X-ray diagnostic apparatus and method for operating an x-ray diagnostic apparatus for determining quality values

• US 7,539,336 B2
• Filed: 12/02/2005
• Issued: 05/26/2009
• Est. Priority Date: 12/13/2004
• Status: Active Grant

• Current Assignee: Siemens Healthcare GMBH (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Kolarjk, Martin, Heer, Volker, Durlak, Peter, Böhm, Stefan
• Primary Examiner(s): BHATNAGAR, ANAND P
• Application Number:
  US11/293,444
• Publication Number:
  US 20060126911A1
• Time in Patent Office: 1,271 Days
• Field of Search: 382/100, 382/128, 382/130, 382/131, 382/132, 378 4- 27, 378/37, 378/38, 378/46, 378/63, 378/90, 378/92, 378/98.4, 378/98.6, 378/98.9, 128/922
• US Class Current: 382/130
• CPC Class Codes: A61B 6/504 for diagnosis of blood vessels, e.g. by angiography
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection
• CPC Class Codes: H04N 5/325 Image enhancement, e.g. by subtraction techniques using polyenergetic X-rays
• CPC Class Codes: Y10S 128/922 including image analysis

Abstract

The invention relates to an angiographic x-ray diagnostic apparatus with an x-ray radiator having an x-ray tube, with a patient positioning table having a radiation-transparent positioning plate and mattress, with an x-ray detector, with an imaging system, an image processing unit and a measuring device to which the output signals of the x-ray detector are fed and which has a first device for determining a value determining the reproduction quality of clinically relevant objects, a second device for determining local variances of the noise in a homogenous image region of different x-ray images and a device for taking the ratio of the output values of the two devices.

Claims

1. Angiographic x-ray diagnostic apparatus, comprising:

an x-ray radiator including an x-ray tube;

a patient positioning table including a radiation-transparent positioning plate and mattress;

an x-ray detector;

an imaging system;

an image processing unit; and

a measuring device connected to the x-ray detector for acquiring output signals of the x-ray detector, the measuring device comprising;

a first device for determining a quality value related to a reproduction quality of a clinically relevant object;

a second device configured to calculate a local variance of a noise present in a homogenous image region of different x-ray images; and

a calculation device for calculating a ratio of the quality value and the local variance of noise.

2. The x-ray diagnostic apparatus as claimed in claim 1, wherein the first device further includes a prediction stage for predicting a position of the clinically relevant object.

3. The x-ray diagnostic apparatus as claimed in claim 2, wherein the quality value is calculated based on an output signal of the prediction stage.

4. The x-ray diagnostic apparatus as claimed in claim 2, wherein the first device comprises a Hough transformation device connected to the prediction stage.

5. The x-ray diagnostic apparatus as claimed in claim 2, wherein the local variance is calculated based on an output signal of the prediction stage.

6. The x-ray diagnostic apparatus as claimed in claim 1, wherein the first device further includes a lookup table containing a-priori knowledge related to the shape of the clinically relevant object.

7. The x-ray diagnostic apparatus as claimed in claim 6, wherein the quality value is calculated based on an output signal of the lookup table.

8. The x-ray diagnostic apparatus as claimed in claim 6, wherein the first device comprises a Hough transformation device connected to the lookup table.

9. The x-ray diagnostic apparatus as claimed in claim 6, wherein the local variance is calculated based on an output signal of the lookup table.

10. The x-ray diagnostic apparatus as claimed in claim 1, wherein the first device further includes a subtraction stage for calculating a difference between a current image extracted from a series of continuous images and a background image.

11. The x-ray diagnostic apparatus as claimed in claim 10, wherein the quality value is calculated based on an output signal of the subtraction stage.

12. The x-ray diagnostic apparatus as claimed in claim 10, wherein the first device comprises a Hough transformation device connected to the subtraction stage.

13. The x-ray diagnostic apparatus as claimed in claim 10, wherein the local variance is calculated based on an output signal of the subtraction stage.

14. The x-ray diagnostic apparatus as claimed in claim 1, wherein the local variance of the noise is calculated using a background image.

15. The x-ray diagnostic apparatus as claimed in claim 1, wherein the local variance of the noise is calculated using a current image of continuous current images.

16. The x-ray diagnostic apparatus as claimed in claim 1, further comprising an adding unit for determining a sum of first and second local variances of noise, the first variance calculated using a background image, and the second local variance calculated using a current image of continuous current images.

17. The x-ray diagnostic apparatus as claimed in claim 1, wherein the x-ray radiator comprises a multi-leaf diaphragm having a collimator unit or a pre-filtering unit.

18. The x-ray diagnostic apparatus as claimed in claim 1, further comprising an anti-scatter grid assigned to the x-ray detector.

19. The x-ray diagnostic apparatus as claimed in claim 1, wherein the clinically relevant object is a guide wire, a catheter or a stent.