Fly-by Scanning X-ray Source for CT Data Completeness
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Solution Overview
Problem
Conventional cone beam CT systems face limitations in acquiring complete data for reconstruction due to incomplete sampling, leading to artifacts, and existing solutions like patient motion or focal spot sweeping complicate mechanical implementation and require rapid acceleration, which may not be tolerable for all patients.
Innovation Solution
A computed tomography system where the x-ray source rotates about an examination region while translating along a longitudinal axis, allowing for fly-by scans that acquire at least 180 degrees plus a fan angle of data, coordinated with anatomical motion to ensure complete sampling and reduce mechanical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the patient is moved through the examination region via patient support while the x-ray source rotates, then complete data for reconstruction can be acquired, but mechanical complexity increases and patient tolerance decreases
Solution Approach 1:
The patent applies dynamics by making the x-ray source itself movable along the longitudinal axis through fly-by motion, eliminating the need for complex patient couch movement mechanisms. The source dynamically changes position during rotation to achieve complete sampling without requiring the patient support to move through the examination region.
2Reliability
If the focal spot is swept through a saddle orbit, then complete data can be acquired, but the source trajectory becomes larger requiring a larger detector and rapid acceleration is required
Solution Approach 1:
The patent segments the data acquisition process into multiple passes, each covering a different angular range (e.g., 0-180 degrees, 180-360 degrees). The x-ray source performs fly-by motion in one direction for one pass, then reverses and performs another pass in the opposite direction. This segmentation allows complete sampling to be achieved through multiple shorter trajectories rather than one long saddle orbit.
3Ease of manufacture
If conventional axial scans following a circular orbit are used, then the scanning procedure is simple, but complete sampling for reconstruction is not achieved leading to cone beam artifacts
Solution Approach 1:
The patent modifies the simple circular orbit by adding longitudinal fly-by motion to the x-ray source. During each angular pass, the source moves forward along the longitudinal axis to cover the required angular range, then reverses direction. This dynamic addition to the circular motion achieves complete sampling while maintaining relative mechanical simplicity compared to saddle orbits or patient movement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables efficient and tolerable data acquisition for CT systems, reducing artifacts and mechanical complications, allowing for effective scanning of larger regions with improved temporal resolution and patient comfort.
Implementation Method 1
an x-ray source that rotates about an examination region and translates along a longitudinal axis... emits x-rays that traverse the examination region
Implementation Method 2
At least one detector disposed opposite from the x-ray source on a different side of the examination region detects x-rays radiated by the x-ray source that traverse the examination region
Data Source
AI summary
A computed tomography system (100) includes an x-ray source (112) that rotates about an examination region (108) and translates along a longitudinal axis (120). The x-ray source (112) remains at a first location on the longitudinal axis (120) while rotating about the examination region (108), accelerates to a scanning speed and performs a fly-by scan of a region of interest (220) in which at least one hundred and eighty degrees plus a fan angle of data is acquired. At least one detector (124) detects x-rays radiated by the x-ray source (112) that traverses the examination region (108) and generates signals indicative thereof. A reconstructor (132) reconstructs the signals to generate volumetric image data.