EP1613711A1 - Verfahren zur herstellung eines nadel- förmigen röntgenspeicherleuchtstoffs sowie röntgenspeicherleuchtstoff - Google Patents
Verfahren zur herstellung eines nadel- förmigen röntgenspeicherleuchtstoffs sowie röntgenspeicherleuchtstoffInfo
- Publication number
- EP1613711A1 EP1613711A1 EP04737298A EP04737298A EP1613711A1 EP 1613711 A1 EP1613711 A1 EP 1613711A1 EP 04737298 A EP04737298 A EP 04737298A EP 04737298 A EP04737298 A EP 04737298A EP 1613711 A1 EP1613711 A1 EP 1613711A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- csbr
- storage phosphor
- doped
- needle
- europium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
- C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
- C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
Definitions
- the invention relates to a method for producing a needle-shaped X-ray storage phosphor and an X-ray storage phosphor made of europium-doped cesium bromide.
- X-ray storage phosphors are used in medical technology and non-destructive material testing. In these applications, storage phosphors with the formation and storage of electrons and holes with subsequent photo-stimulated emission (PSL) are used when irradiated with, for example, red light.
- PSL photo-stimulated emission
- X-ray storage phosphors based on the alkali halides play a very special role. An example of this is CsBr: Eu as a storage phosphor, as described, for example, in "New Needle-crystalline CR Detector", Proc. of SPIE Vol.
- FIG. 1 The significant increase the afterglow from the radiation damage can be seen in FIG. 1, in which a scan over a 40 mm CsBr: Eu layer with a flying spot laser (approx. 100 ⁇ m) after different radiation exposure is shown.
- the normalized read signal S of the flying spot reader is plotted over the scan time t.
- Curve 1 shows the output signal of the flying spot reader before the X-ray endurance test
- curve 2 shows the output signal of the flying spot reader after approximately 3200 irradiation cycles.
- the afterglow decreases somewhat.
- the afterglow can be reduced by briefly post-annealing, for example 0.5 h at 170 ° C of the layer.
- the scanning direction points in the direction of the time axis. The range from 1 to 4 ms indicates the size of the samples.
- the light yield decreases significantly with increasing total X-ray dose, as is described with reference to FIG. 2, in which the relative light yield L re ⁇ is plotted against the number of irradiation cycles.
- FIG. 2 shows the dependence of the intensity (light yield) as a function of the number of irradiation cycles for different samples CsBr: Eu (curves 4 to 8).
- the lower luminous efficacy ultimately results in a deterioration in the image quality (DQE).
- DQE image quality
- the loss of light yield cannot be reversed or influenced thermally, for example by post-heating or irradiation at elevated temperature.
- a second starting point could be the phase formation during the annealing of CsBr: Eu and other Eu-doped alkali halides.
- the effect is the same that occurs when overtemping CsBr: Eu-Schic ten, as is the case, for example, with the dissertation by Hackenschmied "Function and manufacture of storage phosphors for X-ray diagnostics", Shaker Verlag; ISBN no.
- Such phases of the composition of, for example, Cs x Eu y Br ( x + 2y ) can also be evaporated directly with the CsBr and then condensed on the substrate as CsBr: Cs x Eu y Br ( x + 2y ), as described in WO 2004 / 017352 A2.
- EP 0 318 813 describes a photoluminescent storage material which consists of an alkaline earth metal sulfide, for example Sr 2 S, and as a doping agent samarium and a further doping agent from the group of cerium oxide, cerium fluoride, cerium chloride and cerium sulfide.
- the invention is based on the object of designing a method and a device of the type mentioned at the outset in such a way that the acicular x-ray storage phosphor made of europium-doped cesium bromide has the desired long-term stability required for x-ray examinations in medical technology.
- the object is achieved for a method according to the invention by co-doping the europium-doped cesium bromide (CsBr) with small ions of at least one alkali and / or alkaline earth metal and associated anions from the vapor phase.
- This results in a needle-shaped storage phosphor based on alkali halide with improved X-ray resistance.
- the europium-doped cesium bromide can be CsBr: Cs x Eu y Br ( x + 2y ) or CsBr: Eu.
- Lithium (Li) and / or sodium (Na) can be used advantageously as alkali metals and beryllium (Be), magnesium (Mg) and / or calcium (Ca) can be used as alkaline earth metals. Co-doping with Li and Na or Li and Ca can be carried out.
- At least one halide from the group fluorine (F), chlorine (Cl), bromine (Br) and / or iodine (I) or compounds from the group of nitrates, sulfates and / or oxides can be used as the associated anion.
- LiBr lithium bromide
- the alkali or alkaline earth metals with proportions between 100 ppm and 20 mol% can advantageously be used.
- the task for an X-ray storage phosphor is determined by co-doping with LiBr, the sum formula of
- X-ray storage phosphor CsBr Eu, Li and for a phase-containing storage phosphor with a molecular formula CsBr: Cs x Eu y Br ( x + y ), Li with Li as a sensitizer.
- FIG. 2 shows the relative luminous efficacy of various CsBr: Eu storage phosphors as a function of the number of irradiation cycles
- FIG. 3 shows the relative luminous efficacy of differently tempered CsBr: Eu storage phosphors as a function of the number of irradiation cycles
- FIG. 4 shows the relative light yield of a CsBr: Eu storage phosphor layer which is co-doped with 0.5% LiBr, measured at room temperature as a function of the temperature T during tempering,
- FIG. 5 shows the relative light yield of two LiBr-co-doped, differently tempered CsBr: Eu storage phosphor layers as a function of the number of radiation cycles and
- the europium-doped CsBr (CsBr: Cs x Eu y Br x + 2y ) or is doped
- CsBr Eu
- Representatives are the alkali metals Li or Na and in principle also the alkaline earth metals Be, Mg and Ca.
- the halides F, Cl, Br and I are primarily considered as the associated anion. But others too
- Anions such as nitrates, sulfates, oxides etc. are suitable in principle.
- CaS0, Li 2 S0 4 , NaN0 3 , Mg 2 S0 Ca (N0 3 ) 2 , LiN0 3 , NaN0 3 , Mg (N0 3 ) 2 , CaO, MgO, BeO, Na 2 0 and Li 2 0 are suitable for this However, the remainder is limited to LiBr as a co-dopant. Also will look at the examples
- PVD layers physical vapor deposition
- the LiBr in the CsBr grid is very mobile, but at the latest after the final tempering step, it is firmly installed in the CsBr grid (eg on interstitial spaces).
- the procedure described also applies to powder shaped storage phosphor layers, the described concentrations are up to a power of ten higher.
- FIG. 4 shows the intensity of a CsBr: Eu layer co-doped with 0.5% LiBr as a function of the temperature (in each case 1 h) when the phosphor is activated.
- the curve 12 in FIG. 5 belonging to the overheated sample shows a decrease of about 30% during the first approx. 3000 irradiation cycles, while the undertempered sample shows a decrease 20 percent increase shows (curve 13). Thereafter, the overheated sample drops by approx. 10% per 20,000 radiation cycles, while the underheated sample drops at approx. 10% per 10,000 radiation cycles (curve 13).
- FIG. 5 shows the dependence of the intensity (light yield) as a function of the number of irradiation cycles for LiBr-co-doped CsBr: Eu layers.
- the afterglow behavior is also significantly improved, as shown in FIG. 6, in which the afterglow N in% the number n of radiation cycles is plotted.
- Curve 14 shows the profile for a known CsBr: Eu storage phosphor
- curve 15 shows the afterglow behavior of a CsBr: Eu, Li storage phosphor according to the invention.
- FIG. 6 shows the dependence of the afterglow (after 0.25 ms) on the number of irradiation cycles for LiBr-co-doped CsBr: Eu layers.
- the sum formula for co-doping with LiBr CsBr is: Eu, Li, and for the phase-containing storage phosphor CsBr: Cs x Eu y Br ( x + 2y ), Li.
- the Li is to be regarded as a sensitizer here, since the tempering behavior is different.
- the small ion of the present invention as a sensitizer which may be Li
- CsBr and LiBr have the same vapor pressure and this means that advantageous vapor deposition is carried out from two evaporator boats, the evaporator boat with the LiBr dopant having to have a significantly lower temperature. If you hold the Csl evaporator at 640 ° C, you get an approx. 50 at a LiBr evaporating temperature (same evaporator, same evaporating surface) at a temperature of 640 ° C at which CsBr has already melted % Mixture CsBr / LiBr, at 550 ° C an approx.
Landscapes
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Luminescent Compositions (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE10311649 | 2003-03-14 | ||
PCT/EP2004/002682 WO2004081143A1 (de) | 2003-03-14 | 2004-03-15 | Verfahren zur herstellung eines nadel - förmigen röntgenspeicherleuchtstoffs sowie röntgenspeicherleuchtstoff |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1613711A1 true EP1613711A1 (de) | 2006-01-11 |
Family
ID=32980605
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP04737298A Withdrawn EP1613711A1 (de) | 2003-03-14 | 2004-03-15 | Verfahren zur herstellung eines nadel- förmigen röntgenspeicherleuchtstoffs sowie röntgenspeicherleuchtstoff |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP1613711A1 (de) |
WO (1) | WO2004081143A1 (de) |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5956480A (ja) * | 1982-09-27 | 1984-03-31 | Fuji Photo Film Co Ltd | 蛍光体およびそれを用いた放射線像変換パネル |
DE3578081D1 (de) * | 1984-09-14 | 1990-07-12 | Konishiroku Photo Ind | Verfahren zur umwandlung eines radiographischen bildes und schirm zum speichern einer strahlungsenergie mit einer anregbaren phosphorschicht. |
JP2000192034A (ja) * | 1998-12-25 | 2000-07-11 | Fuji Photo Film Co Ltd | 蛍光体の製造方法 |
US20010007352A1 (en) * | 1999-12-27 | 2001-07-12 | Erich Hell | Binderless storage phosphor screen with needle shaped crystals |
-
2004
- 2004-03-15 EP EP04737298A patent/EP1613711A1/de not_active Withdrawn
- 2004-03-15 WO PCT/EP2004/002682 patent/WO2004081143A1/de active Search and Examination
Non-Patent Citations (1)
Title |
---|
See references of WO2004081143A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2004081143A1 (de) | 2004-09-23 |
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