Method for recording a complete projection data set in the central layer for CT reconstruction using a C-arm X-ray apparatus with a limited rotation range
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Publication Number
US-10130314-B2
Publication Date
2018-11-20
Expiration Date
Abstract
A method for recording a scan from a series of 2D X-ray projections using a C-arm X-ray apparatus to reconstruct a region of interest. The method includes positioning the C-arm X-ray apparatus in an initial configuration and, while recording a series of X-ray projection views: translating the C-arm along a first path within a C-arm plane parallel to the periphery of the C-arm until the central ray vector extends through the virtual scan center and the region of interest is disposed within the fan beam, moving the C-arm peripherally along the orbital movement axis by at least 180° minus the fan angle, and translating the C-arm along a second path within the C-arm plane until the second limiting vector of the fan beam is tangential to the region of interest.
Core Innovation
The invention relates to a method for recording a scan of a region of interest (ROI) using a C-arm X-ray apparatus with a virtual scan center located in the center of the ROI. The ROI is handled as a tangential fan-beam region bounded by a first limiting vector and a second limiting vector at a fan angle relative to the first limiting vector. This configuration is used to keep the ROI disposed within the fan beam during recording of a series of X-ray projection views.
During recording, the C-arm is positioned and then moved while the C-arm plane is kept fixed in space. The method includes translating the C-arm along a first path within the C-arm plane until the central ray vector extends through the virtual scan center and the ROI is disposed within the fan beam. The C-arm is then moved peripherally along an orbital movement axis from an initial angular position to a second angular position, with the angular displacement constrained to be at least 180° minus the fan angle and not more than 180°. The ROI remains disposed within the fan beam while the C-arm is moved peripherally.
After the peripheral motion, the C-arm is translated along a second path within the C-arm plane until the second limiting vector of the fan beam is tangential to the ROI. The invention addresses non-isocentric C-arm geometry by synchronously tracking holder motion, and it defines limiting conditions tangential to the ROI by using the virtual scan center at the ROI center. A primary radiation diaphragm is used to remove fan-beam portions outside the ROI, and the focus and detector trajectory design is discussed to avoid abrupt direction changes, high accelerations, oscillations, and to limit detector acceleration for smoother motion.
Claims Coverage
The independent claim defines a C-arm ROI scan recording method centered on a virtual scan center at the ROI center and constrains both the C-arm translation paths and a limited peripheral orbital rotation. The inventive features are concentrated in three features: virtual-scan-center-based fan-beam tangency, bounded angular displacement that keeps the ROI within the fan beam throughout the peripheral motion, and end alignment ensuring tangency at the second limiting vector.
Virtual scan center located at ROI center for fan-beam tangency
A virtual scan center located in the center of the ROI, with the ROI tangential to a first limiting vector of a fan beam generated by an X-ray source and bounded by the first limiting vector and a second limiting vector disposed at a fan angle relative to the first limiting vector.
First and second in-plane translations using central-ray passage through the virtual scan center
Translating the C-arm along a first path within a C-arm plane parallel to the periphery until the central ray vector extends through the virtual scan center and the ROI is disposed within the fan beam, and translating the C-arm along a second path within the C-arm plane until the second limiting vector is tangential to the ROI.
Limited peripheral orbital movement axis with ROI maintained within fan beam
Moving the C-arm peripherally along an orbital movement axis from an initial angular position to a second angular position, wherein the angular displacement is at least 180° minus the fan angle and not more than 180°, and wherein the ROI remains disposed within the fan beam while the C-arm is moved peripherally.
Across the independent claim, the coverage centers on using a virtual scan center at the ROI center to enforce tangency of limiting fan-beam vectors to the ROI, performing two C-arm translations within a fixed C-arm plane, and executing a peripheral orbital move constrained to an angular range that keeps the ROI within the fan beam throughout.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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