielded from radiation, and at the time of the other it is exposed, and the parameters of the exposures are chosen identical. Sources of information taken into account during the examination 1. V. Shmelev. X-ray machines. M., “Energies, IQZ3, p. 23-31. 2. US patent No. 2503075, CL. 250-103. publish 1950. (prototype).