Multi-Spot CT Imaging System for Reduced Cone Beam Artifacts
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Solution Overview
Problem
Current CT scanners face limitations in increasing speed, coverage, and resolution due to mechanical stresses and cone beam artifacts, while also resulting in higher x-ray doses to patients, especially when trying to image larger fields or cardiac regions.
Innovation Solution
A CT imaging system with multiple x-ray emission sources and detector arrays positioned to receive x-rays from multiple sources, allowing for improved angular coverage and reduced cone beam artifacts, and the use of a 'virtual bowtie' to optimize x-ray flux without increasing patient dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gantry speed is increased to improve temporal resolution, then temporal resolution is improved, but mechanical stresses substantially increase
Solution Approach 1:
The patent divides the single x-ray source into multiple discrete focal spots arranged in an array. Each focal spot can be independently activated to project x-rays through different angular paths around the subject. This segmentation allows the system to acquire projection data from multiple angles without increasing gantry rotation speed, thereby improving temporal resolution while avoiding increased mechanical stresses on the gantry.
2Area of stationary object
If the detector array length in Z direction is extended to increase coverage, then coverage is increased, but cone beam artifacts increase
Solution Approach 1:
The patent introduces a second spatial dimension (angular dimension) by arranging multiple focal spots in an array configuration. Instead of extending the detector array in the Z direction, the system uses multiple x-ray sources at different angular positions to provide comprehensive coverage. This dimensional change allows coverage to be increased without increasing the cone beam angle, thereby avoiding cone beam artifacts.
3Illumination intensity
If a bowtie filter is used to uniformize detected flux, then flux uniformity is improved, but scattered radiation increases
Solution Approach 1:
The patent applies local quality by assigning different activation patterns to different focal spots in the array based on the imaging requirements. Specific focal spots can be selectively activated to optimize flux distribution for different regions of interest, eliminating the need for a bowtie filter. This selective activation achieves flux uniformity while avoiding the generation of scattered radiation that would result from using a physical bowtie filter.
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
Enhances temporal resolution, reduces mechanical stresses, and decreases patient x-ray exposure by allowing for larger field-of-view imaging with reduced cone beam artifacts and optimized x-ray flux distribution.
Implementation Method 1
an x-ray source emits a cone-shaped beam toward a subject or object... The beam, after being attenuated by the subject, impinges upon an array of radiation detectors
Implementation Method 2
Each detector element of the detector array produces a separate electrical signal indicative of the attenuated beam received by each detector element
Implementation Method 3
a scintillator for converting x-rays to light energy adjacent the collimator
Implementation Method 4
photodiodes for receiving the light energy from the adjacent scintillator and producing electrical signals therefrom
Data Source
AI summary
A CT imaging system includes a rotatable gantry having an opening to receive an object to be scanned. A plurality of x-ray emission sources are attached to the rotatable gantry, each x-ray emission source configured to emit x-rays in a conebeam toward the object. The CT imaging system also includes a plurality of x-ray detector arrays attached to the gantry and positioned to receive x-rays passing through the object. At least one x-ray detector array of the plurality of x-ray detector arrays is configured to receive x-rays from more than one x-ray emission source.