Slow-Rotate Radiation Source for Uniform Angular Tomosynthesis
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Solution Overview
Problem
4D CBCT imaging is time-consuming and exposes patients to excessive x-ray radiation due to the large number of projections required, while existing techniques for digital tomosynthesis imaging result in non-uniform angular distribution of projections, degrading the geometric fidelity and depth resolution of images.
Innovation Solution
An imaging system with a radiation source rotating along an arc path at a controlled rate, paired with an imager, to obtain a subset of images with uniform angular spacing, allowing for the generation of digital tomosynthesis images that reduce radiation dose and improve image fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If 4D CBCT imaging is performed with a large number of projections, then the volumetric images can be obtained at different breathing states, but the imaging time becomes excessive and the patient is exposed to excessive x-ray radiation
Solution Approach 1:
The patent extracts only the necessary subset of projection images required for digital tomosynthesis reconstruction, rather than using all projections as in 4D CBCT. This selective extraction reduces the number of images processed while maintaining the ability to visualize target motion at different breathing states, thereby reducing radiation dose exposure.
Solution Approach 2:
The patent applies partial action by acquiring and processing only a subset of projections needed for tomosynthesis, rather than performing complete 4D CBCT reconstruction with all projections. This partial processing approach achieves sufficient diagnostic quality while significantly reducing the radiation burden on the patient.
2Productivity
If existing techniques are used to obtain projection images for digital tomosynthesis, then the imaging time is reduced, but the projections within each phase bin have non-uniform angular distribution which degrades the geometric fidelity and depth resolution
Solution Approach 1:
The patent applies preliminary action by pre-planning and pre-acquiring projection images at specifically designed uniform angular intervals before the imaging session begins. The imaging system is configured to acquire projections at predetermined angles that ensure uniform angular distribution, eliminating the need for post-processing corrections and maintaining high geometric fidelity while enabling efficient imaging.
Solution Approach 2:
The patent changes the angular sampling parameter from non-uniform (as in existing rapid imaging techniques) to uniform distribution. By adjusting the angular spacing parameter to be equal across all projections within a phase bin, the system achieves both rapid imaging and high geometric fidelity, resolving the contradiction between speed and precision.
3Loss of time
If the radiation source rotates rapidly to reduce imaging duration, then the imaging time is reduced, but the angular distribution of projections becomes non-uniform
Solution Approach 1:
The patent applies preliminary action by pre-defining the rotational trajectory and angular sampling points of the radiation source before imaging begins. The system is configured with predetermined angular positions that ensure uniform distribution, allowing the source to rotate at optimized speeds while maintaining precise angular spacing between projections.
Solution Approach 2:
The patent uses a pre-planned angular sampling pattern that is copied or replicated across all phase bins. Each phase bin contains projections at the same uniform angular intervals, ensuring consistency and geometric fidelity across all reconstructed images while enabling rapid acquisition through efficient rotation protocols.
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 reduces the radiation dose to the patient and enhances the geometric fidelity and depth resolution of digital tomosynthesis images by ensuring uniform angular spacing of projections, making the imaging process more efficient and effective.
Implementation Method 1
a high energy beam is applied from an external source towards the patient
Implementation Method 2
projection images of the target when the target is at different breathing states are acquired
Data Source
AI summary
An imaging system includes a radiation source, a positioner configured to rotate the radiation source along an arc path at a rate less than 0.5 degree/sec, an imager in operative position relative to the radiation source, wherein the radiation source and the imager are configured to obtain a plurality of images while the radiation source is at different positions along the arc path, and a processor configured to determine a digital tomosynthesis image using a subset of the plurality of images. An imaging method includes generating a control signal to control a positioner to rotate a radiation source through an arc path at a rate less than 0.5 degree/sec, obtaining a plurality of images that are generated using radiation from the radiation source while the radiation source is at different positions along the arc path, and determining a digital tomosynthesis image using a subset of the plurality of images.