Dynamic X-ray Collimator Diaphragm for Spiral Scan Dose Reduction
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Solution Overview
Problem
Current x-ray collimation methods in CT devices result in unnecessary radiation exposure due to limitations in dynamic adjustment, leading to increased unused radiation doses at the start and end of spiral scans, which cannot be fully minimized by existing technologies.
Innovation Solution
A collimator device with at least one movable masking device that can mask more than half of the x-ray beam, preferably using two diaphragm jaws to completely mask the beam fan, allowing for dynamic collimation that minimizes radiation exposure by adjusting the aperture during the scan process, and a method to control this device using linear actuators or rotary drives for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If static collimation is used with predetermined slot widths, then device complexity is reduced and ease of manufacture is improved, but radiation dose efficiency deteriorates due to unnecessary exposure at beginning and end of scan
Solution Approach 1:
The patent applies dynamic collimation by making the diaphragm jaws movable along the beam path, allowing the collimation aperture to be adjusted dynamically during the scan process. This resolves the contradiction by enabling radiation dose optimization through real-time aperture adjustment while maintaining a relatively simple mechanical structure based on conventional diaphragm design.
Solution Approach 2:
The patent changes the collimation parameter (aperture width) dynamically during the scan process, specifically reducing the aperture at the beginning and end of the scan where full coverage is not needed. This parameter change optimizes radiation dose efficiency without requiring complete redesign of the collimation system.
2Loss of energy
If dynamic collimation is implemented with movable diaphragm jaws, then radiation dose efficiency is improved, but device complexity and electromechanical effort increase
Solution Approach 1:
The patent segments the beam path into different zones by introducing additional diaphragm jaws that can be independently positioned. This segmentation allows selective masking of beam portions, achieving dynamic dose optimization while distributing the mechanical complexity across multiple simpler components rather than one complex movable structure.
Solution Approach 2:
The patent introduces intermediate diaphragm structures that act as mediators between the x-ray source and the patient. These intermediate elements provide the necessary dynamic adjustment capability while isolating the complexity of motion control from the primary beam path, simplifying the overall system architecture.
3Loss of energy
If masking region and space height are increased to achieve complete beam fan masking, then radiation dose reduction is improved, but space requirements between radiator and patient increase
Solution Approach 1:
The patent transitions from conventional single-dimension diaphragm movement to multi-dimensional positioning of multiple diaphragm jaws. By arranging jaws at different positions and angles along the beam path, the system achieves complete beam fan masking without requiring increased space height, as the masking is accomplished through spatial distribution rather than extended travel distance.
Data Source
AI summary
A collimator device has at least one masking device that is adjustable between two end positions for collimation of a beam fan in an x-ray CT device, wherein the x-ray fan is schematically not masked in a first end position. The x-ray beam is more than half-masked in a second end position of the masking device. In a method for operation of such a collimator device as well as an x-ray CT device for examination of a subject having an x-ray source, a collimator device, and a control device for regulation of the aperture width of the masking device, an x-ray detector is arranged opposite the x-ray source and the collimator device and that detects the x-rays modified due to the intervening examination subject; and an image construction device reconstructs an image of the examination subject therefrom.