WO2008033051A1

WO2008033051A1 - X-ray image recording method

Info

Publication number: WO2008033051A1
Application number: PCT/RU2007/000063
Authority: WO
Inventors: Andrey Andreevich Bryzgalov; Sergey Vladimirovich Soloboev; Vladimir Oskarovich Saik
Original assignee: Andrey Andreevich Bryzgalov; Sergey Vladimirovich Soloboev; Vladimir Oskarovich Saik
Priority date: 2006-09-14
Filing date: 2007-02-07
Publication date: 2008-03-20
Also published as: RU2307377C1

Abstract

The invention relates to X-ray engineering, in particular to X-ray densitometry which is used for examining a bone tissue density for diagnosticating osteoporosis and which can be used in sophisticated roentgenographic systems for carrying out examinations directed at preventing osteoporosis, thereby making it possible to avoid the fractures of a vertebral body, bones of limbs, femoral neck etc. The inventive method for recording an object x-ray image within different X-ray radiation ranges, consists in exposing a patient to X-ray radiation, in receiving X-ray radiation passed through the object by means of a luminescent screen sensitive to different regions of the X-ray radiation range and in producing an optical image from the luminescent screen. The invention is characterised in that the luminescent screen sensitive to different regions of the X-ray radiation range is embodied in the form of a multilayer screen, each layer of which absorbs X-ray radiation in it's part of the X-ray radiation range in such a way that each layer of the screen closest to the object is used in the form of a filter for X-ray radiation for the following layer, wherein each previous layer of the X-ray screen radiates light in a long-wave region which is larger than that of the subsequent layer and the optical image is obtainable from the luminescent screen with the aid of a colour-sensitive light receiver.

Description

X-ray image registration method

Technical field

The invention relates to x-ray technology, namely to x-ray densitometry, which examines bone density for the purpose of diagnosing osteoporosis and can be used in modern radiographic diagnostic complexes for examinations to prevent osteoporosis, which avoids fractures of vertebral bodies, limb bones, femoral neck and etc.

State of the art

At present, multifunctional X-ray diagnostic complexes (RDKs) of the type PUM-20, TUP-800, and EDP-750 are widely used, which provide almost all types of X-ray diagnostic studies with the exception of X-ray densitometry. Therefore, the patient has to undergo additional examination in specialized medical institutions for the diagnosis of osteoporosis.

A known method of obtaining x-ray images for x-ray densitometry at two energies of x-ray radiation (see US patent N "6285740, H05G 1/64, 2001), including irradiating a patient with x-ray radiation (RI), receiving passed through the object RI containing radiation, as low and high energy obtained by creating a short (shorter than 200 nsec) pulses of radiation, while the voltage on the x-ray tube varies during the pulse, so that a wide energy spectrum of radiation is generated. After passing through the object under study, the X-ray radiation enters a receiving system consisting of two sequentially installed x-ray detectors, each of which includes an optical matrix detector and a luminescent screen, while an additional x-ray filter is placed between the two x-ray receivers in order to select the desired x-ray region spectrum.

The main disadvantages of this method are, firstly, the necessary the ability to use large-sized semiconductor arrays (of the order of 400x400 mm), which significantly increases the cost of the X-ray detector.

Secondly, the installation of an additional x-ray filter leads to the absorption of a noticeable fraction of the radiation energy that has passed through the object without contributing to the optical image, but leading to an increase in the x-ray dose received by the object.

Closest to the claimed method and adopted as a prototype, is a method of obtaining an X-ray image for two different radiation energies in one shot, including irradiating a patient with X-ray, a patient who has passed through an X-ray object, having low and high energy components recorded using a fluorescent screen (LE), consisting of two types of phosphor, sensitive to different parts of the X-ray spectrum and obtaining an optical image by combining two images obtained from LE using two pticheskih receivers, each of which is supplied by the optical filter. The known method allows, without increasing the dose of radiation to the patient, to obtain a snapshot of the object, which focuses the attention of the operator on areas of the image with different bone density.

The main disadvantages of the known method are, firstly, the difficulty of manufacturing LE using two different phosphors sensitive to different areas of x-ray radiation. If it is necessary to obtain an image in more than two parts of the X-ray spectrum, the task becomes practically impossible.

Secondly, each phosphor is rigidly connected with a specific part of the X-ray spectrum, which does not allow, if necessary, the reconstruction of the selected spectral windows.

In addition, combining the two received images into one can lead to a deterioration in image quality associated with spatial diversity of the receivers, namely, the appearance of geometric distortions, blurring and vignetting effects. Disclosure of invention

The technical problem solved by the present invention is to obtain a high-quality image with the ability to visualize two or more different parts of the spectrum of radiation, which, at the request of the operator, can be chosen as your own in each case.

A method is proposed for recording an X-ray image of an object in different ranges of the X-ray spectrum, including: irradiating a patient with X-ray, converting the X-ray transmitted through the object into a visible optical image using a luminescent screen sensitive to different parts of the X-ray spectrum, and subsequent recording of the optical image from the luminescent screen. At the same time, this problem was solved in that a multilayer screen is used as a luminescent screen sensitive to different parts of the X-ray spectrum, each layer of which absorbs X-ray radiation in its part of the X-ray spectrum, so that each layer of the screen located closer to the The project served as an X-ray filter for the subsequent layer. In addition, each previous layer of the x-ray screen (RE) emits light in a longer wavelength optical region, compared with the next layer, and the optical image from the fluorescent screen is produced using a color-sensitive photodetector.

The use of a multilayer screen allows you to fully use the entire spectrum of radiation sources that have passed the studied object.

An optical matrix was used as a color-sensitive photodetector to obtain a digital image of the object being examined, each element of which is equipped with its own optical filter, and an achromatic lens was introduced into the color-sensitive photodetector to change the image scale.

To simplify the image acquisition of the examined object, a color film is used as a photosensitive photodetector, the image on which, if necessary, can be digitized by existing image scanners. To increase the information content of the resulting image, the filtering properties of the LE layer are established by changing the thickness of the phosphor layer. Using a set of phosphors of various thicknesses, it is possible to obtain images with various characteristics of the mineral composition of bone tissues.

Similarly, to increase the information content of the resulting image, the filtering properties of the LE layer are established by introducing additional additives, for example, salts of heavy metals.

The inventive method allows for one x-ray image to obtain an undistorted high-quality image of the object in two or more spectral regions of the X-ray, which has no analogues among the known technical solutions, which means that it meets the criterion of "inventive level".

Brief Description of the Drawings

Figure l shows a diagram of a device for obtaining images of the claimed method using a color photographic film. The device includes: x-ray emitter 1; research object 2; the first layer of the phosphor 3; the second layer of the phosphor 4; color film 5.

Figure 2 shows the optical diagram of a device for implementing the inventive method using an achromatic lens and an optical photodetector array, each element of which is equipped with its own optical filter. The device further includes: lead glass 6; achromatic lens 7; photodetector array 8; computer 9.

In FIG. 3 shows a diagram of a device for obtaining an image by the claimed method using a color photographic film, the device allows you to select different energies of RI by choosing RE of various thickness and composition. The device further includes: a third layer of the phosphor 10 and a device of a revolving type for changing x-ray screens 1 1.

In FIG. Figure 4 shows the X-ray spectra after passing through the X-ray of different thicknesses, where: 12 is the X-ray spectrum incident on the first layer of the X-ray; 13 - spectrum of radiation incident on the second layer of radiation; 14 - spectrum of radiation incident on the third layer of radiation. In FIG. 5 shows a diagram of a device for implementing the inventive method using an optical photodetector array, each element of which is equipped with its own optical filter, moreover, a multilayer RE is connected to the photodetector matrix by means of a fiber optic washer 15. The device rвυ additionally includes: a fiber optic washer 15 between the RE and the photodetector. The relatively small size of the device allows you to use it. for example, in dentistry, for the detection of periodontal disease in patients.

The best embodiment of the invention

The device shown in FIG. 1 operates as follows. The x-ray tube in the x-ray emitter 1 operates at a fixed anode voltage and emits a wide range of radiation sources, limited in energy from above by the magnitude of the applied voltage, and from below by absorption of the materials of the emitter. The emission spectrum is shown in FIG. 4 - curve 12. RI passes through the studied object and is partially absorbed or scattered depending on the mineral composition and density of its tissues. Behind the object under study is a multilayer X-ray screen that converts an invisible image in the X-ray region into a visible optical image, which is then recorded using a color film. The first layer of phosphor 3 absorbs mainly the low-energy part of the X-ray spectrum. Curve 13 in FIG. 4 shows a view of the spectrum of RI incident on the second layer of RE, and curve 14 - incident on the third layer, respectively. In this case, the X-ray absorbed by the 1st layer is the difference of the curves 12 and 13, the absorbed by the second layer is the difference of the curves 13 and 14, etc. The first layer of radiation emits in the longer wavelength optical region than the second and subsequent layers. therefore, the optical radiation of the first layer will not be absorbed by the second, third and subsequent layers. The second layer of radiation emits in the long-wavelength optical region compared with the third and subsequent layers, etc. This allows you to get a color image of the object, each color of which corresponds to its region of the energy spectrum of the RI. By comparing the intensities in different regions of the X-ray spectrum that passed the object under study, one can calculate the density and mineral composition b of its components, which is necessary when performing osteodensitometry.

The device in Fig. 2 works similarly to the device shown in Fig. 1. The difference is that a color image from a multilayer electron microscope is recorded using a semiconductor array detector 8 equipped with an RGB filter and equipped with a lens 7 for scaling an optical image. To protect the semiconductor matrix detector 8 from the past and scattered RI is lead glass b. The signals from the matrix detector after digitization are transmitted to the computer 9 for subsequent processing, storage and printing.

The device in FIG. 3 works similarly to the device shown in FIG. 1. The difference is that instead of a two-layer RE with a fixed thickness of layers 3 and 4, a three-layer RE is used here, recruited from screens with different layer thicknesses. The choice of the desired RE from the ones presented in the kit is made before the study using a revolving device type 1 1.

The device of FIG. 5 operates similarly to the device shown in FIG. 1. The difference is that instead of a photographic film, an optical photodetector is used for recording the optical image, each pixel of which is equipped with an optical filter, and the image is transferred from the RE to the photodetector using fiber optic plate 15, which additionally serves to protect the photodetector from diffuse RI. The signals from the matrix detector after digitization are transmitted to the computer 9.

Technical applicability

A two-layer screen consisting of cesium-iodine single crystals modified with thallium CsJ (TI) and cesium-iodine modified with sodium CsJ (Na) was used as a multilayer RE. The thickness of the front layer of CsJ (Tl) was 0.2 mm, and that of the back (CsJ (Na)) was 0.5 mm. In this case, the first layer absorbed approximately 50% of the energy of X-rays incident on it at a tube voltage of WO kV. The second layer absorbed up to 60% of the radiation transmitted through the first layer. The optical luminescence spectrum of the first layer has a maximum at 550 nm and the second layer (with a maximum of luminescence at 420 nm) is practically transparent for it. The front surface of the first phosphor was covered with black paint to prevent the appearance of reflections from it and increase the resolution of the screens.

In the model of the device, as an X-ray source, we used the ARA-110/160-1 ward x-ray apparatus equipped with a 0.6-ЗБДM29-125 (П) x-ray tube with a fixed tungsten anode. The anode voltage adjustment range was 40–1 10 kV; the voltage accuracy was no worse than 5%.

A revolver type device was manufactured for changing the aircraft. As an optical image receiver, a cassette was used with a set of 16 fragments of a standard color film with a 36x24 mm frame format from Kodak, with a sensitivity of 400 units.

The inventive method of registering an x-ray image of an object was carried out by means of a device for obtaining an image of the claimed method in the form of a prototype. The presented device fully confirmed the main advantages of the claimed method over the prototype in terms of increasing the information content of the resulting image.

Claims

Claim

1. The method of recording an x-ray image of an object in different ranges of the x-ray spectrum, including irradiating the patient with x-ray radiation, receiving the x-ray radiation transmitted through the object using a luminescent screen sensitive to different parts of the x-ray spectrum, and obtaining an optical image from the luminescent screen the fact that, as a luminescent screen sensitive to various parts of the spectrum of x-ray radiation, use a multilayer screen, each layer of which absorbs x-ray radiation in its part of the spectrum, so that each layer of the screen located closer to the object serves as a filter for x-ray radiation for the next layer, while each previous layer of the x-ray screen emits light in a longer wavelength optical region, compared with the subsequent layer, and obtaining an optical image from a fluorescent screen is produced using a color-sensitive photodetector.

2. The method according to claim 1, characterized in that an optical matrix is used as a photosensitive photodetector, each element of which is equipped with its own optical filter.

3. The method according to claim 1, characterized in that a color film is used as a photosensitive photodetector.

4. The method according to claim 1, characterized in that the filtering properties of the luminescent screen layer are determined by changing the thickness of the phosphor layer or the light composition load.

5. The method according to claim 1, characterized in that the filtering properties of the luminescent screen layer are established by introducing additional additives, for example, salts of heavy metals.

SUBSTITUTE SHEET (RULE 26)