Extended Low Contrast Detectability for CT Scanner Protocol Optimization
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Solution Overview
Problem
Current low contrast detectability (LCD) methods in CT scanners characterize performance at only one protocol, failing to account for the full operating range and patient sizes, leading to inaccurate contrast performance assessment and inability to differentiate between scanners.
Innovation Solution
The Extended Low Contrast Detectability (ExLCD) method measures contrast performance over a range of protocols and patient sizes using a flux index and contrast index, enabling characterization of radiographic imaging systems and optimization of scanning protocols for improved image quality at lower doses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If radiation dose is reduced to lower risk of radiation induced cancer, then safety is improved, but image quality deteriorates due to increased image noise
Solution Approach 1:
The patent applies parameter changes by measuring low contrast detectability across multiple protocols with varying parameters (tube current, slice thickness, scan time, dose index) rather than a single protocol. This creates a comprehensive performance function that characterizes scanner behavior across the full operating range, enabling optimization at reduced doses.
Solution Approach 2:
The patent transitions from single-protocol LCD measurement to multi-protocol ExLCD measurement, adding dimensional complexity by incorporating multiple protocol parameters (tube current, slice thickness, scan time, dose index) to create a comprehensive performance characterization that captures scanner behavior across the full operating range.
2Device complexity
If LCD is measured at a single protocol, then measurement simplicity is improved, but measurement precision deteriorates because it fails to characterize performance over the full operating range
Solution Approach 1:
The patent segments the measurement process into multiple discrete protocol measurements across the full operating range, then combines them into a comprehensive performance function. This segmentation allows systematic characterization of scanner behavior at different operating points while maintaining organized, manageable measurement procedures.
Solution Approach 2:
The patent performs preliminary measurements across multiple protocols to establish the performance function before actual clinical use. This preliminary characterization enables subsequent optimization and comparison without requiring repeated multi-protocol measurements, saving time while ensuring accurate performance knowledge.
3Measurement precision
If multiple protocols are measured to characterize full operating range, then measurement precision is improved, but measurement complexity increases
Solution Approach 1:
The patent creates a universal performance function that characterizes scanner behavior across all protocols simultaneously. This single comprehensive function serves multiple purposes: performance comparison, protocol optimization, and quality assurance, eliminating the need for separate measurements for each purpose and reducing overall complexity.
Solution Approach 2:
The patent uses phantom objects with known contrast properties as standardized test targets that can be replicated across multiple protocols. These phantom copies provide consistent, measurable references that enable systematic comparison across different operating conditions without requiring complex variable targets.
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
ExLCD provides a robust capability to connect x-ray dose with image quality metrics, allowing for QA testing, comparison of imaging systems, standardization of protocols, and optimization of scanning protocols for better image quality at lower doses, thereby enhancing the ability to detect smaller, lower contrast objects.
Implementation Method 1
imaging a phantom containing a plurality of objects over each of the protocols
Data Source
AI summary
Systems and methods for determining an extended low contrast detectability performance function for an operating range for a core operating mode of a radiographic imaging system using actual reconstructed images characterize the contrast performance of a radiographic imaging system over its operating range and for any patient size based on the off-line calibration, uses ordered pairs of flux index and contrast index for each scanned object to provide a contrast index for each protocol for each contrast set, and uses the ordered pairs of flux index and contrast index to determine an extended low contrast detectability performance function for the operating range of a radiographic imaging system. Extended low contrast detectability performance data compilation and methods of clinical use, and low contrast phantom configurations and methods of calibration are also disclosed.