Optical Marker Sheet for Radiotherapy Positioning
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Solution Overview
Problem
Current positioning and identification systems for radiotherapy treatments lack the necessary precision and reproducibility, with RFID tags being too inaccurate and photogrammetry-based systems requiring complex setup processes, which increases setup time and risks patient safety.
Innovation Solution
A sheet with a hole and markings is used to accurately place optical markers on patients or equipment, allowing for precise positioning and identification, combining with photogrammetry for movement tracking and using identification markings for quick setup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If RFID tags are used for identification, then identification capability is provided, but positioning precision is insufficient (accurate to about 1 cm, whereas radiotherapy requires 1 mm or less)
Solution Approach 1:
The patent combines identification markings and positioning markings into a single integrated marking system on the sheet. The identification markings enable RFID or optical identification, while the positioning markings (crosshairs, grid patterns) provide precise alignment references. This merging allows both identification and high-precision positioning to be achieved simultaneously using the same physical marker sheet.
2Measurement precision
If photogrammetry-based systems are used for positioning, then positioning precision can be achieved, but the setup process becomes complicated and time-consuming
Solution Approach 1:
The marking sheets are pre-manufactured with precisely positioned identification markings and positioning markings (such as crosshairs and grid patterns) already aligned relative to each other. This preliminary preparation eliminates the need for complex real-time alignment calculations during setup. The operator simply needs to place the pre-marked sheet on the patient or accessory, and the pre-established geometric relationships provide immediate positioning references.
Solution Approach 2:
The patent uses physical marking sheets that replicate the required positioning geometry and identification information in a tangible, easy-to-deploy format. Instead of relying on complex digital photogrammetry systems that require camera calibration and coordinate transformations, the positioning information is copied onto simple visual markings that can be directly observed and aligned, significantly simplifying the setup process.
3Measurement precision
If complex positioning procedures are used to ensure accuracy, then positioning precision is improved, but the complexity of the system increases
Solution Approach 1:
The patent extracts the complex calculation and alignment logic from the operational phase and embeds it into the pre-manufactured marking sheets. The geometric relationships, coordinate transformations, and alignment references are all pre-computed and physically encoded in the marking patterns. This extraction simplifies the runtime system to merely placing and observing the markings, while the complexity resides in the pre-prepared markers rather than the active positioning system.
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 solution enables accurate and reproducible positioning and identification, reducing setup time and improving patient safety by facilitating precise alignment and tracking during radiotherapy treatments.
Implementation Method 1
the optical marker has a reflective element positioned on a substrate
Data Source
AI summary
An apparatus for placement of an optical marker for radiotherapy onto a surface, wherein the optical marker has a reflective element positioned on a body having an outline and shaped and configured such that the reflective element is in a predetermined position relative to the outline of the body, the apparatus comprising a sheet of material having a hole therethrough which is shaped and configured to conform to the outline of the body and which has an upper surface with markings thereon configured for aligning with an image projected onto the surface on which the optical marker is to be placed.