RU2098929C1 - X-ray apparatus for medical diagnostics - Google Patents

Abstract

FIELD: medicine. SUBSTANCE: apparatus has X-ray radiator with high-voltage supply, solid-state multielement X-ray image shaper, stand carrying mechanical scanning system with X- ray radiator and radiator and X-ray image shaper fixed within it in horizontal plane so that X-rays, as they pass thorough investigated entity, reach ends of photodetectors of X-ra image shaper; the latter is set of modules incorporating multielement linear semiconductor photodetector coupled with charge-coupled device through multiplexor. EFFECT: improved reliability of apparatus. 1 dwg, 1 tbl

Description

 The invention relates to the field of electronics and can be used to create a new class of radiographic equipment.

 A number of radiographic units are known, the characteristics of which are given below (see table).

 In all of these analogues, including the prototype, which was chosen as the x-ray unit described in the work "Digital X-ray unit for medical diagnostics", developed at the Institute of Nuclear Physics G.I. Budker (Novosibirsk, 1991). The installation includes a standard X-ray emitter with a high-voltage source feeding it, a tripod with a mechanical scanning system, a multi-element solid-state imager (MTFRI) and a recording and control system.

 The distribution of radiation in the horizontal direction is measured using MTFRI, and in the vertical by mechanical scanning. For this purpose, the x-ray tube, slotted collimator and camera during shooting simultaneously and uniformly move in the vertical direction (for installation with the vertical position of the patient). A collimator with a 1 mm gap forms a thin fan-shaped beam of x-ray radiation, which, after passing through the patient’s body, enters the MTFRI entrance window. In this case, MTFRI placed on it by the control electronics can be considered as 320 independent counters of x-ray quanta. The information accumulated in the counters during the exposure of the line is transferred to the computer memory, and then the registration of the next vertical line begins. At the end of the shooting, a digital image matrix of 320x256 numbers is accumulated in memory, which describes the distribution of radiation after passing through the patient's body. The first raw image on the display occurs simultaneously with the scan.

 The installation is controlled by a computer. The installation software includes the main control program and programs for monitoring the health of the units and the installation as a whole. The program allows the doctor to take several shots, look at the received pictures on the display, write to disk, and also, if necessary, run a special diagnostic task to process the information received. In the processing mode, the doctor can display the image on the display and, using a special, fast display system, quickly convert the image to the most convenient for visual analysis, and thereby improve the diagnostic capabilities of projection radiography. The program allows you to measure the distance between objects in the image, the density at each point in the image and the average density in an arbitrary fragment of the image, as well as carry out other operations.

 The scanning method virtually eliminates the registration of radiation scattered in the patient’s body. Zero background and high speed cameras (600 kHz per channel) significantly expand the dynamic range compared to other registration methods. Despite the long shooting time (about 8 s), there is no reduction in image sharpness due to small patient movements, since the exposure time of each line during scanning is 30 ms.

 The aim of the invention is to reduce exposure time, reduce radiation exposure to the patient, reduce the cost of operation and the cost of the x-ray unit.

 The fundamental difference between the proposed technical solution and the prototype is that, as a multi-element solid-state imager, assemblies of modules of the lines of semiconductor photodetectors coupled with CCD multiplexers are used. This is the fundamental novelty of the proposed technical solution.

 The proposed solution is significant because it allows to construct the device design according to a new principle, where the key element is a multi-element semiconductor photodetector coupled with a CCD switch. Therefore, this feature is significant and, therefore, the entire invention is significant. The proposal is significant, since it allows to significantly increase the sensitivity of the receiving unit of the installation and reduce the operating dose of the device, in addition, the proposal allows you to remove silver-coated films from consumption (see analogue) and reduce the cost of x-ray studies and components. Thus, the present invention can provide a large technical effect, dramatically increase the sensitivity of the installation and reduce the cost of the operation process and the installation itself.

 This proposal has an inventive step, since the elements of novelty in this application do not imply evidence for specialists. It should be noted that it is the proposed combination of novelty elements: the use of multi-element solid-state X-ray imagers (MTFRI) with a classic X-ray tube, but with a reduced emissive power, gives a fundamentally new functional property to the medical diagnostic radiographic apparatus by lowering more than one order of radiation power per patient. The use of highly efficient MTFRI allows to reduce the exposure time, to abandon the use of thick silver-containing films, in comparison with analogues to reduce the weight and size parameters of the x-ray unit, etc.

 The drawing shows a diagram of a radiographic installation according to the proposed technical solution.

 The installation consists of an x-ray tube 1 (see drawing), a collimator 2, a beam 3, an MTFRI 4 unit, an information collection and processing system 5, and a visualization device 6. If necessary, the patient table is included in the installation. The radiation from the x-ray tube through the collimator reaches the patient and, passing through the examined area of the body, reaches the MTFRI unit attached to the patient’s table, where after processing with peripheral electronics in the form of a graduated signal, it reaches the information collection and processing system (SOI). The obtained information is then input to the imaging device. In our proposed technical solution, the MTFRI 4 unit consists of a hybrid photosensitive circuit 7 containing a line of photodetectors 8 coupled to a CCD multiplexer 9.

 In this proposal, the line of photodetectors is made on the basis of cadmium telluride with an element size of 100 x 100 μm, with the number of image decomposition elements of 1280, and the multiplexer is made on the basis of silicon, with a surface channel. The line of photodetectors (which can be made on the basis of gallium arsenide or on the basis of silicon) is coupled to the switch by means of diodes made on the crystal of the switch, which are located between the photodetector and the CCD electrode. The radiation from the x-ray tube after passing through the patient’s body enters the photodetector and the signal from the photodetector enters the diode, and as a result, the diode is turned on in the forward direction and injects a charge proportional to the incoming signal under the CCD electrode, which sequentially enters the system at the exit of the CCD collecting and processing information (SDI) and then to the display device.

 The device provides a snapshot in a period of not more than 3.5 s (when exposing a frame of the 1280x1024 format image element with a resolution of no worse than 0.3 mm), image processing is not more than 5.0 s. The device provides mathematical image processing and storage of at least 2000 x-ray images in order to improve diagnostic capabilities.

The device provides:
sound connection between the doctor and the patient;
detector channel width not more than 0.26 mm;
the number of gray gradations is not less than 256;
management of all necessary movements from the remote and built-in control panel;
issuing a signal to unconditionally turn off the x-ray tube when the scan is stopped for any reason;
the load capacity of the patient table is at least 170 kg;
table dimensions: length 220 cm, width 90 cm, height from the floor 65-110 cm;
fastening an x-ray tube and MTFRI with a mismatch of the collimated beam of x-ray quanta of not more than 0.1 mm;
the focal spot size of the tube is not more than 1.2x0.3 mm;
collimating the flux of x-ray quanta in front of the object under study, taking into account the receipt of a focal spot on the surface of the detectors with a width of not more than 1.0 mm;
selection of the exposure area along the entire length of the table;
the time of continuous operation of the device should be at least 6 hours;
the preparation time of the apparatus for operation should be no more than 15 minutes.

 The surface material of the table passes X-ray quanta emitted by the tube in the voltage range.

The power supply and control X-ray tube (BPU RT) with a remote control provides the ability to control:
anode voltage: from 10 to 140 kV (in several ranges depending on the field of application);
anode current from 4 to 400 mA with step adjustment in four ranges: 4-10 mA after 2 mA, 10 30 mA after 5 mA, 30 100 mA after 10 mA, 100 400 mA through 20 mA, computer control.

Detection Unit:
provides registration of x-ray quanta from the block of x-ray tubes with an efficiency of at least 70% when loading up to 5x10 ⁵ imp / s;
provides preliminary signal processing, followed by pairing with a system for collecting and processing information (SDI) and a visualization device (HC);
provides power to electronic information processing units of all levels.

 The information collection and processing system (SDI) and the visualization device (HC) provide: an image processing mode in a dialogue with a computer operator using a graphic encoder such as a mouse and an AD keyboard in the following types: window, scale, horizontal and vertical lines "," division "," inversion ", distance measurement, density measurement, as well as recording captured frames to external devices for long-term storage.

 The system of protection against scattered radiation provides flows of no more than 25 μR / s at a distance of 1 m in any direction (at a tube voltage of 100 kV and a current of 100 mA).

 The technical and economic efficiency of this technical proposal lies in the fact that the use of solid-state high-performance semiconductor MTFRI can reduce the exposure time, reduce the radiation dose to the patient, and refuse to use thick silver-containing films.

Claims (1)

 Radiographic installation for medical diagnostics, which includes an x-ray emitter with a slit collimator and a multi-element solid-state imager x-ray images, characterized in that the latter is made in the form of an assembly of modules containing a linear multi-element photodetector based on GaAs, electrically connected to a surface-channel CCD multiplexer via direct injection input .

Images