X-ray CT Dynamic Scanning Plan Switching for Dose Optimization
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Solution Overview
Problem
Conventional X-ray CT apparatuses face challenges in optimizing X-ray doses during perfusion analysis, as they often irradiate subjects unnecessarily due to fixed scanning plans that do not adapt to individual variations in contrast medium density, leading to excessive X-ray exposure.
Innovation Solution
The X-ray CT apparatus automatically controls the start and end of scanning plans based on real-time density changes of the contrast medium by detecting index values and switching between predefined scanning plans using a system control unit that analyzes temporal variations in contrast medium density, allowing for dynamic adjustment of scanning intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If scanning plans are set with fixed intervals based on prediction of contrast medium density variations, then the scan can be performed without missing the period during which the density changes markedly, but the subject is irradiated with unnecessary X-rays when the density has peaked out
Solution Approach 1:
The patent applies dynamics by making the scanning plan switchable and adaptable during the scan process. Instead of using fixed predetermined scanning plans, the system dynamically switches between different scanning plans (first, second, and third scanning plans with different time intervals) based on real-time detection of contrast medium density variations, allowing the scanning protocol to adapt to actual physiological conditions
Solution Approach 2:
The patent implements feedback by using the detected contrast medium density information to control the switching of scanning plans. The detection unit continuously monitors density variations, and this feedback signal triggers automatic switching between scanning plans with different time intervals, creating a closed-loop control system that adjusts X-ray exposure based on actual contrast medium behavior
Solution Approach 3:
The patent applies parameter changes by varying the time interval parameter of scanning plans based on contrast medium density. The system switches between scanning plans with different time intervals (shorter intervals when density changes markedly, longer intervals when density stabilizes), thereby optimizing the balance between diagnostic quality and radiation dose
2Reliability
If scanning plans are set with long duration to cover all possible contrast medium density changes, then no period is missed, but the scan continues even when unnecessary
Solution Approach 1:
The patent applies partial action by implementing multiple scanning plans with different levels of detail rather than one prolonged scan. The system uses shorter, more intensive scanning (first scanning plan) only when contrast medium density changes markedly, and switches to longer intervals (second and third scanning plans) when changes slow down, avoiding unnecessary extended scanning
Solution Approach 2:
The system dynamically adjusts scan duration by switching between scanning plans based on real-time density detection. When contrast medium density stabilizes or peaks, the system automatically transitions to scanning plans with longer intervals or terminates scanning, making the total scan duration adaptive rather than fixed
3Measurement precision
If continuous scan or intermittent scan with short intervals is performed to capture detailed data during peak density change, then accurate perfusion analysis is achieved, but X-ray exposure is increased
Solution Approach 1:
The patent applies local quality by using different scanning strategies (different time intervals) for different phases of contrast medium circulation. The first scanning plan with short intervals is applied locally during the critical phase when density changes markedly, while the second and third scanning plans with longer intervals are used during phases when changes are slower, optimizing both precision and dose
Solution Approach 2:
The patent implements periodic action with varying frequencies through multiple scanning plans. The system uses high-frequency scanning (short intervals) during critical periods when contrast medium density changes rapidly, and low-frequency scanning (long intervals) during stable periods, creating an adaptive periodic sampling strategy
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 that X-ray scans are performed with a dose optimal for each subject by dynamically adjusting scanning plans according to the contrast medium density, reducing unnecessary X-ray exposure and improving the efficiency of perfusion analysis.
Implementation Method 1
a gantry apparatus (10) that irradiates a subject (P) with X-rays and detects the transmitted X-rays to obtain projection data
Data Source
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AI summary
An index-value detecting unit (38a) detects an index value that indicates a contrast medium density in a Region Of Interest (ROI) set on an image reconstructed during a scan. A switch-timing detecting unit (38b) detects an inflection point appearing on a curve that indicates temporal variations in the contrast medium density in the ROI, based on an index value detected by the index-value detecting unit (38a). An imaging control unit (38d) then performs control so as to skip the rest of a scanning plan in execution and to start the next scanning plan when the switch-timing detecting unit (38b) detects an inflection point.