X-Ray CT Imaging With Angle-Based Dose Compensation
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Solution Overview
Problem
Existing X-ray CT apparatuses face a trade-off between image quality and exposure dose, particularly due to X-ray attenuation by head holders or top plates, which reduces detected X-ray dose and increases exposure dose to the subject.
Innovation Solution
An X-ray CT apparatus that adjusts X-ray irradiation conditions during rotation to compensate for X-ray attenuation by head holders or top plates, increasing irradiation dose where necessary to maintain image quality and reduce exposure dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the irradiation dose is increased to compensate for X-ray attenuation by the head holder or top plate, then the image quality of the tomographic image is improved, but the exposure dose to the subject increases
Solution Approach 1:
The patent applies local quality by differentiating the irradiation dose based on the projection angle. Specifically, the irradiation dose is increased only in angular ranges where the X-ray beam passes through the head holder or top plate (which cause attenuation), while maintaining normal dose levels in other angular ranges. This localized adjustment compensates for attenuation effects without uniformly increasing the exposure dose to the entire subject, thereby improving image quality in affected regions while minimizing overall exposure.
Solution Approach 2:
The patent implements dynamics by making the irradiation dose variable rather than constant. The controller dynamically adjusts the irradiation dose based on the projection angle of the X-ray beam. As the rotating plate changes the angle of incidence, the system automatically modulates the dose to account for varying levels of attenuation by the head holder or top plate. This dynamic adjustment ensures optimal image quality across all projection angles while avoiding unnecessary exposure.
2Object-affected harmful factors
If the irradiation dose is decreased to reduce exposure dose to the subject, then the exposure dose is reduced, but the image quality of the tomographic image deteriorates
Solution Approach 1:
The patent prevents image quality deterioration by applying local quality enhancement in specific angular regions. Instead of uniformly decreasing the irradiation dose across all angles, the system identifies projection angles where the X-ray beam intersects the head holder or top plate and applies dose compensation only in those specific angular ranges. This ensures that image quality is maintained in regions affected by attenuation while allowing dose reduction in regions where attenuation is minimal.
Solution Approach 2:
The patent uses dynamic dose adjustment to prevent image quality deterioration. The controller continuously monitors the projection angle and dynamically modulates the irradiation dose in real-time during the scanning process. This dynamic response ensures that the dose is sufficient to maintain image quality when attenuation occurs, while allowing lower doses when attenuation is absent, thus preventing overall image quality deterioration while reducing unnecessary exposure.
3Measurement precision
If the irradiation dose is uniformly increased to compensate for X-ray attenuation, then the image quality is improved, but the exposure dose to sensitive areas such as the eye or mammary gland increases significantly
Solution Approach 1:
The patent effectively addresses this contradiction by applying local quality adjustment based on projection angle. The system calculates which angular ranges correspond to X-ray paths passing through the head holder or top plate and applies dose compensation only in those specific angular ranges. This localized approach ensures that image quality is maintained in regions affected by attenuation while avoiding uniform dose increases that would unnecessarily expose sensitive areas such as the eyes or mammary glands to higher radiation levels.
Solution Approach 2:
The patent uses dynamic dose modulation to prevent excessive exposure to sensitive areas. The controller adjusts the irradiation dose in real-time based on the current projection angle, increasing the dose only when the X-ray beam passes through attenuating structures like the head holder or top plate. This dynamic, angle-dependent adjustment prevents uniform dose increases, thereby protecting sensitive areas from unnecessary radiation exposure while maintaining image quality in regions where attenuation occurs.
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 solution effectively suppresses the decrease in image quality caused by X-ray attenuation while minimizing exposure dose to sensitive areas, such as the eye or mammary gland, by dynamically modulating X-ray irradiation based on the position of the head holder or top plate.
Implementation Method 1
an X-ray source that irradiates an X-ray to a subject; an X-ray detector that detects the X-ray transmitted through the subject
Implementation Method 2
a rotating plate that causes the X-ray source and the X-ray detector to rotate around the subject
Implementation Method 3
The X-ray attenuation by the head holder or the top plate reduces the X-ray dose detected by the X-ray detector
Data Source
AI summary
Provided is an X-ray CT apparatus capable of suppressing a decrease in image quality of a tomographic image due to X-ray attenuation in a head holder or a top plate. The X-ray CT apparatus includes an X-ray source that irradiates an X-ray to a subject, an X-ray detector that detects the X-ray transmitted through the subject, a rotating plate that causes the X-ray source and the X-ray detector to rotate around the subject, an image generation section that generates a tomographic image of the subject based on a detection signal of the X-ray detector, and a controller that controls each section, in which the controller changes an irradiation condition of the X-ray irradiated from the X-ray source while the rotating plate rotates, such that an irradiation dose from a side on which a head holder or a top plate is disposed is increased in a range of a projection angle at which the X-ray passes through the head holder or the top plate.