CN102961160B - Composite filtering compensation spectrum modulation device - Google Patents

Abstract

The invention discloses a composite filtering compensation spectrum modulation device. The device comprises a high-density filtering optimization sheet, a low-density filtering compensation sheet, a filter sheet connecting device and an external support bracket, wherein the high-density filtering optimization sheet, the low-density filtering compensation sheet, the filter sheet connecting device and the external support bracket are made of materials with K layers of characteristic absorption edges; the external support bracket supports and arranges the composite spectrum modulator at a specific position between the X-ray light source and the breast to be detected, and the external support bracket is fixed on the support plate. By the device, the dosage accepted by a patient can be reduced on the premise of ensuring the quality of a reconstructed image for a DBCT system, the diagnosis success rate of the system on mammary gland diseases is obviously improved, and the spectral distribution more suitable for mammary gland imaging is provided.

Description

A Composite Filter Compensation Spectrum Modulation Device

technical field

The invention relates to the technical field of breast imaging, in particular to a compound filter compensation spectrum modulation device.

Background technique

At present, breast disease is the most common disease among women, and the death rate of breast cancer ranks second among female tumors. Early detection of breast cancer is an effective means to improve its cure rate. In order to reduce the diagnosis of breast biopsy, a large number of non-destructive diagnostic methods for breast diseases have been produced, mainly including: mammography mammography, ultrasound mammography, magnetic resonance (MRI) breast examination and other functional imaging methods. Among them, mammography is currently the most widely used and most effective method for early detection of breast cancer, but it superimposes three-dimensional breast structure information on a two-dimensional plane, resulting in relatively low detection sensitivity. In addition, molybdenum Targeted imaging is also less successful in diagnosing dense breasts.

In order to improve the success rate of breast disease diagnosis, a new breast imaging technology has emerged in recent years, that is, breast dedicated CT technology (DBCT), which reconstructs the internal three-dimensional structure of the breast through the projection data of the breast in different directions. The DBCT system can provide higher image contrast and spatial resolution at the same dose as two frames of mammography. Compared with mammography, the DBCT system has many advantages, such as providing a three-dimensional breast structure map, imaging denser breast tissue, more uniform breast gland dose distribution during imaging, and improving patient comfort during detection. Pathological detection and treatment provide higher spatial positioning accuracy and so on.

However, the shortcomings of the above-mentioned DBCT system are that the detection of microcalcifications is not as good as that of mammography. Take full advantage of photon information. A feasible way is to modulate and optimize the incident X-ray spectrum, that is, to improve the dose efficiency and imaging quality of imaging by changing the distribution intensity of the spectrum. This device that can modulate the spectrum is called a spectral modulator. However, as a new type of breast imaging equipment, the development of the spectral modulator used in the DBCT system is still in the preliminary stage. Therefore, it is necessary to design the spectral modulator for the special imaging configuration of the breast to improve the overall performance of the DBCT system. performance.

Contents of the invention

The purpose of the present invention is to provide a compound filter compensation spectral modulation device, which can reduce the dose received by the patient under the premise of ensuring the quality of the reconstructed image for the DBCT system, and at the same time significantly improve the success rate of the system for breast disease diagnosis, and provide a more suitable Spectral distribution in breast imaging.

The purpose of the present invention is achieved through the following technical solutions, a compound filter compensation spectrum modulation device, said device includes a high-density filter optimization sheet made of a material with a characteristic absorption edge, made of a material close to the linear attenuation coefficient of the mammary gland The manufactured low-density filter compensator, filter connection device and external support bracket, among which:

The filter connection device connects the high-density filter optimization sheet and the low-density filter compensation sheet together to form a composite spectral modulator, and the low-density filter compensation sheet is located on the side close to the X-ray source;

The external support bracket supports and arranges the composite spectral modulator at a specific position between the X-ray light source and the breast to be detected, and the external support bracket is fixed on a support plate;

The X-rays emitted from the X-ray light source pass through the breast to be detected after being modulated by the compound spectrum modulator, and are received by the X-ray detector carrying the structure information of the breast to be detected.

The structural size and position of the composite spectral modulator are determined according to the positions of the X-ray light source and the X-ray detector and the shape of the breast to be detected, so that different X-rays are combined in the composite spectral modulator and the breast to be detected. The penetration length remains unchanged.

The structure of the low-density filter compensation sheet is a cuboid with a groove, the groove is related to the posture and shape of the breast to be detected, and the cross-section of the groove is two-dimensional symmetrical to the vertical plane where the CT rotation axis is located. Curved surface, the side where the groove surface is located is the side close to the breast to be detected;

The X-rays emitted from the X-ray source in different emission angles pass through the low-density filter compensator and are modulated and compensated by filters with different thicknesses.

The structure of the high-density filter optimization sheet is a thin sheet with uniform thickness, and its thickness is determined by the attenuation ratio of the incident X-ray spectrum and the acceptable dose when the breast imaging is to be detected;

The high-density filter optimization sheet realizes the modulation of the incident X-ray spectrum through the resonant absorption of the K-layer electrons of its material atoms on the incident photon, and the high-density filter optimization sheet absorbs the low-density filter compensation sheet through CommScope The photon generated by the Compton scattering realizes compound filtering.

The high-density filter optimization sheet is made of cerium or gadolinium materials;

The low-density filter compensator is made of plexiglass.

It can be seen from the above-mentioned technical solution provided by the present invention that the device includes a high-density filter optimized sheet made of a material with a K-layer characteristic absorption edge, and a low-density filter made of a material close to the linear attenuation coefficient of the mammary gland. A compensation sheet, a filter connection device and an external support bracket, wherein the filter connection device connects the high-density filter optimization sheet and the low-density filter compensation sheet together to form a composite spectral modulator, and the low-density filter The compensation sheet is located on the side close to the X-ray light source; the external support bracket supports and arranges the composite spectral modulator at a specific position between the X-ray light source and the breast to be detected, and the external support bracket is fixed on the support plate ; The X-rays emitted from the X-ray light source are modulated by the compound spectrum modulator, pass through the breast to be detected, and carry the structure information of the breast to be detected to be received by the X-ray detector. The device can reduce the dose received by the patient under the premise of ensuring the quality of the reconstructed image for the DBCT system, and at the same time significantly improve the system's diagnostic success rate for breast diseases, and provide a more suitable spectral distribution for breast imaging.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative efforts.

FIG. 1 is a schematic structural diagram of the application of a composite filter compensation spectral modulation device provided in an embodiment of the present invention in a breast dedicated CT system;

FIG. 2 is a schematic structural diagram of a composite spectral modulator provided by an embodiment of the present invention;

3 is a schematic diagram of the distribution of the incident spectrum after being modulated by a high-density filter optimization plate with a K-layer characteristic absorption edge in an embodiment of the present invention;

Fig. 4 is a schematic diagram of the outgoing spectrum after the incident spectrum of the same intensity passes through organic glass with different thicknesses;

Fig. 5 is a schematic diagram of the emission spectrum after the same intensity spectrum passes through the aluminum material used in the prior art;

Fig. 6 is a schematic diagram of the change of the average energy after the incident spectrum passes through two materials.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The compound filter compensation spectrum modulation device provided by the embodiment of the present invention combines the posture and shape of the breast to be detected during imaging, and simultaneously realizes the horizontal direction and the vertical direction of the rotation axis through the high-density filter optimization sheet and the low-density filter compensation sheet for the incident X-ray spectrum. The modulation of the surface, the composite spectral modulator composed of two kinds of filters achieves the modulation and optimization of the incident X-ray spectrum for scanning the breast to be detected through the filter compensation and resonance absorption of different X-ray beams connected to the light source and detector pixels, Realize the purpose of reducing the dose received by the breast and improving the imaging quality. The embodiment of the present invention will be further described in detail below in conjunction with the accompanying drawings. As shown in FIG. 1, it is a structural schematic diagram of the application of the compound filter compensation spectral modulation device provided by the embodiment of the present invention in a breast dedicated CT system, as shown in FIG. 2. The structural schematic diagram of the composite spectral modulator provided by the embodiment of the present invention, combined with Fig. 1 and Fig. 2, the composite filter compensation spectral modulation device mainly includes a high-density filter made of a characteristic (such as K-layer characteristic) absorption edge material Optimized sheet 2, a low-density filter compensation sheet 1 made of a material close to the linear attenuation coefficient of the mammary gland, a filter connecting device and an external support bracket 7, wherein:

The filter connection device connects the high-density filter optimization sheet 2 and the low-density filter compensation sheet 1 together to form a composite spectral modulator 4, and the low-density filter compensation sheet 1 is located on the side close to the X-ray light source 3;

The external support bracket 7 supports and arranges the composite spectral modulator 4 at a specific position between the X-ray light source 3 and the breast 5 to be detected, and the external support bracket is fixed on the support plate 8;

The X-rays emitted from the X-ray light source 3 pass through the breast 5 to be detected after being modulated by the composite spectrum modulator 4, and are received by the X-ray detector 6 carrying the structural information of the breast 5 to be detected. The motor 9 can also be used to rotate to obtain the projections of the breast 5 to be detected at different angles, and finally the reconstruction algorithm is used to reconstruct the three-dimensional structural image of the breast to diagnose breast diseases.

In a specific implementation, the above-mentioned low-density filter compensator 1 uses a material close to the attenuation coefficient of the breast. In addition to using plexiglass, other low-density materials that are easy to form can also be used, such as polyvinyl chloride (PVC). The filter optimization sheet 2 uses a material with a K characteristic absorption edge, and the characteristic energy corresponding to the absorption edge is between 30keV and 60keV. In addition to using cerium, other materials such as gadolinium can also be used.

In a specific implementation, the structural size and position of the composite spectral modulator 4 are determined according to the positions of the X-ray light source 3 and the X-ray detector 6 and the shape of the breast 5 to be detected. For different breast CT equipment, the principle of compound spectral modulator design is to ensure that the projection of the breast to be detected on the X-ray detector is almost constant in the end, that is, different X-rays are totally different in the compound spectral modulator and the breast to be detected. The penetration length of is kept almost constant, and the incident photon energy is optimized to the most suitable energy range for the imaging of the breast to be detected.

As shown in Figure 2: the structure of the low-density filter compensation sheet 1 is a cuboid with a groove, the groove is related to the posture and shape of the breast to be detected, and the section of the groove is perpendicular to the CT rotation axis. A planar two-dimensional symmetrical curved surface, the side where the groove surface is located is the side close to the breast to be detected;

The X-rays emitted from the X-ray source 3 in different emission angles pass through the low-density filter compensator 1 and are modulated and compensated by filters with different thicknesses. Specifically, X-rays are emitted from the X-ray light source at the far end, and X-rays in different emission angles are modulated and compensated by filters with different thicknesses through the low-density filter compensation sheet. The principle of modulation compensation is that when X-rays need to be When the detection breast penetrates a long distance, the length of X-ray attenuation in the low-density filter compensation sheet is small; The attenuation length is larger to ensure that the total attenuation length remains almost constant. For example, in the breast tissue close to the chest cavity in the horizontal plane, the central ray has the longest penetration length, and the attenuation of X-rays in the low-density filter compensation film The length is the minimum.

Among Fig. 2, the structure of the high-density filter optimization sheet 2 is a thin sheet with equal thickness, and its thickness is determined by the attenuation ratio of the incident X-ray spectrum and the allowable dose when the imaging of the breast to be detected;

The high-density filter optimization sheet 2 realizes the modulation of the incident X-ray spectrum through the resonant absorption of the K-layer electrons of its material atoms on the incident photon, and the high-density filter optimization sheet 2 absorbs the light from the low-density filter compensation sheet through Compton scattering The photons generated by Compton scattering realize compound filtering and further improve the quality of mammary gland imaging; specifically, for mammary gland special CT equipment, the incident photons are multi-color, and only when the incident photons are of a specific energy, the system can obtain the maximum imaging. The dose efficiency of the high-density filter optimization film 2 is to modulate the polychromatic incident spectrum to the most suitable energy range for breast imaging.

The following is a specific example to describe the specific working process of the above-mentioned complex filter compensation spectral modulation device, in conjunction with Fig. 1 and Fig. 2:

The base of the low-density filter compensation sheet 1 is a plexiglass cuboid with a size of 70mm×100mm×130mm. On the side facing the breast, a symmetrical groove is removed. The cross section of the groove is a two-dimensional curved surface ABCD. The two-dimensional curved surface can be passed as follows way to determine:

First, in the horizontal plane, determine the compensation thickness corresponding to different ray emission angles according to the condition that the section of the breast imaging is circular, and the end point of the compensation forms a curve ACB on the plexiglass; secondly, in the vertical plane passing through the center, according to the cross-section of the breast imaging Determine the compensation thickness corresponding to different ray vertical angles for elliptical conditions, and determine the compensation curve CD; then use the same method to determine the compensation curve ADB corresponding to the organic glass parallel to the X-ray detector plane, and finally use these three curves The method of two-dimensional surface interpolation obtains the entire compensation surface ABCD. In this example, the thinnest compensation thickness is 20 mm, corresponding to the largest penetration length in the breast.

In Fig. 2: a high-density filter optimization sheet 2 is connected to the end face of the plexiglass close to the breast. In this embodiment, the high-density filter optimization sheet 2 is made of cerium (Ce) material whose K absorption edge characteristic energy corresponds to 40.4keV. The thickness (determined by the incident X-ray intensity and mammography requirements) is 0.15mm. In actual use, the thickness can be adjusted according to the imaging conditions. Since photons of different energies have different dose efficiencies when imaging the breast, it is hoped that the photons with the highest dose efficiency will occupy the largest proportion in the spectrum during imaging. Through the optimized filtering of cerium material, the photons used for photons near 40keV in the incident spectrum can be used The proportion of accounted for is significantly improved. As shown in Figure 3, it is a schematic diagram of the distribution of the incident spectrum in the embodiment of the present invention after being modulated by a high-density filter optimized sheet with a K-layer characteristic absorption edge. It can be seen from Figure 3 that the optimized spectrum can be in Under the condition of ensuring the imaging quality, the radiation dose received by the breast is minimal, so as to achieve the highest photon dose efficiency.

In Figure 1: the distances from the X-ray light source to the X-ray detector and the center of rotation are 740mm and 560mm respectively, and the distance from the side of the composite spectral modulator close to the light source to the focus of the light source is 280mm. In this embodiment, the composite spectral modulator is not installed at the exit of the X-ray light source, so it is not sensitive to small displacement errors, which reduces the difficulty of installation. In addition to the structure described in this embodiment, composite spectral modulators of different sizes can also be designed according to different breast-specific CT equipment.

The composite filter compensation spectrum modulation device provided by the embodiment of the present invention is conducive to providing a spectrum with better spatial consistency. As shown in Figure 4, it is a schematic diagram of the outgoing spectrum after the incident spectrum of the same intensity passes through organic glass with different thicknesses, as shown in Figure 4 5 shows a schematic diagram of the outgoing spectrum after the same intensity spectrum passes through the aluminum material used in the prior art, and Figure 6 shows a schematic diagram of the change in average energy after the incident spectrum passes through two materials, from the above-mentioned Fig. 4, It can be seen from FIG. 5 and FIG. 6 that the embodiment of the present invention has less influence on the spectra of different attenuation lengths, that is to say, it can provide imaging spectra with better consistency, which is beneficial to reduce imaging artifacts and improve imaging quality.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (3)

1. A compound filter compensation spectral modulation device, characterized in that, said device comprises a high-density filter optimization sheet made of a material with characteristic absorption edges, and a low-density filter made of a material close to the linear attenuation coefficient of the mammary gland. Filter compensator, filter connection device and external support bracket, of which: The filter connection device connects the high-density filter optimization sheet and the low-density filter compensation sheet together to form a composite spectral modulator, and the low-density filter compensation sheet is located on the side close to the X-ray source; The external support bracket supports and arranges the composite spectral modulator at a specific position between the X-ray light source and the breast to be detected, and the external support bracket is fixed on a support plate; The X-rays emitted from the X-ray light source pass through the breast to be detected after being modulated by the composite spectrum modulator, and carry the structural information of the breast to be detected to be received by the X-ray detector; Wherein, the structural size and position of the composite spectral modulator are determined according to the positions of the X-ray light source and the X-ray detector and the shape of the breast to be detected, so that different X-rays can pass between the composite spectral modulator and the breast to be detected. The total penetration length remains unchanged; The structure of the low-density filter compensation sheet is a cuboid with a groove, the groove is related to the posture and shape of the breast to be detected, and the cross-section of the groove is two-dimensional symmetrical to the vertical plane where the CT rotation axis is located. Curved surface, the side where the groove surface is located is the side close to the breast to be detected; The X-rays emitted from the X-ray source in different emission angles pass through the low-density filter compensation sheet and are modulated and compensated by the low-density filter compensation sheet with different thicknesses. 2. Composite filter compensation spectral modulation device as claimed in claim 1, is characterized in that, The structure of the high-density filter optimization sheet is a thin sheet with uniform thickness, and its thickness is determined by the attenuation ratio of the incident X-ray spectrum and the acceptable dose when the breast imaging is to be detected; The high-density filter optimization sheet realizes the modulation of the incident X-ray spectrum through the resonant absorption of the K-layer electrons of its material atoms on the incident photon, and the high-density filter optimization sheet absorbs the low-density filter compensation sheet through CommScope The photons generated by light scattering realize complex filtering. 3. composite filter compensation spectrum modulation device as claimed in claim 1, is characterized in that, described high-density filter optimization sheet is made of cerium or gadolinium material; The low-density filter compensator is made of plexiglass.