Radiation Shield Filter and Radiographic Apparatus Filter Assembly Comprising Same

Abstract

Disclosed is a filter assembly for a radiographic apparatus, which is positioned at an illumination part of a radiographic apparatus. The disclosed filter assembly for a radiographic apparatus includes a radiation shield filter including silicon dioxide (SiO.sub.2), aluminum oxide (Al.sub.2O.sub.3), boron trioxide (B.sub.2O.sub.3) and sodium oxide (Na.sub.2O), and a radiation alignment filter composed of the same components as the radiation shield filter, laid over the front of the radiation shield filter and having fine holes formed in the surface thereof, and effectively blocks the radiation generated from the radiographic apparatus without greatly affecting the quality of a radiographic image.

Claims

1. A radiation shield filter, positioned at an illumination part of a radiographic apparatus and comprising silicon dioxide (SiO.sub.2), aluminum oxide (Al.sub.2O.sub.3), boron trioxide (B.sub.203) and sodium oxide (Na.sub.2O).

2. The radiation shield filter of claim 1, comprising 75 to 86 wt % of the silicon dioxide, 2 to 4 wt % of the aluminum oxide, 9 to 16 wt % of the boron trioxide and 3 to 5 wt % of the sodium oxide.

3. The radiation shield filter of claim 1, further comprising at least one additive selected from the group consisting of calcium oxide (CaO), chromium oxide (Cr.sub.2O.sub.3), iron oxide (Fe.sub.2O.sub.3), potassium oxide (K.sub.2O), magnesium oxide (MgO) and zirconium oxide (ZrO.sub.2).

4. A filter assembly for a radiographic apparatus, comprising: the radiation shield filter of claim 2; and a radiation alignment filter, composed of same components as the radiation shield filter, laid over a front of the radiation shield filter, and having fine holes formed in a surface thereof.

5. The filter assembly of claim 4, wherein the fine holes formed in the radiation alignment filter have a size of 40 to 50 m and an interval of 120 to 170 m therebetween.

6. The filter assembly of claim 4, wherein a total thickness of the radiation shield filter and the radiation alignment filter is 10 mm or less.

7. The filter assembly of claim 6, wherein the radiation shield filter has a thickness of 4 to 6 mm and the radiation alignment filter has a thickness of 4 to 6 mm.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0017] FIG. 1 shows images captured after application of each of a radiation shield filter according to the present disclosure, a lead filter and a ceramic filter to a radiographic apparatus;

[0018] FIG. 2 schematically shows the configuration of a filter assembly 100 for a radiographic apparatus and the radiation XB transmitted through the filter assembly 100 for a radiographic apparatus; and

[0019] FIG. 3 shows the radiographic images depending on the thicknesses combination of a radiation shield filter 110 and a radiation alignment filter 130.

DESCRIPTION OF THE REFERENCE NUMERALS

[0020] 100: filter assembly for radiographic apparatus [0021] 110: radiation shield filter [0022] 130: radiation alignment filter [0023] XB: radiation

MODE FOR DISCLOSURE

[0024] Hereinafter, a detailed description will be given of a radiation shield filter and a filter assembly 100 for a radiographic apparatus, made with reference to the appended drawings.

[0025] Radiation Shield Filter

[0026] A radiation shield filter according to the present disclosure (hereinafter referred to as a radiation shield filter) includes silicon dioxide (SiO.sub.2), aluminum oxide (Al.sub.2O.sub.3), boron trioxide (B.sub.2O.sub.3) and sodium oxide (Na.sub.2O), and is effective at blocking (ionizing) the transmitted radiation.

[0027] Specifically, the radiation shield filter may be configured to include 75 to 86 wt % of silicon dioxide, 2 to 4 wt % of aluminum oxide, 9 to 16 wt % of boron trioxide and 3 to 5 wt % of sodium oxide.

[0028] Moreover, the radiation shield filter may further include at least one additive selected from the group consisting of calcium oxide (CaO), chromium oxide (Cr.sub.2O.sub.3), iron oxide (Fe.sub.2O.sub.3), potassium oxide (K.sub.2O), magnesium oxide (MgO) and zirconium oxide (ZrO.sub.2).

[0029] Silicon dioxide allows the radiation shield filter to be in the form of glass and accounts for the greatest weight percent among the components of the radiation shield filter.

[0030] If the weight percent of silicon dioxide exceeds wt %, the weight percents of the radiation-blocking materials (aluminum oxide, boron trioxide) may decrease, and thus the radiation-blocking rate of the radiation shield filter may be lowered. On the other hand, if the weight percent of silicon dioxide is less than 75 wt %, the weight percents of radiation-blocking materials (aluminum oxide, boron trioxide) may increase, and thus the sharpness of the photographed radiographic image may be lowered.

[0031] Aluminum oxide functions to block radiation in the low energy region and to induce curing of the mixture.

[0032] If the weight percent of aluminum oxide exceeds 4 wt %, the contrast of the photographed radiographic image increases. Although a certain level of contrast increase aids in identification of the photographed radiographic image, an excessive increase in contrast makes it difficult to identify the photographed radiographic image. On the other hand, if the weight percent of aluminum oxide is less than 2 wt %, the ability to block radiation in the low energy region is lowered.

[0033] Boron trioxide functions to block radiation in the energy region higher than the radiation blocked by aluminum oxide.

[0034] According to tests conducted by the present inventors, the radiation-blocking rate was increased by 3.5 to 4% with an increase in boron trioxide by 1 wt %. On the other hand, the radiation-blocking rate was decreased by 3.5 to 4% with a decrease in boron trioxide by 1 wt %. As the weight percent of boron trioxide was higher, the photographed radiographic image was darkened.

[0035] Sodium oxide functions to increase the thermal shock resistance of the radiation shield filter. Also, when silicon dioxide, aluminum oxide and boron trioxide are solidified, sodium oxide enables these components to be uniformly mixed (distributed).

[0036] According to tests conducted by the present inventors, when using 3 to 5 wt % of sodium oxide, desired effects thereof were obtained.

[0037] Additives such as calcium oxide (CaO), chromium oxide (Cr.sub.2O.sub.3), iron oxide (Fe.sub.2O.sub.3), potassium oxide (K.sub.2O), magnesium oxide (MgO) and zirconium oxide (ZrO.sub.2) do not affect the radiation-blocking rate of the radiation shield filter, but have an influence on the strength and durability of the radiation shield filter.

[0038] Radiation-Blocking Test

[0039] A) Test method and traceability: The X-ray-blocking rate (1C.sub.i/C.sub.0) is determined by the ratio of the dose rate values measured when a sample was present (C.sub.i) and when a sample was absent (C.sub.0) between an X-ray irradiator and a reference ionization chamber.

[0040] B) Specification of standard equipment used for irradiation

TABLE-US-00001 TABLE 1 Expected Device Manufacturer Device date of next Calibration name and Form number calibration institution X-ray YXLON, MG325 9040059413 2017 Apr. 5 KAERI irradiator Reference NE2530 613 2017 Jun. 21 KRISS ionization chamber Ther- WIKA/CTR2000- 024617 2017 Jan. 25 Mokwon mometer 024 University Industry- Academic Cooperation Foundation Barometer Mensor DPGII- 290266 2017 Jul. 27 Mokwon 14500 University Industry- Academic Cooperation Foundation

[0041] C) Test environment: Temperature (235) C/relative humidity (482)% R.H.

[0042] D) Test conditions:

TABLE-US-00002 TABLE 2 Applied voltage Additional filter Average energy Beam Code (kV) (mm) (keV) ISO NS60 60 0.6 Cu 48 ISO NS80 80 2.0 Cu 65 ISO NS100 100 5.0 Cu 83 ISO NS120 120 5.0 Cu + 1.0 Sn 100 ISO NS150 150 2.5 Su 118

[0043] Inherent filtration: 3.0 mm Be+3.7 mm AI [0044] The sample surface and the photon beamline were installed perpendicular to each other. [0045] Distance between a light source and a measurement instrument: 200 cm [0046] Distance between a sample surface and a measurement instrument: 5 cm [0047] Test beam size: about 26 cm in diameter

Test Example 1

[0048] A radiation-blocking test was performed using a radiation shield filter having a thickness of 8.2 mm0.1 mm and composed of 80.2% of silicon dioxide, 2.3% of aluminum oxide, 12.5% of boron trioxide, 3.31% of sodium oxide and 1.69% of other additives. The test results thereof are shown in Table 3 below.

TABLE-US-00003 TABLE 3 Relative Beam Dose rate Dose rate Blocking rate measurement code C.sub.0 (mGy/h) C.sub.i (mGy/h) (1-C.sub.i/C.sub.0) uncertainty (%) ISO 30.89 16.79 0.46 5.3 NS60 ISO 18.31 13.00 0.29 5.4 NS80 ISO 7.91 6.10 0.23 5.3 NS100 ISO 9.37 7.47 0.20 5.4 NS120 ISO 63.33 51.37 0.19 5.3 NS150 * Relative measurement uncertainty: value at approximately 95% confidence level, k = 2.

Test Example 2

[0049] A radiation-blocking test was performed using a radiation shield filter having a thickness of 9.9 mm0.1 mm and composed of 80.2% of silicon dioxide, 2.3% of aluminum oxide, 12.5% of boron trioxide, 3.31% of sodium oxide and 1.69% of other additives. The test results thereof are shown in Table 4 below.

TABLE-US-00004 TABLE 4 Relative Beam Dose rate Dose rate Blocking rate measurement code C.sub.0 (mGy/h) C.sub.i (mGy/h) (1-C.sub.i/C.sub.0) uncertainty (%) ISO 30.89 15.23 0.51 5.3 NS60 ISO 18.31 12.27 0.33 5.4 NS80 ISO 7.91 5.84 0.26 5.3 NS100 ISO 9.37 7.91 0.23 5.3 NS120 ISO 63.33 49.73 0.21 5.3 NS150 * Relative measurement uncertainty: value at approximately 95% confidence level, k = 2.

[0050] Radiographic Imaging

[0051] FIG. 1 shows images captured after application of each of the radiation shield filter [having a thickness of 9.9 mm0.1 mm and composed of 80.2% of silicon dioxide, 2.3% of aluminum oxide, 12.5% of boron trioxide, 3.31% of sodium oxide and 1.69% of other additives], a filter containing 70% of lead and a ceramic filter to a radiographic apparatus.

[0052] With reference thereto, it can be seen that the radiographic image was very clear even with the naked eye when using the radiation shield filter compared to when using the lead filter and the ceramic filter.

[0053] Filter Assembly 100 for Radiographic Apparatus

[0054] FIG. 2 schematically shows the configuration of the filter assembly 100 for a radiographic apparatus and the radiation XB transmitted through the filter assembly 100 for a radiographic apparatus.

[0055] With reference to FIG. 2, the filter assembly 100 for a radiographic apparatus includes a radiation shield filter 100 and a radiation alignment filter 130.

[0056] The radiation shield filter 110 functions to ionize (block) most of the dose except the dose necessary to form a radiographic image.

[0057] The radiation alignment filter 130 includes the same components as the radiation shield filter 100 and has fine holes formed in the surface thereof. The radiation alignment filter 130 is laid over the front of the radiation shield filter 100 (based on the direction of travel of the radiation XB).

[0058] The radiation alignment filter 130 functions to secondarily block the radiation XB. Moreover, the linearity of the radiation XB is corrected, thus improving the radiographic image.

[0059] According to tests conducted by the present inventors, when the fine holes formed in the surface of the radiation alignment filter 130 had a size of 40 to 50 m and an interval of 120 to 170 m therebetween, an effect of improving the radiographic image was obtained.

[0060] Meanwhile, under irradiation conditions of 70 KV and 2.5 mAs for 2.0 sec using a general C-arm, it is preferable for the total thickness of the radiation shield filter 110 and the radiation alignment filter 130 to be 10 mm or less. According to tests conducted by the present inventors, when the total thickness of the radiation shield filter 110 and the radiation alignment filter 130 exceeded 10 mm, the radiographic image was deteriorated.

[0061] Table 5 below schematically shows the extent of blocking the radiation and the state of the image depending on changes in the thicknesses of the radiation shield filter 110 and the radiation alignment filter 130 under irradiation conditions of 70 KV and 2.5 mAs for 2.0 sec.

[0062] FIG. 3 shows the radiographic images depending on the thickness combination of the radiation shield filter 110 and the radiation alignment filter 130.

TABLE-US-00005 TABLE 5 Radiation shield Radiation alignment filter filter Remark 2 mm 8 mm Very low blocking rate/ very good image 3 mm 7 mm Low blocking rate/ good image 4 mm 6 mm Appropriate blocking rate/ fair image 5 mm 5 mm Optimal blocking rate/ good image 6 mm 4 mm Appropriate blocking rate/ fair image 7 mm 3 mm High blocking rate/ bad image 8 mm 2 mm Very high blocking rate/ very bad image

[0063] Specifically, when the filter assembly 100 for a radiographic apparatus, in which the radiation shield filter 110 having an appropriate thickness (4 mm to 6 mm) and the radiation alignment filter 130 having an appropriate thickness (4 mm to 6 mm) are combined together, is mounted to a radiographic apparatus, the radiation generated from the radiographic apparatus is effectively blocked but the quality of a radiographic image is not greatly affected.

[0064] It is apparent to those skilled in the art that the radiation shield filter and the filter assembly 100 for a radiographic apparatus described above may be variously modified (applied) without departing from the spirit of the invention.

[0065] Therefore, the claims of the present disclosure will be broadly interpreted based on the spirit incorporated in the description of the invention and the overall drawings.

INDUSTRIAL APPLICABILITY

[0066] The present disclosure can be applied to radiographic imaging fields.