X-ray CT Material Decomposition Using Effective Length
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Solution Overview
Problem
Conventional X-ray computed tomography (CT) systems face challenges in performing accurate material decomposition due to noise issues caused by low X-ray doses, which result in reduced photon counts and increased noise levels, especially when using narrow energy bins for high monochromaticity.
Innovation Solution
The X-ray CT apparatus generates and uses projection data from multiple energy bins, with a specific configuration that includes a gantry device, X-ray tube, and detector to collect and process data, employing a method to derive constraint conditions and calculate effective lengths of materials, thereby reducing noise influence and enhancing decomposition accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an X-ray having a narrow energy bin is used to increase monochromaticity, then material decomposition accuracy is improved, but the number of photons decreases and noise increases
Solution Approach 1:
The patent combines multiple projection data sets with different energy bins to calculate the effective length. By merging the information from multiple energy ranges, the system maintains the monochromaticity benefit for material decomposition while increasing the total photon count to reduce noise. The processing circuitry integrates projection data from multiple energy bins rather than relying on a single narrow energy bin.
2Object-affected harmful factors
If a low dose of X-ray is used to reduce exposure, then radiation safety is improved, but the number of photons decreases and noise increases
Solution Approach 1:
The system merges projection data from multiple energy bins to compensate for the low photon count resulting from low-dose imaging. By combining information across different energy ranges, the effective length calculation becomes more reliable even when the total number of photons is reduced, thereby maintaining material decomposition accuracy while keeping radiation exposure low.
3Measurement precision
If multiple energy bins are used for material decomposition, then decomposition accuracy is improved, but data processing complexity increases
Solution Approach 1:
The patent extracts the effective length as a separate intermediate parameter from the multiple projection data sets. By isolating this key parameter that represents the total path length through the material, the system simplifies the subsequent material decomposition process. The processing circuitry calculates the effective length first, then uses it along with the projection data to determine material composition, breaking down the complex multi-energy analysis into manageable steps.
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 allows for more accurate material decomposition by increasing photon counts and reducing noise, enabling precise calculation of effective lengths and density distributions of materials within the subject.
Implementation Method 1
an X-ray tube configured to generate an X-ray
Implementation Method 2
an X-ray detector including a plurality of X-ray detection elements configured to output a signal based on the X-ray entered therein
Data Source
AI summary
An X-ray computed-tomography (CT) apparatus of an embodiment includes an X-ray tube, an X-ray detector, and processing circuitry. The X-ray tube is configured to generate an X-ray. The X-ray detector includes a plurality of X-ray detection elements configured to output a signal based on the X-ray entered therein. The processing circuitry is configured to derive a constraint condition by using at least one piece of projection data out of a plurality of pieces of projection data corresponding energy bins of which differ at least partially, calculate an effective length that is a total length for which the X-ray has passed through a region in which a material to be decomposed is present, and generate image data showing information about the material by using the projection data and the effective length.