title: On the impact of improved dosimetric accuracy on head and neck high dose rate brachytherapy.
abstract: To study the effect of finite patient dimensions and tissue heterogeneities in head and neck high dose rate brachytherapy.
  
  
  
  The current practice of TG-43 dosimetry was compared to patient specific dosimetry obtained using Monte Carlo simulation for a sample of 22 patient plans. The dose distributions were compared in terms of percentage dose differences as well as differences in dose volume histogram and radiobiological indices for the target and organs at risk (mandible, parotids, skin, and spinal cord).
  
  
  
  Noticeable percentage differences exist between TG-43 and patient specific dosimetry, mainly at low dose points. Expressed as fractions of the planning aim dose, percentage differences are within 2% with a general TG-43 overestimation except for the spine. These differences are consistent resulting in statistically significant differences of dose volume histogram and radiobiology indices. Absolute differences of these indices are however small to warrant clinical importance in terms of tumor control or complication probabilities.
  
  
  
  The introduction of dosimetry methods characterized by improved accuracy is a valuable advancement. It does not appear however to influence dose prescription or call for amendment of clinical recommendations for the mobile tongue, base of tongue, and floor of mouth patient cohort of this study.
authors.affiliation: Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece.
authors.forename: Vasiliki
authors.initials: V
authors.lastname: Peppa
authors.affiliation: Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece.
authors.forename: Eleftherios
authors.initials: E
authors.lastname: Pappas
authors.affiliation: National Institute of Oncology, Budapest, Hungary.
authors.forename: Tibor
authors.initials: T
authors.lastname: Major
authors.affiliation: National Institute of Oncology, Budapest, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Takácsi-Nagy
authors.affiliation: Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece.
authors.forename: Evaggelos
authors.initials: E
authors.lastname: Pantelis
authors.affiliation: Medical Physics Laboratory, Medical School, National and Kapodistrian University of Athens, Greece. Electronic address: ppapagi@med.uoa.gr.
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Papagiannis
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D006258:Head and Neck Neoplasms / Q000532:radiotherapy*; D006801:Humans; D009010:Monte Carlo Method; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods
keywords: Brachytherapy; Dosimetry; Head and neck; High dose rate; Treatment planning