Dual Energy CT Voltage Current Modulation
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Solution Overview
Problem
Conventional CT systems face challenges in achieving optimal dosage efficiency and image quality due to constant voltage and current settings, leading to either overexposure or underexposure during scanning, especially when dealing with varying body part dimensions, and existing dual energy techniques struggle with data compatibility and cost-effectiveness.
Innovation Solution
The method involves modulating the voltage and current levels of X-ray tubes to optimize dose efficiency by generating dual energy spectra and adjusting them based on attenuation in the subject portion, while acquiring dual energy data sets at a predetermined number of projections per rotation, and performing data domain decomposition to eliminate beam-hardening artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant voltage and current are used in X-ray tube, then the system is simple to operate, but image quality varies and patient dose efficiency is poor
Solution Approach 1:
The patent applies dynamics by making the X-ray tube voltage and current variable rather than constant. The system dynamically adjusts voltage and current levels based on real-time feedback from detectors that measure transmitted X-ray intensity, allowing the exposure parameters to adapt to varying patient anatomy and view angles during the scan.
Solution Approach 2:
The patent implements feedback control by using detectors to continuously monitor the transmitted X-ray intensity and feeding this information back to the control system. The control system then adjusts voltage and current settings based on this feedback to maintain optimal image quality and dose efficiency across different scanning conditions.
2Manufacturing precision
If voltage and current are increased for large dimensional views, then image quality improves, but patient radiation dose increases unnecessarily
Solution Approach 1:
The patent applies local quality by adjusting exposure parameters locally for different viewing angles and patient anatomies. Rather than using a uniform high exposure setting for all views, the system tailors voltage and current levels to the specific requirements of each local region being scanned, optimizing image quality while minimizing unnecessary radiation dose.
Solution Approach 2:
The patent implements parameter changes by dynamically varying voltage and current settings based on the specific scanning conditions. The control system modifies these parameters in real-time according to detected attenuation patterns, allowing optimal dose efficiency for each local view rather than using fixed high settings.
3Object-affected harmful factors
If voltage and current are decreased for small dimensional views, then patient radiation dose is reduced, but image quality suffers from artifacts
Solution Approach 1:
The system dynamically adjusts exposure parameters upward when scanning smaller anatomical regions, ensuring sufficient photon flux to maintain image quality and avoid artifacts. This dynamic adaptation prevents the need to use fixed low exposure settings that would compromise image quality for small structures.
Solution Approach 2:
The feedback mechanism detects when small dimensional views are being scanned and responds by adjusting voltage and current settings to provide adequate exposure. This ensures that image quality is maintained for small anatomical features while still optimizing overall dose efficiency.
4Loss of energy
If tube voltage is modulated during scanning, then dose efficiency improves, but projection data become incompatible for image reconstruction
Solution Approach 1:
The patent applies segmentation by dividing the projection data into separate energy bins corresponding to different voltage levels. The system acquires and processes data from multiple energy spectra independently, then combines them through iterative reconstruction algorithms that account for the energy-dependent attenuation characteristics, maintaining data compatibility despite voltage modulation.
Solution Approach 2:
The system manages parameter changes by implementing a multi-energy data acquisition and reconstruction framework. Rather than treating modulated voltage data as incompatible, the system uses the energy spectrum information from each voltage level to create a comprehensive reconstruction, transforming the parameter variation into useful dual-energy information.
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 minimizes radiation dose while maintaining image quality, achieving improved dose efficiency and reducing noise levels, thereby enhancing patient safety and image reconstruction accuracy.
Implementation Method 1
generating X ray at a predetermined high energy level and a predetermined low energy level at one or more X-ray tube based upon at least one voltage level applied to the X-ray tube
Implementation Method 2
modulating the voltage level of at least one of the high energy level and the low energy level applied to the X-ray tube according to attenuation in the subject portion
Data Source
AI summary
To prevent patients from being overexposed or underexposed, it has been attempted to modulate either voltage or current in conventional single energy CT systems. The voltage modulation causes incompatibility in projection data among the views while the current modulation reduces only noise. To solve these and other problems, dual energy CT is combined with voltage modulation techniques to improve the dosage efficiency. Furthermore, dual energy CT has been combined with both voltage modulation and current modulation to optimize the dosage efficiency in order to minimize radiation to a patient without sacrificing the reconstructed image quality.