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Energy dependence of commercially available diode detectors for in‐vivo dosimetry
Author(s) -
Saini Amarjit S.,
Zhu Timothy C.
Publication year - 2007
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.2719365
Subject(s) - diode , collimator , physics , monte carlo method , dosimetry , detector , photon , optics , photon energy , electron , imaging phantom , beam (structure) , energy (signal processing) , range (aeronautics) , computational physics , atomic physics , nuclear physics , materials science , optoelectronics , nuclear medicine , mathematics , medicine , statistics , quantum mechanics , composite material
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 10 × 10cm 2collimator 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 EDP 2 3 G, 2% for the PFD (photon field detector), 7% for the EDP 10 3 G, and 16% for the EDP 20 3 Gfor 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.