Calibration devices and methods of use thereof

• US 8,588,365 B2
• Filed: 08/15/2011
• Issued: 11/19/2013
• Est. Priority Date: 08/29/2000
• Status: Expired due to Term

• Current Assignee: Imatx, Inc. (Conformis Incorporated)
• Original Assignee: Imatx, Inc. (Conformis Incorporated)
• Inventors: Lang, Philipp, Liew, Siau-Way, Vargas-Voracek, Rene
• Primary Examiner(s): THOMAS, COURTNEY D
• Application Number:
  US13/209,966
• Publication Number:
  US 20120063568A1
• Time in Patent Office: 827 Days
• Field of Search: 378/18, 378/53, 378/54, 378/56, 378/62, 378/207, 250/252.1, 250/505.1
• US Class Current: 378/56
• CPC Class Codes: A61B 6/4423 related to hygiene or sterilisation
• CPC Class Codes: A61B 6/505 for diagnosis of bone
• CPC Class Codes: A61B 6/563 involving image data transmission via a network
• CPC Class Codes: A61B 6/583 using calibration phantoms
• CPC Class Codes: G06T 2207/10116 X-ray image
• CPC Class Codes: G06T 2207/30008 Bone
• CPC Class Codes: G06T 2207/30036 Dental; Teeth
• CPC Class Codes: G06T 7/80 Analysis of captured images to determine intrinsic or extrinsic camera parameters, i.e. camera calibration
• CPC Class Codes: G06V 40/155 use of biometric patterns for forensic purposes

Abstract

The present invention relates to calibration devices and to methods of using these devices.

Claims

1. A system for image analysis, the system comprising:

at least one calibration phantom including a first material and a second material, the first material having an x-ray attenuation coefficient that decreases more rapidly with higher x-ray energy than the second material;

means for analyzing a radiographic image comprising the at least one calibration phantom;

means for comparing the optical density of the first and second material in the image; and

means for estimating at least one image acquisition parameter based on the comparison.

2. The system of claim 1, wherein the radiographic image is generated remotely using a current of 150 mA, energy of 70 kV to 80 kV, an automatic exposure time, a 400 speed screen and a source height of approximately 40 inches (102 cm).

3. The system according to claim 1, wherein the at least one image acquisition parameter estimated is the x-ray energy used to capture the image.

4. The system according to 3, further comprising means for determining a calibration curve adjusted for the estimated x-ray energy.

5. The system according to claim 1, wherein the first material is copper and the second material is aluminum.

6. The system according to claim 1, wherein the at least one calibration phantom includes a radioopaque step-wedge and a radioopaque rod.

7. The system according to claim 6, wherein the step-wedge includes rectangular steps having a long axis, wherein the rod has a long axis, and wherein the long axis of the rod and the rectangular steps are parallel.

8. The system according to claim 1, wherein the image further includes image of bone, the system further comprising means for deriving information on density or structure of the bone from the image using the at least one calibration phantom.

9. A computer program product for use on a computer system for analyzing an image that includes at least one calibration phantom having a first material and a second material, the first material having an x-ray attenuation coefficient that decreases more rapidly with higher x-ray energy than the second material, the computer program product comprising a computer usable medium having computer readable program code thereon, the computer readable program code comprising:

program code for comparing the optical density of the first and second material in the image; and

program code for estimating at least one image acquisition parameter based on the comparison.

10. The computer program product according to claim 9, wherein the program code for estimating at least one image acquisition parameter includes program code for estimating x-ray energy used to capture the image.

11. The computer program product according to claim 10, further comprising program code for determining a calibration curve adjusted for the estimated x-ray energy.

12. The computer program product according to claim 9, wherein the program code for comparing the optical density of the first and second material includes program code for comparing the optical density of copper and aluminum.

13. The computer product according to claim 9, wherein the image further includes bone, the computer product further comprising program code for deriving information on density or structure of bone from the image using the at least one calibration phantom.

14. A method of analyzing an x-ray image, the method comprising the steps of:

obtaining a radiographic image comprising at least one calibration phantom, the at least one calibration phantom including a first material and a second material, the first material having an x-ray attenuation coefficient that decreases more rapidly with higher x-ray energy than the second material, wherein the radiographic image is generated remotely;

comparing the optical density of the first and second material in the image; and

estimating at least one image acquisition parameter based on the comparison.

15. The method according to claim 14, wherein the at least one image acquisition parameter estimated is the x-ray energy used to capture the image.

16. The method according to claim 15, further comprising determining a calibration curve adjusted for the estimated x-ray energy.

17. The method according to claim 14, wherein the first material is copper and the second material is aluminum.

18. The method according to claim 14, wherein the at least one calibration phantom includes a radioopaque step-wedge and a radioopaque rod.

19. The method according to claim 14, wherein the x-ray image includes image of bone of a subject.

20. The method according to claim 14, wherein the radiographic image is digitized and transmitted over a computer network.