Photon Counting CT Energy Range Estimation for Scatter Noise
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Solution Overview
Problem
Photon counting CT systems face image quality deterioration due to noise components like scattered radiation, which are counted along with the X-ray photons, leading to reduced signal-to-noise ratios in reconstructed images.
Innovation Solution
An X-ray CT apparatus that estimates and excludes energy ranges corresponding to noise components, using a control unit to determine the imaging energy range based on the imaging conditions, and reconstructs image data using counting information within this range to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon-counting mode detector is used to individually count X-ray photons, then signal-to-noise ratio is improved, but noise components such as scattered radiation are also counted leading to image quality deterioration
Solution Approach 1:
The patent segments the detected X-ray photons by energy level, separating primary photons from scattered photons into different energy bins. The photon-counting detector measures photons in multiple energy ranges, and the system selectively uses only the primary photon data (excluding scattered photons) for image reconstruction, thereby resolving the contradiction between high counting capability and image quality
Solution Approach 2:
The patent changes the parameter of energy range selection dynamically. By setting appropriate energy thresholds and ranges based on the imaging task and scatter conditions, the system adapts which photon energy ranges to include or exclude from reconstruction, optimizing the balance between signal utilization and noise rejection
2Productivity
If all counted photons are used for image reconstruction, then counting efficiency is maximized, but image quality deteriorates due to inclusion of scattered radiation
Solution Approach 1:
The patent applies partial action by using only a subset of the counted photons for image reconstruction. Specifically, it counts all photons but selectively reconstructs images using only photons within the primary energy range, excluding scattered photons. This partial utilization of counting data maintains high counting efficiency while eliminating the harmful effect of scatter
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 solution effectively enhances the quality of reconstructed images by filtering out noise components, resulting in higher signal-to-noise ratios and improved material identification capabilities.
Implementation Method 1
the signal output by the photon-counting mode detector can be used for measurement (discrimination) of the energy of an X-ray photon
Implementation Method 2
an X-ray tube, and a detector. The detector is configured to output, at each incidence of an X-ray photon, a signal enabling measurement of an energy value of the X-ray photon
Data Source
AI summary
An X-ray computed tomography (CT) apparatus includes a detector, and processing circuitry. The detector is configured to output, at each incidence of an X-ray photon, a signal enabling measurement of an energy value of the X-ray photon. Processing circuitry is configured to estimate an energy range to be used for imaging based on an imaging condition and to reconstruct X-ray CT image data using counting information to which an energy value within the energy range is associated among pieces of counting information that are collected from individual signals output by the detector at each incidence of an X-ray photon that has been irradiated from an X-ray tube and has passed through a subject, and in which a counting value and an energy value of X-ray photons incident to the detector are associated with each other.