Ion Chamber Collector Electrode Occlusion for Beam Profile Precision
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Solution Overview
Problem
Current radiation measurement systems in linear accelerators for radiation therapy lack precise monitoring of radiation beam alignment, symmetry, and energy, which can lead to inconsistencies and potential errors in patient treatment.
Innovation Solution
An ion chamber with a collector electrode positioned between two electrodes, capable of occluding a portion of the first electrode from the second, is used to measure currents generated by collisions between the radiation beam and gas, allowing for the generation of a radiation beam profile and energy calculation, with optional application of electric or magnetic fields to align the beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a collector electrode is positioned between the first electrode and the second electrode to occlude a portion of the first electrode from the second electrode, then measurement precision of radiation beam profile is improved, but device complexity increases
Solution Approach 1:
The ion chamber is segmented into multiple electrodes (first electrode, second electrode, and collector electrode positioned between them). The collector electrode is further divided into multiple segments that can be independently positioned to occlude different portions of the radiation beam, enabling precise measurement of beam profile characteristics while maintaining a modular structure.
Solution Approach 2:
The collector electrode acts as an intermediary element positioned between the first electrode and the second electrode. It mediates the measurement process by occluding specific portions of the radiation beam and collecting charge from ionized gas, thereby enabling indirect measurement of beam profile parameters without requiring direct access to the entire beam path.
2Measurement precision
If multiple collector electrodes are positioned in a symmetrical pattern around an axis to cover annular or circular areas, then measurement precision of beam symmetry and alignment is improved, but device complexity increases
Solution Approach 1:
While the overall arrangement of collector electrodes follows a symmetrical pattern around the central axis, each individual electrode segment can be asymmetrically shaped or positioned to occlude specific portions of the beam. This combination of symmetrical arrangement with asymmetric individual elements enables comprehensive measurement of beam symmetry and alignment characteristics.
Solution Approach 2:
The collector electrodes are arranged in three-dimensional space around the central axis, covering annular or circular areas in multiple planes. This spatial arrangement adds dimensional complexity to the measurement capability, enabling detection of beam characteristics in radial, azimuthal, and axial directions simultaneously.
3Reliability
If the entrance window has a thickness sufficient to stop nearly all electrons from an upstream linear accelerator, then reliability of radiation measurement is improved, but loss of radiation beam intensity increases
Solution Approach 1:
The entrance window is designed with specific local properties: sufficient thickness to stop electrons while maintaining transparency to the intended radiation beam (photons or higher energy particles). This localized quality control at the entrance window enables selective filtering of unwanted electron contamination without significantly attenuating the therapeutic radiation beam.
Solution Approach 2:
The thickness and material composition of the entrance window are carefully selected to change the energy filtration parameters. By optimizing these parameters, the window effectively stops low-energy electrons while allowing the higher-energy therapeutic beam to pass through with minimal attenuation, thus improving measurement reliability without excessive intensity loss.
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
Enables precise monitoring and alignment of radiation beams, ensuring accurate treatment by detecting beam flux, symmetry, and energy, and automatically adjusting operations if parameters fall outside acceptable ranges.
Implementation Method 1
a first current received from the collector electrode. The first current is representative of a first charge generated by collisions between a radiation beam and the gas in the ion chamber
Implementation Method 2
A collector electrode is positioned between the first electrode and the second electrode. The collector electrode is shaped to occlude a portion of the first electrode from the second electrode
Data Source
AI summary
An ion chamber has a chamber having an interior volume. There is a first electrode and a second electrode in the chamber and separated by a gap. A collector electrode is positioned between the first electrode and the second electrode. The collector electrode is shaped to occlude a portion of the first electrode from the second electrode.