Slow-Rotation Radiation Source for Uniform Tomosynthesis Imaging
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Solution Overview
Problem
4D cone beam CT imaging for radiation therapy is time-consuming and exposes patients to excessive x-ray radiation due to the need for numerous projections, which can result in non-uniform angular distribution of projection images, degrading the geometric fidelity and depth resolution of digital tomosynthesis images.
Innovation Solution
A method that controls the rotation rate of the radiation source based on the period of physiological motion, obtaining a plurality of images with uniform angular spacing to reconstruct digital tomosynthesis images, reducing the number of projections and radiation dose while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid imaging techniques are used to reduce imaging session duration, then productivity is improved, but the angular distribution of projection images becomes non-uniform, degrading manufacturing precision of digital tomosynthesis images
Solution Approach 1:
The patent applies dynamics by making the rotation speed variable rather than constant. The radiation source rotates at different speeds during different phases of the imaging process, specifically slowing down during critical angular ranges to ensure uniform angular distribution of projection images. This dynamic adjustment resolves the contradiction by enabling both reasonable imaging speed and precise geometric fidelity.
Solution Approach 2:
The patent changes the parameter of rotation speed from a fixed value to a variable parameter that is adjusted based on the angular position and imaging requirements. By modifying the rotation speed parameter dynamically, the system achieves uniform angular distribution of projections while maintaining efficient imaging throughput, thus resolving the contradiction between productivity and manufacturing precision.
2Measurement precision
If a large number of projections are acquired for 4D CBCT imaging, then measurement precision of target position is improved, but the radiation dose to the patient increases
Solution Approach 1:
The patent applies local quality by differentiating the imaging approach for different angular ranges. Certain angular ranges are imaged with higher resolution and more projections while others use fewer projections. This localized differentiation maintains measurement precision for critical regions while reducing the total number of projections and thus the radiation dose.
Solution Approach 2:
The patent uses partial action by acquiring projections selectively rather than uniformly across all angles. Instead of acquiring an excessive number of projections at all angles, the system acquires sufficient projections only at critical angular ranges where measurement precision is most needed, thereby reducing overall radiation dose while maintaining target position tracking accuracy.
3Ease of operation
If the radiation source rotates at constant speed, then ease of operation is improved, but the angular distribution of projection images becomes non-uniform, worsening manufacturing precision
Solution Approach 1:
The patent transitions from constant speed rotation to dynamic speed adjustment. The rotation speed is modified according to the angular position to achieve uniform angular distribution of projections. This dynamic control resolves the contradiction by maintaining ease of operation through automated speed adjustment while achieving the precision required for high-quality tomosynthesis images.
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 enhances visualization of moving targets by reducing radiation exposure and improving image fidelity, allowing for more precise tracking of respiratory motion without the need for excessive x-ray imaging.
Implementation Method 1
a positioner configured to rotate the radiation source through an angular range at a slow rate
Implementation Method 2
an imager configured to generate a plurality of images using radiation from the radiation source
Data Source
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AI summary
An imaging system includes a radiation source, a positioner configured to rotate the radiation source along an arc path at a rate that is less than 0.4 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 that is less than 0.4 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.