Wedge Collimation for X-ray CT Dose Reduction
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Solution Overview
Problem
Existing X-ray CT apparatuses face challenges in achieving a high-performance, cost-effective solution for reducing radiation dose, particularly due to the high expense of biaxial opening/closing slit mechanisms required for active collimation.
Innovation Solution
An X-ray CT apparatus incorporating a wedge with an integrated X-ray shield and a driving unit that moves the wedge during scanning to optimize X-ray dose distribution, allowing for active collimation without a biaxial slit mechanism, by controlling the wedge's position to block unnecessary X-ray exposure in non-reconstruction ranges and ensure adequate exposure in reconstruction ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a biaxial opening/closing slit mechanism is used to perform active collimation operation, then radiation dose can be optimized by controlling the width and position of openings, but the system cost increases significantly
Solution Approach 1:
The patent combines the collimation function with the wedge structure that is already present in the optical system. By integrating the shielding function into the existing wedge component, the system achieves active collimation capability without adding a separate biaxial slit mechanism, thus reducing system complexity and cost while maintaining radiation dose optimization capability
Solution Approach 2:
The wedge structure is given multiple functions: it serves both as a normal optical component for beam shaping and as a movable shield for active collimation. This multi-functionality eliminates the need for dedicated slit mechanisms, reducing system complexity while achieving radiation dose optimization through controlled movement of the wedge to block or allow X-ray passage
2Object-affected harmful factors
If a biaxial opening/closing slit mechanism is implemented, then active collimation operation can be performed to reduce unnecessary X-ray irradiation, but the system becomes much more expensive
Solution Approach 1:
The patent merges the shielding function required for active collimation with the existing wedge structure in the optical path. This integration approach allows the system to achieve reduced unnecessary X-ray irradiation through controlled wedge movement, without incurring the high costs associated with manufacturing and implementing a separate biaxial slit mechanism
Solution Approach 2:
The existing wedge structure in the optical system is utilized to perform the additional function of active collimation. By making the wedge movable in the slice thickness direction, it serves itself to block unnecessary X-rays, eliminating the need for separate expensive collimation components and reducing overall system cost
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 enables cost-effective active collimation, reducing radiation dose by optimizing X-ray irradiation patterns, even in systems with only simultaneous slit operation, thereby enhancing performance and reducing costs.
Implementation Method 1
a shield for blocking a part of an X ray is formed on the wedge... controls the wedge to a first position where an X ray, which spreads in a slice thickness direction of the X-ray source, unnecessary for reconstruction of an image for medical use is blocked
Data Source
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AI summary
There is provided an X-ray CT apparatus including: an X-ray source; a wedge which is disposed between the X-ray source and a subject and in which a shield blocking a part of an X ray is formed; a wedge driving unit for moving position of the wedge; and a system control unit controlling the wedge driving unit during a scan execution period to control the position of the wedge.