Photon Counting X-ray CT Energy Bin Allocation
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Solution Overview
Problem
Conventional X-ray computed tomography (CT) systems face challenges in accurately discriminating types, amounts, and densities of materials due to the susceptibility to noise caused by low photon numbers resulting from high monochromaticity requirements for material decomposition.
Innovation Solution
A photon counting X-ray CT apparatus that allocates energy measured by signals from a photon counting detector into energy bins and determines optimal energy bins for material decomposition, allowing for precise material discrimination by generating images representing the distribution of decomposition target materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the monochromaticity of X-rays is increased to improve material decomposition accuracy, then the discrimination capability between materials is improved, but the number of photons is reduced causing increased noise
Solution Approach 1:
The patent divides the detected X-ray photons into multiple energy bins based on their energy levels. Instead of using a single monochromatic energy value, the system segments the energy spectrum into discrete bins and processes each bin separately. This allows the system to maintain good monochromaticity within each bin while accumulating sufficient photon counts across multiple bins, thereby resolving the contradiction between measurement precision and noise susceptibility.
2Object-affected harmful factors
If the X-ray dose is reduced to minimize patient exposure, then the safety is improved, but the number of photons is reduced making material decomposition susceptible to noise
Solution Approach 1:
The patent changes the parameter of energy bin configuration to optimize the balance between dose and reliability. By adjusting the number, width, and energy ranges of the bins, the system can maintain reliable material decomposition at lower doses. The processing circuitry adapts the bin parameters to match the specific imaging conditions and material composition, allowing accurate decomposition even with reduced photon counts from lower dose exposure.
3Measurement precision
If the number of energy bins is increased to improve energy resolution, then the material discrimination capability is improved, but the number of photons per bin is reduced increasing noise
Solution Approach 1:
The patent implements dynamic energy bin configuration where the number and boundaries of bins are not fixed but can be adjusted based on the imaging task, material composition, and detected photon statistics. The processing circuitry dynamically optimizes the bin configuration to achieve the necessary energy resolution while maintaining sufficient photon counts per bin. This dynamic adaptation resolves the contradiction by allowing the system to use more bins when photon statistics permit and fewer bins when photon counts are limited.
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
The system effectively reduces noise and improves material decomposition accuracy by optimizing energy bin settings, enabling the precise identification of materials based on their unique energy absorption characteristics.
Implementation Method 1
a photon counting detector that counts the number of photons of the X-rays and measures energy of the photons
Data Source
AI summary
A photon counting X-ray CT apparatus according to an embodiment includes: data acquiring circuitry, and processing circuitry. The data acquiring circuitry is configured to allocate energy measured by signals output from a photon counting detector in response to incidence of X-ray photons to any of a plurality of first energy bins so as to acquire a first data group as count data of each of the first energy bins. The processing circuitry is configured to determine a plurality of second energy bins obtained by grouping the first energy bins in accordance with a decomposition target material that is a material to be decomposed in a imaging region, allocate the first data group to any of the second energy bins so as to generate a second data group, and use the second data group to generate an image representing a distribution of the decomposition target material.