Ferrite Absorbing Device for Radiotherapy Target Localisation Accuracy
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Solution Overview
Problem
Existing electromagnetic target localization systems in radiotherapy face challenges with conductive carbon-fibre couch tops, leading to localisation errors and reduced communication distance due to energy dissipation as heat and electromagnetic noise interference.
Innovation Solution
An absorbing device with a layer of high magnetic permeability ferrite material, configured as multiple overlapping sheets with a spacer layer, positioned between the patient and the conductive treatment table to absorb electromagnetic fields, preventing interaction and maintaining accurate localisation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional carbon-fibre couch top is used, then the structural stability and X-ray transparency are maintained, but electromagnetic energy is dissipated as heat and causes localisation errors
Solution Approach 1:
An absorbing device comprising ferrite material is introduced as an intermediary layer between the conductive couch top and the patient/target localisation system. This mediator absorbs the alternating magnetic field energy before it reaches the conductive couch top, preventing eddy current formation and heat dissipation, thereby eliminating localisation errors while maintaining the structural stability of the conventional carbon-fibre couch top
Solution Approach 2:
The absorbing device is constructed from multiple overlapping sheets of ferrite material with different orientations (e.g., 0 degrees, 45 degrees, 90 degrees). This segmentation approach enhances the overall absorption effectiveness by addressing electromagnetic waves from multiple directions and polarizations, while allowing each individual sheet to maintain thin profiles that minimize interference with the localisation system
2Length of moving object
If the alternating electromagnetic field strength is increased to improve transponder excitation, then the communication distance is extended, but more energy is transferred to circular currents on the conductive surface and dissipated as heat
Solution Approach 1:
The invention converts the harmful effect of the alternating magnetic field (which causes eddy currents and heat dissipation on the conductive couch top) into a beneficial effect by using ferrite material to absorb and redirect this energy. The ferrite absorbs the magnetic field energy that would otherwise be lost to heat, converting it into a useful function that protects the localisation system and improves communication distance without increasing energy dissipation
3Measurement precision
If a non-standard carbon couch top with aligned fibre routing is used, then electromagnetic interference is reduced, but the manufacturing complexity and cost increase significantly
Solution Approach 1:
Instead of investing in expensive, complex non-standard carbon couch tops with precisely aligned fibre routing, the invention uses a simpler, more cost-effective absorbing device made from ferrite sheets that can be placed on top of conventional carbon-fibre couch tops. This disposable or easily replaceable component achieves the same electromagnetic interference reduction without the high manufacturing complexity and cost of custom-designed couch tops
Solution Approach 2:
The absorbing device uses composite ferrite material structures (multiple sheets with different orientations) that provide electromagnetic interference reduction equivalent to or better than non-standard carbon couch tops, but with much simpler manufacturing. The composite structure of overlapping ferrite sheets creates effective electromagnetic shielding without requiring complex fibre alignment or custom manufacturing processes
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 solution ensures accurate target localisation and extended communication distance, reducing localisation errors and maintaining radiation treatment precision while being cost-effective and safe, with minimal impact on X-ray imaging quality.
Implementation Method 1
at least one layer of an electromagnetic radiation absorbing material, wherein the absorbing material is for preventing interaction between a target localisation system having a targeted frequency range of between about 300 kHz and about 500 kHz and a conductive treatment table
Implementation Method 2
the absorbing device comprises a material having high magnetic permeability
Data Source
AI summary
An absorbing device (24, 24′, 24″, 41) for radiotherapy treatment comprising at least one layer of electromagnetic absorbing material wherein the absorbing material is for preventing interaction between a target localisation system (1) having a targeted frequency range of between about 300 kHz and 500 kHz and a treatment table (4).