@inproceedings{fca15fbefdf944b4a21e454336802816,
title = "Interfractional variations of shape and impact on dose of organs at risk in head and neck cancer patients during helical tomotherapy",
abstract = "PURPOSE: IGRT by daily MVCTs is becoming wider used. We analyzed the interfractional variations of shape and the impact on dose of the organs at risk (OARs) - i.e. parotid glands (PGs) and spinal cord (SC) - in head and neckcancer patients. PATIENTS AND METHODS: Ten head and neck patients were investigated retrospectively. All patients were treated up to 50 Gy with helical tomotherapy (HT) (2 Gy/day). Daily pretreatment MVCTs were performed. The OARs were all delineated by the same physician on the corresponding MVCTs for predetermined fractions. The actual delivered doses to the PGs and the SC were assessed by using the TomoTherapy PlannedAdaptive{\textregistered} software. The initial dose-volume histograms (DVHs) and the recalculated DVHs of the OARs of the corresponding fraction were used for the quantitative comparison of the cumulative maximum doses of the SC (CMaDSC) and the cumulative median doses of the PGs (CMeDPG). The interfractional changes of volumes of the PGs that received less than 1 Gy and over 1.6 Gy per fraction and the volumes of the SC that received more than the expected maximum dose were also assessed. RESULTS: Overall, the mean decrease of the PG volume was estimated to be 0.13 cc per day. There was a significantly higher CMeDPG and CMaDSC than initially predicted (mean increase for 6 fractions in Gy: 1.13 and 0.49, respectively). TheVol<1Gy decreased and the Vol>1.6Gy increased significantly with increasing fraction number (mean difference to the planning CT: 1.3 cc and 1.1 cc, respectively). CONCLUSIONS: The delivered dose to the PG and SC is higher than predicted by the PCT DVH data even if daily IGRT is performed.",
keywords = "Helical tomotherapy, IGRT, MVCT, Organs at risk, Parotid glands",
author = "Duma, {M. N.} and S. Kampfer and V. Jacob and Wilkens, {J. J.} and T. Schuster and M. Molls and H. Geinitz",
year = "2009",
doi = "10.1007/978-3-642-03474-9_166",
language = "English",
isbn = "9783642034725",
series = "IFMBE Proceedings",
publisher = "Springer Verlag",
number = "1",
pages = "591--594",
booktitle = "World Congress on Medical Physics and Biomedical Engineering",
edition = "1",
note = "World Congress on Medical Physics and Biomedical Engineering: Radiation Oncology ; Conference date: 07-09-2009 Through 12-09-2009",
}