Premium
The effect of dose rate dependence of p ‐type silicon detectors on linac relative dosimetry
Author(s) -
Wilkins David,
Li X. Allen,
Cygler Joanna,
Gerig Lee
Publication year - 1997
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 - 10.1118/1.597985
Subject(s) - diode , dosimetry , linear particle accelerator , materials science , dosimeter , optoelectronics , detector , beam (structure) , silicon , optics , nuclear medicine , irradiation , physics , nuclear physics , medicine
Cumulative radiation damage to silicon semiconductor diode detectors can induce dose rate dependent sensitivity, a concern in the pulsed beam of a linac. Two p ‐Si diode photon detectors were used in this study, diodes A and B. Both were preirradiated by the supplier to 5 kGy, with diode A receiving an estimated 8 kGy from measurements, and diode B, 25 kGy. At 6 MV, the PDD measured with diode B was lower (by 4.4% at a depth of 25 cm) than diode A. Using SSD to vary the dose per pulse from 0.02 to 0.64 mGy/pulse, diode A was dose rate independent (within 2%), while the sensitivity of diode B changed by 13%. Silicon diode detectors should be checked regularly against ionization chambers in the pulsed beam of a linac, especially older high‐resistivity diodes that have accumulated dose from high‐energy photon beams.