Multi-Energy CT Imaging via Focal Spot Flying and kV Switching
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Solution Overview
Problem
Current CT imaging systems face challenges in acquiring dual or multi-energy data without data misregistration between high and low energy shots, leading to image artifacts and increased radiation dose, while also being cost-competitive.
Innovation Solution
A CT system with a rotatable gantry and a grating collimator made of alternating materials, utilizing focal spot flying and rapid kV switching to acquire high and low kVp data simultaneously through the same detector pixel, allowing for energy separation without the need for multiple scans or expensive dual tube/detector systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential scanning at different kVp levels is used to acquire multi-energy data, then energy discrimination is achieved, but data misregistration and image artifacts occur due to patient motion between scans
Solution Approach 1:
The patent combines high kVp and low kVp scanning into a single gantry rotation cycle by rapidly switching between focal spots and kVp levels. This merging of sequential scans into a simultaneous acquisition process eliminates patient motion between scans, preventing data misregistration while maintaining energy discrimination capability.
Solution Approach 2:
The system dynamically switches between different focal spots and kVp levels during a single rotation. The x-ray tube rapidly alternates between high kVp (first focal spot) and low kVp (second focal spot) modes, allowing the system to adapt its energy spectrum in real-time without requiring multiple separate scans.
2Reliability
If dual tube/detector systems are used to acquire simultaneous high and low kVp data, then data misregistration is eliminated, but system cost and complexity increase significantly
Solution Approach 1:
The patent makes a single x-ray tube and detector system perform multiple functions by implementing rapid kVp switching and focal spot flying capabilities. The same hardware acquires both high kVp and low kVp data sequentially within one rotation, eliminating the need for separate tube/detector pairs while maintaining simultaneous acquisition benefits.
Solution Approach 2:
The system changes operational parameters (kVp level and focal spot position) rapidly during a single rotation rather than changing hardware configuration. By dynamically adjusting these parameters, the system achieves multi-energy data acquisition with a single tube/detector pair, avoiding the complexity of dual systems.
3Measurement precision
If multiple sequential scans are performed to acquire sufficient energy data, then energy discrimination is achieved, but radiation dose to the patient increases
Solution Approach 1:
The patent implements continuous data acquisition throughout a single gantry rotation by rapidly switching between high and low kVp modes. This continuous scanning approach ensures that both energy spectra are collected during one complete rotation, eliminating the need for multiple separate scans and thereby reducing cumulative radiation exposure.
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 accurate and efficient acquisition of multi-energy data with reduced image artifacts and radiation dose, while maintaining cost-effectiveness by achieving energy separation within a single rotation of the gantry, enhancing material decomposition and diagnostic imaging.
Implementation Method 1
a grating collimator made of alternating materials... passing a first beam of x-rays through a first region of the grating collimator and along a ray through a patient, passing a second beam of x-rays through a second region of the grating collimator and substantially along the ray through the patient
Implementation Method 2
In a given energy region relevant to medical CT, two physical processes dominate the x-ray attenuation: (1) Compton scatter and the (2) photoelectric effect
Implementation Method 3
In a given energy region relevant to medical CT, two physical processes dominate the x-ray attenuation: (1) Compton scatter and the (2) photoelectric effect
Implementation Method 4
Each photodiode detects the light energy and generates a corresponding electrical signal
Data Source
AI summary
A CT system includes a gantry, an x-ray source, a detector, and a grating collimator that includes alternating first and second materials. The system includes a controller configured to emit a first beam of x-rays from a first focal spot and to a first detector pixel, wherein the first beam of x-rays passes along a ray and through one of the first materials of the grating collimator, and subsequently emit a second beam of x-rays from a second focal spot and to the first detector pixel, wherein the second beam of x-rays passes substantially along the ray and through one of the second materials of the grating collimator. The system includes a computer programmed to generate first and second kVp image datasets using data acquired from the first beam and second beams of x-rays, and reconstruct a basis material image of the object.