RU2428929C1 - System of automatic testing of digital x-ray irradiation receiver - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: system contains installed in direction of irradiation from X-ray source X-ray screen, optic system of image transfer from screen to photosensitive CCD-matrix, whose outlet is connected with image processing unit. In plane of X-ray screen irradiation and beyond its irradiation surface installed are, at least, three test structures, provided with controlled sources of primary irradiation. Sources are installed in such a way that each test structure is in direct way of the rays from them.

EFFECT: application of invention makes it possible to extend possibilities of testing adjustment of sharpness of digital x-ray irradiation receivers.

3 cl, 2 dwg

Description

The invention relates to x-ray technology, including medical, in particular to devices for monitoring the technical characteristics of digital x-ray machines, and can be used to test digital x-ray receivers.

State of the art

A digital x-ray detector is a device containing an x-ray screen that converts x-ray radiation into a visible, optical system for transferring an image to a photosensitive CCD array (a block of photodetectors based on charge-coupled devices), which converts the image projected onto it into a digital signal. A digital signal from a photosensitive CCD matrix is fed to an image processing unit. Already obtained and appropriately processed image perform diagnostics of the studied object, therefore, the most important parameter of such systems is the quality of the obtained x-ray image of the studied object. An automatic testing system for adjusting image sharpness allows you to reduce the risks of incorrect diagnostics on the obtained x-ray image, eliminating the use of an x-ray detector that is not suitable for the image sharpness parameter. Such a failure, for example, is possible with excessive mechanical stress on the x-ray receiver during improper transportation or incorrect operation.

The known system (patent CA 2412711, IPC AB 6/04, published May 23, 2003, patent analogue US 6869218) automatically tests the image sharpening settings of a digital X-ray receiver containing an x-ray screen installed along the radiation from an x-ray source, an optical image transfer system with screen to the photosensitive matrix of the device with charge coupling (hereinafter CCD), the output of which is connected to the image processing unit. The system contains test structures located on the periphery of the radiating surface of the screen and outside its working area, that is, outside the area of the images to be studied, which are made of material that transmits short waves of ultraviolet radiation. On the side of the radiating surface of the X-ray screen, a source of ultraviolet radiation of a given spectrum is installed, which irradiates the region of the X-ray screen with the test structure. Getting on the x-ray screen, ultraviolet radiation is converted into visible, which forms the image of this test structure. When calibrating the X-ray receiver, reference images of test structures are recorded and stored, with which images obtained during operation are compared.

This system allows you to control the sharpness of the image obtained only when using the specified types of screens having the appropriate absorption bands of ultraviolet radiation and the corresponding emission spectrum. Thus, the choice of x-ray screens that can be used in such x-ray receivers is limited.

If the excitation spectra of the X-ray screen in the ultraviolet range (hereinafter referred to as UV) of the radiation of the X-ray screen and the sensitivity of the X-ray detector in the UV range overlap partially, it is necessary to solve the problem of filtering radiation in order to separate the reflected UV radiation from the secondary UV radiation of the X-ray screen. This leads to additional requirements for optics and, as a consequence, the complexity and cost of construction. The use of such filters leads to a decrease in the useful input signal and, as a consequence, to the need to increase doses during x-ray studies.

Disclosure of invention

The objective of the invention is the creation of such a system for automatically testing the image sharpness of digital X-ray receivers, in which the technical result is achieved, expressed in the possibility of testing the image sharpness of digital X-ray receivers with different types of screens; in increasing the useful input signal and reducing the error.

The specified technical result in the system of automatic testing of a digital x-ray receiver, comprising an x-ray screen installed along the radiation from the x-ray source, an optical system for transferring images from the screen to a photosensitive CCD matrix, the output of which is connected to the image processing unit, and including at least three test structures installed in the plane of radiation of the x-ray screen is achieved by the fact that the test structures are located outside the radiating surface ited ray screen and provided with a controllable source of primary radiation, which are mounted so that each test structure is in direct ray path from the aforementioned sources.

The best result is achieved when light-emitting elements with a maximum spectral characteristic close to the spectral maximum transmission of an optical image transfer system are used as the named sources.

To solve the problem, LEDs with radiation in the visible range can be used.

Unlike the prototype, automatic sharpening testing is performed not by the image of the test structures in the secondary radiation of the X-ray screen, but by the images of the test structures located outside the radiating surface of the screen and equipped with controlled sources of primary radiation, which are installed in such a way that each test structure is located in direct passage of rays from these sources.

The essence of the claimed invention and the possibility of technical implementation is illustrated by an example of a specific implementation, illustrated in figures 1 and 2.

1 shows a digital X-ray receiver.

Figure 2 shows in more detail the test structure with a source of visible radiation based on the LED. In figure 1 and 2 are indicated:

1 - test structure

2 - source of visible radiation,

3 - edge of the radiating surface of the screen,

4 - the edge of the visible field in the plane of the x-ray screen,

5 - beam projection of the source of visible radiation on the input lens of the lens,

6 - lens

7 - image processing unit of a photosensitive CCD matrix,

8 - the substrate of the x-ray screen,

9 - x-ray screen.

In the digital X-ray detector, on the substrate 8 of the X-ray screen 9, in the angles between the edge 3 of the radiating surface of the X-ray screen 9 (Figs. 1 and 2) and the edge 4 of the visible field, visible radiation sources 2 (hereinafter sources) based on LEDs with test structures are installed 1. As shown in figure 2, each test structure 1 is installed in the direct path of the rays from the named sources 2. The image of each test structure 1 is transferred by projection rays 5 (figure 1) to the input lens of the lens 6 and using the lens 6 to block 7 fotoch vstvitelnoy CCD.

The system operates as follows. In the process of calibrating the X-ray receiver, the image of each test structure 1, illuminated by the radiation source 2, is processed in the image processing unit 7 of the photosensitive CCD matrix and stored as a reference frequency-contrast characteristic (hereinafter, CCK characteristic). When the X-ray receiver is in operation, the radiation sources 2 are synchronized with the operation of the image processing unit 7 of the photosensitive CCD matrix in such a way that the image sharpening settings are tested during each shot. When each shot is taken, images of each test structure 1, illuminated at the time of the shot by the radiation source 2, are recorded in the direct course of the projection rays 5 from which it is installed, and the frequency-contrast characteristics (frequency response characteristics) are calculated. Further, the obtained frequency response characteristics are compared with the reference frequency response characteristics obtained by calibrating the x-ray receiver. If the requirement of uniformity within the specified limits of the frequency response characteristics for each test structure 1 is not satisfied, the operation of the X-ray receiver is stopped. The frequency of testing is set based on the selected method of testing the X-ray receiver.

Due to the fact that the sources of visible radiation with test structures are installed between the edge of the radiating surface of the x-ray screen and the edge of the visible field, this system is not tied to the type of x-ray screen used and does not require filtering the optical signal by spectrum, which accordingly does not lead to loss of part of the input signal. All possible errors and inaccuracies associated with the superposition of the spectrum of the primary UV source (UV lamp) with the spectrum of the secondary radiation of the X-ray screen, the transmission spectrum of the optical system and the sensitivity spectrum of the X-ray receiver are excluded.

The best embodiment of the invention

The best embodiment of the invention is a system for automatically testing a digital X-ray receiver, comprising an x-ray screen mounted along the radiation from the x-ray source, an optical system for transferring images from the screen to a photosensitive CCD matrix, the output of which is connected to the image processing unit, and including four test structures, set in the corners of the screen frame. Moreover, each test structure is equipped with backlight controlled LEDs with radiation in the visible range, which are set so that each test structure is located along the radiation of these sources.

Industrial applicability

The inventive system for automatic testing of a digital X-ray receiver is created using known elements and devices. As shown by the operation, the system allows to reduce the risks of incorrect diagnostics by automatically testing the image sharpening setting of a digital X-ray receiver using the received X-ray images, eliminating the possible use of an inoperative receiver according to the image sharpness parameter. Such a failure, for example, is possible with excessive mechanical stress on the receiver during improper transportation or incorrect operation.

Claims (3)

1. A system for automatically testing a digital X-ray receiver, comprising an X-ray screen installed along the radiation from the X-ray source, an optical system for transferring images from the screen to a photosensitive CCD matrix, the output of which is connected to the image processing unit, and including at least three test structures installed in the radiation plane of the x-ray screen, characterized in that the test structures are located outside the radiating surface of the x-ray screen and equipped with controlled sources of primary radiation, which are installed in such a way that each test structure is in the direct path of the rays from these sources. 2. The system according to claim 1, characterized in that light-emitting elements with a maximum spectral characteristic close to the spectral maximum transmission of the optical image transfer system are used as the named sources. 3. The system according to claim 1 or 2, characterized in that as the named sources used LEDs with radiation in the visible range.

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