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Implementation of in vivo dosimetry using diodes as part of quality assurance in radiotherapy

Abstract:

An in vivo dosimetry system for photon beams was implemented in the Oncology Hospital SOLCA-QUITO. The implementation included the calibration of two diodes and a preliminary study with patients. One diode was calibrated for 6 MV and another for 18 MV photon beams. In the preliminary study the doses measured by the diodes were compared with those obtained from the Treatment Planning System for 33 patients with treatment sites: pelvis, abdomen, chest, breast and head-neck in specific treatment fields. The variations between the measured and the reference doses were statistically less than 5% and depended on photon beam energy with a confidence level of 99.9%. In fact, a tolerance of 5% for 6 MV beams and 3% for 18 MV beams were defined. This tolerance will use for the in vivo dosimetry system by personnel in the Hospital. © 2012 American Institute of Physics.