Doped cadmium tungstate scintillator with improved radiation hardness
View Patent ↗This invention provides novel cadmium tungstate scintillator materials that show improved radiation hardness. In particular, it was discovered that doping of cadmium tungstate (CdWO 4 ) with trivalent metal ions or monovalent metal ions is particularly effective in improving radiation hardness of the scintillator material.
1. A sintered body comprising a scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, the scintillator composition being a component of the sintered body, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 .
2. The sintered body of claim 1 , wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof;
B is a trivalent metal ion selected from the group consisting of Bi, Y, La, Ce, Pr, Nd, Gd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof;
X ranges from 0 to about 0.01;
Y ranges from 0 to about 0.01; and
at least one of X or Y is non-zero.
3. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof;
B is a trivalent metal ion selected from the group consisting of: Bi, Y, La, Ce, Pr, Nd, Gd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof;
wherein X is about 0.005; and,
Y ranges from 0 to about 0.01.
4. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof:
B is a trivalent metal ion selected from the group consisting of: Bi, Y, La, Ce, Pr, Nd, Gd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof;
wherein X is about 0.001; and
Y ranges from 0 to about 0.01.
5. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof;
B is a trivalent metal ion selected from the group consisting of: Bi, Y, La, Ce, Pr, Nd, Gd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof;
wherein X is about 0.001 or about 0.005; and,
wherein Y is 0.
6. The sintered body of claim 2 , wherein Y is about 0.005.
7. The sintered body of claim 2 , wherein Y is about 0.001.
8. The sintered body of claim 6 , wherein X is 0.
9. The sintered body of claim 7 , wherein X is 0.
10. The sintered body of claim 2 , wherein X is zero, and Y is greater than zero.
11. The sintered body of claim 10 , wherein B is Gd 3+ .
12. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof;
wherein X ranges from 0 to about 0.01; and,
B is Gd 3+ and Y ranges from about 0.0002 to about 0.001.
13. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof;
B is a trivalent metal ion selected from the group consisting of: Bi, Y, La, Ce, Pr, Nd, Gd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof;
wherein X and Y are both 0.01 or less; and,
wherein X and Y are both greater than zero.
14. The scintillator composition of claim 13 , wherein A is K 1+ or Rb 1+ and B is Bi 3+ .
15. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Li, Na, K, Rb, Cs, Ag, Tl, and combinations thereof;
B is a trivalent metal ion selected from the group consisting of: Bi, Y, La, Ce, Pr, Nd, Gd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, Lu, and combinations thereof;
wherein X ranges from greater than zero to about 0.01, and Y is zero.
16. A scintillator composition comprising a cadmium tungstate doped with a monovalent metal ion and/or a trivalent metal ion, wherein said scintillator composition shows higher radiation tolerance than undoped CdWO 4 ; and,
wherein the doped cadmium tungstate is represented by the formula:
Cd (1−(x+y)) A x B y WO 4
where:
A is a monovalent metal ion selected from the group consisting of: Na, K and combinations thereof;
B is a trivalent metal ion selected from the group consisting of: Bi, Gd, and combinations thereof;
wherein said doped cadmium tungstate is selected from the group consisting of Cd 0.9995 Na 0.0005 WO 4 , Cd 0.9995 Gd 0.0005 WO 4 , and Cd 0.999 (KBi) 0.001 WO 4 .
17. A detector element of an X-ray CT scanner comprising a scintillator composition of any one of claims 1 through 16 .
18. An x-ray detector comprising:
a scintillator composition of any one of claims 1 through 16 ; and
a photodetector disposed to detect light emitted by said scintillator composition.
19. The detector of claim 18 , wherein said photodetector is selected from the group consisting of a photomultiplier, a photodiode, and photographic-film.
20. A method of producing an X-ray image, said method comprising:
providing an x-ray detector comprising a scintillator composition of any one of claims 1 through 16 ;
subjecting said scintillator composition to X-ray radiation; and detecting light emission from said scintillator composition.