REAL-TIME FEEDBACK FOR PREVENTING HIGH DOSE C-ARCH GEOMETRY POSITIONS

• US 20140307855A1
• Filed: 12/05/2012
• Published: 10/16/2014
• Est. Priority Date: 12/14/2011
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Den Hartog, Markus Johannes Harmen, Hoornaert, Bart Pierre Antoine Jozef, Withagen, Petrus Johannes
• Granted Patent: US 9,445,771 B2
• Time in Patent Office: Days
• US Class Current: 378/98
• CPC Class Codes: A61B 6/10 Safety means specially adapted therefor
• CPC Class Codes: A61B 6/4441 the rigid structure being a C-arm or U-arm
• CPC Class Codes: A61B 6/461 Displaying means of special interest
• CPC Class Codes: A61B 6/467 characterised by special input means
• CPC Class Codes: A61B 6/503 for diagnosis of the heart
• CPC Class Codes: A61B 6/5294 involving using additional data, e.g. patient information, image labeling, acquisition parameters
• CPC Class Codes: A61B 6/542 involving control of exposure
• CPC Class Codes: G16H 40/63 for local operation

Abstract

The present invention relates to an apparatus for aiding operation of an interventional x-ray imager during image acquisition, to a method of aiding operation of an x-ray imager, to an interventional x-ray imager, to a computer program element and to a computer readable medium. The X-ray imager is capable of varying X-ray dosages depending on differences in X-ray attenuation levels across an object of interest to be imaged and is capable of assuming any one of a plurality of imaging geometry positions when acquiring an image. An indication, visual, acoustic or haptic, to the operator of an X-ray imager is provided on the incurred change in X-ray dosage when changing from a current projection view to an updated projection view, provided that a given constant image quality is to be maintained throughout the different views.

Claims

1. An apparatus for aiding operation of an X-ray imager during an image acquisition procedure, the imager capable of varying X-ray dosages depending on differences in X-ray attenuation levels across an object of interest to be imaged, the imager further capable of assuming any one of a plurality of imaging geometry positions when acquiring an image, the apparatus comprising:

an input unit (201) configured to receive a request to change a current imaging geometry position for an updated imaging geometry position for use in an image acquisition;

a memory unit (205) configured to store a functional relationship between the imaging geometry positions and the X-ray dosages, the functional relationship based on expected X-ray attenuation levels in the object of interest;

an output unit (210) configured to use the stored functional relationship to provide to a human operator of the interventional X-ray imager an indication of the change in X-ray dosage required at the updated imaging geometry position relative to the X-ray dosage required at a reference position.

2. The apparatus of claim 1, wherein the indication is visual and displayable on a screen as a graphics display, the graphics display when so displayed including a plurality of geometry position versus X-ray dosage indicator elements (305a-c), each indicator element representing one of the geometry positions and the relative change of X-ray dosage required at that imaging geometry position.

3. The apparatus of claim 1, wherein the change in X-ray dosage is visually-coded by the indicator elements, the visual-coding directly varying with the relative changes in X-ray dosage requirements across the indicator elements (305a-c).

4. The apparatus of claim 2, wherein the graphics display further includes at least one dosage usage indicator having a size and positioned at any one of the indictor elements (305a-c), the size changing with the X-ray dosage used in a current imaging procedure or the size representing the dosage used at the respective imaging geometry position in a previous imaging procedure or in a series of previous imaging procedures.

5. The apparatus of claim 1, wherein the indicator elements form points of one of a plurality of contour lines of the stored functional relationship between imaging geometry positions and X-ray dosages.

6. The apparatus of claim 2, wherein the graphics display is a graphical user interface including a cursor, the position of the cursor in the graphics display representative of the current imaging geometry position, the cursor position varying as the X-ray imager changes from the current position to the updated imaging geometry position.

7. The apparatus of claim 1, the indication provided by an acoustical signal having a pitch in direct variance with the relative change in X-ray dosage requirements across the plurality of imaging geometry positions, the pitch so varying as the imaging geometry position changes from the current imaging geometry position to the updated imaging geometry position.

8. The apparatus of claim 1, the indication mechanical in the form of a negative feedback signal acting on a mechanical control device used by the operator to request the change in imaging geometry position such as vibrations imparted on the mechanical control device, a strength of the negative feedback or the frequency of the vibrations in direct variance with the relative change in X-ray dosage requirements at and across the plurality of imaging geometry positions, the feedback strength or the frequency so varying as the imaging geometry position changes from the current position to the updated imaging geometry position.

9. The apparatus of claim 1, wherein the indication is visual and displayable on a screen as a graphics display, the graphics display when so displayed including a grid structure with different grid position indicators (605) representative of different imaging geometry positions, the grid position indicators (605) visually coded, said coding varying across the grid position indicators (605) with the change in required X-ray dosage, said change expressed in terms of the level of X-ray attenuation to be expected when the respective imaging geometry is used for an image acquisition of the object, the graphics display further including at least one dosage usage indicator (610a-c) having a size and positioned at any one of the grid position indicators (605), the size changing with the X-ray dosage used in a current imaging procedure or the size representing the X-ray dosage used at the respective imaging geometry position in a previous image acquisition procedure or in a series of previous imaging acquisition procedures.

10. The apparatus of claim 9, wherein the graphics display includes a further dosage usage indicator having a size, the output unit (210) operative to scale the two sizes relative to one another so that the larger one of the two sizes is not to exceed a predefined maximum size, the maximum size preset in relation to a size of the displayed grid structure.

11. The apparatus of claim 9, wherein the visual-encoding of the level of attenuation is by mapping into any one of i) average water equivalent patient thickness, ii) average or peak air Kerma rate, or iii) effective dosage for the object.

12. The apparatus of claim 1, wherein the indication is visual and displayable on a screen as a graphics display, the object disposed on a table during the image acquisition, the graphics display when so displayed including a visually-coded Source-Image-Distance indicator (708) or table height indicator (706), the visual coding indicating the relative change in X-ray dosage required or used for the respective Source-Image-Distance or table height.

13. The apparatus of claim 1, wherein the indication is visual and displayable on a screen as a graphics display, the graphics display when so displayed including a visually-coded indicator (708) for the x-ray dosage used for a user-selectable detector size in the imaging procedure and a collimation usage indicator (708a,b) indicating collimator usage for said selected detector surface size.

14. The apparatus of claim 3, wherein the visual coding includes any one of i) color coding, ii) gray-value coding or ii) coding by using different line types for lines used in defining the grid structure.

15. The apparatus of claim 1, wherein the X-ray imager is of the interventional C-arm type.

16. The apparatus of claim 1, wherein the imaging geometry position is given by a parameter comprising any one or more of a rotation angle and an angulation angle and X-ray source-to-image distance.

21. An interventional X-ray imager including an apparatus of claim 1.

22. A computer program element for controlling an apparatus according to claim 1.

23. A computer readable medium having stored thereon the program element of claim 22.

17. A method of aiding operation of an X-ray imager during an image acquisition procedure, the imager capable of varying X-ray dosages depending on differences in X-ray attenuation levels across an object of interest to be imaged, the imager further capable of assuming any one of a plurality of imaging geometry positions when acquiring an image, the method comprising:

receiving (S501) a request to change a current imaging geometry position for an updated imaging geometry position for use in image acquisition;

accessing (S510) a memory unit (205) having stored thereon a functional relationship between the imaging geometry positions and the X-ray dosages, the functional relationship based on expected X-ray attenuation levels in the object of interest;

using the stored functional relationship for providing (S520) to a human operator of the interventional X-ray imager an indication of the change in X-ray dosage required at the updated imaging geometry position relative to the X-ray dosage required at a reference position.

18. The method of claim 17, wherein the providing of the indication includes generating for display on a screen a graphics display, the graphics display when so displayed including a plurality of geometry position versus X-ray dosage indicator elements (305a-c), each indicator element representing one of the geometry positions and the relative change of X-ray dosage required at that imaging geometry position.

19. The method of claim 17, wherein the providing of the indication includes delivering a negative feedback signal, the signal acting on a mechanical control device used by the operator to request the change in imaging geometry position such as vibrations imparted on the mechanical control device, a strength of the negative feedback or the frequency of the vibrations in direct variance with the relative change in X-ray dosage requirements at and across the plurality of imaging geometry positions, the feedback strength or the frequency so varying as the imaging geometry position changes from the current position to the updated imaging geometry position.

20. The method of claim 17, wherein the providing of the indication includes generating for display on a screen a graphics display, the graphics display when so displayed including a grid structure with different grid position indicators representative of different imaging geometry positions, the grid position indicators are visually coded with the coding varying across the grid position indicators with the change in required X-ray dosage, said change expressed in terms of the level of X-ray attenuation to be expected when the respective imaging geometry is used for the image acquisition of the object, the graphics display further including at least one dosage usage indicator having a size and positioned at any one of the grid points, the size changing with the X-ray dosage used in a current imaging procedure or in a series of previous imaging procedures at the respective imaging geometry position.