6DoF QA Phantom for Radiation Therapy Linear Accelerators
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Solution Overview
Problem
Current quality assurance methods for six degrees-of-freedom (6DoF) treatment tables in radiation therapy are inefficient and lack a streamlined procedure, requiring cumbersome tests that are not suitable for daily use.
Innovation Solution
A three-dimensional phantom with specific angulation and registration structures is designed for 6DoF alignment, utilizing computer-aided design and 3D printing to facilitate efficient testing of 6DoF tables, including rotational and translational corrections, and incorporating a central ball-bearing for isocentricity testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional quality assurance methods are used for 6DoF tables, then comprehensive testing can be performed, but the testing procedure becomes cumbersome and time-consuming
Solution Approach 1:
The phantom divides the quality assurance testing into separate functional components: translational marks for position testing, rotational marks for angle testing, and isocenter marks for alignment testing. This segmentation allows each degree of freedom to be tested independently and efficiently, reducing overall testing time while maintaining comprehensive coverage
Solution Approach 2:
The single phantom design serves multiple functions simultaneously: it tests all six degrees of freedom (three translational and three rotational), provides isocenter verification, and works with both 4DoF and 6DoF tables. This multi-functionality eliminates the need for multiple separate testing devices and procedures
2Measurement precision
If comprehensive quality assurance testing is performed on 6DoF tables, then alignment accuracy can be verified, but the complexity of the testing procedure increases
Solution Approach 1:
The patent merges all six degrees of freedom testing, isocenter verification, and alignment checks into a single integrated phantom with unified mark systems. The translational marks, rotational marks, and isocenter marks work together in a coordinated manner, allowing comprehensive testing through a simplified single-procedure approach rather than multiple complex separate tests
Solution Approach 2:
The phantom extends traditional 2D alignment marks into 3D spatial configurations with specific angular relationships (e.g., 45-degree angles between rotational marks). This three-dimensional mark arrangement enables simultaneous verification of multiple degrees of freedom through image registration, reducing procedural complexity while maintaining measurement precision
3Adaptability or versatility
If traditional phantoms are used for 4DoF tables, then existing protocols can be maintained, but they are not suitable for 6DoF table testing
Solution Approach 1:
The phantom is designed with dual functionality: it maintains compatibility with existing 4DoF table protocols while adding capability for 6DoF testing. The same phantom structure and mark system work for both table types, requiring only updated imaging and registration procedures, thus achieving broad adaptability without sacrificing manufacturing precision
Solution Approach 2:
The phantom incorporates asymmetric angular relationships between marks (e.g., specific 45-degree configurations) that enable differentiation between 4DoF and 6DoF testing modes. This asymmetric design allows the same physical phantom to provide distinct testing capabilities for different table types through controlled geometric relationships
Data Source
AI summary
A three-dimensional phantom for providing displacement profiles for a CT table having 6 degrees of freedom includes a body having at a top face, a side face and an end face; the top face and the side face sharing a common edge; the top face and the end face sharing a common edge; and the side face and the end face sharing a common edge; wherein an angle formed by the top face and the end face is less than 90 degrees; the side face including a first isocenter mark and a first offset mark, wherein the first offset mark has an angle corresponding to the angle formed by the top face and the end face; and an isocenter marker at the isocenter of the body.