General Electric Company

Ge Medical Systems Global Technology Company, LLC

Robert J Riedner

Charles D Greskovich

David Michael Hoffman

William Paul Minnear

Erdogan O Gurmen

Dominic A Cusano

Matthew R Schedler

Milivoj Konstantin Brun

Robert Joseph Lyons

August O Englert

Chester R O'Clair

Joseph P Chernoch

Eti Ganin

Richard J Ruzga

Timothy J Sporer

To provide simpler, more efficient methods for making scintillator arrays, one embodiment of the present invention is a method for making a scintillator array. The method includes extruding a mixture of a scintillator powder and a binder into rods; laminating the extruded rods with a sinterable reflector material; and sintering the laminated rods and reflector material into a scintillator block. Scintillator array embodiments of the present invention are useful in many types of pixelated radiation detectors, such as those used in computed tomography systems.

Scintillator arrays for radiation detectors and methods for making same

Apparatus and methods for fabricating scintillators for use in a CT systems are described. Adjacent scintillator elements are separated by gaps filled with a composition of white diffuse reflective material, a light absorber, and a castable polymer. The composition increases the strength of the signal to the photodiode by minimizing the amount of light that is lost by the scintillator elements. Additionally, the light absorber minimizes the amount of light transferred between adjacent scintillator elements to limit cross-talk. In addition, the outer edges of the scintillator may have a lower amount of light absorber to compensate for the light lost from the periphery.

Scintillator for a multi-slice computed tomograph system

A method of fabricating scintillators using a inside diameter saw is described. The inner diameter saw includes a blade having a diamond coated inner circumference cutting edge. In one embodiment, a plurality of scintillators are stacked and cut with the ID saw to form a plurality of first bars. The first bars are placed in a fixture creating a gap which is filled with a cast reflector material. The first bars are then cut with the ID saw at a 90 degree angle to the pieces creating second bars. The second bars are placed in a fixture and spaced to create second gaps similar to the first gaps. The second gaps are filled similar to the first gaps with a cast reflector material forming scintillator array. The described method minimizes the number of handling operations, therefore saving time.

Method of fabricating scintillators for computed tomograph system

A polycrystalline ceramic scintillator exhibiting reduced afterglow includes between about 5 and 50 mole percent Gd.sub.2 O.sub.3, between about 0.02 and 12 mole percent of either Eu.sub.2 O.sub.3 or Nd.sub.2 O.sub.3 as a rare earth activator oxide, and between about 0.003 and 0.5 mole percent of either Pr.sub.2 O.sub.3 and Tb.sub.2 O.sub.3 as an afterglow reducer. The remainder of the scintillator composition is Y.sub.2 O.sub.3. The resulting scintillator is especially useful for a radiation detector of the type having a plurality of radiation receiving channels. A scintillator body is disposed in each channel so that radiation being received therein is incident on the scintillator body and causes the body to convert the incident radiation to light energy of a predetermined wavelength. The radiation detector also includes means for converting the light energy from the scintillator into electrical signals which are proportional to the amount of radiation incident on the scintillator body. Methods for preparing the scintillator of the present invention include sintering, sintering combined with gas hot isostatic pressing, and vacuum hot pressing.

Radiation detector employing solid-state scintillator material and

Transparent, polycrystalline garnet bodies having desirable properties for use as laser material, luminescent x-ray scintillator materials and other uses are produced by mixing a chloride source solution of the desired cations with a basic ammonium solution to produce a precipitate having a substantially uniform composition which can be further processed to provide the desired transparent body. This precipitate is separated from the solution, dried, thermally decomposed at a temperature in the range from 700.degree. to 1,000.degree. C., pressed to form a compact, isostatically pressed at up to 60,000 psi to provide a green, unsintered compact having a density in the vicinity of 55% of theoretic density. That green compact is then sintered in oxygen at a temperature between 1,400.degree. and 1,700.degree. C. to produce the desired transparent body. Alternatively, the compact may be sintered in oxygen at temperatures in the range from about 1,400.degree. to about 1,600.degree. C. to a closed pore stage and then hot isostatically pressed at high pressure to provide the desired transparent body.

Transparent polycrystalline garnets

Selected scintillator materials provided in transparent block form for use in systems such as CT scanning systems employ a garnet host material for an activator ion which provides the desired luminescence. The garnet host material preferably includes gadolinium as one of its components in order to provide a transparent host material in bar form which has a high x-ray stopping power (where the radiation to be detected is x-ray radiation). Chromium, cerium and neodymium are preferred activator materials.

High speed, radiation tolerant, CT scintillator system employing garnet

Polycrystalline ceramic bodies having uniform transparent optical characteristics are produced by providing a green compact, presintering that compact at a temperature in the range from about 1,350.degree. C. to about 1,650.degree. C. until the closed porosity stage is reached, hot isostatic pressing the presintered compact to collapse substantially all pores disposed at grain boundaries and resintering the hot isostatically pressed compact at a temperature in the range from 1,700.degree. C.-1,950.degree. C. to cause grain growth under conditions in which pores, within those grains which are consumed by the growth of other grains, collapse as the grain boundary of the growing grain passes through the location of the pore in the smaller grain being consumed.

Preparation of high uniformity polycrystalline ceramics by presintering,

A polycrystalline ceramic scintillator is disclosed for radiographic applications which has received a controlled oxidation anneal to reduce radiation damage otherwise occuring when said scintillator is exposed to X radiation during conversion of said X radiation to the display image. The particular ceramic material treated in said manner comprises a densely sintered rare earth doped gadolinia containing metal oxide having a cubic crystal structure which has been annealed after sintering in a controlled oxygen containing atmosphere. A preferred ceramic composition comprises from about 5 mole percent up to about 50 mole percent Gd.sub.2 O.sub.3, between about 0.5 mole percent and 12 mole percent of a rare earth activator oxide selected from the group consisting of Eu.sub.2 O.sub.3 and Nd.sub.2 O.sub.3, and between about 0.0001 and 0.5 mole percent of at least one afterglow reducer selected from the group consisting of Pr.sub.2 O.sub.3 and Tb.sub.2 O.sub.3, and the remainder of said composition being Y.sub.2 O.sub.3. A treatment to produce said improved x-ray conversion medium is also disclosed along with radiographic imaging systems and methods employing said improved x-ray image conversion medium.

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Waukesha, WI, United States of America

Robert J Riedner