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MOSFET sensitivity dependence on integrated dose from high-energy photon beams
James A Tanyi1, Shane P Krafft, Tomoe Hagio
1Department of Radiation Oncology, University of Arizona Health Science Center, Tucson, AZ 85724, USA. jtanyi@email.arizona.edu
Medical Physics
|February 26, 2008
Summary
This study evaluated a dual MOSFET dosimetry system
Area of Science:
- Medical Physics
- Radiation Oncology
- Dosimetry
Background:
- Accurate therapeutic dose measurement is critical in radiation oncology.
- Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) dosimeters offer potential for in vivo dosimetry.
- Understanding dosimeter performance over its lifetime is essential for clinical reliability.
Purpose of the Study:
- To assess the sensitivity variation of a commercial dual MOSFET dosimetry system.
- To evaluate its dose measurement reproducibility throughout its defined lifetime.
- To determine the impact of cumulative dose on system accuracy.
Main Methods:
- Characterized sensitivity variation of a dual MOSFET system to cumulative doses.
- Used high-energy photon beams (6 and 15 MV).
- Investigated three dose-per-fraction levels (50, 200, 1200 cGy).
Main Results:
- MOSFET system sensitivity increased with integrated dose for both 6 and 15 MV beams.
- Dose measurement reproducibility varied between 1.8% and 7.9% depending on dose-per-fraction and calibration frequency.
- Increased sensitivity was observed in standard sensitivity mode (> or =100 cGy).
Conclusions:
- The dual MOSFET system exhibits increasing sensitivity with cumulative dose.
- Frequent calibration is necessary to maintain measurement accuracy below 3%.
- The dual-MOSFET design necessitates careful quality assurance for reliable therapeutic dose monitoring.
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