CN103239243B - Curved mirror and the X-ray data collecting system comprising this curved mirror - Google Patents

Abstract

The present invention relates to field of medical device, particularly relate to a kind of curved mirror, its concave surface is coated with the reflectance coating of plural layer energy reflection X-ray, and the thickness of described reflectance coating is through the tangential direction distribution gradient of design along described curved mirror, wherein, described curved mirror makes to there is angle between its surface being coated with reflectance coating and each incident X-rays bundle through arranging, after reflecting film reflects described in described incident X-rays Shu Jing, makes outgoing X-ray beam become parallel, that frequency spectrum is identical X-ray beam.The present invention also provides a kind of X-ray data collecting system comprising this curved mirror.To improve the signal to noise ratio of image, and reduce the image artifacts because the geometric parameter of cone beam causes.

Description

Curved mirror and the X-ray data collecting system comprising this curved mirror

Technical field

The present invention relates to field of medical device, particularly relate to a kind of curved mirror of energy reflection X-ray and comprise the X-ray data collecting system of this curved mirror.

Background technology

In x-ray imaging field, the X-ray sent due to X-ray tube has the wide power spectrum of continuous print, such as be distributed in 1 ~ 150keV, wherein low energy X ray (as 1 ~ 10keV) is nonsensical to last imaging results, and can be attenuated when the histoorgan through human body.In order to reduce the radiation of low energy X ray to human body, current common practice is on x-ray spread direction, arrange some thin layers be made up of attenuating material (hereinafter referred to as damping layer), low energy X ray is attenuated before X-ray arrives human body, X-ray after not overdamping still has the wide power spectrum of continuous print, such as 10 ~ 150keV.For current x-ray imaging technology, the power spectrum of X-ray is wider, and the signal to noise ratio of image is poorer.

In view of the X-ray of wide power spectrum is to the restriction of x-ray imaging, some emerging x-ray imaging technology (such as phase contrast imaging) etc. propose the concept of monochromatic (monochromic) X-ray, the power spectrum of desirable homogeneous X-ray is single, be such as 70keV, its signal to noise ratio is very high, and enhancing picture contrast, and provide more image-forming informations.But only under laboratory specified conditions, homogeneous X-ray can be obtained by sychrotron radiation source at present.Because current homogeneous X-ray under household condition cannot obtain, so commercialization is very difficult.

Before the present invention, the applicant also have submitted the application for a patent for invention that a application number is 201010615763.9, propose to use reflective film light filter to produce separation, the X-ray of monoenergetic spectrum, for the energy spikes of more options.This reflective film light filter can carry out power spectrum selection in the spectral range that medical imaging is used, its prove by the several experimental result of the applicant.But, because the angle inciding each X-ray beam in reflective film light filter and reflective film light filter is not quite similar, according to bragg's formula, the frequency spectrum of the X-ray after reflective film light filter reflection is also not quite similar, still there is certain spectrum width, compare homogeneous X-ray Shu Eryan, signal to noise ratio is still poor, and available image-forming information is also limited.In addition, due to the X-ray beam that incides in reflective film light filter be all cone beam from the X-ray beam that this reflective film light filter reflects, it is then fladellum in each imaging plane, the distance of the edge X-ray of fladellum and central X-ray and detector is not etc., thus the reconstruction of restriction to initial data, make to there is artifact in the image after reconstruction.

Summary of the invention

For overcoming the defect of image artifacts that the signal to noise ratio of image in prior art is poor and cause because of the geometric parameter of X-ray cone beam, the present invention propose a kind of can reflection X-ray curved mirror and comprise the X-ray data collecting system of this curved mirror.The concave surface of this curved mirror is coated with the reflectance coating of plural layer energy reflection X-ray, and the thickness of described reflectance coating is through the tangential direction distribution gradient of design along described curved mirror, after curved mirror reflection described in the incident X-rays Shu Jing making different spectral, obtain parallel, monochromatic exit Xray bundle.

In view of this, the invention provides a kind of curved mirror of energy reflection X-ray, the concave surface of this curved mirror is coated with the reflectance coating of plural layer energy reflection X-ray, and the thickness of described reflectance coating is through the tangential direction distribution gradient of design along described curved mirror, wherein, described curved mirror makes to there is angle between its surface being coated with reflectance coating and each incident X-rays bundle through arranging, after reflecting film reflects described in described incident X-rays Shu Jing, makes outgoing X-ray beam become parallel, that frequency spectrum is identical X-ray beam.To improve the signal to noise ratio of image, show more image information, and reduce the image artifacts because the geometric parameter of cone beam causes.

According to one embodiment of present invention, described incident X-rays bundle is cone beam or fladellum.

According to one embodiment of present invention, the thickness of described reflectance coating designs according to following formula:

$D\left(x\right)=\frac{\mathrm{\λ}}{2\sin \left\{\arctan \right\{\frac{\sqrt{2L[1-\cos \left(2{\mathrm{\θ}}_{i0}\right)]\{x+\frac{L}{2}[\cos \left(2{\mathrm{\θ}}_{i0}\right)+1\left]\right\}}}{x+L\cos \left(2{\mathrm{\θ}}_{i0}\right)}\}-\arctan \{\frac{1}{2}\sqrt{\frac{2L[1-\cos \left(2{\mathrm{\θ}}_{i0}\right)]}{x+\frac{L}{2}[\cos \left(2{\mathrm{\θ}}_{i0}\right)+1]}}\left\}\right\}}$

Wherein, D (x) represents the thickness along the reflectance coating of the tangential direction of described curved mirror, θ _i0represent the angle on incident X-rays and described reflectance coating surface, λ represents the wavelength of outgoing X-ray beam, and L represents the distance of X-ray tube focus to reflecting mirror, and x represents described curved mirror length in the horizontal direction.

According to one embodiment of present invention, the thickness of described reflectance coating is nm magnitude.

According to one embodiment of present invention, described reflectance coating is more than 0.5 to the reflectance of X-ray.With reflection X-ray as much as possible, reduce the energy loss of X-ray.Here 0.5 neither exact figures, actually allow rational process deviation.

According to one embodiment of present invention, every one deck of described reflectance coating comprises the sublayer that is made up of W material and by B ₄the sublayer that C material is formed, this two Seed Layer is alternately arranged.The X ray reflection rate of reflective coating to the X-ray energy spectrum scope for imaging comprising this bi-material is higher, and can produce the X-ray of X-ray that be separated, monoenergetic spectrum or appointment power spectrum.

According to one embodiment of present invention, described angle is 0.2 ° ~ 2 °.To realize glancing incidence.

The present invention also provides a kind of X-ray data collecting system, and this system comprises the curved mirror of an x-ray source, a detector and described energy reflection X-ray, and wherein, described x-ray source sends taper or fan-shaped x-ray beam, and incides on described curved mirror; Described curved mirror makes to there is angle between its concave surface being coated with reflectance coating and incident X-rays bundle through arranging, after the concave reflection of curved mirror described in described incident X-rays Shu Jing, reflects parallel, that frequency spectrum is identical X-ray beam; The X-ray beam reflected described in described detector receives.

As can be seen from such scheme, because the present invention proposes a kind of curved mirror of energy reflection X-ray, reflectance coating thickness on the concave surface of this curved mirror is through the tangential direction distribution gradient of design along this curved mirror, after curved mirror reflection described in the incident X-rays Shu Jing making different spectral, obtain parallel, monochromatic exit Xray bundle, so the signal to noise ratio of image can be improved, improve low contrast resolution, show more image information, and decrease the image artifacts that the geometric parameter because of cone beam causes.

Accompanying drawing explanation

Fig. 1 is the X-ray obtaining approximate monoenergetic after carrying out power spectrum selection with curved mirror of the present invention to incident X-rays, and the result schematic diagram compared with the X-ray of full width at half maximum 1keV.

Fig. 2 is the reflectance coating thickness schematic diagram of a part of concave surface adopting curved mirror of the present invention.

Fig. 3 curved mirror of the present invention reflects incident X-rays cone beam, obtains the schematic diagram of parallel, monochromatic exit Xray bundle.

Reference numeral

1-curved mirror

2-X radiographic source

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearly, by the following examples and the present invention is described in more detail by reference to the accompanying drawings.

The invention provides a kind of curved mirror of energy reflection X-ray, the concave surface of this curved mirror is coated with the reflectance coating of plural layer energy reflection X-ray, and the thickness of described reflectance coating is through the tangential direction distribution gradient of design along described curved mirror, after reflecting film reflects described in described incident X-rays Shu Jing, outgoing X-ray beam is made to become parallel, that frequency spectrum is identical X-ray beam.To improve the signal to noise ratio of image, and reduce the image artifacts because the geometric parameter of cone beam causes.

A surface of X-ray filter lens of the present invention is coated with the reflectance coating of plural layer energy reflection X-ray, its every one deck reflectance coating comprises the sublayer that is made up of W material and by B ₄the sublayer that C material is formed, the sublayer thickness be wherein made up of W material is such as 1nm, by B ₄the sublayer thickness that C material is formed is 1.5nm, and this two Seed Layer alternately arranges composition one dimension artificial intraocular lenses structure, and periodicity is such as 150, so the structure of this reflectance coating is: [W (1.0nm)/B ₄c (1.5nm) ₁₅₀.Wherein, described one dimension artificial intraocular lenses can form coherent reflection by band to the specific of incident X-rays, thus obtains high reflectance.So different reflectance coatings can be selected according to specifying to bring, such as, pass through material, thickness and the periodicity etc. selecting to form reflectance coating.But [W (the 1.0nm)/B of the present invention's employing ₄c (1.5nm)] ₁₅₀better to the X-ray energy spectrum Selection effect of (10 ~ 150keV) within the scope of x-ray imaging.In addition, reflectance coating of the present invention is produced in batches by the Special Equipment manufacturing reflectance coating.During preparation, magnetron sputtering technology can be adopted in ultra-smooth substrate to be coated with plural layer reflectance coating.Substrate surface palpus ultra-smooth, effectively to reduce the scattering caused because substrate surface is coarse.After to substrate cleaning, magnetron sputtering coater device is put in substrate, and evacuate air, until reach ultrahigh vacuum, is now filled with sputter gas again, is alternately coated with W sublayer and B ₄c sublayer.

Fig. 1 is the X-ray obtaining approximate monoenergetic after carrying out power spectrum selection with curved mirror of the present invention to incident X-rays, and the result schematic diagram compared with the X-ray of full width at half maximum 1keV.In figure with chain-dotted line represent be full width at half maximum 1keV (FullWidthatHalfMaximum, FWHM), the X-ray of approximate monoenergetic (80keV).Here adopt FWHM to be because the curve of spectral distribution is not square wave, so there is no usually said width, the value of curve width can only be weighed with FWHM, with the broadening of more different spectral line.Represented by dashed line is incident X-rays.The X-ray (79.5 ~ 80.5keV) of indicated by the solid line the is approximate monoenergetic obtained after power spectrum selection being carried out to the incident X-rays that dotted line represents with the reflectance coating on X-ray filter lens of the present invention.Can find out in figure, the frequency spectrum of the X-ray obtained through reflectance coating of the present invention and the X-ray of FWHM1keV quite similar.Because this reflective film light filter of the present invention can be produced in enormous quantities, therefore obtain Single energy X ray absorptionmetry by synchrotron radiation compared to existing technology, be easier to commercialization and batch production.

According to bragg's formula:

2dsinθ＝λ(1)，

Wherein, d represents the thickness of every one deck reflectance coating, θ represents the angle (acute angle) between incident X-rays and reflectance coating, λ represents the wavelength of specifying the X-ray that can be with, incide in the X-ray on reflectance coating and only have wavelength to be that the X-ray of λ could be gone out by every one deck reflecting film reflects, reflection through plural layer reflectance coating is superimposed, and just can obtain the X-ray of specifying and can be with.To reflect the X-ray of high power spectrum, just needing the angle reducing incident X-rays and reflectance coating surface, or reducing the thickness of reflectance coating.Angle is less, also higher to the required precision of angle, and in embodiments of the invention, according to the X-ray energy spectrum for imaging, angle is arranged on 0.2 ° ~ 2 °, namely incident X-rays is along pressing close to the incidence of reflectance coating low-angle, also claims glancing incidence.The thickness of reflectance coating can calculate by specifying the peak value that can be with and width gauge, and thickness is generally nm level, is generally no more than 5nm.And reflectance coating is more than 0.5 to the reflectance of X-ray.With reflection X-ray as much as possible, reduce the energy loss of X-ray.

Fig. 2 is the reflectance coating thickness schematic diagram of a part of concave surface adopting curved mirror of the present invention.Wherein x-ray source 2 sends taper or fan-shaped x-ray beam, and incides on curved mirror 1, and curved mirror 1 makes to there is angle between its concave surface being coated with reflectance coating and incident X-rays bundle, as the θ in figure through arranging _i0, after curved mirror reflection described in incident X-rays Shu Jing, reflect parallel, that frequency spectrum is identical X-ray beam.

If the thickness of reflectance coating is equal everywhere on the concave surface of curved mirror of the present invention, so this curved mirror can only make the angle of incidence of incident X-rays bundle substantially identical, with exit Xray Shu Bianwei parallel beam, but the power spectrum of exit Xray bundle slightly one fixed width.If the present invention adopts the gradient mirror of plane, the thickness of its reflectance coating along the axial distribution gradient of plane mirror, then can make the power spectrum of exit Xray identical, namely produces homogeneous X-ray bundle, but exit Xray bundle but differs and is decided to be parallel beam.Both combines by curved mirror of the present invention, and the reflectance coating thickness on curved mirror concave surface is designed to tangentially distribution gradient, thus produces parallel, homogeneous X-ray bundle.So the reflectance coating thickness on mean camber mirror concave surface of the present invention designs according to following formula (2):

$D\left(x\right)=\frac{\mathrm{\λ}}{2\sin \left\{\arctan \right\{\frac{\sqrt{2L[1-\cos \left(2{\mathrm{\θ}}_{i0}\right)]\{x+\frac{L}{2}[\cos \left(2{\mathrm{\θ}}_{i0}\right)+1\left]\right\}}}{x+L\cos \left(2{\mathrm{\θ}}_{i0}\right)}\}-\arctan \{\frac{1}{2}\sqrt{\frac{2L[1-\cos \left(2{\mathrm{\θ}}_{i0}\right)]}{x+\frac{L}{2}[\cos \left(2{\mathrm{\θ}}_{i0}\right)+1]}}\left\}\right\}}---\left(2\right)$

Wherein, D (x) represents the thickness along the reflectance coating of the tangential direction of described curved mirror, θ _i0represent the angle on incident X-rays and described reflectance coating surface, λ represents the wavelength of outgoing X-ray beam, and L represents the distance of X-ray tube focus to reflecting mirror, and x represents described curved mirror length in the horizontal direction.

Fig. 3 curved mirror of the present invention reflects incident X-rays cone beam, obtains the schematic diagram of parallel, monochromatic exit Xray bundle.Wherein, the parameters occurred in Fig. 3 and coordinate are the labellings conveniently seeing figure.

In addition, the present invention also provides a kind of X-ray data collecting system, and it comprises curved mirror 1, x-ray source 2 and a detector, and wherein, x-ray source 2 sends taper or fan-shaped x-ray beam, and incides on curved mirror 1; Curved mirror 1 makes to there is angle between its concave surface being coated with reflectance coating and incident X-rays bundle through arranging, described incident X-rays bundle, after the concave reflection of curved mirror 1, reflects parallel, that frequency spectrum is identical X-ray beam; The X-ray beam reflected described in described detector receives.

The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (7)

1. a curved mirror for energy reflection X-ray, is characterized in that,

The concave surface of this curved mirror is coated with the reflectance coating of plural layer energy reflection X-ray, and the thickness of described reflectance coating is through the tangential direction distribution gradient of design along described curved mirror, wherein,

Described curved mirror makes to there is angle between its surface being coated with reflectance coating and each incident X-rays bundle through arranging, after reflecting film reflects described in described incident X-rays Shu Jing, make outgoing X-ray beam become parallel, that frequency spectrum is identical X-ray beam, the thickness of described reflectance coating designs according to following formula:

$D\left(x\right)=\frac{\mathrm{\λ}}{2sin\left\{arctan\right\{\frac{\sqrt{2L\[1-cos\left(2{\mathrm{\θ}}_{i0}\right)\]\{x+\frac{L}{2}\[cos\left(2{\mathrm{\θ}}_{i0}\right)+1\]\}}}{x+L\cos \left(2{\mathrm{\θ}}_{i0}\right)}\}-arctan\{\frac{1}{2}\sqrt{\frac{2L\[1-cos\left(2{\mathrm{\θ}}_{i0}\right)\]}{x+\frac{L}{2}\[cos\left(2{\mathrm{\θ}}_{i0}\right)+1\]}}\left\}\right\}},$

Wherein, D (x) represents the thickness along the reflectance coating of the tangential direction of described curved mirror, θ _i0represent the angle on incident X-rays and described reflectance coating surface, λ represents the wavelength of outgoing X-ray beam, and L represents the distance of X-ray tube focus to reflecting mirror, and x represents described curved mirror length in the horizontal direction.

2. curved mirror according to claim 1, is characterized in that, described incident X-rays bundle is cone beam or fladellum.

3. curved mirror according to claim 1, is characterized in that, the thickness of described reflectance coating is nm magnitude.

4. curved mirror according to claim 1, is characterized in that, described reflectance coating is more than 0.5 to the reflectance of X-ray.

5. curved mirror according to claim 1, is characterized in that, every one deck of described reflectance coating comprises the sublayer that is made up of W material and by B ₄the sublayer that C material is formed, this two Seed Layer is alternately arranged.

6. curved mirror according to claim 1, is characterized in that, described angle is 0.2 ° ~ 2 °.

7. an X-ray data collecting system, is characterized in that, described system comprises an x-ray source, a detector and the curved mirror just like the energy reflection X-ray described in claim arbitrary in claim 1-6, wherein,

Described x-ray source sends taper or fan-shaped x-ray beam, and incides on described curved mirror;

Described curved mirror makes to there is angle between its concave surface being coated with reflectance coating and incident X-rays bundle through arranging, after the concave reflection of curved mirror described in described incident X-rays Shu Jing, reflects parallel, that frequency spectrum is identical X-ray beam;

The X-ray beam reflected described in described detector receives.