CN110794448B

CN110794448B - Device and method for measuring X-ray energy

Info

Publication number: CN110794448B
Application number: CN201911197922.5A
Authority: CN
Inventors: 朱常青; 王进光; 冯杰; 何雨航; 陈黎明
Original assignee: Institute of Physics of CAS
Current assignee: Institute of Physics of CAS
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2021-12-03
Anticipated expiration: 2039-11-29
Also published as: CN110794448A

Abstract

The invention provides a device and a method for measuring X-ray energy by using a metal filter disc. The method provided by the invention adopts a modular design scheme, is very favorable for disassembly and assembly, and can be conveniently used for measuring the X-ray energy. By using the combination mode of different types and thicknesses of filter discs, the accurate measurement of the number of X-ray photons in an energy band of 0-90 keV can be realized, and the accurate calculation of the X-ray in a large energy range of 0-300 keV can be performed.

Description

Device and method for measuring X-ray energy

Technical Field

The invention belongs to the field of X-ray energy measurement, and particularly relates to a device and a method for measuring X-ray energy.

Background

X-rays were discovered in 1895 by the german physicist w.k. roentgen and are also referred to as roentgen rays. The wavelength of the electromagnetic wave is between 0.01 and 100 angstroms, and the electromagnetic wave is an electromagnetic wave between ultraviolet rays and gamma rays. Due to its short wavelength, it has high energy and high penetrating power, and can transmit many substances opaque to visible light, such as wood board and plastic. However, because X-rays have high energy, it can be used in various fields such as scientific detection, biological imaging, medical treatment, etc., for example, CT, which is a Computed Tomography (CT) technique commonly used in hospitals, scans a certain part of a human body with a precisely collimated X-ray beam, and diagnoses diseases through imaging. However, the X-ray physical properties of the individual energy segments are very different and their penetration capabilities are also very different. Therefore, we should understand the energy of the X-ray before design and use and measure it.

At present, an X-ray single photon counter (X-ray CCD) is generally used for detecting X-ray energy, and the method is simple and easy to implement, has high sensitivity and can quickly give the energy spectrum distribution of the X-ray. However, the X-ray CCD can only detect the photon energy with lower energy, and cannot detect the photon energy with higher energy. And the X-ray CCD also has requirements on the brightness of X-rays, and the crystal in the CCD is directly damaged when the brightness is too high. X-ray energy can be measured using metal filter sheets of different thicknesses and materials. For example, by using different metals to absorb X-rays K-edge, two by one, the X-ray energy spectrum of the low energy band can be accurately measured, and the X-ray energy spectrum is the so-called Ross-filter. But this approach also fails to measure X-rays below the energy of 30 keV. If higher-energy X-rays are to be measured, filters of different types and thicknesses need to be replaced, but no filter which is combined in a centering mode is available at present, so that the calculation statistics of the number of photons of the generated round light spots can have larger errors, and the measurement can only be used as a relatively rough measurement.

Disclosure of Invention

Accordingly, it is an object of the present invention to overcome the disadvantages of the prior art and to provide an apparatus and method for measuring X-ray energy.

Before the technical solution of the present invention is explained, the terms used herein are defined as follows:

the term "IP" refers to: imaging Plate.

The invention aims to overcome the defects in the prior art, 10 metal filter discs are placed in a centering mode, and the combination mode of different types and thicknesses of filter discs is utilized, so that the accurate measurement of the number of X-ray photons in an energy band of 0-90 keV can be realized, and the accurate calculation of X-rays in a large energy range of 0-300 keV can be realized.

To achieve the above object, a first aspect of the present invention provides an apparatus for measuring X-ray energy, the apparatus comprising: the device comprises a lead screen box, an IP supporting plate, a metal filter sheet supporting plate and one or more groups of metal filter sheets, wherein every two of the metal filter sheets are in one group;

preferably, the device has 2-10 groups of metal filter discs, preferably 5-7 groups of metal filter discs;

and when the device is provided with a plurality of groups of metal filter sheets, the plurality of groups of filter sheets are stacked and arranged on the metal filter sheet supporting plate.

The device according to the first aspect of the present invention, wherein the material of the metal filter sheet is selected from transition metals or third and fourth main group metal elements;

preferably, the transition metal or third and fourth main group metal elements are one or more of the following: ga. Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb, Au, W; and/or

Preferably, the metal filter sheet is triangular, and more preferably is an isosceles triangle with the bottom having the small holes on the central line of the bottom. The thickness of the whole filter disc is uniformly distributed, and the top angle of the filter disc is 25-40 degrees, preferably 30-40 degrees, and most preferably 36 degrees.

The apparatus according to the first aspect of the present invention, wherein when the material of the metal filter is selected from: ga. One or more of Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb and Au, the thickness of the alloy is 1-300 μm, preferably 5-150 μm; and/or

When the material of the metal filter sheet is selected from: when one or more of Al, Ta, Cu and W are used, the thickness is 0.1 to 10mm, preferably 0.1 to 8 mm.

The device according to the first aspect of the invention, wherein the lead screen box is made of lead, two side surfaces of the lead screen box are correspondingly provided with grooves, and the upper side and the bottom surface of the lead screen box are correspondingly provided with small holes; preferably, the thickness of each surface of the lead screen box is 1-5 cm, more preferably 1-3 cm, and most preferably 2 cm.

According to the device of the first aspect of the invention, the IP support plate ridge is inserted from the vertical direction close to the rear side of the lead screen box, the protrusion of the IP support plate and the groove on the side surface of the lead screen box are embedded together, and the IP is inserted into the IP support plate gap from the upper side and is leaned against the IP support plate ridge.

Preferably, the metal filter support plate is provided with front threaded holes and side threaded holes which are uniformly distributed, and the side threaded holes are used for fixing the metal filter support plate on the small holes of the lead screen box.

Preferably, the small holes at the bottom of the metal filter disc are used for fixing the metal filter disc on the threaded holes in the front face of the metal filter disc supporting plate.

A second aspect of the invention provides a method of measuring X-ray energy using a metal filter, the method comprising using the apparatus of the first aspect to make a measurement of X-ray energy.

According to the method of the second aspect of the invention, when the detected photon energy is less than 90keV, the material of the metal filter is selected from one or more of the following: ga. Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb and Au; the thickness of the metal filter sheet is 1-300 μm, preferably 5-150 μm.

According to the method of the second aspect of the invention, when the detected photon energy is within 0-300 keV, the material of the metal filter is selected from one or more of the following materials: al, Ta, Cu, W; the thickness of the metal filter disc is 0.1-10 mm, and preferably 0.1-8 mm.

The device and the method for measuring the X-ray energy by using the metal filter disc have the following beneficial effects that:

1. the modular design is very convenient for disassembly and assembly, and can be conveniently used for measuring the X-ray energy.

2. By using the combination mode of different types and thicknesses of filter discs, the accurate measurement of the number of X-ray photons in an energy band of 0-90 keV can be realized, and the accurate calculation of the X-ray in a large energy range of 0-300 keV can be performed.

Drawings

Embodiments of the invention are described in detail below with reference to the attached drawing figures, wherein:

fig. 1 shows a perspective view of a lead screen box provided in embodiment 1 of the present invention;

FIG. 2 is a perspective view showing an IP (imaging plate) support plate according to embodiment 1 of the present invention;

fig. 3 shows a perspective view of a metal filter support plate of embodiment 1 of the present invention;

fig. 4 shows a perspective view of the front surface of a metal filter sheet of embodiment 1 of the present invention.

FIG. 5 shows the photon energy vs. transmittance of Table 1 of example 2.

FIG. 6 shows the photon energy vs. transmittance of Table 2 of example 2.

Description of reference numerals:

1. the upper side of the lead screen box; 2. the rear side of the lead screen box; 3. the side surface of the lead screen box; 4. a small hole; 5. a groove; 6. a lead screen box base; 7. an IP support plate protrusion; 8. an IP support plate backbone; 9. an IP support plate gap; 10. a metal filter support plate; 11. the front threaded hole of the metal filter supporting plate; 12. the side surface of the metal filter supporting plate is provided with a threaded hole; 13. a metal filter disc; 14. and small holes of the metal filter disc.

Detailed Description

The invention is further illustrated by the following specific examples, which, however, are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever.

This section generally describes the materials used in the testing of the present invention, as well as the testing methods. Although many materials and methods of operation are known in the art for the purpose of carrying out the invention, the invention is nevertheless described herein in as detail as possible. It will be apparent to those skilled in the art that the materials and methods of operation used in the present invention are well within the skill of the art, provided that they are not specifically illustrated.

The materials used in the following examples are as follows:

ga. Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb, Au, W, 5cm x 5cm high purity metal pieces purchased from North China science and technology metal materials.

Example 1

This embodiment is intended to explain the specific structure of the apparatus of the present invention.

Fig. 1 is a perspective view of a lead screen box of the device of the present invention, in order to prevent the external high-energy ray background from affecting the reading of ip (imaging plate), the upper side (1) of the lead screen box, the rear side (2) of the lead screen box, the side (3) of the lead screen box and the base (6) of the lead screen box are all made of lead, have a thickness of 2cm, and can shield X-rays with energy below 600 keV.

Fig. 2 is a perspective view of the IP support plate of the device of the present invention, wherein the IP support plate ridge (8) is inserted from the vertical direction against the rear side (2) of the lead screen box, the IP support plate protrusion (7) and the groove (5) are embedded together, and the IP is inserted into the IP support plate gap (9) from above and is against the IP support plate ridge (8) during implementation.

Fig. 3 is a perspective view of a metal filter support plate of the device of the present invention, wherein the metal filter support plate (10) is used as a support block of a metal filter, 10 uniformly distributed metal filter support plate front threaded holes (11) are punched on the metal filter support plate, and four metal filter support plate side threaded holes (12) are distributed around the metal filter support plate (10) for fixing the metal filter support plate (10) on the small holes (4) of the lead screen box.

Fig. 4 is a perspective view of the front surface of the metal filter of the device of the present invention, the selection of the metal filter (13) is very critical, and the photon number of each energy segment can be calculated more accurately by the proper metal filter. The metal filter sheet small holes (14) are used for fixing 10 metal filter sheets on the threaded holes (11) in the front of the metal filter sheet supporting plate.

Example 2

This example serves to illustrate a specific method of use of the device of the present invention.

10 metal filter sheets were made in the shape shown in fig. 4, the apex angle was 36 °, the metal filter sheets were related to the choice of material and thickness, two groups of metal filter sheets were chosen as follows:

table 1 protocol-selection of metal filter material and thickness

The relationship between photon energy and transmittance is shown in fig. 5.

Table 2 scheme two metal filter material and thickness selection

The relationship between photon energy and transmittance is shown in fig. 6.

The key to the implementation of the method is that the X-ray light spot is required to be circular, and the circle formed by the light spot and the metal filter is centered, so that the photon yield of the X-ray can be accurately calculated.

The photon energy spectrum calculation formula is as follows:

wherein Δ S ═ S_k-S_k+1Represents the difference in PSL across the two filter sheets,

representing the difference of the X-ray transmittances of two filter sheets in a certain energy band,

represents the response of the IP to photons, and

representing the number of photons per unit energy.

The difference delta S between PSL is obtained by subtracting the filter 1 and the filter 2 on the IP imaging plate, the difference delta T between the transmittances of the two filters to a certain energy band can be obtained by calculation, and the response of IP to photons

Can be obtained by looking up the data. Thus, according to equation (1), the average photon number density per unit energy is:

finally, the total number of photons is obtained by adding the energy segments:

where Δ E represents the width of the individual photon energy bins.

The method for measuring the X-ray energy by using the metal filter disc adopts a combination mode of two materials, and needs to predict the energy range of the X-ray according to a theory and select a proper combination mode of the metal filter disc. If the detected photon energy is within 90keV, the first scheme is adopted, and then 5 suitable pairs are selected according to the photon energy range of X-ray to be detected, which is shown in Table 1. The metal filter sheets are sequentially fixed on a support plate (10) and are placed in a centering mode, two metal filter sheets of the filter sheet 1 and the filter sheet 2 in the form are combined in the same pair, and the arrangement sequence of the metal filter sheets in each group is random. It should be noted that if

filter

1 or 2 contains multiple filters, they need to be stacked for use. If necessary, the number of the metal filter pieces can be increased to 7 pairs, and the top angle of the metal filter pieces is changed correspondingly. Since the difference Δ T in the transmittance of photons in this energy band is steep on both sides, the out-of-range cutoff, see FIG. 5, allows the total number of photons in 90keV to be accurately obtained according to equations (2) and (3).

And if the energy range of the photons needing to be detected is larger and is within 0-300 keV, and the calculation of the number of the photons requires less accurate measurement, adopting a second scheme, and showing in a table 2. The difference between the two schemes is that the difference Δ T between the transmittances of photons in the energy band has no cutoff range, so the full width at half maximum of Δ T needs to be calculated, as shown in fig. 6. Response to photons of difference between energy transmission rates Δ T and IP in the full width half maximum energy band

The total number of photons can be calculated more accurately by integrating, then estimating the average photon number density according to equation (2), and finally summing, according to equation (3).

Although the present invention has been described to a certain extent, it is apparent that appropriate changes in the respective conditions may be made without departing from the spirit and scope of the present invention. It is to be understood that the invention is not limited to the described embodiments, but is to be accorded the scope consistent with the claims, including equivalents of each element described.

Claims

1. An apparatus for measuring X-ray energy, the apparatus comprising: the method comprises the following steps that a lead screen box, an IP supporting plate, a metal filter supporting plate and 2-10 groups of metal filters are adopted, and the combination mode of different types and thicknesses of the filters is utilized, so that the accurate measurement of the number of X-ray photons in an energy band of 0-90 keV can be realized, and the accurate calculation of X-rays in a large energy range of 0-300 keV can be realized, wherein every two metal filters are in one group; when the device is provided with a plurality of groups of metal filter sheets, the plurality of groups of filter sheets are stacked and arranged on the metal filter sheet supporting plate;

the material of the metal filter disc is selected from transition metal or third and fourth main group metal elements;

the metal filter disc is an isosceles triangle with small holes at the bottom, and the small holes are formed in the center line of the bottom side.

2. The apparatus of claim 1, wherein the apparatus has 5-7 sets of metal filters.

3. The apparatus of claim 1, wherein the transition metal or third and fourth main group metal elements are one or more of: ga. Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb, Au and W.

4. An apparatus for measuring X-ray energy according to any one of claims 1 to 3, wherein: the thickness of the whole filter disc is uniformly distributed, and the vertex angle of the filter disc is 25-40 degrees.

5. An apparatus for measuring X-ray energy according to claim 4, wherein the filter vertex angle is 30-40 °.

6. An apparatus for measuring X-ray energy according to claim 5, wherein the filter vertex angle is 36 °.

7. The apparatus of claim 1, wherein the metal filter is made of a material selected from the group consisting of: ga. And when one or more of Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb and Au are used, the thickness is 1-300 μm.

8. The apparatus of claim 7, wherein the metal filter is made of a material selected from the group consisting of: ga. And when one or more of Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb and Au are used, the thickness is 5-150 μm.

9. The apparatus of claim 1, wherein the metal filter is made of a material selected from the group consisting of: and when one or more of Al, Ta, Cu and W is/are contained, the thickness is 0.1-10 mm.

10. The apparatus of claim 9, wherein the metal filter is made of a material selected from the group consisting of: and when one or more of Al, Ta, Cu and W is/are contained, the thickness is 0.1-8 mm.

11. The device of claim 1, wherein the lead screen box is made of lead, two side surfaces of the lead screen box are correspondingly provided with grooves, and the upper side and the bottom surface of the lead screen box are correspondingly provided with small holes; the thickness of each face of the lead screen box is 1-5 cm.

12. The device of claim 11, wherein the thickness of each face of the lead housing is 1-3 cm.

13. The apparatus of claim 12, wherein the lead housing has a thickness of 2cm per face.

14. The apparatus of claim 1, wherein the IP support plate ridge is inserted vertically against the back side of the lead case, the protrusion of the IP support plate and the groove on the side of the lead case are nested together, and the IP is inserted into the IP support plate slot from above and against the IP support plate ridge.

15. The apparatus of claim 1, wherein the metal filter support plate has evenly distributed front threaded holes and side threaded holes for fixing the metal filter support plate to the small holes of the lead screen box.

16. The apparatus of claim 1, wherein the metal filter bottom aperture is used to secure the metal filter to the metal filter support plate front threaded hole.

17. A method of measuring X-ray energy using a metal filter, the method comprising using the apparatus of any one of claims 1 to 16 to make a measurement of X-ray energy.

18. The method of claim 17, wherein when the detected photon energy is less than 90keV, the material of the metal filter is selected from one or more of: ga. Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb and Au; the thickness of the metal filter disc is 1-300 mu m.

19. The method of claim 18, wherein when the detected photon energy is less than 90keV, the material of the metal filter is selected from one or more of: ga. Ti, Al, Mo, Sn, Dy, Cu, Ta, Pb and Au; the thickness of the metal filter disc is 5-150 mu m.

20. The method of claim 17, wherein the metal filter is made of a material selected from one or more of the following materials when the detected photon energy is within 0-300 keV: al, Ta, Cu, W; the thickness of the metal filter disc is 0.1-10 mm.

21. The method of claim 20, wherein the metal filter is made of a material selected from one or more of the following materials when the detected photon energy is within 0-300 keV: al, Ta, Cu, W; the thickness of the metal filter disc is 0.1-8 mm.