Photon Counting X-ray CT Apparatus Reconstruction
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Solution Overview
Problem
Conventional X-ray computed tomography apparatuses face limitations in improving image resolution due to the backprojection method's reliance on integral time periods, which do not effectively utilize finer positional and temporal resolution in sinogram projection data.
Innovation Solution
A photon counting X-ray computed tomography apparatus employing a photon counting detector and a time digital converter to output pulses corresponding to X-ray photons, allowing for the acquisition of time information and enabling the determination of accurate X-ray paths, which are used to enhance image reconstruction through methods like Filtered Back Projection and successive approximation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If backprojection method is used with integral time period, then reconstruction is simplified, but image resolution is degraded
Solution Approach 1:
The patent segments the continuous X-ray detection process into discrete photon arrival events, recording each photon's individual position and time of arrival. This segmentation allows the system to bypass the integral time period limitation by treating each photon as an independent measurement point, thereby achieving higher resolution without complicating the reconstruction algorithm.
Solution Approach 2:
The patent performs preliminary sorting and organization of photon data by position and time of arrival before reconstruction. By pre-processing the data to group photons according to their spatial and temporal characteristics, the system prepares the information in a format that can be directly used by standard backprojection algorithms, maintaining operational simplicity while enabling high-resolution reconstruction.
2Productivity
If integral time period is used for backprojection, then processing is faster, but temporal resolution is lost
Solution Approach 1:
The patent replaces the mechanical time-integration process with a digital sorting and filtering system. Instead of physically integrating signals over time periods, the system uses electronic sorting of photon arrival times and selective inclusion/exclusion of photons based on their temporal characteristics. This substitution maintains processing speed while preserving temporal resolution information.
3Device complexity
If conventional backprojection is used, then computational load is reduced, but positional resolution is not utilized
Solution Approach 1:
The patent changes the parameters used in backprojection from integrated time-period-based values to individual photon position and time of arrival parameters. By using the actual positional information of each detected photon rather than averaged values over time periods, the system fully utilizes the detector's positional resolution capabilities while maintaining computational efficiency through straightforward modifications to the backprojection algorithm.
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 the generation of X-ray CT image data with improved resolution and reduced artifacts, such as shower and streak artifacts, by accurately accounting for the position and timing of photon detection, thereby enhancing image quality and processing efficiency.
Implementation Method 1
a photon counting detector configured to output a pulse corresponding to photons included in an X-ray
Data Source
AI summary
A photon counting X-ray computed tomography apparatus according to an embodiment includes a photon counting detector and a time digital converter. The photon counting detector is configured to output a pulse corresponding to photons included in an X-ray; and the time digital converter is configured to obtain time information corresponding to timing at which the photons were detected, on the basis of the pulse.