Energy dependence of commercially available diode detectors for in-vivo dosimetry
- Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, Tampa, Florida 33612 (United States)
The energy dependence of commercially available diode detectors was measured for nominal accelerating potential ranging between Co-60 and 17 MV. The measurements were performed in a liquid water phantom at 5 cm depth for 10x10 cm{sup 2} collimator setting and source-to-detector distance of 100 cm. The response (nC/Gy) was normalized to Co-60 beam after corrections for the dose rate and temperature dependences for each diode. The energy dependence, calculated by taking the percent difference between the maximum and minimum sensitivity normalized to Co-60 beam, varied by 39% for the n-type Isorad Red, 26% for the n-type Isorad Electron, 19% for the QED Red (p-type), 15% for the QED Electron (p-type), 11% for the QED Blue (p-type), and 6% for the EDP10 diode for nominal accelerating potential between Co-60 and 17 MV. It varied by 34% for the Isorad-3 Gold 1 and 2, 35% for the Veridose Green, 15% for the Veridose Yellow, 9% for the Veridose Electron, 21% for the n-type QED Gold, 24% for the n-type QED Red, 3% for the EDP2{sup 3G}, 2% for the PFD (photon field detector), 7% for the EDP10{sup 3G}, and 16% for the EDP20{sup 3G} for nominal accelerating potential between Co-60 and 15 MV. The magnitude of the energy dependence is verified by Monte Carlo simulation. We concluded that the energy dependence does not depend on whether the diode is n- or p-type but rather depends mainly on the material around the die such as the buildup and the geometry of the buildup material. As a result, the value of the energy dependence can vary for each individual diode depending on the actual geometry and should be used with caution.
- OSTI ID:
- 20951301
- Journal Information:
- Medical Physics, Vol. 34, Issue 5; Other Information: DOI: 10.1118/1.2719365; (c) 2007 American Association of Physicists in Medicine; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-2405
- Country of Publication:
- United States
- Language:
- English
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