2Ege Üniversitesi Tıp Fakültesi, Radyasyon Onkolojisi Anabilim Dalı, Tıbbi Radyofizik, İzmir OBJECTIVES
We aimed to measure entrance-exit doses using in-vivo dosimetry for head and neck cancer patients and to compare with planning system doses, to facilitate determination of treatment accuracy.
METHODS
Three diodes were calibrated using water equivalent phantom.
Correction factors had been previously assessed for in-vivo
diodes and applied to the readings. Dose measurements were
performed on 30 treatment setups for 3 patients treated with
isocentric, asymmetric left-right two lateral and supraclavicular
fields using 6MV. Measured doses were compared with
expected doses.
RESULTS
The results indicated a small acceptable deviation from expected
doses. It was found that the mean deviations for entrance
and exit doses were 2.3% and 1.9%, respectively. The
deviation in the delivered dose is well within the 5% International
Commission on Radiation Units and Measurements
(ICRU) recommendation, and thus treatment doses are determined
to be in accordance with the planning system doses.
CONCLUSION
It has been shown that in-vivo dosimetry performed using diodes
is a reliable and high-precision method for patient dose
control.