X-RAY IMAGING PHOTOSTIMULABLE PHOSPHOR SCREEN OR PANEL

• US 20090242836A1
• Filed: 12/03/2008
• Published: 10/01/2009
• Est. Priority Date: 12/06/2007
• Status: Abandoned Application

• Current Assignee: AGFA Healthcare NV (Agfa-Gevaert N.V.)
• Original Assignee: AGFA Healthcare NV (Agfa-Gevaert N.V.)
• Inventors: Silversmit, Geert, Lenaerts, Jens, Vincze, Laszlo, Leblans, Paul, Tahon, Jean-Pierre
• Application Number:
  US12/327,187
• Publication Number:
  US 20090242836A1
• Time in Patent Office: Days
• US Class Current: 252/301.40R
• CPC Class Codes: C09K 11/7733 with alkali or alkaline earth metals
• CPC Class Codes: G21K 4/00 Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens photographic processes using X-ray intensifiers G03C5/17; discharge tubes comprising luminescent screens H01J1/62; cathode ray tubes for X-ray conversion with optical output H01J31/50

Abstract

In a method of preparing a phosphor or scintillator layer to become deposited on a support, a vapor depositing step is applied from a crucible unit by heating as phosphor precursor raw materials present in said crucible, a Cs(X,X′) matrix compound and an activator or dopant precursor compound, wherein said crucible unit comprises at least a bottom and surrounding side walls as a container for phosphor precursor raw materials present in said crucible in liquefied form after heating said crucible, and wherein said Cs(X,X′) matrix compound has a higher vapor pressure than said activator or dopant precursor compound, said method comprising a step of providing said activator or dopant compound in form of a precursor raw material represented by the formula Cs_xEu_yX′_(x+αy), wherein x, y and α are integers, wherein x/y is more than 0.25 and wherein α is at least 2, wherein X represents Br and wherein X′ stands for F, Cl, Br, I or a combination thereof; followed by an annealing step after a vapor depositing step, provided that said annealing step proceeds in an ambient atmosphere after cooling said phosphor or scintillator layer, deposited on said support; and wherein as a result a binderless needle-shaped Cs(X,X′):Eu phosphor or scintillator layer becomes provided, having on top of its needle-shaped phosphors, aligned in parallel, an average ratio of divalent to trivalent europium dopant of more than 1:1; wherein said average ratio decreases to an extent of less than 2% per hour, while being exposed to X-rays having an energy in the range from 1 to 100 keV.

Claims

1. Binderless needle-shaped Cs(X,X′

);

Eu phosphor or scintillator layer having on top of its needle-shaped phosphors, aligned in parallel, an average ratio of divalent to trivalent europium dopant of more than 1;

1;

X representing Br and X′

representing F, Cl, Br, I or a combination thereof, wherein said average ratio decreases to an extent of less than 2% per hour, while being exposed to X-rays having an energy in the range from 1 to 100 keV.

2. Binderless needle-shaped Cs(X,X′

);

Eu,M^I phosphor or scintillator layer having on top of its needle-shaped phosphors, aligned in parallel, an average ratio of divalent to trivalent europium dopant of more than 1;

1;

X representing Br and X′

representing F, Cl, Br, I or a combination thereof, and M^I representing at least one cation, selected from the group consisting of Li, Na, K and Rb, or at least one cation, selected from the group consisting of Cu, Ag and Au, or a combination thereof, wherein said average ratio decreases to an extent of less than 2% per hour, while being exposed to X-rays having an energy in the range from 1 to 100 keV.

3. Method of preparing a phosphor or scintillator layer to become deposited on a support by a vapor depositing step from a crucible unit by heating as phosphor precursor raw materials a Cs(X,X′

) matrix compound and an activator or dopant precursor compound, wherein said crucible unit comprises at least a bottom and surrounding side walls as a container for phosphor precursor raw materials, and wherein said Cs(X,X′

) matrix compound has a higher vapor pressure than said activator or dopant precursor compound, said method comprising a step of providing said activator or dopant compound in form of a precursor raw material represented by the formula Cs_xEu_yX′

<sub>(x+α

y)</sub>, wherein x, y and α

are integers, wherein x/y is more than 0.25 and wherein α

is at least 2, wherein X represents Br and wherein X′

stands for F, Cl, Br, I or a combination thereof, both of them being present in said crucible as raw materials in liquefied form after heating said crucible;

followed by an annealing step in an ambient atmosphere after said vapor depositing step and after cooling said phosphor or scintillator layer deposited on said support.

4. Method according to claim 3, wherein besides said activator or dopant precursor compound, at least one compound is added having a cation, selected from the group consisting of Li, Na, K and Rb, or at least one compound having a cation, selected from the group consisting of Cu, Ag and Au, or a combination thereof.

5. Method according to claim 3, wherein said activator or dopant compound is CsEuBr₃ and wherein said annealing step is performed in an ambient atmosphere at a temperature of more than 150°

C. for more than 1 hour.

6. Method according to claim 4, wherein said activator or dopant compound is CsEuBr₃ and wherein said annealing step is performed in an ambient atmosphere at a temperature of more than 150°

C. for more than 1 hour.

7. Method according to claim 3, wherein said activator or dopant compound is CsEuBr₃ and wherein said annealing step is performed in an ambient atmosphere at a temperature of at least 170°

C. for at least 1 hour.

8. Method according to claim 4, wherein said activator or dopant compound is CsEuBr₃ and wherein said annealing step is performed in an ambient atmosphere at a temperature of at least 170°

C. for at least 1 hour.

9. Method according to claim 3, wherein said activator or dopant compound is CsEuBr₃ and wherein said annealing step is performed in an ambient atmosphere at a temperature of not more than 200°

C. for a time not more than 5 hours.

10. Method according to claim 4, wherein said activator or dopant compound is CsEuBr₃ and wherein said annealing step is performed in an ambient atmosphere at a temperature of not more than 200°

C. for a time not more than 5 hours.

11. Method according to claim 3, wherein said ambient atmosphere is air having a relative humidity of not more than 90%, when determined at room temperature.

12. Method according to claim 4, wherein said ambient atmosphere is air having a relative humidity of not more than 90%, when determined at r in the range from 1 to 100 keV;

i.e. an energy of about 28 keV as for mammographic applications and an energy in the range from 60 to 100 keV for general radiography room temperature.

13. Method according to claim 3, wherein said annealing step starts is at room temperature.

14. Method according to claim 4, wherein said annealing step starts at room temperature.

15. Method according to claim 3, wherein said storage phosphor is CsBr:

Eu.

16. Method according to claim 4, wherein said storage phosphor is CsBr:

Eu,M^I wherein M^I represents at least one cation, selected from the group consisting of Li, Na, K and Rb, or at least one cation, selected from the group consisting of Cu, Ag and Au, or a combination thereof.

17. Method according to claim 3, wherein said vapor depositing step proceeds in a continuous process.

18. Method according to claim 3, wherein said vapor depositing step proceeds in a batch process.

19. Method according to claim 3, wherein said vapor depositing step proceeds by a multi-evaporation process.

20. Method according to claim 3, wherein said vapor depositing step of said phosphor on a substrate proceeds by a method selected from the group consisting of a physical vapor depositing step, a chemical vapor depositing step or a vapor depositing step by an atomization technique.