Curved Movable Beam-Stop Array for CBCT Scatter Correction
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Solution Overview
Problem
Conventional cone-beam CT systems face issues with image quality due to scattered X-ray beams, requiring additional scans and leading to penumbra formation and increased radiation dose, especially when imaging large areas like the chest or abdomen.
Innovation Solution
A curved and movable beam-stop array with a grid of slits and beam-stop units that rotate with the gantry, allowing partial X-ray beams to pass through, reducing the need for multiple scans and minimizing penumbra effects by adjusting slit positions to capture accurate scatter distribution in a single scan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional scans are performed to correct scatter distribution, then image quality is improved, but radiation dose and imaging time increase
Solution Approach 1:
The beam-stop array is positioned in the X-ray beam path before the object to pre-select and block scattered photons before they reach the detector. This preliminary action prevents scattered photons from contaminating the detected signal, thereby improving image quality without requiring additional corrective scans and avoiding increased radiation dose
2Measurement precision
If strip lattices are used to intercept beams for scatter correction, then scatter distribution can be estimated, but penumbra is produced at the edges leading to image contamination
Solution Approach 1:
The beam-stop array employs individually controllable beam-stop units with varying widths and positions along the array. This local differentiation allows precise targeting of scatter photons from different regions of the object, enabling accurate scatter estimation without producing penumbra effects that would contaminate the image data
3Measurement precision
If narrow strip lattice width is used to reduce penumbra, then edge contamination is reduced, but the ability to capture wide area scatter distribution is limited
Solution Approach 1:
The beam-stop array is divided into multiple independently controllable beam-stop units arranged in a curved configuration. Each unit can be individually adjusted in width and position, allowing the array to simultaneously achieve narrow effective width for reduced penumbra at edges while maintaining overall wide coverage for comprehensive scatter distribution measurement across large fields of view
4Device complexity
If fixed beam-stop array is used, then device complexity is reduced, but adaptability to different imaging angles and areas is limited
Solution Approach 1:
The beam-stop array incorporates movable beam-stop units that can be dynamically adjusted in position and width along the curved array structure. This dynamic capability allows the system to adapt to different imaging angles, object sizes, and scan configurations while maintaining a relatively simple overall array structure, thereby achieving high versatility without excessive complexity
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 solution reduces radiation dose, shortens imaging time, and enhances image accuracy by minimizing penumbra and scatter errors, enabling more precise and definite images of wide areas with reduced radiation exposure.
Implementation Method 1
photons of the X-ray beams that have a reduced energy of 100 keV or less are scattered by the object to be examined
Implementation Method 2
A beam-stop array partially intercepts scattered beams, so that it is possible to estimate and correct the distribution of the scattered beams
Data Source
AI summary
A curved movable beam-stop array which has a generator, a curved grid and a controller. The generator generates radiation beams while rotating to a gantry angle. The curved grid is positioned in the radiation direction of the radiation beams generated from the generator. The controller controls operations of the grid. A plurality of slits of the grid are spaced apart from each other at a predetermined distance and allow at least a portion of the radiation beams generated from the generator to pass through. The controller moves the slit by a predetermined distance when the generator moves by a predefined angle.