# US 7,608,836 B2 · X-ray detector with CsI:T1 conversion layer

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 7,608,836 B2
- Document ID: US7608836B2
- Status: Granted
- Kind: B2
- Application number: 10/516,137
- Filed: 2003-05-16
- Published: 2005-09-15
- Granted: 2009-10-27
- Earliest claimed: 2002-05-29
- Assignees: Koninklijke Philips Electronics N.V.
- Inventors: Herfried Karl Wieczorek
- Web page: https://patentgrep.com/patent/US7608836B2

## CPC

- G01T 1/20: with scintillation detectors
- G01T 1/20183: {Arrangements for preventing or correcting crosstalk, e.g. optical or electrical arrangements for correcting crosstalk}
- G01T: MEASUREMENT OF NUCLEAR OR X-RADIATION (radiation analysis of materials, mass spectrometry G01N23/00; tubes for determining the presence, intensity, density or energy of radiation or particles H01J47/00)

## Abstract

An x-ray detector comprises a conversion layer for converting x-radiation into optical radiation. Photosensitive elements notably photodiodes to derive electronic signals from the optical radiation received by the photosensitive elements. The conversion layer contains Caesium-iodide doped with Thallium (CsI:Tl); the Caesium-iodide doped with Thallium is ultrapure and the Tl-doping level is in the range of 0.25-1.00 at %.

## Claims

### Claim 1

A method of forming an x-ray detector, the method comprising the steps of:
providing a plurality of photosensitive elements to generate electronic signals from optical radiation;
disposing alternate layers of CsI and TlI to form a conversion layer that is spatially homogeneous, the conversion layer being configured to convert x-rays into optical radiation in the range of about 400 to 700 nanometers, the conversion layer comprising cesium iodide doped with TlI, which includes from 0.25% to 1% of thallium and from one to 100 parts per million of indium; and
connecting the conversion layer to the plurality of photosensitive elements using an optical adhesive that is in contact with a surface of each of the conversion layer and the plurality of photosensitive elements.

### Claim 2 (depends on 1)

The method of claim 1, further comprising forming the conversion layer with a thickness less than about 500 μm.

### Claim 3 (depends on 2)

The method of claim 2, further comprising providing a diffusive reflector layer adjacent to the conversion layer on a side opposite to the optical adhesive.

### Claim 4 (depends on 3)

The method of claim 3, further comprising forming a scatter grid adjacent to the diffusive reflector layer on a side opposite to the conversion layer, wherein the scatter grid has alternating x-ray transparent and x-ray opaque channels.

### Claim 5 (depends on 1)

The method of claim 1, wherein the conversion layer of the x-ray detector has from one to ten parts per million of indium.

### Claim 6 (depends on 1)

The method of claim 1, wherein the conversion layer of the x-ray detector has from one to five parts per million of indium.

### Claim 7 (depends on 1)

The method of claim 1, wherein the conversion layer of the x-ray detector has from one to a few parts per million of indium.

### Claim 8 (depends on 1)

The method of claim 1, further comprising applying an annealing step to the conversion layer after disposing the alternate layers of CsI and TlI.

### Claim 9 (depends on 1)

The method of claim 1, further comprising forming the conversion layer as columnar crystals separated by cracks that are distributed at about 200 to 400 cracks per centimeter.

### Claim 10

An x-ray detector comprising:
a plurality of photosensitive elements to generate electronic signals from optical radiation; and
a conversion layer to convert x-rays into the optical radiation in the range of about 400 to 700 nanometers, the conversion layer comprising cesium iodide doped with TlI with from 0.25% to 1% of thallium and from one to 100 parts per million of indium, the conversion layer being connected to the plurality of photosensitive elements by an optical adhesive that is in contact with a surface of each of the conversion layer and the plurality of photosensitive elements.

### Claim 11 (depends on 10)

The x-ray detector of claim 10, further comprising a diffusive reflector layer adjacent to the conversion layer and on a side of the conversion layer opposite to the optical adhesive, wherein the conversion layer is less than 500 μm thick.

### Claim 12 (depends on 11)

The x-ray detector of claim 11, wherein the conversion layer is formed by columnar crystals separated by cracks that are distributed at about 200 to 400 cracks per centimeter.

### Claim 13 (depends on 12)

The x-ray detector of claim 12, wherein the reflector layer is titanium oxide.

### Claim 14 (depends on 11)

The x-ray detector of claim 11, further comprising a scatter grid comprising alternating x-ray transparent and x-ray opaque channels, wherein the scatter grid is adjacent to the diffusive reflector layer on a side opposite to the conversion layer.

### Claim 15 (depends on 10)

The x-ray detector of claim 10, wherein the conversion layer of the x-ray detector has from one to ten parts per million of indium.

### Claim 16 (depends on 10)

The x-ray detector of claim 10, wherein the conversion layer of the x-ray detector has from one to five per million of indium.

### Claim 17 (depends on 10)

The x-ray detector of claim 10, wherein the conversion layer of the x-ray detector has from one to a few parts per million of indium.

### Claim 18

A method for forming an x-ray detector, the method comprising the steps of:
forming a matrix of photosensitive elements to generate electronic signals from optical radiation;
forming a conversion layer by co-evaporating CsI and TlI, the conversion layer being spatially homogeneous and configured to convert x-rays into optical radiation in the range of about 400 to 700 nanometers, the conversion layer comprising cesium iodide doped with TlI with from 0.25% to 1% of thallium and from one to 100 parts per million of indium; and
connecting the conversion layer to the matrix of photosensitive elements.

### Claim 19 (depends on 18)

The method of claim 18, wherein the conversion layer is connected to the plurality of photosensitive elements using an optical adhesive that is in direct contact with the conversion layer and the matrix of photosensitive elements.

### Claim 20 (depends on 18)

The method of claim 18, further comprising providing a diffusive reflector layer adjacent to the conversion layer on a side opposite to the plurality of photosensitive elements.

### Claim 21 (depends on 20)

The method of claim 20, further comprising forming a scatter grid adjacent to the diffusive reflector layer on a side opposite to the conversion layer, wherein the scatter grid has alternating x-ray transparent and x-ray opaque channels.