X-ray CT Tube Current Control for Low-Count Artifact Prevention
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Solution Overview
Problem
Existing X-ray computed tomography systems face challenges in maintaining image quality when imaging large subjects, often resulting in low-count artifacts due to inadequate X-ray dose, as current auto exposure control (AEC) systems do not account for lower X-ray count values, leading to image degradation.
Innovation Solution
An X-ray computed tomography apparatus and imaging condition management system that evaluates the lower limit range of X-ray count values to prevent low-count artifacts by adjusting the tube current and other imaging conditions, ensuring the X-ray count value exceeds the threshold to prevent image degradation, while maintaining a permissible dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If tube current is lowered as designated by operator for low dose imaging, then radiation dose to subject is reduced, but X-ray count value falls below lower limit value causing low-count artifact
Solution Approach 1:
The system performs preliminary evaluation of the subject's attenuation characteristics using a scout view or preliminary scan before the actual CT imaging. Based on this preliminary information, the system predicts the X-ray count value that would result from the operator-designated tube current and warns the operator in advance if low-count artifacts are likely to occur, allowing the operator to adjust imaging conditions before acquiring the main imaging data.
Solution Approach 2:
The system provides feedback to the operator by displaying a warning when the evaluated X-ray count value falls below the lower limit threshold. This feedback mechanism allows the operator to understand the potential image quality issue and make informed decisions about adjusting imaging conditions, such as increasing tube current or modifying other parameters, before performing the actual scan.
2Reliability
If tube current is increased to prevent low-count artifact, then X-ray count value exceeds lower limit value improving image quality, but radiation dose to subject increases
Solution Approach 1:
The system evaluates the relationship between tube current and X-ray count value before actual imaging, allowing prediction of the minimum tube current needed to avoid low-count artifacts. This preliminary evaluation enables optimization of imaging conditions to use the lowest possible tube current that still prevents artifacts, minimizing radiation dose while maintaining image quality.
Solution Approach 2:
The system allows modification of imaging parameters beyond just tube current, such as adjusting scan range, slice thickness, or rotation speed, to achieve adequate X-ray count values without necessarily increasing tube current. By changing multiple parameters, the system can maintain image quality while controlling radiation dose.
3Ease of operation
If existing AEC is used for large subjects, then imaging can be performed with standard conditions, but X-ray count value falls below lower limit value producing low-count artifact
Solution Approach 1:
The system automatically evaluates whether standard imaging conditions are appropriate for the specific subject by analyzing attenuation characteristics from preliminary scans. When standard conditions would result in low-count artifacts, the system provides feedback warnings to the operator, preventing automatic execution of inappropriate imaging conditions and ensuring image quality is maintained even for large or atypical subjects.
Solution Approach 2:
The system performs self-evaluation of imaging conditions based on subject-specific characteristics, automatically determining whether standard AEC conditions are appropriate or if adjustments are needed. This self-service capability reduces reliance on operator expertise while preventing low-count artifacts across diverse subject types.
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
The system effectively prevents low-count artifacts by adjusting imaging conditions, such as increasing tube current, to ensure optimal image quality and reduce unnecessary exposure, thereby supporting better imaging outcomes for larger subjects.
Implementation Method 1
An X-ray tube emits X-rays
Implementation Method 2
a detector detects X-rays that have been emitted from the X-ray tube and have passed through the subject
Data Source
AI summary
According to one embodiment, an X-ray computed tomography apparatus includes an X-ray tube, a detector, and processing circuitry. The X-ray tube emits X-rays. The detector detects X-rays that have been emitted from the X-ray tube and have passed through the subject. The processing circuitry sets an imaging condition. The processing circuitry evaluates the imaging condition based on information on a lower limit range of a count value of the detected X-rays that may cause image degradation.