Combination of contrast medium and mammography CT system with a prespecified energy range and method for generating tomographic mammography CT images by this combination

Patent metadata

Field	Value
Publication number	US-9414797-B2
Application number	US-201314028815-A
Country	US
Kind code	B2
Filing date	Sep 17, 2013
Priority date	Sep 25, 2012
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A mammography CT system is disclosed which includes an X-ray generator; and a first radiator-detector system. A contrast medium, including an opacifying element including an absorption peak in a first energy range, is useable for tomographic imaging of a female breast of a patient. After filtering, the X-rays with a prespecified tube voltage that form at an anode, are configured to emit an X-ray spectrum having a second energy range, wherein the radiator-detector system is configured to acquire a plurality of circumferential projections around the breast. The first energy range is a part of the second energy range and the second energy range includes an upper limit of less than 70 keV and a lower limit of greater than 20 keV. A corresponding method for generating tomographic mammography CT images is also disclosed.

First claim

What is claimed is:

1. A mammography CT system configured to perform a CT scan, comprising:
a contrast medium application apparatus configured to supply a contrast medium to a patient, the contrast medium including an opacifying element having an absorption peak in a first energy range, the first energy range falling within a second energy range and the absorption peak being a K-edge of the opacifying element;
an x-ray generator including a cathode and an anode, the x-ray generator configured to emit x-rays towards a breast of the patient lying in a prone position, the anode having an acceleration voltage applied thereto;
a prefilter configured to prefilter the x-rays before the x-rays reach the breast; and
a computer configured to,
determine a lower limit of the second energy range such that the lower limit is set based on a minimum energy absorbable by the breast and is greater than or equal to 20 keV,
determine an upper limit of the second energy range for the CT scan of the breast such that the upper limit is above the k-edge of the opacifying element, below a subsequent maximum dose enhancement ratio (DER) of the contrast medium and less than or equal to 70 keV,
set the accelerating voltage of the x-ray generator such that a maximum energy of the x-rays that are emitted is the upper limit of the second energy range, the absorption peak of the opacifying element being below the upper limit of the second energy range, and
configure the pre-filter such that the pre-filter filters the x-rays to have a minimum energy equal to the lower limit of the second energy range, the absorption peak of the opacifying element being above the lower limit of the second energy range.

2. The mammography CT system of claim 1 , wherein the first energy range begins with the increase in the absorption peak and extends until a drop in the absorption to not more than 60% of the maximum absorption value of the mass energy absorption coefficient in the absorption peak.

3. The mammography CT system of claim 2 , wherein the first energy range is arranged in the upper third of the second energy range.

4. The mammography CT system of claim 2 , wherein the first energy range is arranged in the upper quarter of the second energy range.

5. The mammography CT system of claim 1 , wherein the first energy range is arranged in the upper third of the second energy range.

6. The mammography CT system of claim 5 , wherein the first energy range is arranged in the upper quarter of the second energy range.

7. The mammography CT system of claim 1 , wherein the first energy range is arranged in the upper quarter of the second energy range.

8. The mammography CT system of claim 1 , wherein the second energy range has an upper limit of between 40 keV and 45 keV.

9. The mammography CT system of claim 1 , wherein the second energy range has a lower limit of between 30 keV and 33 keV.

10. The mammography CT system of claim 1 , wherein the opacifying element is iodine.

11. The mammography CT system of claim 1 , wherein the second energy range has an upper limit of between 50 keV and 60 keV.

12. The mammography CT system of claim 1 , wherein the second energy range has a lower limit of between 40 keV and 50 keV.

13. The mammography CT system of claim 1 , wherein the opacifying element is gadolinium.

14. The mammography CT system of claim 1 , wherein the prefilter includes copper or tin, and the prefilter is arranged in beam path of the x-rays.

15. The mammography CT system of claim 1 , wherein the second energy range has an upper limit which is selected such that, after the thickest tissue layer to be penetrated by x-rays, taking into account the prefilter, between 60% to 90% of the photon flux is absorbed at the maximum X-ray energy.

16. The mammography CT system of claim 15 , wherein the second energy range has a lower limit which is selected such that, after the thickest tissue layer to be penetrated, 90% to 60% of the photon flux is absorbed at the minimum X-ray energy.

17. The mammography CT system of claim 1 , wherein the second energy range has a lower limit which is selected such that, after the thickest tissue layer to be penetrated by x-rays, 90% to 60% of the photon flux is absorbed at the minimum X-ray energy.

18. The mammography CT system of claim 1 , wherein the second energy range is selected such that, after the thickest tissue layer to be penetrated by x-rays, the photon flux arriving at a detector is reduced to not less than 10 6 photons/(s*/mm 2 ).

19. The mammography CT system of claim 1 , wherein the second energy range has an upper limit which is selected such that it is arranged between the peak of the energy-specific absorption coefficient at the K-edge of the opacifying element and the next higher in terms of energy maximum of the DER between tissue and contrast-medium enhanced tissue.

20. The mammography CT system of claim 1 , further comprising:
an apparatus for optically scanning a contour of the breast.

21. The mammography CT system of claim 20 , wherein the apparatus is a LASER scanner.

22. The mammography CT system of claim 21 , wherein the computer is configured to automatically determine the thickest tissue layer to be penetrated by the X-rays based on data from the LASER scanner.

23. The mammography CT system of claim 1 , further comprising:
a detector configured as a direct-converting energy-resolving detector.

24. The mammography CT system of claim 1 ,
wherein the x-ray generator forms a first radiator-detector system, and the system further comprises:
a second radiator-detector system, arranged with an angular offset to the first radiator-detector system.

25. The mammography CT system of claim 24 , wherein the second radiator-detector system has a first energy range that begins with the increase in the absorption peak and extends until a drop in the absorption to not more than 60% of the maximum absorption value of the mass energy absorption coefficient in the absorption peak.

26. The mammography CT system of claim 24 , wherein the prefilter includes the opacifying element of the contrast medium, arranged in the beam path of the first radiator-detector system.

27. The mammography CT system of claim 24 , wherein the prefilter includes the opacifying element of the contrast medium, and the prefilter is arranged in a beam path of at least the first radiator-detector system.

28. The mammography CT system of claim 1 , further comprising:
an apparatus configured to position the patient, which permits uncompressed positioning of the breast during the CT scan.

29. The mammography CT system of claim 1 , wherein the computer includes a memory storing program code and program code segments therein which, during operation, executes:
determining the first energy range, wherein the contrast medium primarily absorbs X-rays in the first energy range, the first energy range including an absorption peak of the opacifying element such that the at least one first energy range lies within the at least one second energy range.

30. The mammography CT system of claim 1 , further comprising:
switches, potentiometers or menu points in a parameterization menu, for adjusting the second energy range.

31. A method for determining X-ray energy ranges, the method comprising:
supplying a contrast medium to a patient, the

Assignees

• Siemens Ag
• Bayer Pharma AG

Inventors

• Flohr Thomas
• Jost Gregor
• Lawaczeck Rüdiger
• Pietsch Hubertus
• Schmidt Bernhard

Classifications

• A61B6/4007

  characterised by using a plurality of source units · CPC title

• A61B6/4035

  the source being combined with a filter or grating · CPC title

• A61B6/482

  involving multiple energy imaging · CPC title

• A61B6/481

  involving the use of contrast agents · CPC title

• A61B6/502 Primary

  for diagnosis of breast, i.e. mammography · CPC title