Radiation Therapy Phantom with Segmented Ball and Visual Alignment
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Solution Overview
Problem
Current phantom objects for radiation therapy quality control face inaccuracies in positioning the radio-opaque ball at the intersection of laser layers and fail to check the orthogonality, coincidence, and spatial position of the three theoretical axes, leading to potential misalignment and irradiation errors.
Innovation Solution
A phantom object comprising a spherical ball with high electron density positioned at the center of a larger sphere, where the ball's diameter is smaller than the radiation beam section and the sphere's diameter is larger, with visual alignment marks on the sphere's surface to facilitate accurate positioning and alignment with laser layers, ensuring the ball is correctly placed at the isocenter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small-sized radio-opaque ball is used for quality control testing, then the ball can be contained within the radiation beam section and imaging precision is improved, but the ball cannot be properly aligned with the laser layers and positioning accuracy deteriorates
Solution Approach 1:
The phantom object is segmented into two distinct components: a small radio-opaque ball (diameter smaller than beam section) for accurate beam imaging, and a larger supporting sphere (diameter larger than beam section) with visual alignment marks for accurate positioning with laser layers. This segmentation allows each component to fulfill its specific function optimally.
Solution Approach 2:
The larger supporting sphere acts as an intermediary between the small radio-opaque ball and the laser layers. It provides visual alignment marks that facilitate proper positioning of the ball at the isocenter, bridging the gap between the ball's small size and the laser alignment requirements.
2Device complexity
If conventional phantom objects are used, then simplicity is maintained, but the ability to check orthogonality, coincidence, and spatial position of the three theoretical axes is lost
Solution Approach 1:
The phantom object is designed with multi-functionality: the small ball enables beam imaging and isocenter detection, while the larger supporting sphere with visual alignment marks enables verification of orthogonality, coincidence, and spatial position of the three theoretical axes. This universal design consolidates multiple quality control functions into a single object.
3Manufacturing precision
If the ball diameter is reduced to improve alignment precision, then positioning accuracy improves, but the ball becomes difficult to detect in radiographies
Solution Approach 1:
Different parts of the phantom object have different properties optimized for their specific functions: the small ball has high radio-opacity for precise alignment marking, while the larger supporting sphere provides structural support and visual alignment references. This local quality differentiation ensures optimal performance of each component.
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 configuration allows for precise alignment and detection of the ball and beam edges, improving the accuracy of quality control tests and ensuring proper alignment of the radiation therapy device's axes, reducing the risk of incomplete tumor irradiation and healthy tissue exposure.
Implementation Method 1
a spherical ball made of a material with an electron density d1, and positioned at the point of convergence of the theoretical axes (V′, H′, C′)
Implementation Method 2
imaging successively a spherical ball made of a material with an electron density d1
Data Source
AI summary
This phantom object is designed for a Winston-Lutz test on a device for radiation therapy treatment comprising a patient support having a rotation axis (V), a stand having a rotation axis (H) and a collimator having a rotation axis (C), locating means being provided for visually representing the theoretical positions (V′, H′, C′) of the three axes (V, H, C). A spherical ball is positioned at the center of a sphere in a material of electron density lower than that of the ball, the ball and the sphere both constituting the phantom object. The sphere has on its outer surface means for a visual alignment with the locating means allowing a positioning of the phantom object at the point of convergence of the three axes (V′, H′, C′).