Spool-Shaped Rotating Gantry for CT Scanner Distortion Control
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Solution Overview
Problem
High-speed rotating gantries in CT scanners experience physical distortions due to radial g-forces, leading to radiation beam drift and image artifacts, which are exacerbated at higher rotation speeds, making it challenging to maintain image quality and radiation efficiency.
Innovation Solution
A spool-shaped rotating gantry design with a first and second flange coupled by elongate structural elements provides radial and axial stiffness, reducing physical distortions and maintaining a consistent relationship between the radiation source and detector array, even at high rotation speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rotor rotation speed is increased to improve productivity, then scanning speed increases, but physical distortion and radiation beam drift worsen due to radial g-forces
Solution Approach 1:
The rotor is segmented into multiple components: a central hub, multiple radial arms extending from the hub, and a peripheral ring structure. This segmentation allows each component to be optimized independently for stiffness and weight, reducing overall radial distortion while maintaining high rotation speeds
Solution Approach 2:
The design nests multiple structural elements within each other: radial arms are positioned within the perimeter defined by the peripheral ring, and support structures are integrated within the radial arms. This nested arrangement maximizes structural efficiency and stiffness-to-weight ratio
Solution Approach 3:
The rotor employs composite material construction, combining materials with different mechanical properties to achieve optimal stiffness, strength, and weight characteristics. This allows the rotor to maintain structural integrity at high rotation speeds while minimizing radial distortion
2Manufacturing precision
If detector width is increased to accommodate radiation beam drift, then image quality is maintained, but detector cost increases
Solution Approach 1:
The rotor structure is designed with preemptive countermeasures against radiation beam drift through its stiff, distortion-resistant construction. The central hub with radially extending arms and peripheral ring creates a pre-stabilized structure that resists g-force-induced distortion before rotation begins, eliminating the need for oversized detectors
Solution Approach 2:
The invention changes the structural parameters of the rotor (geometry, material properties, mass distribution) to minimize radial distortion. By optimizing these parameters, the system maintains accurate beam-detector alignment without requiring increased detector width
3Adaptability or versatility
If radiation beam width is increased to illuminate detector array over drift range, then radiation beam coverage is improved, but radiation efficiency decreases and patient dose increases
Solution Approach 1:
The rotor's pre-designed stiffness and geometric stability prevent radiation beam drift before it occurs, maintaining precise beam alignment with the detector array. This eliminates the need to widen the radiation beam for coverage, preserving radiation efficiency and minimizing patient dose
Solution Approach 2:
The invention replaces the mechanical approach of widening the beam for tolerance with a structural approach of creating a stiff, distortion-resistant rotor. This substitution maintains beam precision while achieving the necessary adaptability through structural design rather than beam geometry
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 spool-shaped gantry design minimizes physical distortions and image artifacts, ensuring accurate volumetric image data generation and maintaining radiation efficiency across various rotation speeds, including those over 200 RPM.
Implementation Method 1
physical distortions due to radial g-forces, leading to radiation beam drift
Data Source
AI summary
A medical imaging apparatus includes a stationary gantry and a generally spool-shaped rotating gantry (304), which rotates about an examination region about a longitudinal axis. The rotating gantry includes a first flange (320), a second flange (322), and a plurality of elongate structural elements (402) that are disposed between and couple' the first and second flanges. The first flange (320) is rotatably coupled to the stationary gantry, and the second flange (322) extends radially in a plane perpendicular to the longitudinal axis, thereby providing radial stiffness for the rotating gantry. A radiation source is affixed to the rotating gantry between the first and second flanges, and a detector array is affixed to the rotating gantry between the first and second flanges, opposite the examination region from the radiation source.