Multi-layer detector and method for imaging

• US 20060151708A1
• Filed: 01/11/2005
• Published: 07/13/2006
• Est. Priority Date: 01/11/2005
• Status: Active Grant

• Current Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Original Assignee: Siemens Medical Solutions USA Incorporated (Siemens AG)
• Inventors: Bani-Hashemi, Ali, Ghelmansarai, Farhad A.
• Granted Patent: US 7,671,342 B2
• Time in Patent Office: Days
• US Class Current: 250/370.110
• CPC Class Codes: G01T 1/2008 using a combination of different types of scintillation detectors, e.g. phoswich
• CPC Class Codes: G01T 1/2018 Scintillation-photodiode combinations

Abstract

X-ray portal imaging detectors have multiple layers, such as multiple layers of phosphor screens and/or detectors. Some x-rays that pass through one layer are detected or converted into light energies in a different layer. For example, one phosphor screen is provided in front and another behind that panel detector circuitry. Light generated in each of the phosphor screens is detected by the same detector circuitry. As another example, multiple layers of phosphor screens and associated detector circuits are provided. Some x-rays passing through one layer may be detected in a different layer. High energy x-rays associated with Megavoltage sources as well as lower or higher energy x-rays may be detected.

Claims

1. A detector for imaging as a function of x-rays, the detector comprising:

a first phosphor screen;

a second phosphor screen; and

a first layer of photosensitive elements between the first and second phosphor screens.

2. The detector of claim 1 wherein the photosensitive elements comprise amorphous silicon photo diode detectors.

3. The detector of claim 1 wherein the photosensitive elements comprise direct photo diode detectors.

4. The detector of claim 1 wherein the first layer comprises a glass substrate with the photosensitive elements on a first surface of the glass substrate, the first phosphor screen adjacent the first surface and the second phosphor screen adjacent an opposite surface of the glass substrate than the first surface.

5. The detector of claim 1 further comprising a buildup plate adjacent the first phosphor screen.

6. The detector of claim 1 wherein the first phosphor screen has a first thickness and the second phosphor screen has a second thickness different than the first thickness.

7. The detector of claim 1 further comprising:

at least a second layer of photosensitive elements adjacent the second phosphor screen and spaced away from the first layer.

8. The detector of claim 1 wherein the first phosphor screen, the first layer and the second phosphor screen are positioned in parallel at different distances away from a surface for receiving the x-ray radiation.

9. The detector of claim 1 in a mega voltage radiation therapy system.

10. A detector for imaging as a function of x-rays, the detector comprising:

a first layer of semiconductor sensing devices; and

a second layer of semiconductor sensing devices, the first and second layers positioned at different distances away from a surface for receiving the x-ray radiation.

11. The detector of claim 10 wherein the first and second layers comprise charge coupled devices.

12. The detector of claim 10 wherein the semiconductor sensing devices comprise photosensitive elements.

13. The detector of claim 10 wherein the first and second layers each comprise a glass substrate with the semiconductor sensing devices on a first surface of the glass substrate and a phosphor screen adjacent the first surface.

14. The detector of claim 13 wherein each of the first and second layers further comprises a buildup plate adjacent the phosphor screen.

15. The detector of claim 13 wherein the phosphor screen of the first layer has a different thickness than the phosphor screen of the second layer.

16. The detector of claim 10 in a mega voltage radiation therapy system.

17. A method for portal imaging as a function of x-rays for therapy, the method comprising:

(a) generating the x-rays with megavoltage energy;

(b) converting the x-rays with a first layer;

(c) converting the x-rays with a second layer spaced from the first layer; and

(d) generating an image as a function of the conversions of the first and second layers.

18. The method of claim 17 wherein the first and second layers comprise phosphor screens separated by a detector layer, wherein (d) comprises generating data with the detector layer in response to light from both the first and second layers.

19. The method of claim 17 wherein the first layer comprises a first phosphor screen and a first detector layer, wherein the second layer comprises a second phosphor screen and a second detector layer, and wherein (d) comprises generating the image as a function of first data from the first detector layer and second data from the second detector layer.

20. The method of claim 19 further comprising:

(e) transforming the first and second data to a common geometric scale as a function of the first and second layers position relative to a source of the x-rays.

21. The method of claim 19 wherein the first and second data comprise intensities;

and further comprising;

(e) correcting the intensities of the first data relative to the second data as a function of a distance of the first and second layers from a source of the x-rays.

22. The method of claim 19 wherein (d) comprises subtracting a blank image from the second data, the blank image corresponding to data detected with the second detector layer without an object between a source of the x-rays and the first detector layer.

23. The method of claim 19 wherein (a) comprises generating a cone-beam, and wherein (d) comprises combining the first data representing a volume with the second data representing the volume, the combination being weighted as a function of a gradient of the first data.

24. The method of claim 17 wherein (a) and (d) comprise image guided radiation therapy.