RU2417385C1 - X-ray image recorder and generator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: proposed device comprises solid-stage multichannel X-ray receiver made up of multiline multi-element matrix and data collection system. Note here that said matrix is made up of structure with its one side furnished with solid electrode applied thereon and its opposite side provided with signal electrodes arranged so that each nest line of elements is shifted relative the previous line by element part corresponding to the number of lines in matrix.

EFFECT: eliminating dependence of X-ray receiver resolution on its inlet opening slot width, reducing dose load on patients, reducing radiation background and current load.

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Description

The invention relates to x-ray technology, in particular to x-ray receivers, and is intended for use in medical x-ray units, tomographs, mammographs, in industrial introscopes with high spatial resolution.

Recently, in medical research and diagnosis of various pathologies of internal organs, X-ray and tomography units with high spatial resolution and digital image processing methods are widely used, followed by their output to a television monitor or paper. Obtaining a high resolution x-ray image is especially important in the diagnosis of fractures in the form of cracks and analysis of bone structure, as well as in the registration of small formations in the early stages of breast diseases. So, for example, the characteristic size of the "bridges" in the bone is about 50 microns.

An X-ray receiver is known that contains a linear converter based on silicon detectors, the outputs of which are connected through pre-amplifiers to an analog switch, the output of which is connected to a signal processor, and its output is connected to a video monitoring device through a series-connected digital memory unit and a non-linear image converter (see Defectoscopy , 1987, N7, pp. 38-42).

The small size of the semiconductor silicon detectors allows you to create a receiver with a high spatial resolution (0.1-0.2 mm), but the low efficiency of the absorption of x-ray radiation in silicon requires a significant increase in the dose of the object, which is undesirable for reasons of radiation safety of both the patient and the patient staff.

In addition, a significant drawback of the known device is the temporary instability of the characteristics of individual channels, requiring constant adjustment during operation.

The closest (prototype) to the claimed technical solution is a linear X-ray receiver (LRS) device for a digital X-ray medical device mounted on a movable tripod of a mechanical scanning device containing a linear multi-element X-ray sensitive receiver (LMRP), the output of which is connected to a charge interrogation and reading system, connected through an analog-to-digital converter (ADC) to the input of a personal electronic computer (PC). LMRP is made in the form of a multiwire proportional chamber with a fan anode plane, placed in a sealed enclosure and filled with an inert gas under a pressure of 3 atmospheres. Having an input LMRP input window width of about 0.5 mm and a wire spacing of 1 mm, the X-ray receiver provides a spatial resolution of about 1 mm (see preprint of the Institute of Nuclear Physics SB RAS N89-73, Novosibirsk, pp. 4-9).

It is known that line-by-line input systems of digital x-ray images, in which a slit diaphragm is installed in front of the object of study and the LRS behind the object, work effectively with a resolution of no better than 1 mm. When reducing the size of the radiation receiver element to a value of 50 μm, it is impossible to proportionally reduce the width of the strip incident on the object of x-ray radiation, because the focus of the x-ray tube is 1-2 mm, the distance to the object is 1 m and the size of the object in the direction of x-ray radiation is about 0.5 m. As a result, when the line-by-line input of the image occurs, the object is unreasonably overexposed 25-50 times. In the case of using sharp focus tubes (focus sizes 50 μm), for example, in mammography there are difficulties in alignment due to the large ratio of the length of the receiver line to the width of the diagnostic x-ray beam, as well as the exclusion of real backlash and vibration of mechanical components.

In addition, with line-by-line input, the x-ray tube is turned on for a long time (1-20 seconds), necessary for scanning the object, which leads to its accelerated failure, as well as to a multiple (100 or more times) increase in the level of background x-ray radiation in the room .

Known devices in which instead of a line of sensitive elements a multiline matrix is used, this solution allows the use of a large part of the x-ray beam and eliminates the above-described disadvantages, however, such a device has another drawback - the high complexity of manufacturing a multiline matrix in which the number of sensitive elements, as well as the corresponding electronic cascades of reading signal from sensitive elements, increased in comparison with a single-line device in the number of times equal to the number of lines in the matrix. The high complexity of manufacturing a multi-line device reduces its reliability and increases its cost.

The aim of the present invention is to remedy these disadvantages of a single-line device while maintaining the number of sensitive elements.

In the device for recording and forming an x-ray image containing a multi-channel x-ray receiver, this is achieved by the fact that the x-ray receiver is made in the form of a multi-line multi-element matrix, on one side of which a solid electrode is deposited, and on the opposite side the signal electrodes are formed so that each subsequent row of elements shifted relative to the previous one by part of the element, while the amount of shift corresponds to the size of the sensitive element in the direction perpendicular The linear direction of scanning, divided by the number of lines in the matrix, and also by the fact that an image line forming controller is additionally included in the device.

The introduction of the image line formation controller to the X-ray receiver made it possible to provide scanning of the entire X-ray image of the object with the format of a multi-line matrix containing several lines, which ensures the preservation of the spatial resolution specified by the detector while reducing radiation loads on the patient, radiation background radiation, and current load on the X-ray tube.

This ensures high efficiency of the use of x-ray radiation along with the implementation of high spatial resolution, since there is no need to reduce the size of the diagnostic strip of x-ray radiation using the slotted collimator to the dimensions of the image structure element, and the spatial resolution in the scanning direction is determined by the row height (k), and direction perpendicular to the scan direction, line-to-line shift d.

The indicated embodiment of the matrix X-ray detector, which made it possible to eliminate the dependence of the resolution of the X-ray detector on the slit width of its input window and at the same time to save the number of channels of the receiver as for a single-line one, reduces dose loads on the patient, the level of background radiation, and also reduces the current load on the X-ray tube, which has no analogues in X-ray technology, which means that it meets the criterion of "scientific novelty."

Figure 1 shows the kinematic diagram of the device, explaining its operation, where 1 is an X-ray tube, 2 is a slotted diaphragm, 3 is an object to be studied, 4 is an X-ray detection unit (XDR), 5 is a scanning device of an X-ray apparatus.

Figure 2 shows a block diagram of the inventive device, where 10 is an X-ray detector (DRI), 5 is a scanning device, 6 is an interrogation and reading system of charges (SOiSZ), 7 is an analog-to-digital converter (ADC), 8 is a controller formation of the image line, 9 - PC.

Figure 3 shows an example of the arrangement of the sensitive elements of the detector for a two-line matrix, where γ is the direction of x-ray and gamma radiation, k is the size of the sensitive element in the scanning direction, h is the size of the sensitive element in the direction perpendicular to the scanning direction, d is the relative shift sensitive elements located in adjacent rows of the matrix.

The inventive device operates as follows.

The operator of the x-ray unit from the control panel includes x-ray radiation. Simultaneously with the inclusion of x-ray radiation from the control panel to the input of the PC 9, a signal is received that starts the program, according to which the PC 9 includes a scanning device of the x-ray apparatus 5 and controller 8, which collects information from the DRI 10 through the interrogation and reading system of charges 6 and ADC 7. This is as follows. The electric signal generated by the sensitive elements of the DRI 10 is proportional to the incident X-ray radiation and enters the SOiSZ, where it is amplified, accumulated and stored. The controller 8 generates time diagrams for the ADC 7 and SIOZZ 6. From the first control output of the controller 8 to the control input of the ADC 7 receive clock pulses. From the second control output of controller 8, control pulses of a logical level are supplied to the control input of the SoiSZ 6, according to which the operation of the SoiSZ is controlled, as well as the information accumulated in the SoiSZ on the signals received from the DRI to the ADC input is received. From the output of the ADC 7, the digitized signal is fed to the signal input of the controller 8, which stores the array of data received from the detector to form the line of the x-ray image of the object by adding the obtained image fragments in a certain order, after which the generated line of the x-ray image of the object from the controller 8 is transmitted to the PC 9, where, in turn, a complete image of an object is formed from image lines.

For example, when using a matrix consisting of 2 rows with a resolution of 200 μm, the size of the sensitive element will be: k = 200 μm, h = 400 μm, d = 200 μm, the full format of the X-ray sensor is 410 mm × 0.4 mm (1024 × 2 elements). The image of the object is obtained as follows. After turning on the x-ray tube, the image of the object fragment recorded by the matrix of 1024 × 2 elements is read and transmitted to the controller 8. Then, the recording matrix and the slotted X-ray source are synchronously moved along the object for a certain predetermined distance (step = 200 μm) and the transmission of the next fragment of the object image to the controller 8 is registered. Next, the registration system moves to the next step, and the above steps are performed in a cycle until the entire object is registered and transferred to the controller 8. After each movement, the controller 8 generates the current line according to a predetermined algorithm and transfers it to the PC. In relation to the considered example, the final value of the image row can be formed from data collected in two steps of the matrix move, and the odd row elements are formed from the data obtained from the sensitive elements of the second row of the detector matrix of the current move step, and the even ones from the elements of the first row of the previous step (figure 3). Therefore, the resulting image of the row contains the number of image elements equal to the total number of sensitive elements of the matrix, and, accordingly, the maximum resolution of the system in the direction perpendicular to the scanning direction will be determined by the shift value of the sensitive elements of two adjacent rows, which allows us to produce a matrix with a greater than in analogs, the size of the sensitive elements

Thus, the claimed device allows you to eliminate the dependence of the resolution of the x-ray receiver on the width of the slit of its input window, reduces the dose on the patient, the level of background radiation, and also reduces the current load on the x-ray tube and does not increase the number of sensitive elements relative to the single-line detector.

Claims (1)

A device for recording and forming an x-ray image containing a solid-state multi-channel x-ray receiver, made in the form of a multi-line multi-element matrix, and a data acquisition system, characterized in that said matrix is made in the form of a structure, on one side of which a solid electrode is deposited, and on the opposite side side, the signal electrodes of the matrix are formed so that each subsequent line of elements is shifted relative to the previous one by a part of the element corresponding to the number of ok in the matrix.

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