X-ray detector and X-ray examination system utilizing fluorescent material

• US 5,302,817 A
• Filed: 06/19/1992
• Issued: 04/12/1994
• Est. Priority Date: 06/21/1991
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Saito, Akihisa, Yokota, Kazuto, Yagi, Noriaki
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): LE, QUE TAN
• Application Number:
  US07/901,476
• Time in Patent Office: 662 Days
• Field of Search: 250/483.1, 250/485.1, 250/486.1, 250/214 VT, 378/57, 378/185, 313/543, 313/532, 252/301.4
• US Class Current: 250/214.0VT
• CPC Class Codes: C09K 11/7733 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7771 Oxysulfides
• CPC Class Codes: C09K 11/7791 with alkali or alkaline earth metals
• CPC Class Codes: G01V 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays
• CPC Class Codes: G01V 5/222 measuring scattered radiation
• CPC Class Codes: G21K 2004/06 with a phosphor layer
• 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

An X-ray detector has a transmission type intensifying screen provided on the X-ray incident area of the detector body and a reflection type intensifying screen provided on the inner wall surface of the detector body except for the X-ray incident area. Visible rays from the transmission type intensifying screen and the reflection type intensifying screen are detected by a photomultiplier installed in the detector body. The transmission type intensifying screen and the reflection type intensifying screen use fluorescent materials such as Gd₂ O₂ S:Tb; Gd₂ O₂ S:Tb, Ce; GD₂ O₂ S:Tb, Yb; Gb₂ O₂ S:Pr; BaFCl:Eu; BaFBr:Eu; La₂ O₂ S:Tb; La₂ O₂ S:Tb, Ce; La₂ O₂ S:Tb, Yb; La₂ O₂ S:Pr; Y₂ O₂ S:Tb; Y₂ O₂ S:Tb, Ce; Y₂ O₂ S:Tb, Yb; and Y₂ O₂ S:Pr.

Claims

1. An X-ray detector comprising:

a housing;

a fluorescent generator, mounted in said housing, for generating a fluorescent output in response to X-rays impinged thereon, said fluorescent generator having a peak luminous wavelength;

a photomultiplier, mounted in said housing, for converting the output of the fluorescent generator to electrical image signals, said photomultiplier having a peak wavelength sensitivity independent of said peak luminous wavelength;

wherein said fluorescent generator includes at least one fluorescent material selected from the group consisting of;

space="preserve" listing-type="equation">A.sub.2 O.sub.2 S;

D and BaFX;

E

wherein

A is at least one element selected from Gd, La and Y,

D is at least one element selected from Tb and Pr, or,

D is at least one element selected from Tb and Pr, and at least one element selected from Ce and Yb,

X is at least one element selected from Cl and Br,

E is Eu or a mixture of Eu and at least one element selected from the group consisting of Ce and Yb.

2. The X-ray detector of claim 1, wherein said fluorescent material comprises a material selected from the group consisting of:

Gd₂ O₂ S;

Tb;

Gd₂ O₂ S;

Tb, Cl;

Gd₂ O₂ S;

Pr_r ;

BaFCl;

Eu;

BaFBr;

Eu;

La₂ O₂ S;

Tb;

La₂ O₂ S;

Tb, Ce;

La₂ O₂ S;

Pr;

Y₂ O₂ S;

Tb;

Y₂ O₂ S;

Tb, Yb;

Y₂ O₂ S;

Tb, Ce; and

Y₂ O₂ S;

Pr.

3. The X-ray detector of claim 1, wherein the fluorescent generator comprises a transmission type fluorescent generator.

4. The X-ray of detector of claim 1, wherein the fluorescent generator comprises a reflection type fluorescent generator.

5. The X-ray detector of claim 1, wherein the fluorescent generator includes an intensifying screen comprised of said fluorescent material.

6. The X-ray detector of claim 5, wherein the amount of said fluorescent material is in the range of 80 mg/cm² to 300 mg/cm².

7. The X-ray detector of claim 1, wherein said fluorescent material has an afterglow time of 1.0 msec. or less.

8. The X-ray detector of claim 1, wherein the detector detects Compton scattering X-rays.

9. A system for examining an object with X-rays, said system comprising:

an X-ray source for irradiating the object to be examined with X-rays;

an X-ray detector for detecting Compton scattering X-rays from the object and for generating image signals based on the detected Compton scattering X-rays;

a display for displaying an image of the interior of the object in accordance with said image signals generated by the X-ray detector,

wherein the X-ray detector includes

a housing,

a fluorescent generator, mounted in said housing, for generating a fluorescent output in response to X-rays impinged thereon, said fluorescent generator having a peak luminous wavelength,

a photomultiplier, mounted in said housing, for converting the output of the fluorescent generator to electrical image signals, and for providing said image based on the electric signals, said photomultiplier having a peak wavelength sensitivity independent of said peak luminous wavelength,

wherein said fluorescent generator includes at least one fluorescent material selected from the group consisting of;

space="preserve" listing-type="equation">A.sub.2 O.sub.2 S;

D and BaFX;

E

wherein

A is at least one element selected from Gd, La and Y,

D is at least one element selected from Tb and Pr, or,

D is at least one element selected from Tb and Pr, and at least one element selected from Ce and Yb,

X is at least one element selected from Cl and Br,

E is Eu or a mixture of Eu and at least one element selected from the group consisting of Ce and Yb.