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Characterization of a scintillating GEM detector with low energy x-rays
E Seravalli1, M R de Boer, F Geurink
1Delft University of Technology, Faculty of Applied Sciences, Delft, The Netherlands. e.seravalli@tudelft.nl
Physics in Medicine and Biology
|October 16, 2008
Summary
This study optimized a 2D position-sensitive dosimetry system using scintillating gas detectors and Gas Electron Multipliers (GEMs) for charged particle therapy. Smaller GEM holes (60 µm) and 8% CF(4) concentration yielded improved light and electric signals for accurate dose verification.
Area of Science:
- Medical Physics
- Radiation Detection and Measurement
- Charged Particle Therapy
Background:
- Accurate dose distribution verification is critical in charged particle therapy.
- Scintillating gas detectors offer a promising approach for real-time dosimetry.
- Gas Electron Multipliers (GEMs) enhance signal detection in gas-based detectors.
Purpose of the Study:
- To optimize the light yield of a 2D position-sensitive dosimetry system based on scintillating gas and GEMs.
- To investigate the impact of GEM hole size and gas mixture concentration on detector performance.
- To evaluate the suitability of this system for pre-treatment dose verification in charged particle therapy.
Main Methods:
- Development of a 2D position-sensitive dosimetry system using an Ar/CF(4) scintillating gas mixture and cascaded GEMs.
- Investigation of different GEM hole diameters (60 µm and 80 µm) and CF(4) concentrations (volume percentage).
- Simultaneous measurement of light intensity (using CCD camera/photomultiplier tube) and GEM charge signals.
Main Results:
- Optimized GEMs with 60 µm diameter double conical holes produced significantly brighter light and higher electric signals compared to 80 µm holes.
- An Ar + 8% CF(4) gas mixture concentration resulted in the highest voltage, light, and electric signals.
- The emission spectrum of Ar/CF(4) was found to be independent of applied voltages, X-ray beam intensity, and GEM hole diameter.
Conclusions:
- The optimized scintillating GEM detector shows enhanced performance for dosimetry applications.
- The findings support the potential of this system for pre-treatment verification of dose distributions in charged particle therapy.
- Further optimization of gas concentration can fine-tune spectral characteristics for specific applications.
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