X-ray CT Apparatus Helical Pitch Adjustment for Image Quality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional X-ray CT apparatuses face challenges in maintaining optimal image quality when the X-ray tube current is limited, leading to increased unnecessary exposure and suboptimal image noise, especially when scanning large subjects or requiring fast scan speeds.
Innovation Solution
The X-ray CT apparatus adjusts other imaging parameters such as helical pitch and channel-direction filtering to maintain optimal image quality, prioritizing noise index values and using scout images to set desired parameter values for specific irradiation positions, independent of X-ray tube current limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If X-ray tube current is increased to maintain image quality, then image quality is improved, but unnecessary exposure increases
Solution Approach 1:
The patent applies local quality by adjusting imaging parameters specifically for regions where the subject size exceeds predetermined thresholds. The control device identifies peripheral regions with large subject sizes and selectively modifies parameters such as helical pitch and channel-direction filtering only in those regions, rather than uniformly across the entire scan area. This localized adjustment maintains image quality where needed while avoiding unnecessary exposure in regions where the subject size is within acceptable limits.
Solution Approach 2:
The patent employs parameter changes by dynamically modifying imaging parameters based on detected subject size. When the control device determines that the subject size in a particular region exceeds predetermined values, it automatically adjusts parameters including helical pitch, channel-direction filtering strength, and tube current distribution. These parameter changes enable the system to maintain optimal image quality for large subjects while reducing overall exposure by adapting to local conditions rather than using fixed high-exposure settings throughout.
2Object-affected harmful factors
If X-ray tube current is limited, then exposure is reduced, but image noise increases and image quality deteriorates
Solution Approach 1:
The system applies local quality by implementing region-specific parameter adjustments rather than uniform parameter settings across the entire scan. The control device divides the scan area into regions based on subject size detection, and applies different parameter sets to different regions. In regions where subject size exceeds thresholds, the system enhances channel-direction filtering and adjusts helical pitch to compensate for limited tube current, thereby maintaining image quality locally without requiring increased overall exposure.
Solution Approach 2:
The patent implements dynamics by making imaging parameters adaptive and variable rather than fixed. The control device continuously monitors subject size during scan planning and dynamically adjusts parameters such as helical pitch and channel-direction filtering strength based on detected subject characteristics. This dynamic parameter adjustment allows the system to optimize image quality for each specific region's subject size while maintaining reduced overall exposure levels.
3Ease of operation
If conventional parameter settings are used, then device operation is simple, but image quality is suboptimal for large subjects or fast scan speeds
Solution Approach 1:
The patent applies self-service by implementing an automated control device that autonomously determines optimal imaging parameters based on detected subject characteristics. The system automatically performs subject size detection, compares measurements against predetermined thresholds, and adjusts parameters including helical pitch and channel-direction filtering without requiring manual intervention. This self-service approach maintains ease of operation while significantly improving image quality for large subjects or fast scan speeds compared to conventional fixed parameter settings.
Solution Approach 2:
The system employs parameter changes by automatically modifying imaging parameters based on detected subject size and scan conditions. The control device adjusts helical pitch, channel-direction filtering strength, and tube current distribution according to predetermined thresholds and subject characteristics. These automatic parameter changes enable the system to adapt to different subject sizes and scan speeds, maintaining optimal image quality without requiring complex manual parameter tuning by the operator.
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 ensures consistent and optimal image quality along the z-direction, even when X-ray tube current is limited, by adjusting parameters like helical pitch and channel-direction filtering, thereby reducing noise and maintaining image quality across scans.
Implementation Method 1
X-ray data acquisition device for acquiring X-ray projection data by performing a scan, which X-rays being irradiated to a subject from a X-ray tube and the X-rays being transmitted through the subject by a X-ray detector
Data Source
AI summary
The present invention aims to obtain a tomographic image similar in image quality to a tomographic image obtained by executing a scan at X-ray tube current value set by an X-ray automatic exposure function even when the X-ray tube current value set by the X-ray automatic exposure function are not within a standard range of the X-ray tube current values settable at the X-ray tube (21). X-ray tube current value supplied to the X-ray tube (21) are set by the X-ray automatic exposure function. Thereafter, when the X-ray tube current value set by the X-ray automatic exposure function is not within in the standard range of the X-ray tube current value settable at the X-ray tube, the X-ray tube current value at a portion not within the standard range are changed so as to be within the standard range, and the set value of helical pitch is changed so as to correspond to the ratio between the pre-changed x-ray tube current value and the post-changed X-ray tube current value.