PCCT Material Density Calibration Across Focal Spot Sizes
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Solution Overview
Problem
The generation of calibration vectors for photon counting computed tomography (PCCT) systems is time-consuming, leading to customer downtime and reduced availability of the system for patient scans, particularly due to the complexity and time required for material decomposition (MD) calibration vectors, which are dependent on focal spot sizes.
Innovation Solution
A method is introduced to reduce the number of MD calibration scans by generating common sets of MD calibration vectors applicable to various focal spot sizes, reducing the time spent on calibration and increasing system availability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate MD calibration vectors are generated for each focal spot size, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent applies universality by generating a single set of MD calibration vectors that can be used across multiple focal spot sizes. Instead of creating separate calibration vectors for each focal spot size (which would be time-consuming), the system develops universal calibration vectors that work for different focal spot configurations, reducing calibration time while maintaining adequate measurement precision
Solution Approach 2:
The patent employs parameter changes by varying the focal spot size parameter during calibration scans while using a common calibration approach. The system acquires calibration data at different focal spot sizes and generates unified calibration vectors that account for these parameter variations, thereby reducing the need for separate calibration procedures for each focal spot size
2Reliability
If multiple calibration vectors are generated for different scan protocols, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies merging by combining the generation of MD calibration vectors with air calibration vectors into a unified calibration process. Instead of treating these as separate calibration procedures that would increase system complexity, the system integrates them into a single workflow that produces both types of calibration vectors simultaneously, reducing operational complexity while maintaining reliability
Solution Approach 2:
The patent uses universality by creating a calibration framework where a single set of MD calibration vectors serves multiple scan protocols and focal spot sizes. This universal approach reduces the number of separate calibration vectors needed, thereby simplifying the calibration system while ensuring reliable image accuracy across different scanning conditions
3Manufacturing precision
If comprehensive calibration is performed for all focal spot sizes, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The patent applies universality by developing MD calibration vectors that are not specific to any single focal spot size but work across multiple focal spot configurations. This universal calibration approach maintains manufacturing precision (calibration accuracy) while significantly reducing the time required for calibration, thereby improving system availability and productivity
Solution Approach 2:
The patent employs preliminary action by performing comprehensive calibration data acquisition at different focal spot sizes during the initial calibration phase. The resulting universal calibration vectors are then reusable for subsequent scans, eliminating the need for repeated comprehensive calibration and improving ongoing system productivity while maintaining accuracy
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 decreases the time spent on MD calibration by up to 60% while maintaining image quality, enhancing the availability of the PCCT system for patient scans and reducing computational and memory resource consumption.
Implementation Method 1
an electron beam generated by a cathode is directed towards a target within an X-ray tube
Implementation Method 2
A fan-shaped or cone-shaped beam of X-rays produced by electrons colliding with the target
Implementation Method 3
where the X-ray detectors are photon counting detectors, and photons are counted to provide spectral information
Data Source
AI summary
Methods and systems are provided for calibrating a photon counting computed tomography (PCCT) system. To reduce an amount of calibration data stored in a memory of the PCCT system, and to reduce a time spent calibrating the PCCT system, a method is provided for using a material decomposition (MD) calibration vector generated for a first focal spot size to correct projection data acquired using the PCCT system at different focal spot sizes. To compensate for spectral differences due to focal spot size, the projection data is corrected and normalized by air calibration vectors generated for each different focal spot size.